USE OF RARE EARTH COMPLEXES AS MARKERS OF PETROLEUM PRODUCTS, CRUDE OILS, BIODEGRADES OR LUBRICANTS

Description

TECHNICAL FIELD

[0001] The present invention relates to the marking of petroleum products, crude oils, biofuels or lubricants.

[0002] More specifically, this invention relates to the use of rare earth complexes as markers for petroleum products, crude oils, biofuels or lubricants. The invention also relates to a method for time-resolved fluorescence detection of these markers. BACKGROUND OF THE INVENTION

[0003] Petroleum products are commonly marked with substances to enable later identification of these products.

[0004] In particular, to prevent fraud, government agencies and regulatory authorities mark petroleum products when paying excise taxes. Manufacturers may also want to mark their petroleum products to ensure traceability.

[0005] The most commonly used markers are dyes. The color of the petroleum product is specifically changed by the addition of the marker, and this change is visible to the naked eye. For example, Solvent Yellow 124, a yellow dye, is used to label certain diesel and kerosene fuels.

[0006] Other markers that are not detectable by the naked eye can also be used. In this case, the markers are detectable by chemical analysis techniques such as plasma torch spectrometry (ICP) and high-performance liquid chromatography (HPLC). However, the use of these analytical techniques most often requires cumbersome preparations and / or experimental techniques, which are not compatible with rapid detection of the markers used.

[0007] Fluorescence is an attractive analytical technique because it can be performed easily and does not require complex experimental techniques. This technique has already been used to detect petroleum product markers. However, petroleum products often intrinsically exhibit significant fluorescence, making it difficult to differentiate the marker's fluorescence from the fluorescence naturally emitted by petroleum products. This requires high concentrations of markers or compounds capable of emitting a signal in wavelengths, particularly infrared, that are distinct from those of the fluorescent compounds naturally present in petroleum products.

[0008] WO96 / 22345 describes petroleum product markers that are derived from 2(3H)-furanone and are detected by fluorescence after addition of a reagent. These markers can be detected at a concentration of 10 ppm.

[0009] WO2004 / 068113 describes the use of organic molecules at a concentration of 1 ppm as marking agents for petroleum products. These markers are detected by ion mobility spectrometry.

[0010] WO96 / 10620 describes petroleum product markers based on squaraine, phthalocyanine or naphthalocyanine that can be used at a concentration below one ppm. They are detected by near-infrared fluorescence.

[0011] Document WO 2014 / 091144 describes aqueous-soluble fluorescent tracers for marking oilfield injection waters.

[0012] To the inventors' knowledge, the concentration of markers actually used in petroleum products remains high for effective marking, and is often higher than one ppm.

[0013] One of the objectives of the present invention is therefore to provide new markers, detectable at very low concentrations in crude oils, biofuels, lubricants or petroleum products, and in particular gasoline, diesel, fuel oil or kerosene.

[0014] Another objective of the invention is to provide new markers for petroleum products, crude oils, biofuels or lubricants, which are stable over time, so that their use is optimal.

[0015] Another objective of the invention is to provide markers of petroleum products, crude oils, biofuels or lubricants which meet the following criteria: Relative difference in labeling signal <5% after 3 months at room temperature; Soluble and stable product from -40 to +60°C; Non-volatile product; Chemically stable product; No retention on silica or activated carbon column.

[0016] The present invention also aims to provide a method for marking petroleum products, crude oils, biofuels or lubricants and a method for detecting these markers which are simple and which can be easily implemented. SUMMARY OF THE INVENTION

[0017] These objectives, among others, are achieved by the invention which primarily aims at the use, as markers of petroleum products, crude oils, biofuels or lubricants, of rare earth complexes.

[0018] The invention also relates to a method for time-resolved fluorescence detection of these complexes in petroleum products, crude oils, biofuels or lubricants.

[0019] Unexpectedly, the inventors discovered that rare earth complexes could be used as markers for petroleum products, crude oils, biofuels or lubricants. In particular, these complexes can be easily detected at concentrations below 1 ppm and even 100 ppb, or even 1 ppb. Advantageously, these complexes are detectable by time-resolved fluorescence, this technique allowing simple and rapid detection of the marker in a sample of petroleum product, crude oil, biofuel or lubricant. BRIEF DESCRIPTION OF THE FIGURES

[0020] On the Figure 1A The time-resolved emission spectrum is shown in solid lines (delay 0.2 ms, acquisition time 1 ms, total decay time 20 ms, accumulation of 0.2 s per point) under excitation at 225 nm of the DOTA(Tb) marker at 160 ppb in the n-hexanol prepared according to example 5, and in broken line the associated reference, corresponding to n -hexanol, analyzed under the same conditions. On the Figure 1B is represented in solid line the time-resolved emission spectrum (delay 0.2 ms, acquisition time 1 ms, total decay time 20 ms, accumulation of 0.5 s per point) under excitation at 225 nm of the DOTA(Eu) marker at 50 ppb in the n -hexanol prepared according to example 4, and in broken line the associated reference, corresponding to n- hexanol, analyzed under the same conditions. On the Figure 1C is represented in solid line the time-resolved emission spectrum (delay 0.2 ms, acquisition time 1 ms, total decay time 20 ms, accumulation of 0.2 s per point) under excitation at 225 nm of the PCTA(Tb) marker at 100 ppb in the n -hexanol prepared according to example 2, and in broken line the associated reference, corresponding to n-hexanol, analyzed under the same conditions. On the Figure 1D The time-resolved emission spectrum is shown in solid lines (delay 0.2 ms, acquisition time 1 ms, total decay time 20 ms, accumulation of 0.2 s per point) under excitation at 225 nm of the TMPAC(Tb) marker at 100 ppb in the n -hexanol prepared according to example 8, and in broken line the associated reference, corresponding to n -hexanol, analyzed under the same conditions. The Figure 2A represents the time-resolved emission spectra (delay 0.2 ms, acquisition time 1 ms, total decay time 20 ms, accumulation of 1 s per point) under excitation at 225 nm of the DOTA(Tb) marker at different concentrations in the n -hexanol prepared according to Example 5. In increasing order of intensity at 540 nm, the curves represent respectively: the reference ( n -hexanol), 6.25, 12.5, 25, 50, 100 and 200 ppb of DOTA(Tb) and the Figure 2Brepresents the correlation between the concentration and the intensity of the emission signal. On the Figure 3A is represented in broken line (---) the time-resolved excitation spectrum (delay 0.1 ms, acquisition time 1 ms, total decay time 20 ms, accumulation of 0.05 s per point) considering the emission line at 545 nm of the PCTA(Tb) marker at 100 ppb in diesel diluted 10 times in the n -hexanol according to example 10, and alternating dash-dot (-·-) the associated reference, corresponding to n -hexanol with 10% diesel, analyzed under the same conditions. In this figure, the time-resolved excitation spectrum of the PCTA(Tb) marker at 100 ppb in unleaded 95 prepared according to Example 11 analyzed under the same conditions is also represented in solid line (-), and the associated reference, corresponding to n -hexanol with 10% unleaded 95, analyzed under the same conditions. On the Figure 3Bis represented in dotted line (···) the time-resolved emission spectrum (delay 0.1 ms, acquisition time 1 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 275 nm of the PCTA(Tb) marker at 100 ppb in diesel diluted 10 times in the n -hexanol according to example 10, and in solid line (-) the associated reference, corresponding to n -hexanol with 10% diesel, analyzed under the same conditions. In this figure, is also represented in broken line (---) the time-resolved emission spectrum of the PCTA(Tb) marker at 100 ppb in unleaded 95 prepared according to example 11 analyzed under the same conditions, and in alternating dash-dot (-··-) the associated reference, corresponding to n -hexanol with 10% unleaded 95, analyzed under the same conditions. On the Figure 4AThe time-resolved excitation spectrum is represented in solid lines (delay 0.1 ms, acquisition time 1 ms, total decay time 20 ms, accumulation of 0.05 s per point) considering the emission line at 545 nm of the TMPAC(Tb) marker at 100 ppb in diesel diluted 10 times in the n -hexanol according to example 12, and in broken line the associated reference, corresponding to n -hexanol with 10% diesel, analyzed under the same conditions. On the Figure 4B is represented in solid line the time-resolved emission spectrum (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 275 nm of the TMPAC(Tb) marker at 100 ppb in diesel diluted 10 times in the n -hexanol prepared according to example 12, and in broken line the associated reference, corresponding to n -hexanol with 10% diesel, analyzed under the same conditions. The Figure 5represents a possible assembly for the time-resolved fluorescence detection of complexes according to a particular embodiment of the invention. This is an assembly used for detection using a solid support. The Figure 6A represents the time-resolved emission spectra (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 270 nm of the PCTA(Tb) marker at different concentrations in lead-free 95 prepared according to Example 13. In increasing order of intensity at 550 nm, the curves represent respectively: the reference (lead-free 95), 25, 50 and 100 ppb of PCTA(Tb). On the Figure 6Bare represented the time-resolved emission spectra (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 270 nm of the TMPAC(Tb) marker at different concentrations in lead-free 95 prepared according to Example 14. In an increasing order of intensity at 550 nm, the curves represent respectively: the reference (lead-free 95), 25 and 50 ppb of TMPAC(Tb). On the Figure 7A is represented in solid line the time-resolved emission spectrum (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 270 nm of the PCTA(Eu) marker at 50 ppb in lead-free 95 and in broken line the same marker at 200 ppb in lead-free 95, both prepared according to example 15. On the Figure 7Bis represented in solid line the time-resolved emission spectrum (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 270 nm of the TMPAC(Eu) marker at 200 ppb in lead-free 95 and in broken line the same marker at 50 ppb in lead-free 95, both prepared according to example 16. On the Figure 7C is represented in solid line the time-resolved emission spectrum (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 270 nm of the TMPAC(Eu) marker at 5 ppb in diesel and in broken line the same marker at 20 ppb in diesel, both prepared according to example 17. Figure 8Arepresents the time-resolved emission spectra (delay 0.5 ms, acquisition time 1 ms, total decay time 20 ms, accumulation of 0.1 s per point) under excitation at 225 nm of the DOTA(Tb) marker at different concentrations in lead-free 95 prepared according to Example 18. In increasing order of intensity at 550 nm, the curves represent respectively: the reference (lead-free 95), 5.76, 11.52, 23.04, 38.40, 64.00 and 80.00 ppb of DOTA(Tb). The Figure 8B represents the correlation between the concentration and the intensity of the emission signal. The Figure 9Arepresents the time-resolved emission spectra (delay 0.5 ms, acquisition time 1 ms, total decay time 20 ms, accumulation of 0.1 s per point) under excitation at 225 nm of the DOTA(Tb) marker at different concentrations in diesel prepared according to Example 19. In increasing order of intensity at 550 nm, the curves represent respectively: the reference (diesel), 5, 10, 20, 40, 60 and 80 ppb of DOTA(Tb). Figure 9B represents the correlation between the concentration and the area of ​​the emission signal between 531 and 557 nm. The Figure 10represents the time-resolved emission spectrum of the DOTA(Tb) marker at 0.8 ppb in unleaded 95 prepared according to Example 20. The solid line corresponds to an analysis with a delay of 0.5 ms, an acquisition time of 1 ms and a total decay time of 20 ms with an accumulation of 1 s per point. The broken line corresponds to an analysis with a delay of 0.2 ms, an acquisition time of 1 ms and a total decay time of 20 ms with an accumulation of 1 s per point. On the Figure 11 The time-resolved emission spectrum (delay 0.5 ms, acquisition time 1 ms, total decay time 20 ms, accumulation of 1.5 s per point) under excitation at 225 nm of the DOTA(Tb) marker at 160 ppb in crude oil prepared according to Example 21 is shown in solid lines. The dashed line represents the associated reference, corresponding to unlabeled crude oil, analyzed under the same conditions. Figure 12Arepresents the time-resolved emission spectrum (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 395 nm of the ligand at different concentrations in diesel prepared according to Example 28. In increasing order of intensity at 620 nm, the curves represent respectively: the reference (diesel), 100 and 200 ppb of ligand. Figure 12B represents the time-resolved emission spectrum (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 395 nm of the ligand at different concentrations in lead-free 95 prepared according to Example 29. In increasing order of intensity at 620 nm, the curves represent respectively: the reference (lead-free 95), 100 and 200 ppb of the ligand. Figure 13 Arepresents the time-resolved emission spectrum (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 315 nm of the terbium salt at different concentrations in lead-free 95 prepared according to Example 30. In increasing order of intensity at 545 nm, the curves represent respectively: the reference (lead-free 95), 10 and 100 ppb of terbium salt. Figure 13 B represents the time-resolved emission spectrum (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 315 nm of the europium salt at different concentrations in lead-free 95 prepared according to Example 31. In increasing order of intensity at 615 nm, the curves represent respectively: 37.5, 50 and 100 ppb of europium salt. Figure 14 Arepresents the time-resolved emission spectrum (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 315 nm of the 200 ppb terbium salt in crude oil prepared according to Example 32 and Figure 14 B represents the time-resolved emission spectrum (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 315 nm of the 200 ppb europium salt in crude oil prepared according to Example 33. The Figure 15 A represents the time-resolved emission spectrum (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 315 nm of the terbium and europium salts at 100 ppb in lead-free 95 prepared according to examples 30 and 31 with the europium salt in solid line and the terbium salt in broken line. Figure 15 B and the Figure 15Crepresent the time-resolved emission spectra (delay 0.1 ms, acquisition time 5 ms, total decay time 10 ms, accumulation of 0.1 s per point) under excitation at 315 nm of the mixtures of salts in lead-free 95 prepared according to example 34 with for 15B a concentration of terbium salt and europium salt in lead-free 95 of 50 ppb and for 15C a concentration of terbium salt of 75 ppb and a concentration of europium salt of 25 ppb. DETAILED DESCRIPTION OF THE INVENTION

[0021] The invention therefore relates to the use, as markers for petroleum products, crude oils, biofuels or lubricants, of a rare earth complex

[0022] A "marker" is a chemical substance introduced alone or in combination into a product, and having specific physicochemical properties that make it possible to authenticate the origin or verify the integrity of a product previously marked by a quantitative, semi-quantitative or qualitative physical or chemical analysis method. The marker must therefore be detectable in the marked product to ensure its traceability.

[0023] The term "rare earth complex" means a polyatomic structure comprising at least the following constituents: (i) a rare earth metal cation and (ii) one or more ligands, said metal cation being associated with said ligands by non-covalent bonds to form the rare earth complex.

[0024] The term "rare earths" refers to the group consisting of scandium, yttrium and the lanthanides. Preferably, the rare earth in the metal complex is a metal from the lanthanide series. The metals in the lanthanide series are elements with atomic numbers ranging from 57 (lanthanum) to 71 (lutetium). For example, the lanthanides will be chosen from the group consisting of: Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb.

[0025] The term "ligand" refers to any molecule capable of forming a complex with a metal cation. A single metal cation can be complexed by one or more ligands. When the metal complex includes several ligands, these can be identical or different.

[0026] Preferably, the ligand is chosen so that the metal complex has a dissociation constant Kd less than 1×10 -5< and preferably less than 1×10 -10< corresponding to a pKd greater than 5 and preferably greater than 10.

[0027] For the purposes of the invention, the term "dissociation constant" means the value of the equilibrium constant between the metal cation in the state complexed by the complexing agent, and the free metal cation and complexing agent dissociated in the solvent (Kd). Specifically, the pKd is the opposite of the base 10 logarithm of the dissociation constant (-log(Kd)), defined as the equilibrium constant of the reaction which reflects the transition from the complexed state to the ionic state.

[0028] The ligand is preferably a polydentate ligand comprising at least 3, preferably at least 4, coordination sites. Preferably, the ligand is chosen from polyamine and / or polycarboxylic acid type molecules and their derivatives, among which esters and amides may be mentioned. It is preferably a cyclic molecule.

[0029] According to a preferred embodiment of the invention, the polydentate ligand comprises a heterocycle and at least 3, preferably 4, coordination sites of said polydentate ligand form, with other atoms, said heterocycle.

[0030] In a more preferred embodiment, the ligand of the rare earth complex is chosen from: 2,2',2",2‴-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (DOTA), of formula (I) and its derivatives, among which may be mentioned DOTA-GA (2,2',2"-(10-(2,6-dioxotetrahydro-2H-pyran-3-yl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid), DOTAEt (2,2',2",2‴-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetate tetraethyl), DOTAM (2,2',2",2‴-(1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetamide) and DO3A-pyridine of formula (II); 2,2',2"-[3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-3,6,9-triyl]triacetic acid (PCTA), of formula (III) and its derivatives, among which may be mentioned esters and amides; tetra-6-(methylene) picolinic acid cyclen (TMPAC) of formula (IV) and its derivatives, among which may be mentioned esters and amides; 2,2',2"-(1,4,7-triazonane-1,4,7-triyl)triacetic acid (NOTA), of formula (V), and its derivatives, including esters and amides. 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA or cyclam) and its derivatives, including tetra-6-(methylene) picolinic acid cyclam (VI)

[0031] Among the other ligands that can be used according to the invention, mention may be made of dendrimers, ethylenediaminetetraacetic acid (EDTA), nitriloacetic acid (NTA), glutamic diacetic acid (GLDA), phosphonates, cyclodextrins and their derivatives, chitosan and bacterial or algal polysaccharides.

[0032] Advantageously, the rare earth complex is detectable by time-resolved fluorescence. The time-resolved fluorescence detection method, i.e. triggered with a delay after excitation (i.e. a few microseconds), is for example described in the article "Ultrasensitive Bioanalytical Assays Using Time-Resolved Fluorescence Detection", Pharmac. Ther. Vol. 66, pp. 207-235, 1995. This method makes it possible to eliminate a large part of the luminescence intrinsic to the labeled petroleum product and to measure only that relating to the marker.

[0033] According to one embodiment of the invention, the ligand comprises an aromatic cycle comprising at least one nitrogen or sulfur atom or several conjugated aromatic cycles which act as an antenna, i.e. they amplify the fluorescent signal emitted by the marker.

[0034] The term "petroleum product" means crude oil derivatives resulting from the refining of crude oil. Specifically, this includes gasoline, diesel, kerosene, fuel oil, LPG, bitumen, and tar. The petroleum product is preferably gasoline, diesel, fuel oil, or kerosene.

[0035] Crude oils mean mineral oils composed of an unrefined mixture of hydrocarbons.

[0036] The term "biofuel" refers to a fuel derived from biomass. Biofuels can be used alone or in a blend with fossil fuels. Examples of biofuels include biodiesel and bioethanol.

[0037] A "lubricant" is a product that reduces friction between two elements in contact and moving relative to each other. These are most often oils, including: Mineral oils, which include all types of oils obtained by atmospheric or vacuum distillation of fossil fuels; Vegetable oils, which include all types of oils obtained by crushing the seeds, kernels or fruits of plants, in particular oil-producing plants. Examples include linseed, rapeseed, sunflower, soybean, olive, palm, palm kernel, castor, wood, corn, pumpkin, grape seed, jojoba, sesame, walnut, hazelnut, almond, shea, peanut, copra, tungsten wood, macadamia, cottonseed, alfalfa, rye, safflower, peanut, copra, pine, pumpkin, rice, and argan oils.Also considered as lubricants are derivatives of these oils, in particular their isomers and / or acids and / or amides and / or esters, more particularly their transesterification derivatives; animal oils such as tallow and lard oils; synthetic oils such as polyalphaolefins.

[0038] The rare earth complexes may also be used in combination with other markers of petroleum products, crude oils, biofuels or lubricants, or with other rare earth complexes as defined above, or one of its constituents chosen from rare earth ligands or salts and being capable of forming a rare earth complex after addition of a revealing solution.

[0039] The invention also relates to the provision of a petroleum product, crude oil, biofuel or lubricant characterized in that it comprises as marker at least one rare earth complex as defined above.

[0040] According to the invention, said rare earth complex is contained in the petroleum product, crude oil, biofuel or lubricant, at a concentration less than or equal to 1 ppm, and even more preferably less than or equal to 100 ppb, for example between 1 ppb and 1 ppm, and in particular between 10 ppb and 100 ppb.

[0041] According to one embodiment of the invention, said ligand capable of forming a rare earth complex contained in the petroleum product, crude oil, biofuel or lubricant, is chosen from DOTA, NOTA, DOTAM, PCTA, TMPAC and their derivatives. The invention also relates to a crude oil, a biofuel, a lubricant or a petroleum product, in particular gasoline, fuel oil, kerosene or diesel, characterized in that it comprises a rare earth complex, for example a lanthanide complexed with a ligand, at a concentration less than or equal to 100 ppb, said rare earth complex being detectable by time-resolved fluorescence.

[0042] The invention also relates to a method for marking petroleum products, crude oils, biofuels or lubricants, characterized in that it essentially consists of adding to a petroleum product, crude oil, biofuel or lubricant a rare earth complex or a rare earth salt, said rare earth salt being capable of forming a rare earth complex, after adding a revealing solution comprising a ligand.

[0043] The invention also relates to a method for detecting a rare earth complex as a marker for petroleum products, crude oils, biofuels or lubricants.

[0044] This method comprises the time-resolved fluorescence detection of the rare earth complex as defined above, in a sample of petroleum product, crude oil, biofuel or lubricant.

[0045] Advantageously, the rare earth complex is detected by time-resolved fluorescence after extraction thereof into an immiscible solution, preferably an aqueous solution. In this case, the method comprises the following steps: a) Mixing a sample of petroleum product, crude oil, biofuel or lubricant comprising as a marker a rare earth complex detectable by time-resolved fluorescence with an immiscible solution, preferably an aqueous solution; b) Detection of the rare earth complex by time-resolved fluorescence of the immiscible solution.

[0046] The rare earth complex can also be detected using a solid support such as paper, strip, filter or solid planar support. In this case, the method includes the following steps: a) Impregnation of a solid support with the petroleum product, crude oil, biofuel or lubricant comprising as a marker a rare earth complex; b) Detection of the rare earth complex by time-resolved fluorescence carried out on the solid support.

[0047] An example of a setup used for time-resolved fluorescence analysis using a solid support is provided in Figure 5 .

[0048] According to one embodiment described, the marking can be done indirectly. The petroleum product, crude oil, biofuel or lubricant then contains only one of the constituents of the rare earth complex, namely, the ligand or the rare earth ion, and the complex is formed only at the time of detection, by adding a revealing solution comprising the other constituent, the rare earth ion or ligand, to form said complex. By "revealing solution", we mean a solution comprising the other constituent in sufficient concentration to form a quantity of complex sufficient to be detectable by time-resolved fluorescence under appropriate conditions. The following two embodiments are thus also part of the invention: According to one embodiment of the invention, the method comprises the following steps: a) Preparation of a sample of petroleum product, crude oil, biofuel or lubricant comprising a ligand, said ligand being capable of forming a rare earth complex detectable by time-resolved fluorescence, after addition of a revealing solution comprising a rare earth salt; b) Formation of the rare earth complex by addition of a revealing solution comprising a rare earth salt; c) Detection of the rare earth complex by time-resolved fluorescence.

[0049] According to another embodiment, the method comprises the following steps: a) Preparation of a sample of petroleum product, crude oil, biofuel or lubricant comprising a rare earth salt, said rare earth salt being capable of forming a rare earth complex detectable by time-resolved fluorescence, after addition of a revealing solution comprising a ligand; b) Formation of the rare earth complex by addition of a revealing solution comprising a ligand; c) Detection of the rare earth complex by time-resolved fluorescence.

[0050] In the above detection methods, the step of detecting the rare earth complex by time-resolved fluorescence may comprise the following substeps: a) emitting pulsed light on the sample of petroleum product, crude oil, biofuel or lubricant, b) detecting the light emitted by the sample after at least 100 nanoseconds, preferably at least 1 microsecond after the end of the excitation pulse,

[0051] The detection of certain specific wavelengths of the rare earth complex to determine the presence of said complex in the sample. EXAMPLES

[0052] Time-resolved fluorescence analyses were performed on a Varian Cary Eclipse spectrofluorometer or an Agilent Cary Eclipse spectrofluorometer.

[0053] Unless otherwise stated, the microcuvettes used are Hellma ®< fluorescence quartz microcuvettes.

[0054] Ligands were purchased from CheMatech ®< (Dijon, France) and were used as received.

[0055] LH8, which is a ligand capable of forming a rare earth complex according to the invention, was purchased from Nano-H (Saint Quentin Fallavier, France) and used as is.

[0056] Crude oil comes from the Middle East. 1) Preparation of complexes

[0057] Example 1:20 mg of PCTA (2,2',2"-[3,6,9,15-tetraazabicyclo[9.3.1] pentadeca-1(15),11,13-triene-3,6,9-triyl]triacetic acid) are placed in a 120 mL flask. 100 mL of DMSO are added to the flask, which is then stirred until the ligand is completely dispersed. A 200 ppm solution of PCTA is then obtained. 40 mg of europium trichloride hexahydrate (EuCl 3 .6H 2 O) are weighed into a 120 mL flask. Subsequently, 100 mL of DMSO are added to the flask, which is stirred for approximately 1 h. A 400 ppm solution of EuCl 3 .6H 2 O is then obtained in the flask.

[0058] 1 mL of PCTA solution is introduced into a 15 mL flask in the presence of 1 mL of EuCl 3 .6H 2 O solution. The mixture is stirred and then 8 mL of n-hexanol is added to the mixture. The system is then stirred at 50°C for approximately 12 hours. A 200 ppm PCTA(Eu) solution is then obtained.

[0059] Example 2: A solution of PCTA(Tb) complex is prepared according to the procedure described in Example 1 using terbium trichloride hexahydrate (TbCl 3 .6H 2 O) instead of EuCl 3 .6H 2 O.

[0060] Example 3 : A solution of PCTA(Dy) complex is prepared according to the procedure described in Example 1 using dysprosium trichloride hexahydrate (DyCl 3 .6H 2 O) instead of EuCl 3 .6H 2 O.

[0061] Example 4 : A DOTA(Eu) complex solution is prepared according to the procedure described in Example 1 using DOTA (2,2',2",2"'-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid) instead of PCTA.

[0062] Example 5: A DOTA(Tb) complex solution is prepared according to the procedure described in Example 1 using DOTA (2,2',2",2"'-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid) instead of PCTA and using terbium trichloride hexahydrate (TbCl 3 .6H 2 O) instead of EuCl 3 .6H 2 O.

[0063] Example 6 : A DOTA(Dy) complex solution is prepared according to the procedure described in Example 1 using DOTA (2,2',2",2"'-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid) instead of PCTA and using dysprosium trichloride hexahydrate (DyCl 3 .6H 2 O) instead of EuCl 3 .6H 2 O.

[0064] Example 7 : A solution of TMPAC(Eu) complex is prepared according to the procedure described in Example 1 using TMPAC (Tetra-6-(methylene)picolinic acid cyclen) instead of PCTA.

[0065] Example 8: A solution of TMPAC(Tb) complex is prepared according to the procedure described in Example 1 using TMPAC (Tetra-6-(methylene)picolinic acid cyclen) instead of PCTA and using terbium trichloride hexahydrate (TbCl 3 .6H 2 O) instead of EuCl 3 .6H 2 O.

[0066] Example 9 : A solution of TMPAC(Dy) complex is prepared according to the procedure described in Example 1 using TMPAC (Tetra-6-(methylene)picolinic acid cyclen) instead of PCTA and using dysprosium trichloride hexahydrate (DyCl 3 .6H 2 O) instead of EuCl 3 .6H 2 O.

[0067] THE Figures 1A, 1B , 1C and 1D represent the time-resolved emission spectra of the DOTA(Tb), DOTA(Eu), PCTA(Tb) and TMPAC(Tb) complexes in the n -hexanol. The Figures 2A and 2B represent the emission spectra of the DOTA(Tb) complex at different concentrations in the n-hexanol and the correlation between concentration and emission intensity. These data show that it is possible to perform quantitative analyses of complexes down to very low concentrations, below 100 ppb. 2) Detection of complexes in unleaded 95 and diesel

[0068] The obtained complexes are tested as markers of unleaded 95 and diesel.

[0069] Example 10 : A PCTA(Tb) solution obtained according to example 2 is diluted in diesel to reach a PCTA(Tb) concentration of 100 ppb. The solution obtained is then diluted by 10 in n -hexanol. This mixture is analyzed by time-resolved fluorescence at a rate of 500 µl placed in a cuvette (ref: semi-micro cuvette in PMMA, BRAND ®< ).

[0070] Example 11: A PCTA(Tb) solution obtained according to example 2 is diluted in unleaded 95 to reach a PCTA(Tb) concentration of 100 ppb. The solution obtained is then diluted by 10 in n -hexanol. This mixture is analyzed by time-resolved fluorescence at a rate of 500 µl placed in a cuvette (ref: semi-micro cuvette in PMMA, BRAND ®< ).

[0071] Example 12 : A solution of TMPAC(Tb) obtained according to Example 8 is diluted in diesel to reach a TMPAC(Tb) concentration of 100 ppb. The solution obtained is then diluted by 10 in n -hexanol. This mixture is analyzed by time-resolved fluorescence at a rate of 500 µl placed in a cuvette (ref: semi-micro cuvette in PMMA, BRAND ®< ).

[0072] THE figures 3(A and B) and 4 (A and B) represent the time-resolved excitation and emission spectra of the PCTA(Tb) complex in unleaded 95 and diesel fuel and the time-resolved excitation and emission spectra of the TMPAC(Tb) complex in diesel fuel, respectively. These data show that unleaded 95 and diesel fuel can be labeled with rare earth complexes. 3) Detection of complexes in unleaded 95 and diesel using a solid support

[0073] Example 13: A PCTA(Tb) solution obtained according to example 2 is diluted in lead-free 95 to reach a PCTA(Tb) concentration of 100 ppb, 50 ppb or 25 ppb. After incubating a nylon membrane (ref: Magna Nylon Membrane Filter 47 mm NY Membrane 0.45 µm) for 30 seconds in one of the solutions obtained, the membrane is analyzed by time-resolved fluorescence using a solid sample holder (ref: Agilent Cary Eclipse solid sample holder). The measurements are carried out with a sample placed at 45° in the beam according to the device shown in Figure 5 .

[0074] Example 14 : A TMPAC(Tb) solution obtained according to Example 8 is diluted in unleaded 95 to reach a TMPAC(Tb) concentration of 50 ppb or 25 ppb, then analyzed according to the protocol described in Example 13.

[0075] Example 15: A PCTA(Eu) solution obtained according to Example 1 is diluted in lead-free 95 to reach a PCTA(Eu) concentration of 200 ppb or 50 ppb, then the mixture is analyzed according to the protocol described in Example 13.

[0076] Example 16 : A TMPAC(Eu) solution obtained according to Example 7 is diluted in unleaded 95 to reach a TMPAC(Eu) concentration of 200 ppb or 50 ppb, then the mixture is analyzed according to the protocol described in Example 13.

[0077] Example 17 : A TMPAC(Eu) solution obtained according to Example 7 is diluted in diesel to reach a TMPAC(Eu) concentration of 200 ppb or 50 ppb. The solution is then diluted by 10 in isopropanol and the mixture is analyzed according to the protocol described in Example 13.

[0078] THE Figures 6A and 6B represent the time-resolved emission spectra of the PCTA(Tb) and TMPAC(Tb) complexes in unleaded 95. The Figures 7A and 7Brepresent the time-resolved emission spectra of the PCTA(Eu) and TMPAC(Eu) complexes in lead-free 95. The Figure 7C represents the time-resolved emission spectrum of the TMPAC(Eu) complex in diesel. These data show that these complexes are detectable in unleaded 95 and diesel at quantities below 100 ppb, up to 25 ppb for some complexes. 4) Detection of complexes in unleaded 95 and diesel by extraction using an immiscible solution

[0079] Example 18:A DOTA(Tb) solution obtained according to Example 5 is diluted in lead-free 95 to achieve a DOTA(Tb) concentration of 100 ppb. This solution is then diluted in lead-free 95 to achieve the desired DOTA(Tb) concentration and 25 mL are placed in the presence of 5 mL of ultrapure water in a suitable flask. The whole is shaken vigorously for 30 seconds. The flask is then opened to allow the separation of the two phases. After approximately 10 minutes, 500 µl of the aqueous phase are collected and then analyzed by time-resolved fluorescence in a micro-cuvette. Between each analysis, the micro-cuvette is first washed with hydrochloric acid (12 M) then thoroughly rinsed with water and finally with ethanol.

[0080] Example 19:A DOTA(Tb) solution obtained according to Example 5 is diluted in diesel to achieve a DOTA(Tb) concentration of 100 ppb. This solution is then diluted in diesel to achieve the desired DOTA(Tb) concentration and 25 mL are placed in the presence of 5 mL of ultrapure water in a suitable flask. The whole is shaken vigorously for 30 seconds. The flask is then opened to allow the separation of the two phases. After approximately 10 minutes, 500 µl of the aqueous phase are collected and then analyzed by time-resolved fluorescence in a micro-cuvette. Between each analysis, the micro-cuvette is first washed with hydrochloric acid (12 M) then thoroughly rinsed with water and finally with ethanol.

[0081] Example 20: A DOTA(Tb) solution obtained according to Example 5 is diluted in unleaded 95 to reach a DOTA(Tb) concentration of 80 ppb. This solution is then diluted in unleaded 95 to reach a DOTA(Tb) concentration of 0.8 ppb and 100 mL are placed in the presence of 10 mL of ultrapure water in a 250 mL single-necked flask. The mixture is stirred vigorously. Then, approximately 95 mL of the mixture is evaporated. 5 mL of water is then added and the mixture is stirred. After 5 minutes of rest, 500 µl of the aqueous phase is taken and then analyzed by time-resolved fluorescence in a micro-cuvette.

[0082] THE figures 8(A and B) and 9 (A and B) represent the time-resolved emission spectra of the DOTA(Tb) complex at different concentrations in unleaded 95 and diesel and the correlation between concentration and emission intensity. These data show that it is possible to perform quantitative analyses of rare earth complexes in these fuels down to very low concentrations.

[0083] There Figure 10 represents the time-resolved emission spectrum of the DOTA(Tb) complex at 0.8 ppb in unleaded 95. These data show that the detection of rare earth complexes as markers can be performed at concentrations below 1 ppb. 5) Detection of complexes in crude oil.

[0084] Example 21: A DOTA(Tb) solution obtained according to Example 5 is diluted in n-hexanol to achieve a DOTA(Tb) concentration of 10 ppm. 100 mL of crude oil is then labeled at 160 ppb using this solution. After adding 10 mL of water to the labeled crude oil, the mixture is stirred for at least 1 hour. The mixture is placed in a 250 mL separating funnel. 100 mL of cyclohexane is then added. After closing the funnel, it is stirred, taking care to degas the pressurized system. The funnel is then left to stand after opening. Once the phases are separated, the aqueous phase is sampled and analyzed by time-resolved fluorescence in a microcuvette.

[0085] There Figure 11 represents the emission spectrum of the DOTA(Tb) complex in crude oil. These data show that it is also possible to use rare earth complexes as crude oil markers. 6) Indirect marking Examples 22: Preparation of a europium revealing solution

[0086] 100 mg of europium chloride hexahydrate (EuCl 3 .6H 2 O) is weighed into a 100 mL flask and 100 mL of water is added. 2.5 mL of the resulting solution is then introduced into a 50 mL flask and 47.5 mL of n -hexanol are added. Example 23: Preparation of a LH8 revealing solution in organic medium (5% H 2 O )

[0087] 10 mg of LH8 are weighed into a 100 mL flask and 100 mL of ultrapure water are added. The mixture is stirred for approximately 10 minutes. 2.5 mL of the resulting solution is introduced into a 60 mL flask containing 47.5 mL of n- hexanol with stirring. Example 24: Preparation of a LH8 revealing solution in aqueous medium

[0088] 10 mg of LH8 is weighed into a 100 mL flask and 100 mL of ultrapure water is added. The mixture is stirred for approximately 10 minutes. 2.5 mL of the resulting solution is added to a 60 mL flask. 47.5 mL of ultrapure water is then added and the system is stirred. Example 25: Preparation of a ligand (label) solution

[0089] 20 mg of 1,3-di-pyridin-3-yl-propane-1,3-dione are weighed into a 100 mL bottle and 100 mL of n -hexanol are then added. A 200 ppm solution is then obtained. Example 26: Preparation of a europium solution (marker)

[0090] 10 mL of europium chloride solution prepared according to Example 1 and 90 mL of n- hexanol are introduced into a 100 mL flask and the system is stirred. A 40 ppm solution is then obtained. Example 27: Preparation of a terbium solution (marker)

[0091] 10 mL of terbium chloride solution prepared according to Example 2 and 90 mL of n- hexanol are introduced into a 100 mL flask and the system is stirred. A 40 ppm solution is then obtained.

[0092] Example 28: 250 µL of ligand solution prepared according to Example 25 are introduced into a 10 mL bottle and 9.75 mL of diesel are then added. This 5 ppm ligand solution is then diluted in diesel to the desired concentration. 1 mL of the solution obtained is placed in the presence of 1 mL of europium revealing solution, prepared according to Example 22, in a cuvette (ref: Sarstedt ®< PMMA cuvette 2.5-4.5 mL). 100 µL of ultrapure water are then added to the cuvette. After approximately 10 minutes, the contents of the cuvette are analyzed by time-resolved fluorescence.

[0093] Example 29: 250 µL of the ligand solution prepared according to Example 25 are introduced into a 10 mL vial and 9.75 mL of lead-free 95 are then added. This 5 ppm ligand solution is then diluted in lead-free 95 to the desired concentration. 1 mL of the solution obtained is placed in the presence of 1 mL of europium revealing solution, prepared according to Example 22, in a cuvette (ref: Sarstedt ®< PMMA cuvette 2.5-4.5 mL). 100 µL of ultrapure water are then added to the cuvette. After approximately 10 minutes, the contents of the cuvette are analyzed by time-resolved fluorescence.

[0094] THE Figures 12A and 12B represent the time-resolved emission spectra of the rare earth complex after addition of a developer solution to a ligand solution in diesel fuel and in unleaded 95 gasoline. These data show that indirect labeling is possible by adding only the ligand to the petroleum product.

[0095] Example 30:250 µL of the terbium chloride solution prepared according to Example 27 are introduced into a 60 mL flask with 49.75 mL of 95 unleaded gasoline. The system is then stirred. This 200 ppb rare earth salt solution is then diluted in 95 unleaded to the desired concentration. 200 µL of the solution obtained are placed in the presence of 1.8 mL of developer solution, prepared according to Example 23, in a cuvette (ref: Sarstedt ® PMMA cuvette < 2.5-4.5 mL). After approximately 10 minutes, the contents of the cuvette are analyzed by time-resolved fluorescence.

[0096] Example 31:250 µL of the europium chloride solution prepared according to Example 26 are introduced into a 60 mL flask with 49.75 mL of lead-free 95. The system is then stirred. This 200 ppb rare earth salt solution is then diluted in lead-free 95 to the desired concentration. 200 µL of the resulting solution are placed in the presence of 1.8 mL of developer solution prepared according to Example 23 in a cuvette (ref: Sarstedt ® PMMA cuvette < 2.5-4.5 mL). After approximately 10 minutes, the contents of the cuvette are analyzed by time-resolved fluorescence.

[0097] THE Figures 13A and 13B represent the time-resolved emission spectra of the complex after addition of a developer solution to a rare earth salt solution in unleaded 95 gasoline. These data show that indirect labeling is possible by adding only the rare earth salt to the petroleum product.

[0098] Example 32:250 µL of the terbium chloride solution prepared in Example 27 is introduced into a 60 mL flask with 49.75 mL of crude oil. The system is then stirred. 2 mL of the resulting 200 ppb rare earth salt solution is placed in a 50 mL centrifuge tube and 18 mL of developer solution prepared according to Example 24 is then added. The sample is shaken vigorously for 30 seconds and then centrifuged at 1500 rpm for 5 minutes. 3 mL of aqueous phase is taken and placed in a cuvette (ref: Sarstedt ® PMMA cuvette < 2.5-4.5 mL). The contents of the cuvette are then analyzed by time-resolved fluorescence.

[0099] Example 33:250 µL of the europium chloride solution prepared in Example 26 is introduced into a 60 mL flask with 49.75 mL of crude oil. The system is then stirred. 2 mL of the resulting 200 ppb rare earth salt solution is placed in a 50 mL centrifuge tube and 18 mL of developer solution prepared according to Example 24 is then added. The sample thus prepared is stirred vigorously for 30 seconds and then centrifuged at 1500 rpm for 5 minutes. 3 mL of aqueous phase is taken and then placed in a cuvette (ref: Sarstedt ® PMMA cuvette < 2.5-4.5 mL). The contents of the cuvette are then analyzed by time-resolved fluorescence.

[0100] THE Figures 14A and 14Brepresent the time-resolved emission spectra of europium and terbium complexes after addition of a developer solution to crude oil containing a rare earth salt. These data show that indirect labeling is also possible in crude oil.

[0101] Example 34: Unleaded 95 solutions comprising both terbium salt and europium salt are prepared. The different concentrations are obtained after successive dilutions from the stock solutions of unleaded 95 gasoline labeled at 200 ppb in terbium or europium salt (respectively examples 27 and 26). 200 µL of the solution obtained are placed in the presence of 1.8 mL of developer solution, prepared according to example 23, in a cuvette (ref: Sarstedt ® PMMA cuvette < 2.5-4.5 mL). The contents of the cuvette are then analyzed by time-resolved fluorescence.

[0102] THE figures 15A, 15B And 15Crepresent the time-resolved emission spectra of europium and terbium complexes after addition of a developer solution in unleaded 95 gasoline comprising a combination of rare earth salts. These data show that it is possible to combine several markers.

Claims

1. The use, as markers of petroleum products, crude oils, biofuels or lubricants, of a rare earth complex.

2. The use as claimed in claim 1, characterized in that the rare earth is selected from the lanthanides, preferably from Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb.

3. The use as claimed in one of claims 1 or 2, characterized in that said rare earth complex comprises at least one multidentate ligand comprising at least 3, preferably at least 4, coordination sites.

4. The use as claimed in claim 3, characterized in that the multidentate ligand comprises a heterocycle and in that at least 3, preferably 4, coordination sites of said multidentate ligand form, with other atoms, said heterocycle.

5. The use as claimed in any one of the preceding claims, characterized in that the rare earth complex comprises a ligand selected from molecules of the polyamine and / or polycarboxylic acid type, and preferably the ligand is selected from DOTA, NOTA, DOTAM, PCTA, TMPAC and derivatives thereof.

6. The use as claimed in any one of the preceding claims, characterized in that the rare earth complex is detectable by time-resolved fluorescence.

7. The use as claimed in any one of the preceding claims, characterized in that the rare earth complex comprises a ligand, said ligand comprises at least one aromatic ring containing at least one nitrogen atom or sulfur atom or conjugated aromatic rings, to produce an antenna effect.

8. The use as claimed in any one of the preceding claims, characterized in that the petroleum product is gasoline, fuel oil, kerosene or gas oil.

9. A petroleum product, crude oil, biofuel or lubricant, characterized in that it comprises, as a marker, at least one rare earth complex as defined in the preceding claims and in that said rare earth complex is contained in the petroleum, product biofuel or lubricant at a concentration less than or equal to 1 ppm, preferably less than or equal to 100 ppb, for example between 1 ppb and 1 ppm, and notably between 10 ppb and 100 ppb.

10. A method for marking petroleum products, crude oils, biofuels or lubricants, characterized in that it consists essentially of adding, to a petroleum product, crude oil, biofuel or lubricant a rare earth complex or a rare earth salt, said rare earth salt being capable of forming a rare earth complex, after adding a developing solution comprising a ligand.

11. A method for detecting a rare earth complex as a marker of petroleum products, crude oils, biofuels or lubricants, characterized in that it comprises time-resolved fluorescence detection of the rare earth complex in a sample of petroleum product, crude oil, biofuel or lubricant.

12. The method as claimed in claim 11, characterized in that it comprises the following steps: a) Preparing a sample of petroleum product, crude oil, biofuel or lubricant comprising a ligand, said ligand being capable of forming a rare earth complex detectable by time-resolved fluorescence, after adding a developing solution comprising a rare earth salt; b) Forming the rare earth complex by adding a developing solution comprising a rare earth salt; c) Detecting the rare earth complex by time-resolved fluorescence.

13. The method as claimed in claim 11, characterized in that it comprises the following steps: a) Preparing a sample of petroleum product, crude oil, biofuel or lubricant comprising a rare earth salt, said rare earth salt being capable of forming a rare earth complex detectable by time-resolved fluorescence, after adding a developing solution comprising a ligand; b) Forming the rare earth complex by adding a developing solution comprising a ligand; c) Detecting the rare earth complex by time-resolved fluorescence.

14. The method as claimed in claim 11, characterized in that it comprises the following steps: a) Mixing a sample of petroleum product, crude oil, biofuel or lubricant comprising, as marker, a rare earth complex detectable by time-resolved fluorescence, with an immiscible solution, preferably an aqueous solution; b) Detecting the rare earth complex by time-resolved fluorescence of the immiscible solution.

15. The method as claimed in claim 11, characterized in that it comprises the following steps: a) Impregnating a solid support with the petroleum product, crude oil, biofuel or lubricant comprising a rare earth complex as a marker; b) Detecting the rare earth complex by time-resolved fluorescence performed on the solid support.