METHOD FOR SAMPLING LIQUEFIED HYDROCARBONS UNDER PRESSURE

Abstract

The invention relates to methods for sampling pressurized liquefied hydrocarbon products (PLHP). The methods consist of the following steps: collecting PLHP containing at least one tracer into a first gas cylinder; transferring at least a portion of PLHP into a second gas cylinder; transferring a mixture of PLHP, at least one tracer, and solvent into a receiving container and allowing the PLHP to evaporate. The PLHP can then be validated by further determination of the concentration of analyte atoms and / or analyte functional groups of at least one tracer by analytical techniques. Following the validation process, the PLHP can be evaluated by quantifying its mixture by further calculation of the concentration of at least one tracer in the PLHP and comparing the calculated concentration with a predetermined concentration of at least one tracer in the PLHP.

Description

METHODS FOR THE SAMPLING AND AUTHENTICATION OF MARKERS IN PRESSURIZED LIQUIFIED HYDROCARBON PRODUCTSFIELD OF INVENTION

[0001] The present invention relates to a method for sampling marked pressurized liquified hydrocarbon fluids (PLHPs) and for the detection of markers included therein. The present invention also relates to a method for authenticating the marked PLH, i.e. detecting the markers of the PLHP. Should the markers be present, the present invention also relates to quantifying the marker concentration in a sample of a marked PLHP. The present invention also relates to a method for detecting and quantifying adulteration in a PLHP.BACKGROUND OF INVENTION

[0002] Liquified petroleum gas (LPG, LP gas) is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, propylene, butylene, isobutane, and n-butane. LPG is used as a fuel gas in heating appliances, cooking equipments and vehicles. It is increasingly used as an aerosol propellant and a refrigerant (replacing chlorofluorocarbons in an effort to reduce damage to the ozone layer). When specifically used as a vehicle fuel, it is often referred to as autogas or even just as gas. Varieties of LPG that are bought and sold include mixes that are mostly propane, mostly butane, and, most commonly, mixes including both propane and butane.

[0003] WO 2009 / 017505 A1 discloses an apparatus for detecting a marker previously inserted into a pressurized hydrocarbon fluid, said apparatus comprising a first valve, a vessel coupled to the first valve and a detector configured to be coupled to the vessel, wherein the detector is operable to detect a presence or absence of the marker in the pressurized hydrocarbon fluid in the vessel. The apparatus is suitable in particular for online detection of fluorescent markers in pressurized LPGs. The apparatus and the detection method require the use of specific equipment for analyzing product being under high pressure.

[0004] WO 2011 / 040910 A1 discloses a method and an apparatus for marking, with a solution of a marker and a solvent, a pressurized LPG, transporting the LPG and then determining the amount of marker into the LPG. The apparatus is fixed in a pressurized hydrocarbon fluid supply line such that pressurized hydrocarbon fluid flowing from a first location to a second location in the supply line passes through the detection system. The method and the apparatus also require specific equipment, e.g. an intrinsically safe detection apparatus fixed in the supply line such that a first portion of pressurized hydrocarbon fluid flowing through the supply line from a first location to a second location flows through the detection apparatus, and an explosion-proof electronics unit coupled to the detection apparatus and to the supply line, such that a second portion of the pressurized hydrocarbon fluid flowing through the supply line from a first location to a second location flows through the electronics unit.

[0005] EP 0677568 A1 discloses a process suitable for marking a LPG or NPG with nitro compound(s). The disclosed detection / authentication method is however qualitative but not quantitative.

[0006] US 5980593 discloses a method for extracting markers using a solvent from a marked hydrocarbon fluid for the authentication of the marked fluid. The disclosed method may be applied to liquid hydrocarbon products, but not to pressurized liquid hydrocarbon products.

[0007] A large number of methods for marking and authenticating liquid hydrocarbons products are known in the literature. Methods for marking and authenticating pressurized liquid hydrocarbon products (PLHP), e.g. Liquified Petroleum Gas (LPG), are far less spread.

[0008] In-line detection methods as disclosed in WO 2009 / 017505 A1 and WO 2011 / 040910 A1 require the installation and use of specific apparatus.

[0009] There remains a need for a sampling method, an authenticating method and a batch detection method of markers in pressurized liquid hydrocarbon products (PLHPs). In particular, there is a need for in-field sampling and authentication methods suitable for qualitative and quantitative detection of markers in pressurized liquid hydrocarbon products (PLHPs).SUMMARY OF INVENTION

[0010] The present invention provides a method for sampling a pressurized liquified hydrocarbon product (PLHP), preferably selected from the group consisting of liquified petroleum gases (LPGs), natural gases (NGs), liquified natural gases (LNGs), natural piped gases (NPGs) and mixtures thereof, comprising at least one marker containing at least one analyzable atom and / or at least one analyzable functional group, said sampling method comprising the steps of:A. collecting in a first gas cylinder a sample of the pressurized liquified hydrocarbon product (PLHP) comprising the at least one marker from a storage container;B. connecting a second gas cylinder to a vacuum pump to evacuate the second gas cylinder;C. weighing the second gas cylinder;D. transferring a predetermined volume of solvent into the second gas cylinder;E. weighing the second gas cylinder containing the solvent to obtain the exact weight and volume of the solvent;F. transferring at least part of the pressurized liquified hydrocarbon product (PLHP) comprising the at least one marker comprised in the first gas cylinder from the first gas cylinder into the second gas cylinder;G. weighing the second gas cylinder and calculating the amount of pressurized liquified hydrocarbon product (PLHP) comprising the at least one marker transferred into the second gas cylinder by subtracting the obtained weight value from the value obtained in step E; andH. transferring the mixture of the pressurized liquified hydrocarbon product (PLHP), the at least one marker and the solvent into a receiving container and allowing the pressurized liquified hydrocarbon product (PLHP) to evaporate.

[0011] The present invention also provides a method for sampling a pressurized liquified hydrocarbon product (PLHP), preferably selected from the group consisting of liquified petroleum gases (LPGs), natural gases (NGs), liquified natural gases (LNGs), natural piped gases (NPGs) and mixtures thereof, comprising at least one marker containing at least one analyzable atom and / or at least one analyzable functional group, said sampling method comprising the steps of:A. collecting in a first gas cylinder a sample of the pressurized liquified hydrocarbon product (PLHP) comprising the at least one marker from a storage container;B. connecting a second gas cylinder to a vacuum pump to evacuate the second gas cylinder;C. weighing the second gas cylinder;D. transferring a predetermined volume of solvent into the second gas cylinder, wherein the solvent has a boiling point (BP) equal to or higher than about 60°C and a miscibility in the pressurized liquified hydrocarbon product (PLHP) comprised in a range from about 10 wt% to about 90 wt%;E. weighing the second gas cylinder containing the solvent to obtain the exact weight and volume of the solvent;F. transferring at least part of the pressurized liquified hydrocarbon product (PLHP) comprising the at least one marker comprised in the first gas cylinder from the first gas cylinder into the second gas cylinder;G. weighing the second gas cylinder and calculating the amount of pressurized liquified hydrocarbon product (PLHP) comprising the at least one marker transferred into the second gas cylinder by subtracting the obtained weight value from the value obtained in step E; andH. transferring the mixture of the pressurized liquified hydrocarbon product (PLHP), the at least one marker and the solvent into a receiving container and allowing the pressurized liquified hydrocarbon product (PLHP) to evaporate.

[0012] The present invention also provides a method for authenticating the pressurized liquified hydrocarbon product (PLHP), i.e. the method described herein further comprising a step for authenticating the pressurized liquified hydrocarbon product (PLHP), said method comprising: i) the steps A to H of the sampling method described herein, and ii) a step of determining the at least one analyzable atom and / or the at least one analyzable functional group presence of the at least one marker with an analytical technique.

[0013] The present invention also provides a method for quantifying adulteration of the pressurized liquified hydrocarbon product (PLHP), i.e. the method described herein further comprising a step for authenticating the pressurized liquified hydrocarbon product (PLHP) and further comprising a step for quantifying adulteration of the pressurized liquified hydrocarbon product (PLHP), said method comprising: i) the steps A to H of the sampling method described herein; ii) the step of determining the at least one analyzable atom and / or the at least one analyzable functional group presence described herein; iii) a step of calibration the analytical instrument so that a concentration for the identified marker can be obtained; iv) a step of calculating the concentration of the at least one marker in the pressurized liquified hydrocarbon product (PLHP); and v)a step of comparing the concentration of the at least one marker calculated in step iv) with a predetermined concentration of the at least one marker in the pressurized liquified hydrocarbon product (PLHP).

[0014] In one embodiment, after step H, the remaining fluid (solvent-marker mixture) is analyzed to detect, and if present quantify, the presence of the at least one marker with a suitable analytical technique.

[0015] The term “pressurized liquid hydrocarbon products” or “PLHP” is used herein to refer to liquified petroleum gas (LPG) such as for example propane or butane, natural gas (NG) such as for example methane, liquified natural gas (LNG), and natural piped gas (NPG). Natural piped gas comprises a mixture of methane with a very small percentage of ethane, propane, butane and pentane. According to one embodiment, the pressurized liquified hydrocarbon product (PLHP) is preferably selected fromthe group consisting of liquified petroleum gases (LPGs), natural gases (NGs), liquified natural gases (LNGs), natural piped gases (NPGs) and mixtures thereof.

[0016] The method of the present invention requires the marker to be extracted by the solvent from the PLHP. As such, the concentration of the marker within the collected and analyzed sample is different from the concentration of the marker within the PLHP.

[0017] According to one embodiment, the at least one marker of the PLHP described herein has a boiling point Bp equal to or higher than about 60°C.

[0018] According to one embodiment, the at least one marker of the PLHP has a solubility in the PLHP comprised in a range from about 0.00001 wt.% to about 1 wt.%, preferably from about 0.0001 wt.% to about 0.1 wt.%, based on the total weight of the marker and PLHP. Preferably, the at least one marker has a solubility in the PLHP of 0.0001 wt% or more, more preferably 0.001 wt% or more, particularly preferably 0.01 wt% or more.

[0019] According to one embodiment, the at least one marker of the PLHP has a solubility in the solvent of from about 0.0001 wt% to about 10 wt%, preferably 0.001 wt% or more, more preferably 0.001 wt% or more, more particularly preferably 0.01 wt% or more, based on the total weight of the solvent and marker.

[0020] According to one embodiment, the at least one marker of the PLHP described herein has a boiling point Bp equal to or higher than about 60°C and a solubility in the PLHP comprised in a range from about 0.00001 wt.% to about 1 wt.%, preferably from about 0.0001 wt.% to about 0.1 wt.%, based on the total weight of the marker and PLHP.

[0021] According to one embodiment, the solvent has a boiling point Bp equal to or higher than about 60°C.

[0022] According to one embodiment, the solvent has a miscibility with the PLHP comprised in a range from about 10 wt.% to about 90 wt.%.

[0023] According to one embodiment, the solvent described herein has a boiling point Bp equal to or higher than about 60°C and a miscibility with the PLHP comprised in a range from about 10 wt.% to about 90 wt.%.

[0024] According to one embodiment, the step of determining the at least one analyzable atom and / or the at least one analyzable functional group concentration of the at least one marker with the analytical technique described herein is carried out using a transportable mobile apparatus.

[0025] The method extracts the marker from the marked pressurized liquified hydrocarbon products (marked PLHPs). Therefore, the method has the advantage of decreasing any potential interference resulting from further additives or impurities present in the marked PLHPs.

[0026] The method of the present invention is preferably performed at room temperature and under atmospheric pressure environment. By performing the sampling method at ambient temperature and under atmospheric pressure, the PLHP may readily evaporate during the step H. Pressurized conditions are only present within the storage container and the first and second cylinders. The first and / or second cylinder may for example be stainless-steel sample cylinders.

[0027] In another aspect of the invention, the method of the present invention comprises a step I of shaking the second gas cylinder, said step being performed after the step G and before the step H.

[0028] In a further aspect of the invention, the method of the present invention comprises a step J of maintaining the second gas cylinder in a vertical position for a time lapse of at least 10 seconds, said step being performed after the step I and before the step H.

[0029] In a further aspect of the invention, the method of the present invention comprises a step K of heating and / or agitating the receiving container to accelerate the evaporation of the PLHP, said step being performed after the step H (and before the step ii) in the authentication method and step ii) in the method for quantifying adulteration).

[0030] Suitable analytical methods for detecting the presence of the at least one marker described herein include optical methods such as fluorescence spectroscopy, (Surface Enhanced) Raman spectroscopy SERS, Fourier transform-infrared (FT-IR) spectroscopy, UV spectroscopy, UV spectroscopy coupled with HPLC, atomic absorption technique employing elemental analysis, atomic absorption technique coupled with high performance liquid chromatography (HPLC-AAS), mass spectrometry, inductively coupled plasma mass spectrometry (ICP-MS), laser ionization mass spectrometry (LI MS), gas-chromatography coupled with mass spectrometry (GC-MS), high performance liquid chromatography coupled with mass spectrometry (HPLC-MS), emission spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectroscopy (ICP-OES), electron capture detection, electron capture detection coupled to gas chromatography (GC-ECD), flame ionization detection, flame ionization detection coupled with gas chromatography (GC-FID), X-ray fluorescence (XRF) spectroscopy or any combinations thereof, preferably Fourier transform-infrared (FT-IR) spectroscopy, laser ionization mass spectrometry LIMS, X-ray fluorescence (XRF) spectroscopy or any combinations thereof, more preferably X-ray fluorescence (XRF) spectroscopy.

[0031] The authentication method and the method for quantifying adulteration described herein allows the qualitative as well as quantitative detection of markers in marked PLHPs, in particular marked LPGs, from batch samples at various locations, e.g. at gas stations, without requiring complicated equipment.Brief Description of Figures

[0032] The invention is now described in more detail with reference to the drawings and to particular embodiments, whereinFig. 1 is a schematic illustration of an apparatus for collecting a sample of a marked PLHP from a storage container into a first cylinder.Fig. 2a is a schematic illustration of the step of adding a predetermined amount of solvent with a syringe through a valve into a second cylinder.Fig. 2b is a schematic illustration of the step of weighing the second cylinder comprising the solvent.Fig. 2c is a schematic illustration of the step of transferring a sample of the marked PLHP from the first cylinder of Fig. 1 into the second cylinder containing the solvent.Fig. 2d is a schematic illustration of the step of weighing the second cylinder containing the mixture of the PLHP, the at least one marker (i.e. the marked PLHP) and the solvent to determine the weight of transferred marked PLHP in the second cylinder.Fig. 3 is a schematic illustration of collecting the mixture of the solvent, the at least one marker (extracted in the solvent) and PLHP in a receiving container and the concomitant evaporation of the PLHP according to one embodiment of the present invention.Detailed DescriptionDefinitions

[0033] The following definitions are to be used to interpret the meaning of the terms discussed in the description and recited in the claims.

[0034] As used herein, the article "a" indicates one as well as more than one and does not necessarily limit its referent noun to the singular.

[0035] As used herein, the term “about” means that the amount or value in question may be the value designated or some other value about the same. The phrases are intended to convey that similar values within a range of ± 5% of the indicated value promote equivalent results or effects according to the invention.

[0036] As used herein, the term “at least one” is meant to define one or more than one, for example one or two or three.

[0037] As used herein, the term “and / or” means that either all or only one of the elements of said group may be present. For example, “A and / or B” shall mean “only A, or only B, or both A and B”. In the case of “only A”, the term also covers the possibility that B is absent, i.e. “only A, but not B”.

[0038] The term “comprising” as used herein is intended to be non-exclusive and open-ended. The term “comprising” also covers, as a particular embodiment thereof, the more restrictive meanings of “consisting essentially of and “consisting of”.

[0039] Where the present description refers to “preferred” embodiments / features, combinations of these “preferred” embodiments / features shall also be deemed as disclosed as long as this combination of “preferred” embodiments / features is technically meaningful.

[0040] “Analyzable atom” means an element (from the periodical table) being detectable in a quantitative manner by a selected analytical technique.

[0041] “Analyzable functional group” means a chemical group being detectable in a quantitative manner by a selected analytical technique. A functional group contains at least two atoms. In the present invention, the term “analyzable functional group” is not limited to “analyzable chemical functional group” as used commonly; the term “analyzable functional group” includes molecules which can be analyzed by a suitable analytical method, such as some of those disclosed herein (e.g. Mass Spectrometry).

[0042] “ Marker” means a chemical compound containing at least one analyzable atom and / or one analyzable functional group, wherein said chemical compound is used for authenticating PLHP and / or for quantifying adulteration of said PLHP.

[0043] “ Authentication” means a process of proving the presence of a marker in a PLHP by an analytical technique.

[0044] “Adulteration quantification” means a process for measuring the amount or extent of alteration of a marked product (e.g. marked PLHP) by the addition of a foreign or inferior product.

[0045] The method for sampling the marked PLHP, i.e. the PLHP comprising the at least one marker,described herein (steps A-H), the method for authenticating the PLHP (steps A-H and step ii)) described herein and the method for quantifying adulteration of the PLHP (steps A-H, step ii), step iii), step iv) and step v)) described herein each comprise the steps A-H, the steps i) (same as steps A-H) and ii) for the authentication method and the steps i) (same as steps A-H),-ii) -iii), iv) and v) for the adulteration quantifying, respectively. In a preferred embodiment, the steps are to be performed one after the other as defined. However, it is well within a skilled person’s expertise to rearrange some of the steps or perform them in parallel without losing the essence of the method and where it is logical to do so.

[0046] With reference to the Figures, Fig. 1 illustrates one embodiment for collecting a volume of marked PLHP (100) comprising at least one marker (101) from a storage container (300).

[0047] In the illustrated embodiment the marked PLHP (100) comprising the at least one marker (101 ) is collected in a first stainless steel double ended sample cylinder (200). It is to be understood that the marked PLHP could be collected in any suitable cylinder configured to receive a PLHP.

[0048] Due to the presence of the at least one analyzable atom and / or the at least one analyzable functional group of the at least one marker described herein, said at least one analyzable atom and / or the at least one analyzable functional group may be determined and quantified with an analytical technique. The analytical technique is not limited and include without limitation a technique selected from the group consisting of fluorescence spectroscopy, (Surface Enhanced) Raman spectroscopy SERS, Fourier transform-infrared (FT-IR) spectroscopy, UV spectroscopy, UV spectroscopy coupled with HPLC, atomic absorption technique employing elemental analysis, atomic absorption technique coupled with high performance liquid chromatography (HPLC-AAS), mass spectrometry, inductively coupled plasma mass spectrometry (ICP-MS), laser ionization mass spectrometry (LIMS), gaschromatography coupled with mass spectrometry (GC-MS), high performance liquid chromatography coupled with mass spectrometry (HPLC-MS), emission spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectroscopy (ICP-OES), electron capture detection, electron capture detection coupled to gas chromatography (GC-ECD), flame ionization detection, flame ionization detection coupled with gas chromatography (GC-FID), X-ray fluorescence (XRF) spectroscopy or any combination thereof, preferably selected from the group consisting of Fourier transform-infrared (FT-IR) spectroscopy, laser ionization mass spectrometry LIMS, X-ray fluorescence (XRF) spectroscopy and combinations thereof, more preferably X-ray fluorescence (XRF) spectroscopy.

[0049] The at least one marker (101) is preferably compatible with the PLHP to be marked. The term “compatible” is used herein to mean that the at least one marker(s) is stable and miscible in the PLHP which is to be marked, at a concentration comprised preferably between about 0.00001 wt.% and about 1 wt.% (corresponding to from about 0.1 ppm to about 10000 ppm), more preferably between about 0.0001 wt.% and about 0.1 wt.% (corresponding to from about 1 ppm to about 1000 ppm) at room temperature.

[0050] The type of marker(s) and the amount of marker(s) added to the PLHP must be suitable to enable the subsequent detection of the marker(s) by a suitable analytical technique.

[0051] Preferably, the at least one marker (101 ) is soluble in the PLHP at ambient temperature and at a temperature of below 0°C, preferably at a temperature of -20°C or below.

[0052] Preferably, the at least one marker (101 ) has a lower volatility than the PLHP.

[0053] More preferably, the at least one marker (101) has a boiling point Bp equal to or higher than about 60°C (i.e. Bp > about 60°C), preferably equal to or higher than about 70°C (i.e. Bp > about 70°C), more preferably equal to or higher than about 80°C (i.e. Bp> about 80°C), even more preferably equal to or higher than about 90°C (i.e. Bp > about 90°C).

[0054] According to one embodiment, the at least one marker is a halogen containing compound with the halogen being selected from the group comprising fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). The halogen containing compound may be selected for example from the group of chlorohexane (CAS Nr 544-10-5), 1,1 ,2-trichloroethane (CAS Nr 79-00-5), 1 ,1 ,2,2-tetrachloroethane (CAS Nr 79-34- 5), pentachloroethane (CAS Nr 76-01-7), hexachloroethane (CAS Nr 67-72-1 ), 1 ,2,4-trichlorobenzene (CAS Nr 120-82-1 ), 1 ,2,4,5-tetrachlorobenzene (CAS Nr 95-94-3), 1 -bromo-propane (CAS Nr 106-94-5), 1 -bromo-butane (CAS Nr 109-65-9), 1 -bromo-octane (CAS Nr 111-83-1 ), bromobenzene (CAS Nr 108-86-1 ), 1 ,2-dibromo-ethane (CAS Nr 106-93-4), 1, 1,2-tribromo-propane (CAS Nr 23511-78-6), 1 ,2,3- tribromo-propane (CAS Nr 96-11-7), 1 ,2-dibromo-benzene (CAS Nr 583-53-9), ethyliodide (CAS Nr 75- 03-6), 1,4-diiodobutane (CAS Nr 628-21-7), 1 ,6-diiodohexane (CAS Nr 629-09-4), 1 -iodohexadecane (CAS Nr 544-77-4), iodobenzene (CAS Nr 591-50-4), 1 ,2-difluoro-1 ,2-dibromo-ethane (CAS Nr 20705- 29-7), 1,2-dibromo-1,1 ,2-trifluoro-ethane (CAS Nr 354-04-1 ), 1-bromo-4-fluoro-benzene (CAS Nr 460- 00-4), 1,2-dibromo-1 ,2-dichloro-ethane (CAS Nr 683-68-1 ), dichlorotribromoethane (CAS Nr 677-32-7), and mixtures thereof.

[0055] According to one embodiment, the at least one marker is a silicon containing compound selected for example from the group consisting of methyltrimethoxysilane (CAS Nr 1185-55-3), dimethoxydimethylsilane (CAS Nr 1112-39-6), methoxytrimethylsilane (CAS Nr 1825-61-2), ethoxytrimethylsilane (CAS Nr 1825-62-3), triethoxymethylsilane (CAS Nr 2031-67-6), isopropoxytrimethylsilane (CAS Nr 1825-64-5), triethoxymethylsilane (CAS Nr 2031-67-6), trimethoxy(octyl)silane (CAS Nr 3069-40-7), trimethoxy(octadecyl)silane (CAS Nr 3069-42-9), hexadecyltrimethoxysilane (CAS Nr 16415-12-6), triethoxy(octy IJsilane (CAS Nr 2943-75-1 ), tetraethyl orthosilicate (CAS Nr 78-10-4), dicyclopentyldimethoxysilane (CAS Nr 126990-35-0), hexamethyldisiloxane (CAS Nr 107-46-0), (3-aminopropyl)trimethoxysilane (CAS Nr 13822-56-5), (3- aminopropyl)triethoxysilane (CAS Nr 919-30-2), (N,N-dimethylaminopropyl)trimethoxysilane (CAS Nr 2530-86-1 ), (3-mercaptopropyl)trimethoxysilane (CAS Nr 4420-74-0), (3-mercaptopropyl)triethoxysilane (CAS Nr 14814-09-6), triethoxy-3-(2-imidazolin-1-yl)propylsilane (CAS Nr 58068-97-6), and mixtures thereof.

[0056] According to one embodiment, the at least one marker is a silicon containing compound being selected from the group of cyclomethicone compounds, i.e. compounds having a backbone of [(CH3)2SiO]n, and being selected for example selected from the group consisting of hexamethylcyclotrisiloxane, (CAS Nr 541-05-9), octamethylcyclotetrasiloxane (CAS Nr 556-67-2), decamethylcyclopentasiloxane (CAS Nr 541-02-6), dodecamethylcyclohexasiloxane (CAS Nr 540-97-6), tetradecamethylcycloheptasiloxane (CAS Nr 107-50-6), hexadecamethylcyclooctasiloxane (CAS Nr 556-68-3), octadecamethylcyclononasiloxane (CAS Nr 556-71-8), eicosamethylcyclodecasiloxane (CAS Nr 18772-36-6), docosamethylcycloundecasiloxane (CAS Nr 18766-38-6),tetracosamethylcyclododecasiloxane (CAS Nr 18919-94-3), hexacosamethylcyclotridecasiloxane (CAS Nr 23732-94-7), and mixtures thereof.

[0057] According to one embodiment, the at least one marker is a silicon containing compound being selected from the group of silanol compounds and being for example trimethylsilanol (CAS Nr 1066-40- 6).

[0058] According to one embodiment, the at least one marker is a silicon containing compound being selected from the group of silazane compounds and being selected for example from the group consisting of hexamethyldisilazane (CAS Nr 999-97-3), 1 ,1,3,3-tetramethyldisilazane (CAS Nr 15933- 59-2) 1 ,3-diethyl-1 , 1 ,3,3-tetramethyldisilazane (CAS Nr 17882-94-9), 2, 2, 4, 4,6,6- hexamethylcyclotrisilazane (CAS Nr 1009-93-4), and mixtures thereof.

[0059] According to one embodiment, the at least one marker is a silicon containing compound being selected from the group consisting of halogenated silane compounds and being selected for example from the group of chlorodimethylsilane (CAS Nr 1066-35-9), dichloromethylsilane (CAS Nr 75-54-7), dichlorodimethylsilane (CAS Nr 75-78-5), chloromethyltrimethylsilane (CAS Nr 2344-80-1 ), bromotrimethylsilane (CAS Nr 2857-97-8), iodomethyl)trimethylsilane (CAS Nr 4206-67-1 ), chloro(chloromethyl)dimethylsilane (CAS Nr 1719-57-9), trichloro(octadecyl)silane (CAS Nr 112-04-9), trichlorododecylsilane (CAS Nr 4484-72-4), trichloro(octyl)silane (CAS Nr 5283-66-9), trichloro( phenethyl)silane (CAS Nr 940-41-0), trichloro( hexyl)silane (CAS Nr 928-65-4), methyltrichlorosilane (CAS Nr 75-79-6), chloro(3-chloropropyl)dimethylsilane (CAS Nr 10605-40-0), (3- chloropropyl)trimethoxysilane (CAS Nr 2530-87-2), (3-bromopropyl)trimethoxysilane (CAS Nr 51826- 90-5), (3-iodopropyl)trimethoxysilane (CAS Nr 14867-28-8), trimethylsilyl trifluoromethanesulfonate (CAS Nr 27607-77-8), and mixtures thereof.

[0060] According to one embodiment, the at least one marker is a germanium containing compound selected for example from the group consisting of tetramethyl germane (CAS Nr 865-52-1), tetraethyl germane (CAS Nr 597-63-1 ), tetrapropyl germane (CAS Nr 994-65-0), tetrabutyl germane (CAS Nr 1067-42-1 ), germanium tetramethoxide (CAS Nr 992-91-6), germanium tetraethoxide (CAS Nr 14165- 55-0), germanium tetrapropoxide (CAS Nr 128426-02-8), germanium tetraisopropoxide (CAS Nr 21154- 48-3), germanium tetrabutoxide (CAS Nr 25063-27-8), dimethylgemanium dichloride (CAS Nr 1529-48- 2), trimethylgermanium chloride (CAS Nr 1529-47-1 ), diethylgermanium dichloride (CAS Nr 13314-52- 8), dibutylgermanium dichloride (CAS Nr 4593-81-1 ), triethylgermanium hydride (CAS Nr 1188-14-3), and mixtures thereof.

[0061] According to one embodiment, the at least one marker is an aromatic alcohol compound or a phenol compound selected for example from the group consisting of benzyl alcohols (CAS Nr 100-51- 6), phenyl ethanol (CAS Nr 60-12-8), tyrosol (CAS Nr 501-94-0), tryptophol (CAS Nr 526-55-6), phenol (CAS Nr 108-95-2), hydroquinone (CAS Nr 123-31-9), 4-aminophenol (CAS Nr 123-30-8), 4- hydroxybenzilamine (CAS Nr 696-60-6), 4-methoxyphenol (CAS Nr 150-76-5), and mixtures thereof.

[0062] According to one embodiment, the at least one marker is an aromatic ketone compound being selected for example from the group consisting of acetophenone (CAS Nr 98-86-2), propiophenone (CAS 93-55-0), butyrophenone (CAS Nr 495-40-9), 1-phenyl-2-propen-1-one (CAS Nr 768-03-6), 1- phenyl-2-propyn-1-one (CAS Nr 3623-15-2), phenylglyoxal (CAS Nr 1074-12-0), isobutyrophenone(CAS Nr 611-70-1), 2-aminoacetophenone (CAS Nr 613-89-8), 4 hydroxyacetophenone (CAS Nr 99- 93-4), 4-methylpropiophenone (CAS Nr 5337-93-9), and mixtures thereof.

[0063] According to one embodiment, the at least one marker is a carboxylic acid containing compound selected for example from the group consisting of aliphatic carboxylic acids, aromatic carboxylic acids, and mixtures thereof.

[0064] According to one embodiment, the at least one marker is a metal carboxylate salt, the carboxylate being for example selected from the group consisting of acetate, propanoate, 2-methyl- propanoate, 2,2-dimethyl-propanoate, butanoate, 3-methyl butanoate, pentanoate, 4-methyl- pentanoate, hexanoate, heptanoate, octanoate, nonanoate, decanoate, undecanoate, dodecanoate, benzoate, 2-methyl benzoate, 3-methyl benzoate, 4-methyl benzoate, and the metal being selected from the group consisting of alkali metals (preferably Li, Na and K), alkaline-earth metals (preferably Mg and Ca), transition metals of the 4th period (preferably Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn), transition metals of the 5th period (preferably Zr and Mo), and transition metals of the 6th period (preferably Ce and Gd), and mixtures thereof; for example, the at least one marker may be selected from the group consisting of lithium salt of acetate (CAS Nr 546-89-4), sodium salt of acetate (CAS Nr 127-09-3), potassium salt of acetate (CAS Nr 127-08-2), calcium salt of acetate (CAS Nr 62-54-4), copper (I) salt of acetate (CAS Nr 589-54-9), copper (II) salt of acetate (CAS Nr 147-71-2), zirconium salt of acetate (CAS Nr 7585-20- 8), cerium (II) salt of acetate (CAS Nr 57023-24-2), cerium (III) salt of acetate (CAS Nr 537-00-8), potassium salt of 2-methyl benzoate (CAS Nr 16463-31-3), lithium salt of 3-methyl benzoate (CAS Nr 172273-79-9), sodium salt of 4-methyl benzoate (CAS Nr 17264-54-9), and mixtures thereof.

[0065] According to one embodiment, the at least one marker is a lactone compound for example selected from the group consisting of butyrolactone (CAS Nr 96-48-0), y-valerolactone (CAS Nr 108-29- 2), a-methyl-y-butyrolactone (CAS Nr 1679-47-6), 8-valerolactone (CAS Nr 542-28-9), s-caprolactone (CAS Nr 24980-41-4), 2-oxo-canone (CAS Nr 539-87-7), 5-undecalactone (CAS Nr 710-04-3), 5- dodecalactone (CAS Nr 713-95-1 ), 5-tridecalactone (CAS Nr 7370-92-5), 5-tetradecalactone (CAS Nr 2721-22-4), and mixture thereof.

[0066] According to one embodiment, the at least one marker is a ethylene glycol compound for example selected from the group consisting of diethylene glycol (CAS Nr 11-46-6), triethylene glycol (CAS Nr 112-27-6), tetraethylene glycol (CAS Nr 112-60-7), diethylene glycol dibutyl ether (CAS Nr 112- 73-2), triethylene glycol monobutyl ether (CAS Nr 143-22-6), tetraethylene glycol monomethyl ether (CAS Nr 23783-42-8), diethylene glycol diethyl ether (CAS Nr 99106-87-3), tetraglyme (CAS Nr 143-24- 8), tetraethylene glycol monoethyl ether (CAS Nr 56-20-4), alkoxy-phenyl containing compounds (e.g. anisole (CAS Nr 100-66-3), 2-methyl anisole (CAS Nr 578-58-5), p-ethyl-anisole (CAS Nr 1515-95-3)); 2-ethyl-9, 10-dimethoxy-anthracene (CAS Nr 26708-04-3) and mixtures thereof.

[0067] According to one embodiment, the at least one marker is a nitro group containing compound, preferably an aromatic nitro compound, for example selected from the group consisting of nitro ethane (CAS Nr 79-24-3), 1-nitropropane (CAS Nr 108-03-2), nitrobenzene (CAS Nr 98-95-3), 1- nitronaphthalene (CAS Nr 86-57-7), and mixtures thereof.

[0068] According to one embodiment, the at least one marker is a hydrazine containing compound for example selected from the group consisting of CnH2n+4N2 with n > 1 (e.g. methyl hydrazine (CAS Nr 60-34-4), dimethyl hydrazine (CAS Nr 540-73-8), 1-ethyl-2-methyl-hydrazine (CAS Nr 18247-19-3), and mixtures thereof.

[0069] According to one embodiment, the at least one marker is an aromatic amine containing compound selected for example from the group consisting of N,N-dimethyl benzenamine (CAS Nr 121 - 69-7), N,N-diethyl benzenamine (CAS Nr 91-66-7), N-methyl-N-ethyl-benzenamine (CAS Nr 613-97-8), N,N-dipropyl-benzenamine (CAS Nr 2217-07-4), N,N-dibutyl-benzenamine (CAS Nr 613-29-6), N,N- dipentyl-benzenamine (CAS Nr 6249-76-9), N,N-hexyl benzenamine (CAS Nr 4430-09-5-66-7), 1 ,4- benzendiamine (CAS Nr 106-50-3), N1,N1,N4,N4-tetramethyl-1 ,4-benzenediamine (CAS Nr 100-22-1), N,N-dimethyl-1-naphtalenamine (CAS Nr 86-56-6), N-ethyl-N-methyl-1-naphthalenamine (CAS Nr 83777-94-0), N,N,4-trimethyl-1-naphthalenamine (CAS Nr 4523-52-8), N,N,5-trimethyl-1- naphthalenamine (CAS Nr 847449-78-9), N,N,2-trimethyl-1-naphthalenamine (CAS Nr 57585-25-8), N, N-diethy 1-1 - naphthalenamine (CAS Nr 84-95-8), N-isopropyl-N-methyl-1- naphthalenamine (CAS Nr 110014-41-0), N1 ,N1 ,N3,N3-tetramethyl-1 ,3-benzenediamine (CAS Nr 22440-93-3), N1 , N1 , N4, N4- tetraethyl-1 ,4-naphtalenediamine (CAS Nr 861352-30-9), N1, N1 , N5, N5-tetramethyl-1 ,5- naphtalnediamine (CAS Nr 10075-69-1 ), N1, N1 , N5, N5-tetraethyl-1,5-naphtalnediamine (CAS Nr 861347-34-4), N,N,4,5-tetramethyl-1-naphthalenamine (CAS Nr 4619-41-4), N-ethyl-N-isopropyl-1- naphthalenamine (CAS Nr 114326-20-4), N,N-bis(2-methylpropyl)-2-naphtalenamine (CAS Nr 109554- 95-2), 1 -(1 -naphthalenyl)piperidine (CAS Nr 62062-39-9), and mixtures thereof.

[0070] The solvent (400) used in the method described herein may be miscible with the PLHP at ambient temperature and at a temperature of below about 0°C, preferably at a temperature of about - 20°C or below to form a single liquid phase or monophasic liquid when mixed with the PLHP. According to the present invention, a solvent is miscible with the PLHP if a mixture comprising from about 10wt.% to about 90 wt.% of the solvent, and from about 90 wt.% to about 10 wt.% of the PLHP form a homogeneous monophasic mixture.

[0071] The solvent (400) must be suitable for dissolving the at least one marker (101 ).

[0072] The solvent preferably has a high boiling point (Bp), preferably the solvent has a boiling point higher than the boiling point of the PLHP. For example, the solvent may have a boiling point Bp equal to or higher than about 60°C (i.e. Bp > about 60°C), preferably equal to or higher than about 75°C (Bp > about 75°C), more preferably equal to or higher than about 80°C (Bp > about 80°C).

[0073] Suitable solvents may be selected from the group consisting of aliphatic or aromatic hydrocarbons such as but not limited to n-heptane (CAS Nr 142-82-5), n-octane (CAS Nr 111-65-9), n- nonane (CAS Nr 111-84-2), n-decane (CAS Nr 124-18-5), n-undecane (CAS Nr 1120-21-4), n-dodecane (CAS Nr 112-40-3), benzene (CAS Nr 71-43-2), toluene (CAS Nr 108-88-3), ethylbenzene (CAS Nr 100- 41-4), C14-C18, n-alkanes, isoalkanes, cyclics, aromatics (2-30 %) CAS: [920-360-0]; aliphatic alcohols such as but not limited to ethanol (CAS Nr 64-17-5), propanol (CAS Nr 71-23-8), isopropanol (CAS Nr 67-63-0), butanol (CAS Nr 71-36-3), 1 ,6-hexanediol (CAS Nr 629-11-8), 1-methoxy-2-propanol (CAS Nr 107-98-2), C 4-C48, n-alkanes, isoalkanes, cyclics, aromatics (2-30 %) CAS: [920-360-0], 2,2,4-trimethyl 1,3 pentanediol (CAS Nr 25265-77-4), 1 -methoxy propan-2-ol (CAS Nr 107-98-2); esters such as but not limited to ethyl acetate (CAS Nr 141-78-6), isopropyl acetate (CAS Nr 108-21-4), 2-methoxy-1- methylethyl acetate (CAS Nr 108-65-6), n-propyl acetate (CAS Nr 109-60-4), benzyl acetate (CAS Nr140-11-4), 1-methoxy-2-propyl acetate (CAS Nr 108-65-6), butyl benzoate (CAS Nr 136-60-7), 2-(2- butoxyethoxyjethyl acetate (CAS Nr 124-17-4), 2-butoxyethyl acetate (CAS Nr 112-07-2), pentyl propionate (CAS Nr 624-54-4); aliphatic ketones such as but not limited to methyl ethyl ketone (CAS Nr 78-93-3), diethyl ketone (CAS Nr 96-22-0), 3-pentyn-2-one (CAS Nr 7299-55-0), acetonylacetone (CAS Nr 110-13-4), disiobutyl ketone (CAS Nr 108-83-8), methyl isoamyl ketone (CAS Nr 110-12-3), diisopropyl ketone (CAS Nr 565-80-0), 4-methylpentan-2-one (CAS Nr 108-10-1 ); ethers such as but not limited to dipropyl ether (CAS Nr 111-43-3), diisopropyl ether (CAS Nr 108-20-3), dibutyl ether (CAS Nr 142-96-1), dioxane (CAS Nr 123-91-1 ); acids such as but not limited to 9-cis-octadecenoic acid (oleic acid) (CAS Nr 112-80-1 ); mixtures of aliphatic and aromatic hydrocarbons such as but not limited to naphtha (CAS Nr 8002-05-9), heavy aromatics naphtha (CAS Nr 64742-94-5), hydrotreated heavy naphtha (CAS Nr 64742-48-9); and mixtures thereof.

[0074] As schematically illustrated in Fig. 1, the marked PLHP (100 & 101 ) is transferred from the storage container (300) to the first cylinder (200) being a stainless steel double ended sample cylinder.

[0075] A second cylinder (500), being a stainless steel double ended sample cylinder, is connected to a vacuum pump to evacuate the air (not illustrated).

[0076] As schematically illustrated in Fig. 2a, a solvent (400) suitable for extracting the marker (101) is introduced into the second cylinder (500).

[0077] As schematically illustrated in Fig. 2b, the second cylinder (500) containing the solvent (400) is weighted to determine the exact weight and volume of introduced solvent.

[0078] As schematically illustrated in Fig. 2c, a sample of the marked (marked PLHPs) (100 & 101 ) is transferred from the first cylinder (200) into the second cylinder (500) comprising the solvent (400).

[0079] As schematically illustrated in Fig. 2d, the second cylinder (500) containing the solvent (400) and the marked PLHP (100 & 101) is weighted to determine the exact amount of transferred marked PLHP, by calculating the weight difference with the previous weighing step illustrated in Fig. 2b.

[0080] The second cylinder (500) is optionally agitated, by for example shaking, for a predetermined time period. In one embodiment, the second cylinder (500) comprising the marked PLHP (100 & 101 ) and solvent (400) is shaken for between about 10 seconds and about 20 seconds. It is to be understood that the method of agitation, the frequency of agitation and the time period of agitation may vary depending on the particular requirements.

[0081] After agitation, the second cylinder (500) may rest for a predetermined time period. In one embodiment, the second cylinder (500) is allowed to rest for about one minute in a vertical arrangement with the sampling valve of the cylinder (500) located at the bottom. It is however to be understood that the second cylinder (500) may be utilized immediately after agitation, during agitation, or after any suitable time period of resting. It is also to be understood that the second cylinder (500) may be utilized and / or rested in any suitable configuration and is not limited to a vertical configuration.

[0082] As schematically illustrated in Fig. 3, the second cylinder (500) is positioned above a receiving container (for example a beaker). The second cylinder (500) is positioned in a vertical configuration with the sampling valve located at the bottom above or within, preferably within, the receiving container. The sampling valve of the second cylinder (500) is opened to eject the solvent (400), the PLHP (100) and the marker (101). The PLHP (100) evaporates on exposure to ambient pressure and temperatureconditions, ant the solvent (400) and the marker (101 ) are collected in the receiving container.

[0083] Residual PLHP (100) that may still be contained in the solvent (400) in the receiving container is allowed (and for example encouraged) to evaporate from the container until no further bubbling of the fluid is observed (i.e. until all the residual PLHP (100) has evaporated). For example, the fluid (comprising a mixture of solvent (400), extracted marker (101) and the residual PLHP (100)) present within the container may be heated and / or agitated (for example by shaking and / or stirring).

[0084] The remaining fluid (solvent-marker mixture) is then analyzed to detect, and if present quantify, the presence of the at least one marker with a suitable analytical technique as disclosed herein.

[0085] The marker concentration in the marked PHLP is calculated from the measured marker concentration of the extraction solution (solvent-marker mixture) according to the following equation:with % (PHLP) being the marker concentration in the marked PHLP, (extraction solution) being the marker concentration in the extraction solution and m and p being the mass and the density of the solvent or of the PHLP (the marker being the analyzable atom or the analyzable functional group).

[0086] Preferably the determined marker concentration of the sample is compared with a predetermined marker concentration of the marked PHLP contained in the storage container 300). The predetermined marker concentration in the PHLP is the marker concentration determine during the marking process of the PHLP (not part of the invention).

[0087] By using a second gas cylinder comprising a solvent, it has been found that the marker can be rapidly and reliably extracted from the PHLP.

[0088] The volume of the sampled PHLP is difficult to estimate directly. As such, the mass of the sampled PHLP may be measured (by measuring the mass of the second cylinder before and after the PHLP sampling). The volume may then be calculated using the density of the PLHP.

[0089] The first and second cylinders are preferably cleaned after the analysis. The first and second cylinders are preferably cleaned with at least one organic solvent. Preferably, the first and second cylinders are cleaned with chloroform. The first and second cylinders may be further cleaned with ethanol. The first and second cylinders may be dried after cleaning with at least one organic solvent. For example, the first and second cylinders may be dried with pressurized dry air.

[0090] The steps of determining / detecting the at least one marker and determining the concentration of said at least one marker may be performed directly in field, for example at the gas stations with a transportable analytic apparatus, or in a remote location, for example in a dedicated central analytic laboratory. Furthermore, the method can be performed in a highly time-effective manner. The method for sampling, authenticating and adulteration quantifying the marked PLHP may be performed, for example by XRF spectroscopy, within 15 minutes.

[0091] The step of determining the concentration of the at least one marker is carried out on the extracted marker. As such, a very large variety of analytical methods may be used, and as a consequence and as described herein a large variety of markers may be analyzed as described herein.

[0092] There is an inherent error rate associated with the method which may limit its usefulness for low percentage levels of adulteration (e.g. adulteration levels <5 wt.%). Nevertheless, due to the inherent difficulties of adulterating marked PLHP (as a result of the gaseous nature of the PLHP at room temperature and normal pressure and of the containers type used to store the PLHP), only adulterations at large percentage levels (> 5wt.%) seem attractive and achievable for counterfeiters.EXAMPLES

[0093] The present invention is now described in more details with reference to non-limiting examples. The Examples below provide more details for the method, in particular for the sampling and authentication and quantification method of the marker from the Liquid Pressurized Gas (LPG) and the calculation of the marking level in the LPG.Preparation of a marked LPG sample

[0094] A synthetic LPG fuel was prepared by mixing 60% V / V of propane (3.5* from Messer) and 40 % V / V of butane (3.5* from Air Product) in a 2-liter stainless steel reservoir (300) (7.6 bar at 25°C) equipped with a pressure transducer and a valve.

[0095] The density of the LPG was calculated using the REFPROP software for a mixture of 60% VA / propane and 40% V / V butane at 25°C and resulted in a density value d(LPG) = 530 g / L (at room temperature).

[0096] A 2 ml sample of a 10 wt.% solution of a marker (101) 1-bromooctane (CAS Nr 111-83-1 ) in PKWF® 6 / 9 (EINECS 927-632-8, from Haltermann Carless, https: / / www.haltermann- carless.com / products / printing-ink-distillates-pkwf-paraset-printosol) was added to the synthetic LPG fuel using a syringe connected to the valve.

[0097] The total amount of bromine M(Br) and the concentration of bromine c(Br) in the marked LPG fuel (Table 1 and Table 2, line D) could be derived from the amount of 1-bromooctane (101) in the 2 ml sample, the ratio of the atomic weight of bromine to the molecular weight of 1-bromooctane, and the volume (It) of LPG that has been marked (the volume of LPG was derived from the weight and density of the LPG).Materials

[0098] The sampling cylinders used for the method of the present invention were supplied by Swagelok® (https: / / products.swagelok.com / )

[0099] The first cylinder (200) was a stainless steel double ended sample cylinder (316L Stainless Steel Double Ended Sample Cylinder, % in. FNPT, 500 cm3, 1800 psig (124 bar).

[0100] The second cylinder (500) was a stainless steel double ended sample cylinder (316L Stainless Steel Double Ended Sample Cylinder, % in. FNPT, 150 cm3, 1800 psig (124 bar).

[0101] The solvent was C14-C18, n-alkanes, isoalkanes, cyclics, aromatics (2-30 %) CAS: [920-360-0]Method of extraction of the marker from the marked LPG (invention) (Examples E1-E4)

[0102] The analysis process of extraction of the marker from the marked LPG obtained in Example 1 was repeated four times (E1-E4) and each extraction solution was analyzed three times by XRF analysis. The three measured values were averaged (Table 1 , line C). Results are provided in Table 1.

[0103] A sample of the marked synthetic LPG fuel was transferred from the 2-liter stainless steel reservoir into the first cylinder (200) (step A described herein).

[0104] The second cylinder (500) was connected to a vacuum pump for evacuating the contained air and facilitating the solvent injection (pressure at the end of evacuation: 10 mbar) (step B described herein). Subsequently, the second cylinder (500) was weighed on a balance (Mettler Toledo CC1200; precision: 0.1 mg) (step C described herein).

[0105] A volume V(solvent) (Table 1 , line A) of solvent (400) was introduced into the second cylinder (500) (Table 1) (step D described herein). Subsequently, the second cylinder (500) was weighed on the balance described hereabove (step E described herein).

[0106] The second cylinder (500) containing the solvent (400) was connected to the first cylinder (200) (Fig. 2a) and a sample of the marked synthetic LPG fuel (100 + 101 ) was transferred from the first cylinder (200) to the second cylinder (500) through a valve opened for a time between about 10 and about 20 seconds (step F described herein).

[0107] After closing the outlet and inlet valve of the first and second cylinders (200 and 500), the first and second cylinders (200 and 500) were disconnected. The amount m(LPG) (Table 1 , line B) of transferred marked synthetic LPG fuel (100 + 101 ) was calculated by weighing the second sample cylinder (500) and calculating the weight difference with the previously obtained weight (step G described herein).

[0108] The second cylinder (500) was shaken manually for about 20 seconds. The second cylinder (500) was then allowed to rest in a vertical position with the outlet valve at the bottom for about 20 seconds.

[0109] After placing the outlet valve within a receiving recipient (as illustrated in Fig. 3), the outlet valve was gently opened and the mixture of solvent (400) containing the extracted marker (101 ) was collected in the receiving recipient while the synthetic LPG fuel (100) evaporated as a result of the ambient normal pressure and room temperature (step H described herein). To ensure that all the synthetic LPG had been removed, the solvent (400) containing the marker (101 ) was stirred under heating at about 35°C for 5 minutes.

[0110] Three 5 ml samples of the solution comprising the solvent (400) with the marker (101) were collected using a syringe and individually analyzed by XRF spectroscopy (each measurement was repeated three times). The averaged bromine concentrations for Example E1-E4, as measured by XRF spectroscopy, are disclosed in Table 1 (line C).

[0111] For each example, the bromine concentration obtained by the XRF analysis of the extraction solutions (solvent and extracted marker) (Table 1, line C) was compared with the calculated bromine concentration (Table 1 , line D), as disclosed hereabove, to validate the method.

[0112] The bromine concentration in the marked LPG fuel was calculated from the bromine measured concentration in the extraction solution according to the following equation:x(LPG) = bromine concentration in the marked LPG fuel; x (extraction solution) = bromine concentration in the extraction solution; m and p = mass and density of solvent or LPG.Table 11) Average value from three measured samples; value calculated according to equation here above2) Calculated for the prepared marked synthetic LPG fuelExtraction of the marker from a stored marked LPG (invention) (Example E5-E9)

[0113] In order to assess the reproducibility of the method over time, in particular over storage of the marked LPG fuel, the method of the present invention was applied to a sample of marked LPG fuel at several time intervals between the marking of the LPG fuel and the extraction and analysis processes. Table 2 discloses the analysis results of the marked LPG fuel at different lapses of time.Table 21) Average value from three measured samples; value calculated according to equation here above2) Calculated for the prepared marked synthetic LPG fuel3) Lapse of time between the marking of the LPG fuel, and the extraction and analysis of the markedLPG fuel

[0114] As illustrated in Tables 1 and 2, the method disclosed herein showed an acceptable accuracy with difference of measured versus calculated bromine concentration being in a range between 0.08% and 12.01%. The sometimes-large difference between measured and calculated bromine concentration (e.g. see examples E2 and E3) may be explained by the handlings of the cylinders during the process, in particular the connecting and disconnecting of the cylinders.

Claims

CLAIMS1. A method for sampling a pressurized liquified hydrocarbon product (PLHP), preferably selected from the group consisting of liquified petroleum gases (LPGs), natural gases (NGs), liquified natural gases (LNGs), natural piped gases (NPGs) and mixtures thereof, comprising at least one marker containing at least one analyzable atom and / or at least one analyzable functional group, said sampling method comprising the steps of:A. collecting in a first gas cylinder a sample of the pressurized liquified hydrocarbon product (PLHP) comprising the at least one marker from a storage container;B. connecting a second gas cylinder to a vacuum pump to evacuate the second gas cylinder;C. weighing the second gas cylinder;D. transferring a predetermined volume of solvent into the second gas cylinder, wherein the solvent has a boiling point (BP) equal to or higher than about 60°C and a miscibility in the pressurized liquified hydrocarbon product (PLHP) comprised in a range from about 10 wt% to about 90 wt%;E. weighing the second gas cylinder containing the solvent to obtain the exact weight and volume of the solvent;F. transferring at least part of the pressurized liquified hydrocarbon product (PLHP) comprising the at least one marker comprised in the first gas cylinder from the first gas cylinder into the second gas cylinder;G. weighing the second gas cylinder and calculating the amount of pressurized liquified hydrocarbon product (PLHP) comprising the at least one marker transferred into the second gas cylinder by subtracting the obtained weight value from the value obtained in step E; andH. transferring the mixture of the pressurized liquified hydrocarbon product (PLHP), the at least one marker and the solvent into a receiving container and allowing the pressurized liquified hydrocarbon product (PLHP) to evaporate; wherein the at least one marker has a boiling point equal to or higher than about 60°C, and the at least one marker has a solubility in the PLHP comprised in a range from about 0.00001 wt.% to about 1 wt.%, preferably 0.0001 wt% or more, more preferably 0.001 wt% or more, particularly preferably 0.01 wt% or more, based on the total weight of the marker and PLHP, and the at least one marker has a solubility in the solvent of from about 0.0001 wt% to about 10 wt%, preferably 0.001 wt% or more, more preferably 0.001 wt% or more, more particularly preferably 0.01 wt% or more, based on the total weight of the solvent and marker.

2. The method according to claim 1 for further authenticating the pressurized liquified hydrocarbon product (PLHP), said method comprising: i) the steps A to H of the sampling method recited in claim 1, and ii) a step of determining the at least one analyzable atom and / or the at least one analyzable functional group presence of the at least one marker with an analytical technique.

3. The method according to claim 2 for further quantifying adulteration of the pressurized liquified hydrocarbon product (PLHP), said method comprising:i) the steps A to H of the sampling method recited in claim 1; ii) the step of determining the at least one analyzable atom and / or the at least one analyzable functional group presence recited in claim 2; iii) a step of calibration the analytical instrument so that a concentration for the identified marker can be obtained iv) a step of calculating the concentration of the at least one marker in the pressurized liquified hydrocarbon product (PLHP); and v) a step of comparing the concentration of the at least one marker calculated in step iv) with a predetermined concentration of the at least one marker in the pressurized liquified hydrocarbon product (PLHP).

4. The method according to any one of claims 1 to 3, wherein the sampling method further comprises a step I of shaking the second gas cylinder, said step being performed after the step G and before the step H.

5. The method according to claim 4, wherein the sampling method further comprises a step J of maintaining the second gas cylinder in a vertical position for a time lapse of at least 10 seconds, said step being performed after the step I and before the step H.

6. The method according to any one of claims 1 to 5, wherein the sampling method further comprises a step K of heating and / or agitating the receiving container to accelerate evaporation of the pressurized liquified hydrocarbon product (PLHP), said step being performed after the step H.

7. The method according to any one of claims 2 to 6, wherein the analytical technique is selected from the group consisting fluorescence spectroscopy, (Surface Enhanced) Raman spectroscopy SERS, Fourier transform-infrared (FT-IR) spectroscopy, UV spectroscopy, UV spectroscopy coupled with HPLC, atomic absorption technique employing elemental analysis, atomic absorption technique coupled with high performance liquid chromatography (HPLC- AAS), mass spectrometry, inductively coupled plasma mass spectrometry (ICP-MS), laser ionization mass spectrometry (LIMS), gas-chromatography coupled with mass spectrometry (GC-MS), high performance liquid chromatography coupled with mass spectrometry (HPLC- MS), emission spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectroscopy( ICP-OES), electron capture detection, electron capture detection coupled to gas chromatography (GC-ECD), flame ionization detection, flame ionization detection coupled with gas chromatography (GC-FID), X- ray fluorescence (XRF) spectroscopy and any combinations thereof, preferably selected from the group consisting of Fourier transform-infrared (FT-IR) spectroscopy, laser ionization mass spectrometry LIMS, X-ray fluorescence (XRF) spectroscopy and combinations thereof.

8. The method according to claim 7, wherein the at least one marker is selected from the group consisting of: i. halogen-containing compounds; ii. silicon-containing compounds; iii. cyclomethicone compounds;iv. silanol compounds; v. silazane compounds; vi. halogenated silicon-containing compounds; vii. germanium containing compounds; viii. aromatic alcohol compounds or phenol compounds; ix. aromatic ketone compounds; x. carboxylic acid compounds; xi. metal carboxylate compounds; xii. lactone compounds; xiii. ethylene glycol compounds or alkoxy phenyl compounds; xiv. nitro-group containing compounds; xv. hydrazine containing compounds; xvi. aromatic amine containing compounds; and xvii. mixtures thereof.

9. The method according to claim 8, wherein the at least one marker is selected from the group consisting of i, ii, Hi, iv, v, vi, vii, xi, xiii, xvi and mixtures thereof.

10. The method according to any one of claims 1 to 9, wherein the solvent is selected from the groups consisting of a. aliphatic or aromatic hydrocarbons, preferably n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, benzene, toluene, ethylbenzene, C14-C18, n-alkanes, isoalkanes, cyclics, aromatics (2-30 %) CAS: [920-360-0]; b. aliphatic alcohols, preferably ethanol, propanol, isopropanol, butanol, 1 ,6-hexanediol, 1- methoxy-2-propanol, 2,2,4-trimethyl 1 ,3 pentanediol, 1-methoxypropan-2-ol; c. esters, preferably ethyl acetate, isopropyl acetate, 2-methoxy-1 -methylethyl acetate, n- propyl acetate, benzyl acetate, 1-methoxy-2-propyl acetate, butyl benzoate, 2-(2- butoxyethoxy)ethyl acetate, 2-butoxyethyl acetate, pentyl propionate; d. aliphatic ketones, preferably methyl ethyl ketone, diethyl ketone, 3-pentyn-2-one, acetonylacetone, diisobutyl ketone, methyl isoamyl ketone, diisopropyl ketone, 4- methylpentan-2-one; e. ethers, preferably dipropyl ether, diisopropyl ether, dibutyl ether, dioxane; f. acids, preferably 9-cis-octadecenoic acid (oleic acid); g. mixtures of aliphatic and aromatic hydrocarbons, preferably naphtha, heavy aromatics naphtha, hydrotreated heavy naphtha, and h. mixtures thereof11. The method according to any of the claims 2 to 10, in which the step of determining the at least one analyzable atom and / or the at least one analyzable functional group concentration of the at least one marker with the analytical technique is carried out using a transportable mobile apparatus.

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