Acid gases simultaneous determination

A gas chromatographic method may be employed for analysis for both benzoic acid and sorbic acid in food, as described in AOAC method 983.16. The acids are extracted from an acidified aqueous homogenized food sample into ether. The acids are then extracted from the ether solution into aqueous alkali, and after acidification they are re-extracted into dichloromethane. Treatment of the residue with N-methyl-N-trimethylsilyltrifluoroacetamide converts the benzoic and sorbic acids into trimethylsilyl esters. These esters are then analyzed with a glass column packed with a support coated with OV-1, in a temperature programmed analysis. Phenylacetic and caproic acids are used as internal standards for benzoic and sorbic acids, respectively. An LC method has also been described for analysis of benzoic acid with simultaneous determination of sorbic acid, and methyl, ethyl, propyl, and butyl p-hydroxybenzoates. The preservatives were extracted from meat or seasonings with 70% ethanol, and analyzed by reversed-phase LC using a Cig stationary phase with a linear gradient from 10 to 70% methanol in 1.5% aqueous ammonium acetate and 1.5% aqueous acetic acid. 

Silva FO, Ferraz V (2004) Microwave-assisted preparation of sugars and organic acids for simultaneous determination of citric fruits by gas chromatography. Food Chem 88 609 12... 

KATONA, Z.F., SASS, P., MOLNAR-PERL, I., Simultaneous determination of sugars, sugar alcohols, acids, and amino acids in apricots by gas chromatography-mass spectrometry, J. Chromatogr., 1999, 847, 91-102. 

ADAMS, M.A., CHEN, Z., LANDMAN, P., COLMER, T., Simultaneous determination by capillary gas chromatography of organic acids, sugars, and sugar alcohols in plant tissue extracts as their trimethylsilyl derivatives, Anal. Biochem., 1999, 266, 77-84. 

Kavetskii et al. [224] developed a method for the simultaneous determination of pesticides in soil. A combination of thin layer chromatography and gas chromatography was used. The pesticides examined were 4,4 DDT, 4,4 DDD, 4,4 DDE, 2,4 DDT, GHCG, aGHCG, Metaphos, Phosphamidon, Phozalone, Atrazine, Prometryne, Simazine and 2,4 dichlorophenoxy acetic acid. Detection limits were in the range 0.5-5pg kgy1. 

Suzuki, M. and Lund, C.W. (1980) Improved gas-liquid chromatography for simultaneous determination of volatile fatty acids and lactic acid in silage. Journal of Agricultural and Food Chemistry 28,... 

System (6) has been described for the simultaneous determination of submicrogram amounts of 17a-deoxy and 17a-hydroxy corticosteroids [145]. Prior to analysis, the corticosteroids were treated with periodic acid in 50% aqueous dioxane, and extracted with dichloromethane. Acylation of the 3- and 17a-hydroxyl groups was carried out using 1 1 butyric anhydride and pyridine. 4- C -cholesterol was added as the tracer, and cholesterol isobutyrate as the internal standard. The column used was glass (8 ft X 5 mm) packed with 1% SE 30 or QF-1 on GasChrom Q (100-120 mesh), and was operated at 250-260°C. Argon (at a flow rate of 30 mL/min) was used as the carrier gas, and detection was by a Sr detector. It was reported that the corticoids could be determined with a precision of approximately 15% down to levels as low as 0.1-0.2 pg. 

Scheiffer, G. W., Palermo, P. J., and Pollard-Walker, S. (1984), Simultaneous determination of methyl, ethyl, propyl, and butyl 4-hydroxybenzoates and 4-hydroxybenzoic acid in liquid antacid formulations by gas chromatography, J. Pharm. Sci., 73,128. 

I. Matsunaga, T. Imanari, and Z. Tanura, Simultaneous determination of urinary uronic acids and saccharic acids by gas chromatography, Chem. Pharm. Bull. (Tokio), 18 (1970) 2535-2543. 

J. Libeer, S. Scharpe, et al., Simultaneous determination of p-aminobenzoic acid and p-aminohippuric acid in serum and urine by capillary gas chromatography with use of a nitrogen-phosphorus detector, Clin. Chim. Acta, 775 119-123 (1981). 

The Frank and Demint [200] method is directly applicable to water samples. After addition of sodium chloride (340g IT1) and aqueous hydrochloric acid (1 1) to bring the pH to 1, the sample was extracted with ethyl ether and the organic layer was then extracted with 0.1M sodium bicarbonate (saturated with sodium chloride and adjusted with sodium hydroxide to pH8). The aqueous solution adjusted to pHl with hydrochloric acid was extracted with ether and after evaporation of the ether to a small volume, Dalapon was esterified at room temperature by addition of diazomethane (0.5% solution in ether) and then applied to a stainless steel column (1.5m/3mm) packed with Chromosorb P (60-80 mesh) pretreated with hexamethyldisilazane and then coated with 10% FFAP. The column was operated at 140°C, with nitrogen carrier gas (30mL muT1) and electron capture detection. The recovery of Dalapon ranged from 91 to 100% the limit of detection was O.lng. Herbicides of the phenoxyacetic acid type did not interfere trichloroacetic acid could be determined simultaneously with Dalapon. 

Xie, T.M., Dyrssen, D. (1984) Simultaneous determination of partition coefficients and acidity constants of chlorinated phenols and guaiacols by gas chromatography. Anal. Chem. Acta 160, 21-30. 

Wu, H., Haig, T., Pratley, J., Lemerle, D., and An, M. 1999. Simultaneous determination of phenolic acids and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one in wheat (Triticum aestivum L.) by gas chromatography-tandem mass spectrometry. J. Chromatogr. A 864, 315-321... 

Chromatographic methods, notably hplc, are available for the simultaneous determination of ascorbic acid as well as dehydroascorbic acid. Some of these methods result in the separation of ascorbic acid from its isomers, eg, erythorbic acid and oxidation products such as cHketogulonic acid. Detection has been by fluorescence, uv absorption, or electrochemical methods (83—85). Polarographic methods have been used because of flieti accuracy and their ease of operation. Ion exclusion (86) and ion suppression (87) chromatography methods have recently been reported. Other methods for ascorbic acid determination include enzymatic, spectroscopic, paper, thin layer, and gas chromatographic methods. Excellent reviews of these methods have been published (73,88,89). 

Porter WH, Rutter PW, Yao HH. Simultaneous determination of ethylene glycol and glycolic acid in serum by gas chromatography-mass spectrometry. J Anal Toxicol 1999 23 591-7. 

Ranee MJ, Jordan BJ, Nichols JD. A simultaneous determination of acetylsalicylic acid, saHcyhc acid and salicylamide in plasma by gas-liquid chromatography. J Pharm Pharmacol 1975 27 425-9. 

Yao HH, Porter WH. Simultaneous determination of ethylene glycol and its major toxic metabofite, glycolic acid, in serum by gas chromatography. Clin Chem 1996 42 292-7. 

In the following we present an experimental set up which allows the simultaneous determination of the gas phase composition and the oxygen activity of the solid catalyst under operating conditions along a tubular fixed bed reactor. Preliminary results of the partial oxidation of acrolein to acrylic acid at an oxidic catalyst illustrate the possibilities of the procedure. 

The most commonly applied methods for the analysis of polyamines in erythrocytes make use of amino acid analyzers and HPLC techniques. A capillary gas chromatographic method with nitrogen-phosphorous detection was applied to the simultaneous determination of 1,3-diaminopropane, putrescine, cadaverine (Cad), spermidine (Sd), and spermine (Sp) in human erythrocytes. Blood samples, collected by venipuncture into EDTA containing Venoject tubes, were subjected to the removal of plasma by centrifugation and erythrocytes were washed three times with two volumes of 0.9% NaCl. The stability of polyamines in erythrocyte suspensions was also investigated. Quantification of polyamines was done by comparing the peak-area ratio of each analyte and its internal standard with that of the standard. The polyamine samples were eluted with 0.1 M hydrochloric acid solutions. The eluate was evaporated to dryness at 120°C under a stream of air and 200 each of acetonitrile and heptafluorobutyric anhydride were added. The isolation of derivatives... 

Jia, M. Wu, W.W. Yost, M.G. Chadik, P.A. Stacpoole, P.W. Henderson, G.N. Simultaneous determination of trace levels of nine haloacetic acids in biological samples as their pentafluorobenzyl derivatives by gas chromatogra-phy/tandem mass spectrometry in electron capture negative ion chemical ionization mode. Anal. Chem. 2003, 75, 4065 080. 

Paik, M.-J. Kim, K.-R. Sequential ethoxycarbonylation, methoximation and fert-butyldimethylsilylation for simultaneous determination of amino acids and carboxylic acids by dual column gas chromatography. J. Chromatogr. A, 2004,1034, 13-23. 

Simultaneous Determination of Urinary Uronic Acids and Saccharic Acids by Gas Chromatography Chem. Pharm. Bull. 18(18) 2535-2543 (1970) CA 74 61486n... 

Simultaneous Determination of Acetyl-salicylic Acid, Salicylic Acid, and Salicylamide in Plasma by Gas-Liquid Chromatography J. Pharm. Pharmacol. 27(6) 425-429 (1975) CA 83 172321k... 

Simplified Simultaneous Determination of Valproic Acid and Ethosux-imide in Serum by Gas-Liquid Chromatography... 

Banno, K., Matsuoka, M., Horimoto, S., and Kato, J., 1990. Simultaneous determination of pantothenic acid and hopantenic acid in biological samples and natural products by gas chromatography-mass fragmentography. Journal of Chromatography. 525 255-264. 

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