FR2965615A1 - SOLVENTS FOR THE DETERMINATION OF AMINES IN WATER - Google Patents

Abstract

The present invention relates to the use of non-volatile and non-toxic solvents for the quantitative determination by spectrocolorimetry of amines and derivatives in any aqueous medium, replacing the chloroform usually used for the extraction of colored complexes, in particular those formed with said amines. and derivatives and methyl orange, bromocresol violet and the like.

Description

SOLVENTS FOR THE DETERMINATION OF AMINES IN WATER

The present invention relates to the field of methods for assaying organo-nitrogen compounds, particularly amines, in water. More specifically, the present invention relates to the determination of amine corrosion inhibitors used in the drilling of oil wells, gas, geothermal water in general, and drinking water in particular, in the oil and gas industry. gas, including the transport of liquid and gaseous materials extracted from the basement, and the like. The extraction of oil, gas, water and other liquids or underground gases, is a complex technique and one of the recurring problems in the exploitation of these deposits is the corrosion of pipes, pipes, valves, pipes, and others. Indeed, all the extraction deposits contain a greater or lesser quantity of water in which are very often dissolved acids (or precursors), such as carbonic acid, hydrogen sulphide, and the like, and which are responsible for corrosion of metals. [0003] This corrosion occurs due to the amount of acidic water, more or less important, present in the drilling muds, but also formed by condensation in pipes, pipes, valves, pipes, and the like. used for the extraction, transportation and transportation of these products extracted from the subsoil. [0004] In order to solve these corrosion problems, specific corrosion inhibitors have been used for many years, which are injected at various points in order to protect the metal parts coming into contact with the acids contained in the products that come up from drilling. These inhibitors which are injected in very small amounts in the corrosive medium, thus limit its aggressiveness without modifying it. The injection mode can be either continuous or discontinuous or mixed, that is to say that in addition to a continuous injection, it may be necessary to add punctually an additional amount (a "plug"). inhibitor. The injections of anticorrosive additives can be made at several points and in particular by "squeeze", that is to say at the bottom of the production well. 2965615 -2

The amount of additive injected is very variable depending on the extraction conditions, the nature of the extracted products, the nature of the additive itself. In particular, the anti-corrosion additives, under the conditions of use, can degrade (we speak of "aging") and it is necessary to ensure an accurate monitoring 5 ("monitoring") of the content of anti-corrosion additive present in corrosive environments, in order to adjust as precisely as possible the necessary and sufficient quantity of additive to be injected. The most commonly used inhibitors are generally organic compounds having one or more nitrogen functions, mainly amines, quaternary ammonium salts or imidazolines, for example. For the monitoring of these corrosion inhibitors, the treatment is followed by assaying the amines present in the water. The method of assaying these organo-nitrogen compounds commonly used today relies on the principle of colorimetric dosing in water of colored complexes formed by organo-nitrogen compounds (eg corrosion inhibitors) and at least one complexing agent. [0009] The most commonly used complexing agents today are, without limitation, methyl orange (or helianthine), ethyl orange, bromocresol zo green, bromocresol violet, blue thymol, bromothymol blue, bromochlorophenol blue, chlorophenol red, cresol red, iodophenol blue, metacresol violet and phenol red, to name just a few, methyl orange and bromcresol green and violet being the most commonly used. The complex thus formed is extracted with a water-immiscible solvent and then the complex in the solvent is subjected to a quantitative colorimetric assay. Alternatively, the solvent may be removed in whole or in part, for example by evaporation, before the assay of the complex. This assay method is, for example, described in ASTM D2327-68, where the complex is extracted from water with chloroform or dichloroethane, and the complexed amine is determined by spectroscopy at a specific length. given wave. 2965615 -3

The choice of immiscible solvent in water is very important: the solvent must solubilize as completely as possible the colored complexes to be assayed for obvious reasons of measurement accuracy. The first solvent used was benzene, which was quickly abandoned for toxicity reasons. [0013] Today, immiscible solvents in water are mainly chlorinated solvents, such as, in a non-limiting manner, chloroform, methylene chloride, ethylene dichloride, carbon tetrachloride, chlorobenzene, and also mixtures thereof with alcohols, such as methanol, ethanol, propanol, butanol, or with acetonitrile, dioxane, tetrahydrofuran, and the like. Chloroform and ethylene dichloride are in particular very widely used today. Indeed, it is known that the amines form with methyl orange, at pH = 3.75, a complex soluble in chloroform or ethylene dichloride. This complex is then extracted from chloroform with an acidic solution and the amino complex is measured in this acidic solution by spectrocolorimetry. The monitoring of corrosion inhibitors is performed closer to the injection sites, for example on the drilling platforms, that is to say, often in laboratories or control centers that do not zo do not always have the necessary protections required for the protection of operator personnel, including protection against the fumes of the products used during the monitoring of corrosion inhibitors. However, chloroform is a solvent suspected today to be carcinogenic, and it is sought to substitute other less toxic compounds. Dichloroethane is often cited as a potential substitute for chloroform (Silverstein, Ronald M, Anal Chem, (1963), 35, 154-7) but this product is also toxic. Other chlorinated solvents that could replace chloroform are also toxic and carcinogenic products. There remains therefore a need for compounds capable of substituting chloroform, and chlorinated solvents in general, in the amine assay for solubilizing the complexes formed with said amines, and which are of little or no toxicity for the charged persons. of corrosion inhibitors monitoring 2965615 -4

and more generally the colorimetric determination of amines by complexation reaction. It has now been discovered that certain compounds can advantageously replace chloroform, and chlorinated solvents in general, in the amine dosing reactions. A solvent replacing the chloroform must be advantageously insoluble in water, be slightly or not, or non-toxic, and low volatility, that is to say, have a vapor pressure as low as possible. Indeed, the chloroform considered today as toxic, is very volatile, with a vapor pressure of 211 hPa at 20 ° C, and users are thus regularly subjected to chloroform vapor, if no equipment (ventilation adequate suction is provided in the control rooms where the dosages are carried out. In addition, the solvent must have a very good solvent power of the complexes formed with the amines, in order to be able to extract them from the water, and allow a quantitative colorimetric assay by spectroscopy as accurate as possible. Quantitative spectroscopic assays are most often made from a standard which is precisely known absorption wavelength. The percentage of absorbance (Abs) at various concentrations of this standard makes it possible to plot the absorption graph as a function of the concentration of the colored complex [C], for example expressed in ppm, which can then be expressed by the relation Abs = f ([C]). In order to allow the most accurate measurements possible, the absorption graph, including the calibration curve, is advantageously in the form of a straight line (at least in the masure concentration range) in order to allow an assay to be performed. as precise as possible in the simplest possible conditions for the user. The absorption graph, a function of the complex concentration, can then be written in the form: Abs = ki [C] + k2, where Abs and [C] are as defined previously and k1 and k2 are constants . 2965615 -5

Despite the very large number of solvents available today, there is however no indication allowing the skilled person to select a solvent that can replace chloroform for the determination of amines, and in particular can combine all characteristics required and discussed above to allow amine assay by color complex absorption spectroscopy. The Applicant has now discovered that some solvents can advantageously replace chloroform in the aforementioned assay method. Thus, the present invention firstly relates to the use of at least one water immiscible solvent, vapor pressure, measured at 20 ° C, less than or equal to 200 hPa, preferably less than or equal to 100 hPa, more preferably less than or equal to 50 hPa, advantageously less than or equal to 30 hPa, for the quantitative colorimetric assay, organo-nitrogen compounds in general, and more particularly fatty amines, and derivatives, present in an aqueous fluid. By solvent immiscible with water, or immiscible in water, is meant a solvent whose miscibility in water at 20 ° C is less than 1.00 / 0 by weight, preferably less than 0.50 wt%, more preferably less than 0.1 wt%, more preferably less than 0.050 wt%, most preferably less than 0.01 wt%. By fatty amines is more specifically meant organo-nitrogen compounds comprising at least one hydrocarbon chain, linear or branched, containing more than 10 carbon atoms, in particular from 10 to 100 carbon atoms, preferably from 10 to 50 atoms. of carbon. The fatty amines may be primary, secondary or tertiary amines, linear, cyclic, heterocyclic or aromatic, contain two or more nitrogen atoms, one or more carbonyl groups, and may also contain from 1 to 30 EO units. (ethyleneoxy) and / or OP (propyleneoxy). [0030] The term "fatty amines" also includes their mineral or organic salts, such as halides, quaternary ammoniums and the like. More specifically, the organo-nitrogen compounds whose complexes are the subject of the assay according to the present invention, are chosen from amines 2965615 -6.

fats of the following formulas, and their salts: a) R-NH2, R-NH-R ', RR'R "N, where R, R' and R", which may be identical or different, represent, independently of one another, a radical linear or branched hydrocarbon containing from 10 to 100 carbon atoms, preferably from 10 to 50 carbon atoms; b) R- [NH (CH2) 3] nNH2, where n varies from 0 to 4 and R is as defined above; c) R- [NH (CH2) 3] n (EO) X (OP) yNH2, n and R being as defined above, x and y, which are identical or different, ranging from 0 to 30, the (CH2) 3 units , OE and OP being distributed randomly or in blocks, without their order being specified; d) fatty amido-amines, optionally containing OEX and / or OPy groups, x and y being as defined above; e) fatty imidazolines, optionally containing groups OEX and / or OPy, x and y being as defined above; and f) fatty amino acids. In the context of the present invention, the particularly suitable amines and derivatives are corrosion inhibitors, among which, by way of nonlimiting examples, those marketed by CECA SA under the names Cecanefe may be mentioned. 03H (mixture comprising amino acid, quaternary ammonium and polyoxyethyl amine), Noruse IG49 (composition based on fatty imidazoline derivative), and those marketed by Nalco under the names EC-1154A and EC-11546, and others and generally all corrosion inhibitors based on fatty amines, imidazolines, and their derivatives. The solvents which are particularly suitable for use according to the present invention, which are not very volatile, are not very toxic, are immiscible with water and are capable of extracting the complexes formed with the amines from water, and which allow a colorimetric determination. by linear absorption in the desired concentration range are advantageously chosen from brominated organic compounds and esters. Among the brominated compounds, mention may be made, in a nonlimiting manner, of the bromoalkanes, the bromochloroalkanes, in particular the bromopropanes, the

bromochloropropanes, preferably 1-bromo-3-chloropropane which has a vapor pressure at 20 ° C of about 75 hPa. Among the esters, there may be mentioned alkyl acetates, alkyl propionates, alkyl butyrates, the term alkyl to be understood as including methyl, ethyl, propyl, buyyl, pentyl, hexyl, 2 -ethylhexyl, without this list being limiting. Butyl acetate, which has a vapor pressure at 20 ° C of about 14 hPa, is most preferred. The abovementioned solvents, which may replace chloroform in the amine assays as indicated above, and in particular butyl acetate and 1-bromo-3-chloropropane, may be used alone or as a mixture, all proportions, and also alone or in admixture with one or more other solvents known to those skilled in the art, specializing in the determination of amines and derivatives in water. However, it is preferred to use butyl acetate alone or 1-bromo-3-chloropropane alone for the determination of amines and derivatives as defined in the present invention. More particularly the invention relates to the use of the abovementioned solvents, in particular butyl acetate or 1-bromo-3-chloropropane, for the assays of nitrogen-containing corrosion inhibitors, more specifically inhibitors of nitrogenous corrosion used in the fields of extraction, production, transport and storage of water and fossil materials extracted from the subsoil and in particular oil and gas. According to a preferred embodiment, the invention relates to the use of butyl acetate or 1-bromo-3-chloropropane for the determination of the amines and derivatives, as they have just been defined. in water, according to the methyl orange method, that is to say by formation of complexes with methyl orange. In addition to the fact that butyl acetate and 1-bromo-3-chloropropane allow the straight lines of Abs type = ki [C] + k2 such as chloroform, these two solvents have the advantage to have low vapor pressure values, relative to chloroform. They are therefore less volatile than chloroform. Furthermore, with respect to chlorinated solvents, in particular chloroform, the esters, and in particular butyl acetate, have the advantage 2965615 -8

to be almost completely biodegradable; butyl acetate is a chloroform replacement solvent particularly well suited for use according to the present invention. In addition, the solvents which can be used in the context of the present invention, and in particular 1-bromo-3-chloropropane and the esters, of which butyl acetate, are less toxic than chloroform, or even nontoxic ( this is particularly the case for butyl acetate), and above all are not considered today as potentially carcinogenic. [0042] Thus, butyl acetate or 1-bromo-3-chloropropane can advantageously be used as chloroform replacement solvents for the extraction of the colored complexes used in the determination of all types of organic compounds. nitrogen, such as for example those defined above, and in particular when measuring amines and amine derivatives in the form of complexes with methyl orange, or other complexing agents as previously mentioned. As examples of assays of amines, and derivatives, present in water and which can be carried out, with extraction of the colored complex to be assayed, mention may be made, by way of nonlimiting examples, of the determination of corrosion inhibitors. in products of extraction of the subsoil, such as for example oil, gas, water, such as those marketed by CECA SA under the names Cecanefe, Noruse, as indicated above. The solvents which can be used in the context of the present invention are also particularly well suited for the determination of amines and their derivatives in drinking water, industrial water, waste water, sewage, in the air, in the determination of amines, and their derivatives, present in amino acids, peptides, nucleotides, but also in body fluids (blood, urine, physiological fluid, amniotic fluid, vaginal secretions), and others, and in general any type of quantitative colorimetric assays involving an amine or its derivatives capable of forming a colored complex, the optical absorption of which can be assayed by spectroscopy. 2965615 -9

The present invention also relates to a process for the determination of amines, and their derivatives, as defined above in an aqueous medium, said assay method comprising at least the following steps: a) sampling of an aqueous sample containing at least an organo-nitrogen compound to be assayed; b) possible dilution with water of the sample; c) adjusting the pH of the sample, possibly diluted with a buffer solution; d) adding a complexing agent capable of forming a complex colored with the at least one amine to be assayed; e) adding at least one water-immiscible solvent, vapor pressure, measured at 20 ° C, less than or equal to 200 hPa, preferably less than or equal to 100 hPa, more preferably less than or equal to 50 hPa, advantageously less than or equal to 30 hPa; F) stirring and separation by decantation of the aqueous phase and the organic phase containing the colored complex; g) possible concentration of the organic phase; h) extracting said colored complex in an aqueous acid solution of pH less than 2, and preferably less than 1; I) measuring by color spectrometry the absorbance of said aqueous acidic phase; and j) plotting on a calibration curve the absorbance value for determining the amine concentration in the aqueous sample. The pH of the aqueous solution containing the sample to be assayed is advantageously adjusted to the value or around the value at which it is known that the complex is formed in the presence of the complexing agent used, and of the solvent organic used. The complexing agent used in the process of the present invention may be of any kind, and for example chosen from those listed previously in the description. Similarly, the solvent that makes it possible to extract the complex formed is a low-volatility, water-immiscible solvent chosen from the solvents selected for use in the water.

the use object of the present invention, and preferably selected from butyl acetate and 1-bromo-3-chloropropane. According to another object, the invention relates to a dosing kit, advantageously portable, comprising the reagents necessary for the amine and derivative assay method as just described, and in particular at least one solvent for extraction of the colored complex allowing the quantitative determination of said amines and derivatives, said at least one solvent being chosen from water immiscible solvents, vapor pressure, measured at 20 ° C, less than or equal to 200 hPa, preferably less than or equal to 100 hPa, more preferably still less than or equal to 50 hPa, advantageously less than or equal to 30 hPa, and preferably selected from butyl acetate and 1-bromo-3-chloropropane. The assay kit described above may further comprise an optical absorption assay apparatus, such as an optical spectroscope, as well as possibly a calculator connected to a display or a printer making it possible to visualize the results. from the determination of amines and derivatives. The present invention is now illustrated by means of the following examples, without presenting any limiting character, and which can not therefore be understood as being capable of restricting the scope of the invention as claimed.

EXAMPLE 1 Method for Assaying Amines and Derivatives According to the Methyl Orange Method The determination of the amines and derivatives by the methyl orange method is carried out according to the following procedure: [0052] A buffer solution is prepared with 125 g of potassium chloride (KCl) and 70 g of trihydrated sodium acetate in 500 ml of distilled water, to which 300 ml of glacial acetic acid is added. The whole is completed to 1000 ml with distilled water. The pH of this solution is 3.75. In parallel, a solution of methyl orange is prepared by mixing 250 mg of methyl orange powder (marketed by VWR) in 500 ml of distilled water. 2965615 -11

In a 250 ml separatory funnel, 1 ml of methyl orange solution prepared as indicated above is added. 2 mL of buffer solution prepared above is then added. It is homogenized while stirring vigorously. 25 ml of test sample containing the corrosion inhibitor whose concentration is to be assayed are pipetted, and then the whole is homogenized. 25 ml of chloroform (sold by VWR) are then added and the ampoule is vigorously stirred for one minute, while depressurizing regularly. The densest phase (organic phase) is collected in a clean, dry second bulb, taking care not to drive the interface. Again introducing 25 mL of chloroform in the first ampoule, and stirred vigorously for one minute, while depressurizing regularly. The denser phase (organic phase) is then added to the second separating funnel. Pipette exactly 25 mL of 1N hydrochloric acid solution into the second separating funnel, and stir vigorously for one minute, depressurizing from time to time. The two phases are allowed to separate. The lower organic phase is completely eliminated, as well as the interface; the remaining aqueous phase, tinted in pink, is collected in a spectrometer vial; if the aqueous phase is cloudy, the aqueous solution is filtered on a paper filter; the absorbance is then measured at a wavelength of 500 nm. By comparing the absorbance obtained with that corresponding to the calibration curve, the concentration of the corrosion inhibitor can be deduced therefrom.

Example 2: Determination of an Imidazoline-based Corrosion Inhibitor The procedure described in Example 1 is applied to a sample of an imidazoline-based corrosion inhibitor: Noruse IG 49 company 2965615 -12

CECA S.A .. Three assays are performed: with extraction with chloroform, butyl acetate, and 1-bromo-3-chloropropane. The results obtained are shown in Figure 1. In all three cases, we obtain straight lines, which demonstrates that it is possible to replace chloroform 5 with butyl acetate or 1-bromo-3 chloropropan. The absorbance is a linear function of the concentration (expressed in ppm by weight), the linear regression equations are as follows: with chloroform: Abs = 0.0056 [C] + 0.0008, with x2 = 0.9945, where x2 represents the correlation coefficient (the accuracy is greater as io x2 tends to the value 1); with butyl acetate: Abs = 0.0061 [C] - 0.0159, with x2 = 0.9809; with 1-bromo-3-chloropropane: Abs = 0.00077 [C] - 0.0121 with x2 = 0.9874.

EXAMPLE 3 Assay of a Corrosion Inhibitor Based on Amine Derivatives The procedure described in Example 1 is applied to a sample of a corrosion inhibitor based on amine derivatives: Cecanefe 03H of the company CECA SA Three assays are performed: with extraction with chloroform, butyl acetate, and 1-bromo-3-chloropropane. The results obtained are shown in FIG. 2. In all three cases, lines are obtained, which demonstrates that it is possible to replace chloroform with butyl acetate or with 1-bromo-3. chloropropan. The absorbance is a linear function of the concentration (expressed in ppm by weight), the linear regression equations are as follows: with chloroform: Abs = 0.027 [C] + 0.09, with x2 = 0 , 9955; With butyl acetate: Abs = 0.0229 [C] + 0.2013, with x2 = 0.9945; with 1-bromo-3-chloropropane: Abs = 0.0258 [C] + 0.0192, with x2 = 0.9955.

Claims (10)

REVENDICATIONS1. Use of at least one water immiscible solvent, vapor pressure, measured at 20 ° C., of less than or equal to 200 hPa, preferably less than or equal to 100 hPa, more preferably less than or equal to 50 hPa advantageously less than or equal to 30 hPa, for the quantitative colorimetric assay, organo-nitrogen compounds in general, and more particularly fatty amines, and derivatives, present in an aqueous fluid. io 2. Use according to claim 1, wherein the amine to be determined is chosen from primary, secondary or tertiary amines, linear, cyclic, heterocyclic or aromatic, which may contain two or more nitrogen atoms, one or more carbonyl groups, and may also contain from 1 to 30 EO (ethyleneoxy) and / or OP (propyleneoxy) units. 3. Use according to claim 1 or claim 2, wherein the assay is the assay of nitrogen-containing corrosion inhibitors, more specifically nitrogen-containing corrosion inhibitors used in the fields of extraction, production, transportation and transportation. storage of fossil materials extracted from the subsoil including oil and gas. 4. Use according to any one of the preceding claims, wherein the solvent is selected from brominated organic compounds and esters, preferably the solvent is butyl acetate or 1-bromo-3-chloropropane. 5. Use according to any one of the preceding claims, wherein the complexing agent is selected from methyl orange, ethyl orange, bromcresol green, bromocresol violet, thymol blue, bromothymol blue, bromochlorophenol blue, chlorophenol red, cresol red, iodophenol blue, metacresol violet and phenol red, preferably from methyl orange and green or bromocresol violet, preferably the complexing agent is methyl orange. 6. Use according to any one of the preceding claims, wherein the assay of the at least one amine in an aqueous medium is a quantitative absorbance measurement assay of the formula Abs = ki [C] + k2, where Abs represents the absorbance, [C] represents the color complex concentration and here and k2 are constants. io 7. Amine assay method, and derivatives thereof, as defined in claim 1, said assay method comprising at least the following steps: a) sampling an aqueous sample containing at least one organo-nitrogen compound to be assayed; B) possible dilution with water of the sample; c) adjusting the pH of the sample, possibly diluted with a buffer solution; d) adding a complexing agent capable of forming a colored complex with the at least one amine to be assayed; E) adding at least one water-immiscible solvent, vapor pressure, measured at 20 ° C, less than or equal to 200 hPa, preferably less than or equal to 100 hPa, more preferably less than or equal to at 50 hPa, advantageously less than or equal to 30 hPa; f) stirring and decanting separation of the aqueous phase and the organic phase containing the colored complex; g) possible concentration of the organic phase; h) extracting said colored complex in an aqueous acid solution of pH less than 2, and preferably less than 1; i) colorimetric spectrometric measurement of the absorbance of said aqueous acidic phase; and j) plotting on a calibration curve the absorbance value for determining the amine concentration in the aqueous sample. 2965615 -15- 8. The method of claim 7, wherein the complexing agent is selected from methyl orange, ethyl orange, bromcresol green, bromocresol violet, thymol blue, bromothymol blue, bromochlorophenol blue, chlorophenol red, cresol red, iodophenol blue, metacresol violet and phenol red, preferably methyl orange and bromcresol green or violet, preferred way the complexing agent is methyl orange. io 9. The method of claim 7 or claim 8, wherein the solvent is selected from brominated organic compounds and esters, preferably the solvent is butyl acetate or 1-bromo-3-chloropropane. 10. Assay kit comprising the reagents necessary for the process for the determination of the amines and derivatives according to any one of Claims 7 to 9, and at least one extraction solvent of the colored complex allowing the quantitative determination of said amines and derivatives, said at least one solvent being chosen from brominated organic compounds and esters, preferably chosen from butyl acetate and 1-bromo-3-chloropropane. 20