Determination of methyl-substituted phenols in water by gas chromatography with preliminary iodination

A procedure is developed for determining phenol; 2-, 3-, and 4-methylphenols, and 2,4- and 2,6-dimethylphenols in aqueous media, which consists in the synthesis of iodine derivatives, their extraction with toluene, and determination by gas chromatography with electron-capture detection. The optimal conditions for the iodination of phenols in water are found; also the extraction and gas chromatography behavior of methylphenols and their iododerivatives are investigated. To make the identification of iododerivatives of methylphenols more reliable, they are subjected to acylation with acetic anhydride in the extract. The analytical range of phenols in water is 0.01–10 μg/L, the relative standard deviation is 2–6%, and the duration of analysis is up to 40 min.     

Synthesis of (E)-2-methoxy-6-(R-imino)methylphenols and 2-methoxy-6-(R-amino)methylphenols

(E)-2-Methoxy-6-(R-imino)methylphenols were synthesized by the condensation of 2-hydroxy-3-methoxybenzaldehyde with primary amines. By reduction of the iminophenols with sodium triacetoxyborohydride 2-methoxy-6-(R-amino)methylphenols were obtained.     

Gas-chromatographic determination of chlorostyrene and dichlorostyrene isomers in workplace air

Conditions for a gas-chromatographic determination of vapors and aerosols of p-chlorostyrene and 2,6-dichlorostyrene contained in workplace air samples were determined. The method is based on the adsorption of p-chlorostyrene and 2,6-dichlorostyrene on activated charcoal and fiberglass, desorption with toluene and analysis of the obtained solution by capillary gas chromatography with flame ionization detection (FID). The determination limit of the method is 5 mg m(-3) for each substance.     

Gas-chromatographic determination of trace amino alcohols in water, air, and bitumen-salt masses forming in the detoxication of chemical warfare agents

A procedure was proposed for the determination of trace amino alcohols in various media using hydrochloric acid and acetic anhydride as gas-chromatographic derivatizing reagents. The developed procedures provide the determination of amino alcohols in water and air at a level of their maximum permissible concentrations (0.5 mg/L and 0.5 mg/m³, respectively) and in a bitumen-salt mass in a concentration of 5 x 10^-4%.     

Extractive concentration of halogen-substituted phenols in their gas-chromatographic determination in aqueous media

Method for recovery of chlorophenols from natural and drinking water for their subsequent gas-chromatographic determination was considered. Processes of microliquid extraction of bromo derivatives of chlorophenols and the method for liquid extraction with intermediate concentration of these compounds in an alkaline solution were studied.     

Determination of the diastereomers of vitamin K1

A method is described for the gas-chromatographic determination of the diastereomers of vitamin K₁ (phylloquinone) in the form of their dihydro dimethyl ethers. The reported method of derivatization and chromatographic analysis in conjunction with optical rotation measurements are useful approaches for characterization of vitamin K₁ samples with respect to their origin.     

Gas-chromatographic determination of selenium as an organo-selenium compound with acetophenone

A gas-chromatographic method with electron-capture detection is presented for the determination of selenium after reaction with acetophenone to obtain an organo-selenium compound. This compound is extracted into benzene and chromatographed on an alumina column. The relative standard deviation for the average value (5 mug) is +/-6% (n = 8, P = 95%). The method has been applied to the determination of selenium in metals, alloys, ores and biological samples.     

Liquid-phase reactions of isomeric methylphenols with ozone

Ozonation of isomeric methylphenols in acetic anhydride was studied. Here, acetic anhydride acts simultaneously as solvent and acylating agent. In the presence of a mineral acid methylphenols were converted into methylphenyl acetates during preparation of solutions for ozonation. The major products in the oxidation of isomeric methylphenyl acetates with ozone were aliphatic peroxides (80–90%); oxidation of the methyl group gave rise to the corresponding acetoxybenzyl acetates (7–14%) and acetoxybenzylidene diacetates (3–6%). A probable scheme for the liquid-phase oxidation of methylphenyl acetates with ozone in acetic anhydride was proposed.     

Gas-chromatographic determination of carboxylic acid anhydrides in oxidation products of alcohols and other organic compounds

A procedure was developed for the gas-chromatographic determination of carboxylic acid anhydrides in the composition of oxidation products of organic compounds after their conversion into alkyl formate by formic acid and benzyl alcohol or other primary alcohol introduced into the reaction medium. The reaction proceeds through the mixed anhydride, which is formed in situ from formic acid and the determined anhydride and is predominantly transformed into the corresponding alkyl formate in alcoholysis with alcohol. The potentialities of the procedure were illustrated by the determination of anhydrides in oxidation products of cyclohexane, cyclohexanone, and cyclohexanol.     

Gas-chromatographic determination of alkylphenols in atmospheric air and the air of the working area

Sampling conditions are optimized in the determination of industrial alkylphenols (agidols) in atmospheric air and in the air of the working area using solid-phase preconcentration on Amberlite KhAD-7 and absorption by toluene. A procedure is developed for the gas-chromatographic determination of alkylphenols on their simultaneous presence in concentration ranges from 0.01 to 1 mg/m³ in atmospheric air and 0.1–50 mg/m³ in the air of the working area.     

Identification and Determination of Chlorophenols in Potable Water by a Kinetic Gas-Chromatographic Method

A kinetic gas-chromatographic method was developed for the identification and trace determination of 2- and 4-chlorophenols, 2,4- and 2,6-dichlorophenols, and 2,4,6-trichlorophenol in potable water. The method is based on the oxidation of bromo derivatives of chlorophenols by excess molecular bromine. Optimal conditions of analysis, analytical range (0.05–50 g/L), and relative standard deviation (5–20%) were determined.     

Gas-chromatographic study of the retention of components of the reaction of the catalytic oxidation of propylene on porous polymers

The gas-chromatographic retention of oxygen, carbon dioxide, propane, propylene, water, propylene oxide, acrolein, acetone, and acetaldehyde on polar and nonpolar adsorbents was studied. A procedure was proposed for the gas-chromatographic determination of gaseous and liquid components of the reaction of the catalytic oxidation of propylene using one column.     

Gas-chromatographic determination of carbon-containing impurities in high-purity sulfur

A gas-chromatographic procedure was developed for the determination of carbon-containing impurities in sulfur with a detection limit of 6 x 10^-6%. Carbon-containing substances and elemental carbon can be effectively separated from sulfur samples as CO₂ and COS.     

Gas-chromatographic determination of the product distribution in the synthesis of sodium borohydride

A gas-chromatographic method has been developed for determination of the sodium borohydride and methanol content of alkaline aqueous solutions of NaBH(4). From the ratio between NaBH(4) and CH(3)OH the product distribution in NaBH(4) synthesis from NaH and B(OCH(3))(3) in mineral oil can be calculated and the amount of the by-product NaBH(OCH(3))(3) formed can be estimated. A separation and extraction procedure for the mineral oil dispersion must precede the gas-chromatographic analysis. Sodium borohydride is determined by measurement of the 2-propanol formed after treatment of the solution with acetone, whereas methanol can be determined directly by gas chromatography, with 1-propanol as internal standard. The analysis of the synthesis products is thus the separation and detection of simple alcohols.     

Gas-Chromatographic Separate Determination of Trace β-Chlorovinylarsonous Dichloroanhydride (Lewisite) and Anhydride (Lewisite Oxide) in Soil and Construction Materials

A method was proposed for the separate gas-chromatographic determination of β-chlorovinylarsonous dichloroanhydride (lewisite) and anhydride (lewisite oxide) in samples of soil and construction materials. Because of the absence of regulations for the maximum permissible concentration (MPC) of lewisite and lewisite oxide in construction materials (concrete, bricks, facing tile, etc.), the MPC level of lewisite in soil (0.1 mg/kg) was taken as the maximum permissible concentration in the development of the method for their determination in the above samples. The method is based on the solid-liquid extraction converting lewisite and lewisite oxide into components that can be separated at the stage of blowing-out the extractant in an inert gas flow and their subsequent conversion into acetylene with a 30% aqueous solution of sodium hydroxide and the chromatography of the vapor phase with flame-ionization detection. The error in the determination is no larger than ±20 rel %. The time of analysis is within 1.5 h.     

Gas-chromatographic determination of the components of the catalytic oxidation of ethylene glycol to glyoxal

The gas-chromatographic retention of formaldehyde, acetaldehyde, glyoxal, formic acid, and ethylene glycol on polar and nonpolar polymeric adsorbents was studied, and a procedure was developed for the determination of these components. The time of analysis was 12–14 min. The detection limits were 0.02 (acetaldehyde) to 0.7 (formic acid) ppm.     

Gas-chromatographic determination of monoethanolamine and its salts of inorganic and organophosphorus acids present in combination

A gas-chromatographic procedure was proposed for the separate determination of monoethanolamine and its salts of hydrofluoric, hydrochloric, and alkylphosphonic acids in the reaction mixtures formed in the course of detoxication of chemical warfare agents of various classes. The procedure is based on the conversion of monoethanolamine and its salts into acyl derivatives and their elution from a Chromatographie system at different injector temperatures. The determination error is no worse than 5 rel %.     

Equilibrium Model in the Description of Gas Extraction and Headspace Analysis

The main regularities of equilibrium gas extraction were considered for the static, dynamic, and flow versions of headspace gas-chromatographic determination of volatiles in solutions. The efficiency of these analytical techniques was assessed.     

Combustion processes in laboratory devices — fire simulations using the lambda'' concept — extent of formation of hydrocyanic acid and aromatic compounds

Summary A gas-chromatographic method for the determination of the total organic fraction (TOF) present in the total particulate matter (TPM) of mine aerosols and the analysis of this fraction by gas chromatography — mass spectrometry is presented. The method is statistically evaluated and the standard deviation is calculated. The method for the determination of TOF was checked by a series of analyses of TPM in an iron-ore mine and in a deep mine for magnesite.

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Analyse der organischen Gesamtfraktion von Gruben-Aerosolen

     

Gas-chromatographic determination of aliphatic amines in natural surface water and wastewater

A procedure was developed for the gas-chromatographic determination of aliphatic amines C₇–C₂₀ with prederivatization by N-methyl-bis(trifluoroacetamide), in the concentration range of natural surface water, to 10^?4-1 mg/L, and wastewater, to 10^?3-1 mg/L. The conditions were optimized for the extraction preconcentration of aliphatic amines with toluene from natural surface water and wastewater. The detection limit for aliphatic amines at a signal-to-noise ratio of 3: 1 was 50 ng/L.