CS238910B1 - A method for analyzing ionogenic components of salts of alkyldithiocarbamic acids - Google Patents

Abstract

A method for analyzing ionogenic components of salts of alcldithiocarbamic acids, characterized in that the analysis of ionic components, most particularly, has alkyldithiocarbamates, sulphates, nitrates, chlorides, acetates, ammonium, ethylenediamine, hexamethylenetetramine, Na +, Mn 2+, Zn 2+, Co 2+, 3+, Fe2 +, 3 +, Ni2 +, Cu2 +, Cd2 +, Sn2 +, Sb2 +, Hg2 +, Al3 +, Cr3 + water-soluble and / or insoluble salts of alkyldithiocarbamide acids after their chemical distribution by chelating agents and / or ion exchangers and / or acids and / or oxidation-reducing agents and / or the effect of heat on water-soluble ionic components, is carried out in an isotachophoretic column at a selected electric current with a conducting electrolyte and a terminating electrolyte, the components analyzed in their respective zones being detected by conductivity and / or gradient-potential and / or spectrophotometric and / or thermometric and / or high-frequency conductivity The content of the components or their identification in the analyzed component is determined from the measured and / or radiation detector and from the measured zone lengths of the components analyzed or the proportional mobility detector signal of the analyte.

Description

The general formula I represents N,N-dialkyldithiocarbamic acids and the formula II represents N,N-dialkylbisdithiocarbamic acids, in which R ¹ , R ² , R ³ and R ⁴ represent alkyl such as methyl, ethyl, propyl or butyl or hydrogen in various combinations.

By replacing the hydrogen cation in alkyldithiocarbamic acids of the general formula I or II with cations of alkali metal elements, alkaline earth elements or ammonium ions, water-soluble salts are formed, and by replacing hydrogen with cations of metal elements M, salts with low water solubility are formed.

Salts of alkyldithiocarbamic acids or preparations containing them are used as fumigants, rubber accelerators, analytical reagents, components of pharmaceuticals and have found perhaps the most widespread application in agricultural practice in the field of plant protection as fungicides.

The most widespread, highly effective and universal fungicidal preparations based on salts of alkyldithiocarbamic acids include metal salts of ethylenebisdithiocarbamic acid, of which the best known are manganese /2+/ or zinc /2+/ ethylenebisdithiocarbamidan /known under the general name maneb, zineb/, manganese /2+/ zinc /2+/ ethylenebisdithiocarbamidan /mancozeb/ mixed complex salts containing maneb and some metal element from group M and also zinc /2+/ or iron /3+/ methylenedithiocarbamidan /general name feribam or zirebam/,

The basic substances for the production of metal salts of ethylenebisdithiocarbamic acids are the disodium or diammonium salt of ethylenebisdithiocarbamic acid /common name nabam or ambam/.

For the determination of alkyldithiocarbamates, their precipitation reactions with metal salts can be used; electrochemical methods, volumetric methods, e.g. direct titration with iodine. All analytical methods based on these principles lack specificity in the presence of interfering substances, which are often normal impurities of alkyldithiocarbamates.

Chromatographic separation methods, especially paper and thin-layer chromatography, high-performance liquid chromatography or gas chromatography, have greater application and advantages, especially in the analysis of alkyldithiocarbamides.

The widespread and officially recommended analytical method for the determination of alkyldithiocarbamidans is the method based on the decomposition of alkyldithiocarbamidan, the conversion of the decomposition product (carbon sulfur) to xanthate and its determination by iodine titration.

Although this method is considered specific for alkyldithiocarbamates, it has been proven that thiosulfates cause lower determination results and the interfering effect of some other impurities in the analyzed sample is not eliminated.

The analysis of cationic components in salts of alkyldithiocarbamic acids can be carried out by various methods after the sample has been mineralized, if necessary. Chelatometric titration methods are widely used for the determination of metal elements in salts of alkyldithiocarbamic acids.

It has now been found that the analysis of the ionic components of salts of alkyldithiocarbamic acids can be carried out by the method according to the invention.

The essence of the invention lies in the fact that the analysis of ionic components, in particular alkyldithiocarbaides, sulfates, nitrates, chlorides, acetates, ammonium, ethylenediamine, hexamethylenetetramine, sodium ions Na ⁺ , manganese Mn^ ⁺ , zinc Zn ⁺ , cobalt Co ⁺ , Co^ ⁺ , iron Fe^*, Fe^ ⁺ , nickel Λ i ² t, copper Cu ⁺ , cadmium Cd ^{2 +} , tin Sn ²⁺ , antimony Sb^ ⁺ , mercury Hg ²⁺ , aluminum Al^ ⁺ , _ 3+ chromium Cr in water-soluble and/or insoluble salts of alkyldithiocarbamic acids after their chemical decomposition by chelating agents and/or ion exchangers and/or acids and/or oxidation-reduction agents and/or the effect of heat on water-soluble ionic components, is carried out in an isotachophoretic column at a selected electric current intensity with a leading electrolyte and a terminating electrolyte, the analyzed components are detected in their corresponding zones by a conductivity and/or gradient-potential and/or spectrophotometric and/or thermometric and/or high-frequency conductivity and/or thermometric and/or high-frequency conductivity and/or radiation detector, and from the measured lengths of the zones of the analyzed components or the detector signal proportional to the mobility of the analyzed component, the content of the components is determined or their identification in the analyzed component is carried out.

As part of the leading electrolyte in anionic isotachophoresis, an anion with a greater or equal mobility among the analyzed anions and a cation with a buffering property in the pH range of 2.0 to 10.0 is used, in cationic isotachophoresis, a cation with a greater or equal mobility among the analyzed cations and an anion with a buffering property in the pH range of 1.8 to 10.0, and as part of the terminating electrolyte in anionic isotachophoresis, an anion with the lowest mobility among the analyzed anions and in cationic isotachophoresis, a cation with the lowest mobility among the analyzed cations. The analysis of the ionogenic components of salts of alkyldithiocarbamic acids by the method according to the invention is based on a completely different principle than in the analytical methods used so far and has a number of advantages over them.

According to the method of the invention, the analyzed components are separated in an isotachophoretic column based on their different mobility in an electric field. The analyzed solution is injected into the isotachophoretic column between the interface of two basic electrolytes, namely the so-called leading and terminating electrolyte.

The conducting electrolyte contains the ion (cation or anion depending on whether it is a cationic or anionic isotachophoretic analysis) with the greatest mobility in the electric field of all the analyzed ionogenic components, i.e. cations or anions.

The conducting electrolyte contains a counterion that has acid-base buffering properties.

The second basic electrolyte - the terminating electrolyte - contains the ion with the lowest mobility in the electric field of all the analyzed ionogenic components.

The separation is carried out at a constant electric current and the ionic forms of the substances migrate to the opposite, charged electrode. After a certain separation time, a steady state is reached, and then the separated substances are arranged based on their mobilities into the corresponding zones, all zones migrating at a constant speed.

Each zone contains, in addition to the corresponding separated substance, a substance used as a counterion. The physicochemical properties of the individual zones are homogeneous and change stepwise from zone to zone.

This fact is used to detect separated components in the corresponding zones.

In the direction from the leading electrolyte to the terminating electrolyte, the ^intensity of the electric field, resistance, temperature, pH or the absorption properties of the electromagnetic238910 change in individual zones.

Based on the measurement of a change in one of the physicochemical properties, a gradient - potential and/or conductivity and/or thermal and/or spectrophotometric and/or pH and/or high-frequency conductivity detector - can be used to detect separated substances in their zones.

Under certain analysis conditions, which are expressed by the so-called analysis operating system /electric current intensity, composition and concentration of the conducting electrolyte, geometric dimensions of the isotachophoretic column used, etc./ the magnitude of the measured detector signal in the corresponding zone of the separated substance is constant and characteristic for a certain substance.

This fact is used in the qualitative analysis of substances, especially in their identification. For qualitative analysis, it is sufficient to measure the wave height on the isotachophoreogram registered by the recorder and compare it with the wave height of the presumed substance.

There is a direct proportional relationship between the length of the zone of a certain substance and its substance quantity in the zone, i.e. its injected quantity into the isotachophoretic column in a steady state of separation, i.e. the measure of quantity in isotachophoretic analysis is the length of the zone of the analyzed substance.

The concentration of separated substances in the zones is determined mainly by the concentration and composition of the conducting electrolyte and is independent of the concentration of the analyzed solution. Quantitative analysis can be most easily performed by the calibration curve method.

According to the method of the invention, salts of alkyldithiocarbamic acids, which are insoluble in water, are decomposed by the action of chelate-forming substances, preferably from the group of aminopolycarboxylic acids, e.g. nitrilotriacetic acid, diethyltriaminopentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), cyclohexanediaminetetraacetic acid (CHEDTA), bis-2-aminoethylenetetraacetic acid, 1,2-bisaminoethoxyethanetetraacetic acid into ionic components soluble in water, namely into chelates of metal elements and alkyldithiocarbamides with a negative charge.

This allows for simultaneous separation of ionogenic components, i.e. cations and anions in salts of metal elements of water-insoluble alkyldithiocarbamic acids, by anionic isotachophoresis and their quantitative or qualitative analysis by evaluating the isotachophorogram immediately after the separation is completed, which is an advantage over other analytical methods.

According to the method of the invention, the analysis of metal elements M can also be carried out in such a way that their water-insoluble alkyldithiocarbamide salt is decomposed or completely mineralized by the action of mineral and/or organic acids and/or oxidation-reduction substances and/or heat, and the released cations of metal elements M are bound into a chelate complex, which is again analyzed by anionic isotachophoresis.

After the release of cations of metal elements M from the water-insoluble salts, the analysis of metal cations can advantageously be carried out by the method according to the invention by anionic isotachophoretic analysis also in such a way that only the analyzed solution of the released cations is injected into the isotachophoretic column and a chelating agent is used as the final electrolyte, which chelates the analyzed cations during the anionic isotachophoretic separation.

The method according to the invention can be used to analyze cations of alkali elements, alkaline earth elements, ammonium ions in water-soluble alkyldithiocarbamates and cations of metal elements M after their release from water-insoluble alkyldithiocarbamates by cationic isotachophoresis.

The method according to the invention can be used to perform isotachophoretic analysis of ionogenic components in insoluble alkyldithiourea salts after their decomposition by ion exchangers and desorption of ionic components from the ion exchanger.

The possibility of combining the analysis of metal elements M by cationic or anionic Isotachophoresis in the form of chelates, alone or in the presence of alkyldithiocarbamates, is an advantage when it is not possible to find optimal conditions for the separation of all ionogenic components in the analyzed mixture and/or when the interference effect of competing reactions of ligands of chelating agents and alkyldithiocarbamic acids with cations of metal elements is manifested during the separation of components or the decomposition of the metal element chelate occurs and/or the formation of mixed zones of the separated components occurs.

The great advantage of the analysis of ionic components in salts of alkyldithiocarbamic acids by the method according to the invention is specificity, speed and simplicity.

Reaction admixtures or decomposition products of alkyldithiocarbamides are mostly non-ionic substances, i.e. they do not migrate during isotachophoretic separation and thus cannot interfere with the analysis.

The decomposition of the complex salt of a metal element of alkyldithiocarbamidan with a chelating agent takes 10 to 15 minutes. Isotachophoretic analysis using an isotachophoretic analyzer /column with gradient-potential detector/ can be performed in 6 to 10 minutes.

The method according to the invention allows the analysis of water-soluble salts of alkyldithiocarbamidic acids to be carried out simply, directly by analyzing their aqueous solutions without any treatment, which at the same time, in addition to simplicity, represents a reduction in the analysis time.

The advantage of determining the manganese and zinc content in fungicidal preparations of the mancozeb type by the method according to the invention is that it is not necessary to use potassium cyanide - a strong poison - in the analysis for the purpose of masking zinc, as prescribed by the official complexometric method.

Another advantage of the analysis of ionic components in salts of alkyldithiocarbamic acids by the method according to the invention is that their concentration in the steady state of the separation process is adjusted to the concentration of the conducting electrolyte and by appropriately choosing its concentration, the detection limit of the method can be increased.

This fact is of practical importance in the analysis of alkyldithiocarbamidans in very diluted samples, e.g. in the study of decomposition processes of fungicide preparations /in determining residues/ in plant material, in water, etc.

The limit of proof of isotachophoresis analysis is very high. For a complete quantitative or qualitative analysis of substances, it is sufficient to inject a substance amount —β — 11 3 from 10 to 10 moles of the analyzed substance in a volume of 1 ml of solution into the isotachophoretic column.

The method according to the invention can also be used to analyze the ionic components of salts of alkyldithiocarbamic acids by performing isotachophoretic separation in a non-aqueous environment, preferably in a water-alcoholic solvent (e.g. a mixture of water and methanol or ethanol), which can sometimes improve the efficiency of the separation process, which is an advantage.

The accuracy of the analysis by isotachophoresis is high and is comparable, for example, to the method of gas chromatography. The advantage of the analysis by the method according to the invention is also that it is possible to analyze ionoaene reaction mixtures of alkyldithiocarbamic acids such as sulfides, thiocarbonates, thiosulfates, further anions of water-soluble salts of metal elements M, such as sulfates, chlorides, nitrates, acetates, etc. and also other substances that are used in the treatment of commercial preparations, e.g. hexamethylenetetramine in fungicidal preparations.

An advantage of analyzing the subject group of substances by the method according to the invention is that isotachophoretic analyzers with a two-column system, i.e. with a pre-separation and analytical column, are currently commercially available.

These analyzers allow, during isotachophoretic analysis, to filter out at a higher value of the electric current from the analyzed mixture of substances those substances that are not interesting from an analytical point of view /e.g. sulfates, nitrates, chlorides, which are excess substances in the analyzed solution after the completion of sample mineralization/ and to subject only analytically significant substances to analysis in the analytical column. The possibility of such an operation contributes to shortening the time of isotachometric analysis.

As a terminating electrolyte in anionic isotachophoresis, it is possible to advantageously use, for example, glutamic acid, caproic acid, morpholinoethanesulfonic acid, cacodylic acid, p-aminobenzoic acid, nicotinic acid, pelargonic acid, EDTA, CHEDTA, etc., and as a conducting electrolyte, a mixture of hydrochloric acid and glycine, betaalanine, creatinine, hexamethylenetetraamine, L-histidine, aniline, imidazole, trishydroxymethylaminoethane and other substances that have buffering acid-base properties in the pH range of 2 to 10.

As a terminating electrolyte in the case of cationic isotachophoresis, it is possible to use, with advantage, for example, lithium chloride, tetramethylammonium chloride, trishydroxymethylaminoethane, etc., and as a conducting electrolyte, hydrochloric, sulfuric, iodic acids, either alone or in a mixture with their salts, preferably potassium.

The attached Figs. 1 to 2 show isotachophorograms of the separation of some components.

In fig. 1 sd shows lzotachophorograms of the following components of salts of alkyldithiourea 2+ acids: chlorides 1, ethylene isdithiourea 2, CHEDTA Zn chelate 3, CHEDTA chelate 2+

Mn 4^, CHIDTA _5, glutamate 6, isotachophorogram A shows the separation of chlorides 1^, ethylenebisdithiocarbamidans 2_, CHIDTA Zn ^{2 +} 3, CHEDTA Mn ^{2 +} 4, CHIDTA _5 and glutamate 6, isotachophorogram B shows the separation of chlorides 1^, CHIDTA Zn ^{2 +} 2« CHIDTA Mn ²⁺ 4 and CHIDTA 5 and isotachophorogram C shows the separation of chlorides 1, CHEDTA Zc? ⁺ 2» CHIDTA Mn ²⁺ 4, CHIDTA J and glutamate £. R is the resistance in zones aj: time of analysis.

Fig. 2 shows the isotachophorogram of the separation of chlorides JL^, ethylenebisdithiocarbamides _2, dimethyldithiocarbamides 7., morpholinodithiocarbamides 8, diethyldithiocarbamides 9(, piperidyldithiocarbamides 10, dipropyldithiocarbamides 11, dibutyldithiocarbamides 12, and MES 13.

R is the resistance in the zones and t is the analysis time. The analysis conditions are given in Table JU

The isotachophoreogram in Fig. 1 A, B and 2 represents the analysis of the model sample. The isotachophoreogram in Fig. 1 C represents the analysis of mancozeb (Dlthan sample - M 45).

The isotachophoreograms in Fig. 1 and 2 were constructed under the analysis conditions given in Table 1. The isotachophoreograms were constructed at an electric current value of 200μA /Fig. 1/ and 80μA /Fig. 2/.

The isotachophorograms in Fig. 1 were constructed using an isotachophoretic analyzer manufactured at the Research Institute of Analytical Chemistry - ČSAV, Brno /planar column made of organic glass and Teflon with a length of 20 cm and a cross section of 0.2 x 1 mm; gradient - potential detector/. <

The isotachophorogram in Fig. 2 was constructed using an isotachophoretic analyzer manufactured at the Technical University of Eindhoven, the Netherlands (Teflon capillary column about 20 cm long and 0.3 mm in diameter; conductivity detector with differential recording).

The method for analyzing ionic components in salts of alkyldithiocarbamic acids according to the invention is illustrated, but not limited, by the following examples.

Example

Determination of alkyldithiocarbamides, sulfates, manganese, zinc /nitrates, chlorides and other metal elements from group M/ in water-insoluble salts of alkyldithiocarbamic acids. ³

3

Weigh 0.3 to 0.4 g of the sample into a 150 cm beaker, add 50 cm of a 0.05 M solution

38910

CHEDTA, 5 cm 10* ammonia solution in water. The contents of the beaker are stirred vigorously for about 12 min.

using an electromagnetic stirrer and after dissolving the components, the clear solution obtained is transferred to a 100 cm volumetric flask,

2 μl of this solution is used for isotachophoretic analysis. Isotachometric analysis is carried out under the conditions given in Table 1. The length of the zones of the individual components is read from the isotachophorogram and their concentration in the analyzed solution is read from the calibration curve and the content in the sample is calculated.

The calibration curve is constructed as a dependence of the measured length of the zone of a certain component on the isotachograph on its analyzed substance amount in the standard solution used for analysis.

Standard solutions of components for constructing the calibration curve are prepared so that the concentration of components in the solutions is in the range from 0.001 to 0.01 mol. dm ³ . The length of the chloride zone is determined by measuring the time difference between the basic zone on the isotachophoreogram corresponding to the leading and terminating electrolyte and the first zone of the component on the isotachophoreogram analyzed in the presence of chlorides.

Example 2

Determination of alkyldithiocarbamidans in water-insoluble salts.

The sample is decomposed using an oxalate-forming substance, e.g. IDTA, DTPA, CHHOTA as in Example 1 and the analyzed solution is prepared similarly. The separation of the components is carried out under the conditions given in Table 1. The analysis is evaluated by the calibration curve method.

Example 3

Determination of alkyldithiocarbamidans, nitrates, /sulfates, chlorides, acetates/ in water-soluble salts.

The analyzed sample solution for analysis is prepared by dissolving it in water so that the total concentration of the components is about 0.01 mol. ^dm3 . From this solution, 1 to 2 mm^ is used for isotachophoretic analysis and the separation of the components is carried out under the conditions given in Table 1. The analysis is evaluated by the calibration curve method.

Example 4

Determination of manganese and zinc (or other elements from group M) in salts of alkyldithiocarbamic acids.

3

Weigh 0.3 to 0.5 g of sample into a 250 cm conical flask, add 2 cm of concentrated nitric acid and 6 cm of concentrated hydrochloric acid /or 4 cm of conc.

nitric acid and 5 cm of 10% hydrogen peroxide solution/.

The contents of the flask are heated on an electric hotplate until the acid residues evaporate. Into the flask

3, 30 cm of water is added, the solution is transferred to a 100 ml volumetric flask and the volume of the solution is adjusted to the mark with water.

. 3

From this solution, a 2 mm is injected into an isotachophoretic column. Isotachophoretic separation is carried out under the conditions given in Table 1. The analysis is evaluated by the calibration curve method.

Example 5

Determination of sodium, ammonium, calcium (elements from group M) in salts of alkyldithiocarbamic acids.

Prepare a sample solution for analysis by dissolving or leaching it in water (in the case of water-insoluble salts as in Example 4) so that the concentration of the components is about 0.01 mol. dm \

Isotachophoretic separation shall be carried out under the conditions given in Table 1. The analysis shall be evaluated by the calibration curve method.

Example 6

Identification of an unknown substance in a sample.

The separation of components in the analyzed solution without and with the addition of the comparison substance is carried out under certain analysis conditions /e.g. given in example 1 /tab. 1//. If the heights of the peaks or lengths of the zones of the identified and compared substances on the isotachophoreogram coincide or increase proportionally to the injected amount of the comparison substance, it is likely that the comparison substance is identical to the unknown - identified substance.

To ensure greater reliability of the correctness of the identification, the procedure is repeated under changed conditions in the analysis operating system /e.g. under conditions as in example 2 /tab. 1// When selecting the compared substances, one can be guided by the mutual correlation of the dissociation constants and the mobility of the substances in the electric field.

Table 1

Analysis operating system assumptions used in the examples of the analysis procedure and in constructing isotachophoreograms using the method according to the invention

example number image number Leading electrolyte Final electrolyte Electric current intensity in /iA Method of separation 1 0.01 M HCl/beta-alanine pH = 3.30, 0.01 M acid. glutamic or CHEDTA 20 - 500 anionic 2 2 0.01 M HCl/1-histidine pH = 5.0 0.01 M acid. glutamic, caproic, MES, EDTA, CHEDTA 20 - 500 anionic 3 0.01. M HCl/hexamethylenetetramine pH « 5.3 0.01 M MES 20 - 500 anionic 4 1 A, B, C 0.01 M HCl/beta-alaninej 3.20 0.01 M CHEDTA, acid. glutamic 20 - 500 anionic 5 0.01 M acetic acid/KOH; pH = 5.0 0.01 M trlshydroxymethylaminoethane, acid. 2-aminocapronic 20 - 300 cationic

Claims (2)

OBJECT OF THE INVENTION Method for the analysis of ionogenic components of salts, alkyldithiocarbamic acids, characterized in that the analysis of ionogenic components, in particular alkyldithiocarbamidates, sulphates, nitrates, chlorides, acetates, ammonium, ethylenediamine, hexamethylenetetraamine, sodium Na ⁺ ions, manganese Zn, manganese Zn , Co °, iron Fe 4+, Fe ^-5 , nickel Ni, Cu medium, cadmium Cd ⁴⁺ , tin Sn ⁴⁺ , antimony Sb ⁴⁺ , mercury H ⁴⁺ , aluminum Al ⁴⁺ , chromium Cr ⁴⁺ in v. from soluble and / or insoluble salts of alkyldithiocarbamic acids to their chemical decomposition with chelating agents and / or acids and / or redox substances and / or the effect of heat on the water-soluble ionic components, is carried out in an isotachophoretic column at a selected electric current intensity by electrolyte and electrolyte terminating, the analyzed components are detected in their respective zones by conductivity and / or gradient-potential and / or spe determine the content of the components or identify them in the component to be analyzed by measuring the lengths of the zones of the components to be analyzed or the detector signal proportional to the absorbency of the component to be analyzed by trophotometric and / or thermometric and / or high-frequency conductivity and / or radiation detectors. 2. Method according to claim 1, characterized in that an anionic isotachophoresis using an anion with greater or equal mobility among the anions to be analyzed and a cation with a buffer property in the pH range of 2.0 to 10.0, cationic isotachophoresis using cationic isotachophoresis with an mobility of greater than or equal to the analyzed cations and an anion having a buffering property in the pH range of 1.8 to 10.0 and an anionic isotachophoresis terminating electrolyte component with the least mobility of the anions analyzed and cationic isotachophoresis with the least of the analyzed cations.