Method for generating nitrite and / or nitrate ions from nitrate esters

Abstract

The present invention provides a method for generating nitrite and / or nitrate ions from a nitrate ester and a method for detecting nitrate esters in a mixture by generating and detecting nitrite and / or nitrate ions.

Description

[0001] DSM IP Assets B.V. 34802-WO-PCT

[0002] Method for generating nitrite and / or nitrate ions from nitrate esters

[0003] Technical Field

[0004] The present invention relates to a method for generating nitrite and / or nitrate ions from a nitrate ester and use thereof.

[0005] Background of the Invention

[0006] Organic nitrate esters are a class of compounds derived from the esterification of nitric acid with alcohols. They are widely used in applications such as explosives (e.g., nitroglycerin, PETN), propellants, food, feed and medicinal purposes (e.g., nitroglycerin as a vasodilator for heart conditions).

[0007] There are various methods for detecting organic nitrate esters which have advantage and disadvantages. For example, Gas Chromatography-Mass Spectrometry (GC-MS) and High- Performance Liquid Chromatography (HPLC) provide high sensitivity and specificity but are expensive and time-consuming, and Infrared Spectroscopy (IR) and Raman spectroscopy offer rapid, nondestructive analysis but lack sensitivity and are affected by sample complexity.

[0008] 3-nitrooxypropane-1-ol (3-NOP), as one of organic nitrate esters, is the active ingredient of animal feed additive for reducing the methane emissions from cows. Detection of 3-NOP in premix and animal feed is important to control if the animals received the compound and if the correct dose was administered. Currently, this requires shipment of a sample under controlled frozen conditions to a specialized lab. Fast and on-site detection of 3-NOP is useful.

[0009] Accordingly, there is still demand in fast, cheap and sensitive method for detection of organic nitrate ester, especially 3-NOP, in the industry.

[0010] Summary of the Invention

[0011] The present invention provides a method for generating nitrite and / or nitrate ions from a nitrate ester, and a method for detecting a nitrate ester in a mixture by generating and detecting nitrite and / or nitrate ions.

[0012] Detailed description of the Invention

[0013] Unless otherwise defined herein, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by those of ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular. Thus, as used in this specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly indicates otherwise. For example, reference to "a nitrate ester" includes populations of a plurality of nitrate esters.

[0014] In the present invention, the term “lower alkyl” as used refers to C1-10 alkyl, i.e., branched or unbranched, cyclic or non-cyclic, saturated hydrocarbon comprising 1-10 carbon atoms, including but not limited to methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, isobutyl, tert-butyl, cyclobutyl, pentyl, iso-pentyl, tert-pentyl, cyclopentyl, hexyl, isohexyl, tert-hexyl, cyclohexyl, octyl, isooctyl, tertoctyl, cyclooctyl, nonyl, isononyl, tert-nonyl, cyclononyl, decyl, isodecyl, tert-decyl, cyclodecyl. More preferably, the “lower alkyl” is C1-6 alkyl, more preferably is methyl or ethyl.

[0015] In the present invention, the term “substituent” or “substituents” as used refers to lower alkoxyl, hydroxyl, halo and / or -NH2.

[0016] In the present invention, the term “lower alkoxyl” as used refers to the structure represented by (lower alkyl)-O-, wherein the lower alkyl is as defined herein.

[0017] In the present invention, the term “halo” or “halogen” as used refers to a group of elements including fluorine (F), chlorine (Cl), bromine (Br) and iodine (I), preferably refers to Cl or Br.

[0018] Particularly, in the first aspect, the present invention provides a method for generating nitrite and / or nitrate ions from a nitrate ester, comprising contacting the nitrate ester with a reductant in an acidic solution.

[0019] In the present invention, the term “nitrate ester” refers to one or more chemical molecules with the following formula (I)

[0020] X-R-(ONO2)n (I)

[0021] Wherein:

[0022] R is lower alkyl, optionally substituted by one or more substituents,

[0023] X is H, OH or R’(CO)O- wherein R’ is lower alkyl, optionally substituted by one or more substituents, and n is 1 or 2.

[0024] R is preferably C3-10 alkyl such as propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, iso-pentyl, tertpentyl, hexyl, isohexyl, tert-hexyl, octyl, isooctyl, tert-octyl, nonyl, isononyl, tert-nonyl, decyl, isodecyl and tert-decyl, and more preferably propyl or isopropyl. X is preferably H, OH or R’(CO)O- wherein R’ is C1-6 alkyl, more preferably OH or CH3(CO)O- or C2H5(CO)O-.

[0025] In one embodiment, R is C3-10 alkyl such as propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, tert-pentyl, hexyl, isohexyl, tert-hexyl, octyl, isooctyl, tert-octyl, nonyl, isononyl, tert-nonyl, decyl, isodecyl and tert-decyl; and X is H, OH, CH3(CO)O- or C2H5(CO)O-; and X is 1 or 2.

[0026] As understood by any person skilled in the art, the position of the group “X” and the groups “-ONO2” are not limited in the formula (I), so they could be at any position of the lower alkyl group “R” as long as the chemical principle is satisfied. For example, the group “X” is at a “a” position, and the group “- ONO2” can be at a “a”, “p”, “y”, “6”,... or “co” position, or the group “X” is at a “p” position, and the group “-ONO2” can be at a “a”, “p”, “y”, “6”,... or “co” position. In case the compound of formula (I) contains two group “-ONO2”, the two could be also at any position of the lower alkyl group “R” as long as the chemical principle is satisfied.

[0027] More preferably, the nitrate ester in the present invention is selected from branched and non-branched nitrooxyC3-ioalkane-1-ols, as well as nitrates and lower alkyl esters thereof.

[0028] Examples of the nitrooxyC3-ioalkane-1-ols include but are not limited to 2-nitrooxypropane-1-ol, 3- nitrooxypropane-1 -ol, 2-nitrooxybutane-1-ol, 3-nitrooxybutane-1-ol, 4-nitrooxybutane-1-ol, 2 nitrooxypentane-1-ol, 3-nitrooxypentane-1-ol, 4-nitrooxypentane-1-ol, 5-nitrooxypentane-1-ol, 2- nitrooxyhexane-1-ol, 3-nitrooxyhexane-1 -ol, 4-nitrooxyhexane-1-ol, 5-nitrooxyhexane-1-ol, 6- nitrooxyhexane-1-ol, 2-nitrooxyheptane-1-ol, 3-nitrooxyheptane-1 -ol, 4-nitrooxyheptane-1-ol, 5- nitrooxyheptane-1-ol, 6-nitrooxyheptane-1-ol, 7-nitrooxyheptane-1 -ol, 2-nitrooxyoctane-1-ol, 3- nitrooxyoctane-1-ol, 4-nitrooxyoctane-1-ol, 5-nitrooxyoctane-1 -ol, 6-nitrooxyoctane-1-ol, 7- nitrooxyoctane-1-ol, 8-nitrooxyoctane-1-ol, 2-nitrooxynonane-1 -ol, 3-nitrooxynonane-1-ol, 4- nitrooxynonane-1-ol, 5-nitrooxynonane-1-ol, 6-nitrooxynonane-1 -ol, 7-nitrooxynonane-1-ol, 8- nitrooxynonane-1-ol, 9-nitrooxynonane-1-ol, 2-nitrooxydecane-1 -ol, 3-nitrooxydecane-1-ol, 4- nitrooxydecane-1 -ol, 5-nitrooxydecane-1 -ol, 6-nitrooxydecane-1-ol, 7-nitrooxydecane-1-ol, 8- nitrooxydecane-1 -ol, 9-nitrooxydecane-1-ol, and 10-nitrooxydecane-1-ol, and mixture thereof.

[0029] Examples of the nitrates of nitrooxyC3-ioalkane-1-ols include but are not limited to propane-1 , 2-diyl dinitrate, propane-1 , 3-diyl dinitrate, butane-1 , 2-diyl dinitrate, butane-1 ,3-diyl dinitrate, butane-1 ,4-diyl dinitrate, pentane-1 , 2-diyl dinitrate, pentane-1 , 3-diyl dinitrate, pentane-1 ,4-diyl dinitrate, pentane-1 , 5- diyl dinitrate, hexane-1 ,2-diyl-dinitrate, hexane-1 ,3-diyl-dinitrate, hexane-1 ,4-diyl-dinitrate, hexane-1 ,5- diyl-dinitrate, hexane-1 ,6-diyl-dinitrate, heptane-1 ,2-diyl-dinitrate, heptane-1 ,3-diyl-dinitrate, heptane- 1 ,4-diyl-d in itrate, heptane-1 ,5-d iy l-d initrate, heptane-1 ,6-diyl-d in itrate, heptane-1 ,7-d iy l-d initrate, octane-1 ,2-d iy l-dinitrate, octane-1 ,3-d iyl-d in itrate, octane-1 ,4-diyl-d in itrate, octane-1 ,5-d iy l-d initrate , octane-1 ,6-d iy l-dinitrate, octane-1 , 7-d iy l-dinitrate, octane-1 , 8-diy l-d in itrate, nonane-1 ,2-d iyl-din itrate, nonane-1 , 3-diyl-dinitrate, nonane-1 ,4-diyl-dinitrate, nonane-1 , 5-diyl-dinitrate, nonane-1 ,6-diyl-dinitrate, nonane-1 , 7-diyl-dinitrate, nonane-1 ,8-d iyl-d in itrate, nonane-1 , 9-diyl-d in itrate, decane-1 ,2-d iyl-d in itrate, decane-1 , 3-diyl-dinitrate, decane-1 ,4-diyl-dinitrate, decane-1 , 5-diyl-dinitrate, decane-1 ,6-diyl-dinitrate, decane-1 , 7-diyl-dinitrate, decane-1 , 8-diyl-dinitrate, decane-1 , 9-diyl-dinitrate and decane-1 ,10-diyl- dinitrate.

[0030] The lower alkyl esters of nitrooxyC3-ioalkane-1-ols are preferably C1-10 alkyl esters such as methyl ester, ethyl ester, propyl ester, butyl ester, isobutyl ester, pentyl ester, isopentyl ester, hexyl ester, heptyl ester, octyl ester, nonyl ester and decyl ester. Examples of the lower alkyl esters of nitrooxyCs-ioalkane- 1-ols include but are not limited to 2-(nitrooxy)propyl acetate, 3-(nitrooxy)propyl acetate, 4- (nitrooxy)butyl acetate, 5-(nitrooxy)pentyl acetate, 6-(nitrooxy)hexyl acetate, 7-(nitrooxy)heptyl acetate, 8-(nitrooxy)octyl acetate, 9-(nitrooxy)nonyl acetate, 10-(nitrooxy)decyl acetate, and the mixture thereof.

[0031] In one embodiment, the nitrate ester according to the present invention is selected from the group consisting of the group consisting of: nitrooxyC3-ioalkane-1-ols such as 2-nitrooxypropane-1-ol, 3- nitrooxypropane-1 -ol, 2-nitrooxybutane-1-ol, 3-nitrooxybutane-1-ol, 4-nitrooxybutane-1-ol, 2 nitrooxypentane-1-ol, 3-nitrooxypentane-1-ol, 4-nitrooxypentane-1-ol, 5-nitrooxypentane-1-ol, 2- nitrooxyhexane-1-ol, 3-nitrooxyhexane-1 -ol, 4-nitrooxyhexane-1-ol, 5-nitrooxyhexane-1-ol, 6- nitrooxyhexane-1-ol, 2-nitrooxyheptane-1-ol, 3-nitrooxyheptane-1 -ol, 4-nitrooxyheptane-1-ol, 5- nitrooxyheptane-1-ol, 6-nitrooxyheptane-1-ol, 7-nitrooxyheptane-1 -ol, 2-nitrooxyoctane-1-ol, 3- nitrooxyoctane-1-ol, 4-nitrooxyoctane-1-ol, 5-nitrooxyoctane-1 -ol, 6-nitrooxyoctane-1-ol, 7- nitrooxyoctane-1-ol, 8-nitrooxyoctane-1-ol, 2-nitrooxynonane-1 -ol, 3-nitrooxynonane-1-ol, 4- nitrooxynonane-1-ol, 5-nitrooxynonane-1-ol, 6-nitrooxynonane-1 -ol, 7-nitrooxynonane-1-ol, 8- nitrooxynonane-1-ol, 9-nitrooxynonane-1-ol, 2-nitrooxydecane-1 -ol, 3-nitrooxydecane-1-ol, 4- nitrooxydecane-1 -ol, 5-nitrooxydecane-1 -ol, 6-nitrooxydecane-1-ol, 7-nitrooxydecane-1-ol, 8- nitrooxydecane-1 -ol, 9-nitrooxydecane-1-ol and 10-nitrooxydecane-1-ol; nitrates of nitrooxyCs- ioalkane-1-ols such as propane-1 , 2-diyl dinitrate, propane-1 , 3-diyl dinitrate, butane-1 ,2-diyl dinitrate, butane-1 ,3-diyl dinitrate, butane-1 ,4-diyl dinitrate, pentane-1 , 2-diyl dinitrate, pentane-1 , 3-diyl dinitrate, pentane-1 ,4-diyl dinitrate, pentane-1 ,5-diyl dinitrate, hexane-1 ,2-diyl-dinitrate, hexane-1 ,3-diyl- dinitrate, hexane-1 ,4-diyl-dinitrate, hexane-1 ,5-diyl-dinitrate, hexane-1 ,6-diyl-dinitrate, heptane-1 ,2- diyl-dinitrate, heptane-1 ,3-diyl-dinitrate, heptane-1 ,4-diyl-dinitrate, heptane-1 ,5-diyl-dinitrate, heptane- 1 ,6-diyl-dinitrate, heptane-1 ,7-diyl-dinitrate, octane-1 , 2-diyl-dinitrate, octane-1 , 3-diyl-dinitrate, octane- 1 ,4-diyl-dinitrate, octane-1 , 5-diyl-dinitrate, octane-1 ,6-diyl-dinitrate, octane-1 , 7-diyl-dinitrate, octane- 1 ,8-diyl-d in itrate, nonane-1 , 2-diyl-dinitrate, nonane-1 , 3-diyl-dinitrate, nonane-1 ,4-diyl-dinitrate, nonane-1 , 5-diyl-dinitrate, nonane-1 ,6-diyl-dinitrate, nonane-1 , 7-diyl-dinitrate, nonane-1 , 8-diy l-din itrate , nonane-1 , 9-d iy l-dinitrate, decane-1 , 2-diyl-dinitrate, decane-1 , 3-diyl-dinitrate, decane-1 ,4-diyl-dinitrate, decane-1 , 5-diyl-dinitrate, decane-1 ,6-diyl-dinitrate, decane-1 , 7-diyl-dinitrate, decane-1 ,8-d iy l-dinitrate, decane-1 , 9-d iyl-d in itrate and decane-1 , 10-diyl-dinitrate; and C1-10 alkyl esters of nitrooxyC3-ioalkane-1- ols such as 2-(nitrooxy)propyl acetate, 3-(nitrooxy)propyl acetate, 4-(nitrooxy)butyl acetate, 5- (nitrooxy)pentyl acetate, 6-(nitrooxy)hexyl acetate, 7-(nitrooxy)heptyl acetate, 8-(nitrooxy)octyl acetate, 9-(nitrooxy)nonyl acetate and 10-(nitrooxy)decyl acetate; and glycerol-1 , 3-dinitrate.

[0032] In a preferable embodiment, the nitrate ester according to the present invention is selected from the group consisting of 2-nitrooxypropane-1-ol, 3-nitrooxypropane-1-ol, 4-nitrooxybutane-1-ol, 5- nitrooxypentane-1-ol, 6-nitrooxyhexane-1-ol, 7-nitrooxyheptane-1-ol, 8-nitrooxyoctane-1-ol, 9- nitrooxynonane-1-ol, 10-nitrooxydecane-1-ol, propane-1 , 2-diyl dinitrate, propane-1 , 3-diyl dinitrate, butane-1 ,4-diyl dinitrate, pentane-1 ,5-diyl dinitrate, hexane-1 ,6-diy l-d in itrate, heptane-1 ,7-diyl-d in itrate , octane-1 , 8-d iy l-dinitrate, nonane-1 ,9-d iy l-d initrate, decane-1 ,10-d iyl-din itrate, 2-(nitrooxy)propyl acetate, 3-(nitrooxy)propyl acetate, glycerol-1 , 3-dinitrate, and mixture thereof. In a most preferable embodiment, the nitrate ester according to the present invention is 3-nitrooxypropane-1-ol.

[0033] In the present invention, the reductant may be selected from a group consisting of metals such as Zinc and Magnesium, salts such as titanium (III) salts including but not limited to titanium (III) citrate and titanium (III) chloride (TiCh), tin (II) slats such as tin (II) chloride, and samarium salts such as samarium diiodide (Smh), preferably the reductant is Zinc. Any person skilled in the art could understand that the reductant may be in any forms, such as powders.

[0034] In the present invention, the reductant is used in an amount ranging from 0.5 mole to 10 moles, preferably from 1 moles to 8 moles, more preferably from 1 .5 moles to 6 moles, and the most preferably from 2 moles to 4 moles, per 1 mole of the nitrate ester.

[0035] In the present invention, the acidic solution may be an aqueous solution of an acid such as organic acid and inorganic acid. Examples of the organic acid include but are not limited to acetic acid, butyric acid, citric acid, lactic acid, malic acid, tartaric acid and oxalic acid. Examples of the inorganic acid include but are not limited to hydrochloric acid, sulfuric acid, phosphoric acid, carbonic acid, hydrofluoric acid and boric acid.

[0036] Preferably, the acid contained in the acidic solution is selected from the group consisting of acetic acid, butyric acid, citric acid, lactic acid, malic acid, tartaric acid, oxalic acid, hydrochloric acid, sulfuric acid, phosphoric acid, carbonic acid, hydrofluoric acid and boric acid, and mixture thereof. More preferably, the acid is selected from the group consisting of acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid and boric acid, and mixture thereof. The most preferably, the acid is phosphoric acid.

[0037] In the present invention, the acidic solution contains the acid as described herein in a concentration ranging from 0.1 % to 98%, preferable from 1 % to 50% and more preferable from 2% to 10%. Preferably, the acidic solution according to the present invention is an aqueous solution of an acid selected from the group consisting of acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid and boric acid, and mixture thereof, in a concentration ranging from 0.1 % to 98%, preferable from 1 % to 50% and more preferable from 2% to 10%.

[0038] In the present invention, the acid may be used in an amount ranging from 0.5 mole to 20 moles, preferably from 1 moles to 15 moles, more preferably from 2 moles to 10 moles, and the most preferably from 3 moles to 6 moles, per 1 mole of the nitrate ester.

[0039] The method of the present invention may be run at the temperature ranging from 0 to 50°C, preferably from 5 to 40°C, more preferably at a room temperature.

[0040] Surprisingly, the method according to the present invention successfully generates nitrate and nitrite ions from a nitrate ester in a mild condition such as at a room temperature in a sufficient amount which is detected by a method known in the art. Particularly, the method according to the present invention generates nitrate and nitrite ions in an amount of at least 20 times, preferably at least 50 times, more preferably at least 100 times such as at least 150 times and 200 times of the amount of nitrate and nitrite ions generated from a nitrate ester by a process without the reductant and / or the acidic solution as defined herein.

[0041] More surprisingly, the amount of the nitrate and nitrite ions generated by the method of the present invention is dependent on the amount of the nitrate ester. As a result, the method of the present invention makes it possible to detect a nitrate ester qualitatively or quantitively by determining nitrate and nitrite ions with a method known in the art.

[0042] Accordingly, in the second aspect, the present invention also provides a method for detecting a nitrate ester in a mixture comprising the steps: a) contacting the mixture with a reductant in an acidic solution to generate nitrate and / or nitrite ions, and b) detecting the nitrate and / or nitrite ions generated in the step a), wherein the nitrate ester, the reductant and the acidic solution are described as above.

[0043] The techniques for detecting nitrate and / or nitrite ions in a mixture is known in the art. Examples of the techniques include but are not limited to Griess reaction, UV / Vis Spectrophotometry, Chemiluminescence, Fluorescence Spectroscopy, Infrared detection (IR), Raman Spectroscopy, atomic absorption spectrophotometry (AAS), Capillary Electrophoresis (CE), Electrochemical Methods, High-Performance Liquid Chromatography (HPLC), Gas chromatography (GC), Ion Chromatography (IC) and Mass Spectrometry (MS). A detailed review of nitrate and nitrite detection methods can be found in M.J. Moorcroft et al. Taianta, 54 (2001): 785-803. The present invention allows both qualitative and quantitative detection of a nitrate ester. In one embodiment, the nitrate ester is detected qualitatively by observing the presence of nitrite and / or nitrate ions. In another embodiment, the method allows for quantitative detection, whereby the concentration of the nitrate ester in the mixture is determined based on the detected amount of nitrate and / or nitrite ions. Preferably, the nitrate ester are detected quantitatively.

[0044] Preferably, the detection of nitrite and / or nitrate ions is performed using Griess reaction, wherein the Griess reagents reacts with the nitrite to produce a colorimetric change proportional to the amount of nitrite present. The reagents and reaction conditions for the Griess test are well-known in the art (see: V. M. Ivanov, Journal of Analytical Chemistry, Vol. 59, No. 10, 2004, pp. 1002-1005 and international patent publication WO2015 / 033003 A1).

[0045] Accordingly, the present invention preferably provides a method for detecting a nitrate ester in a mixture comprising: a) contacting the mixture with a reductant and Griess reagents in an acidic solution to form a colour, and b) detecting the colour formed in the step a), wherein the nitrate ester, the reductant, the Griess reagents and the acidic solution are described as above. Surprisingly, the change of the colour formed in the step a) according to the method of the present invention is concentration dependent.

[0046] The method of the present invention can be performed in a mild condition in a fast, cheaper and sensitive way, so it can be operated conveniently on site and avoid shipment of nitrate ester samples.

[0047] The present invention are further illustrated with the following examples.

[0048] Example 1

[0049] 1 . Preparation of 1 % 3-NOP solution

[0050] 10 mg 3-NOP was dissolved in ca. 0.7 mL water and then the solution was further diluted with water until reaching a weight of 1.00 g, resulting in 1 % 3-NOP solution.

[0051] 2. Preparation of 1 % 3-NOP in 0.5M H3PO4

[0052] 10 mg 3-NOP was dissolved in about 0.7 mL 0.5 M phosphoric acid and then further diluted with water until reaching a weight of 1.00 g, resulting in 1 % 3-NOP solutions in 0.5 M H3PO4.

[0053] 3. Preparation of 1 % 3-NOP in water with Zn

[0054] The 1 % 3-NOP solution as prepared above was added 4.0 mole equivalent of Zinc powder.

[0055] 4. Preparation of 0.5%, 1 %, 1.5% and 2% 3-NOP in 0.1 M HsPC with Zn 5 mg, 10 mg, 15 mg and 20 mg of 3-NOP were, respectively, dissolved in ca. 0.7 mL 0.1 M phosphoric acid and then the solutions were further diluted with water until reaching a weight of 1.00 g. 4.0 mole equivalent of zinc powder was added to provide 0.5%, 1%, 1.5% and 2% 3-NOP in 0.1 M H3PO4 with Zn, respectively.

[0056] 5. Detecting nitrate / nitrite ions in each of solutions

[0057] After the solutions as prepared above were stirred at 23°C for 1 h, they were submitted to ion chromatography detection (IC) for quantification, which was calibrated for nitrite and nitrate ions. For the solutions with Zn, the solid was filtered before they were submitted to IC. The measured concentrations are listed in the table below.

Claims

Claims1 . A method for generating nitrite and / or nitrate ions from a nitrate ester, comprising contacting the nitrate ester with a reductant in an acidic solution, wherein the nitrate ester is one or more compounds with the following formula (I)X-R-(ONO2)n (I)Wherein:R is lower alkyl, optionally substituted by one or more substituents,X is H, OH or R’(CO)O- wherein R’ is lower alkyl, optionally substituted by one or more substituents, and n is 1 or 2.

2. The method according to claim 1 , wherein R is C3-10 alkyl.

3. The method according to claim 1 or 2, wherein X is preferably H, OH or R’(CO)O- wherein R’ is C1-6 alkyl, more preferably OH, CH3(CO)O- or C2H5(CO)O-.

4. The method according to claim 1 , wherein the nitrate ester is selected from nitrooxyCs- ioalkane-1-ols, as well as nitrates and lower alkyl esters thereof.

5. The method according to claim 1 , wherein the nitrate ester is selected from the group consisting of 2-nitrooxypropane-1-ol, 3-nitrooxypropane-1-ol, 4-nitrooxybutane-1-ol, 5-nitrooxypentane-1- ol, 6-nitrooxyhexane-1-ol, 7-nitrooxyheptane-1-ol, 8-nitrooxyoctane-1-ol, 9-nitrooxynonane-1- ol, 10-nitrooxydecane-1-ol, propane-1 ,2-diyl dinitrate, propane-1 ,3-diyl dinitrate, butane-1 ,4- diyl dinitrate, pentane-1 ,5-diyl dinitrate, hexane-1 ,6-diyl-dinitrate, heptane-1 ,7-diyl-dinitrate, octane-1 ,8-diyl-dinitrate, nonane-1 ,9-diyl-dinitrate, decane-1 ,10-diyl-dinitrate, 2- (nitrooxy)propyl acetate, 3-(nitrooxy)propyl acetate, glycerol-1 ,3-dinitrate, and mixture thereof.

6. The method of any one of claims 1-5, wherein the reductant is selected from a group consisting of metals such as Zinc and Magnesium, salts such as titanium (III) salts including but not limited to titanium (III) citrate and titanium (III) chloride (TiCh), tin (II) slats such as tin (II) chloride, and samarium salts such as samarium diiodide (Smh).

7. The method of any one of claims 1-5, wherein the reductant is used in an amount ranging from 0.5 mole to 10 moles, preferably from 1 moles to 8 moles, more preferably from 1 .5 moles to 6 moles, and the most preferably from 2 moles to 4 moles, per 1 mole of the nitrate ester.

8. The method of any one of claims 1-5, wherein the acidic solution is an aqueous solution of an acid such as organic acid and inorganic acid.

9. The method of claim 8, wherein the acid is selected from the group consisting of acetic acid, butyric acid, citric acid, lactic acid, malic acid, tartaric acid, oxalic acid, hydrochloric acid, sulfuric acid, phosphoric acid, carbonic acid, hydrofluoric acid and boric acid, and mixture thereof.

10. The method of any one of claims 1-5, wherein the acid is used in the acidic solution in an amount ranging from 0.5 mole to 20 moles, preferably from 1 moles to 15 moles, more preferably from 2 moles to 10 moles, and the most preferably from 3 moles to 6 moles, per 1 mole of the nitrate ester.11 . A method for detecting a nitrate ester in a mixture comprising the steps: a) contacting the mixture with a reductant in an acidic solution to generate nitrate and / or nitrite ions, and b) detecting the nitrate and / or nitrite ions generated in the step a), wherein the nitrate ester, the reductant and the acidic solution are defined as claims 1-10.

12. A method for detecting a nitrate ester in a mixture comprising: a) contacting the mixture with a reductant and Griess reagents in an acidic solution to form a colour, and b) detecting the colour formed in the step a) wherein the nitrate ester, the reductant and the acidic solution are defined as claims 1-10.

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