Gas-liquid chromatographic determination of capsaicin.

A simple and accurate method has been developed for the quantitative determination of capsaicin in capsicum spices and their oleosresins. Capsaicin is extracted with acetone and separated from interfering substances, using an activated alumina column. The column is first eluted with acetone, and then the capsaicin is eluted with acetone-methanol-water (75+25+2). The capsaicin is quantitated by gas-liquid chromatography, using a Carbowax 20M-Teflon column and piperine as an internal standard. Results can be calculated as per cent capsaicin or Scoville units. Recovery of added capsaicin averaged 101%.     

Gas-liquid chromatographic determination of morphine, heroin, and cocaine.

Morphine, heroin, and cocaine are quantitatively determined with the same gas-liquid chromatographic system. The compounds are separated on a 6 ft X 2 mm id glass column packed with a 1:1 mixture of 5% SE-30 on 80--100 mesh Chromosorb W and 3% OV-17 on 80--100 mesh Varaport 30. The column is temperature-programmed. Flame ionization detector responses are measured with a computer-based data system. Heroin and cocaine are chromatographed directly; morphine is derivatized first. The procedure was evaluated with previously analyzed commercial and forensic samples. Accuracy and precision were 5 and 3%, respectively.     

Rapid thin layer chromatographic determination of zearalenone in corn, sorghum, and wheat

A rapid method is described for determining zearalenone in corn, sorghum, and wheat. The mycotoxin is extracted with a mixture of acetonitrile and 4% KCl in HCl. The extract is cleaned up with isooctane, evaporated, and redissolved in chloroform. Zearalenone is separated by thin layer chromatography; identity is confirmed with various developing solvents and spray reagents. Zearalenone is then quantitated by the limit detection method. The minimum detectable concentration is 140-160 micrograms/kg when aluminum chloride solution is used as spray reagent, and 85-110 micrograms/kg when Fast Violet B salt is used as spray reagent.     

Gas-liquid chromatographic determination of nikethamide in injectable preparations.

A gas-liquid chromatographic (GLC) method, using a 4% XE-60 on 80-100 mesh Gas-Chrom Q column, a flame ionization detector, and anthracene as the internal standard, has been developed for the direct determination of nikethamide. Eight collaborators analyzed 4 samples, using methanol as the solvent; the coefficients of variation obtained ranged from 1.19 to 3.20%. In a limited study with acetone as the solvent, the coefficients of variation ranged from 0.59 to 1.96%. The GLC method with acetone as a solvent has been adopted as official first action.     

Gas-liquid chromatographic determination of strychnine in grain baits.

A simple and rapid gas-liquid chromatographic procedure, using a 6' times 1/4' glass column packed with 5% SE-30 on Chromosorb W (DMCS) and a flame ionization detector, is described. Grain baits containing strychnine alkaloid are ground, mixed, and extracted by shaking with chloroform containing an internal standard, 1,3,5-triphenylbenzene. Without further cleanup, extract filtrates are injected directly into a gas chromatograph. Peak height ratios are used for quantitation of strychnine. The analysis of commercial samples shows that the method compares well with a commonly employed ultraviolet spectrophotometric method; good precision, with recoveries ranging from 89.9 to 91.7%, is obtained in the analysis of prepared samples. The method is sensitive to 2 mug strychnine.     

Gas-liquid chromatographic determination of beta-asarone in wines and flavors.

Wine samples containing beta-asarone (cis-2,4,5-trimethoxy-l-propenylbenzene) are distilled; beta-asarone is extracted by hexane and then quantitatively determined by gas-liquid chromatography (GLC), using ethyl palmitate as the internal standard. The GLC procedure is rapid and yields precise and accurate results. Mass spectrometry confirmed the identity of the GLC peak as beta-asarone. The ultraviolet spectra of beta-asarone and its isomer were also determined.     

Gas-liquid chromatographic determination of p-chloroacetanilide in acetaminophen

Gas-liquid chromatography GLC) coupled with column chromatography was used to accurately determine as little as 25 ppm p-chloroacetanilide in acetaminophen. p-Chloroacetanilide was eluted from a pH 8 phosphate-buffered diatomite partition column by using purified tetrachloroethylene (acetaminophen was retained). This solution was concentrated, internal standard (docosane) was added, and p-chloroacetanilide was determined by using a 0.9 m X 2 mm glass column packed with 3% Poly A 103 on Supelcoport and a flame ionization detector with electronic integration. Standard curves were linear for 10-100 ppm p-chloroacetanilide. Various chromatographic materials were investigated for optimal retention characteristics. High pressure liquid chromatography (HPLC) was also evaluated as an alternative; however, lack of reproducibility of the HPLC column favored the GLC procedure.     

Gas-liquid chromatographic determination of kepone residues in finfish, shellfish, and crustaceans.

Finfish, shellfish, and crustacean samples are extracted with isopropanol and benzene; the extract is filtered and then concentrated. The extract, dissolved in hexane, is treated with oleum and extracted with aqueous alkali. The aqueous phase is acidified and extracted with petroleum ether-ethyl ether (1 + 1). The Kepone residue is determined by electron capture gas-liquid chromatography (GLC). Recoveries obtained by 8 laboratories from 15 species of finfish fortified at 0.02-0.23 ppm ranged from 37 to 107% with a mean +/- relative standard deviation of 79.4 +/- 14.5%. For oysters fortified at 0.01-0.10 ppm, recoveries range from 63 to 129% with a mean of 78.8 +/- 20.8%. For crustaceans fortified at 0.05-0.26 ppm, recoveries ranged from 52 to 110% with a mean of 78 +/- 16.4%. The approximate limits of quantitation for finfish and for shellfish and crustaceans are 0.02 and 0.05 ppm, respectively, under the GLC conditions used in this study.     

Gas-liquid chromatographic determination of pentachlorophenol in milk

A gas-liquid chromatographic (GLC) method developed by other workers for determining pentachlorophenol (PCP) in water has been adapted for determining PCP in raw and homogenized milk. PCP is extracted from milk with benzene and from the benzene into a potassium carbonate solution. Acetic anhydride is added to the aqueous solution to form PCP acetate, which is extracted into hexane and then determined by electron capture GLC. Duplicate determinations of PCP in milk fortified at levels of 0.02, 0.2, and 2.0 ppm gave respective average recoveries of 80.0, 87.2, and 85.0%. PCP levels as low as 0.005 ppm can be detected in 20 g milk.     

Gas-liquid chromatographic determination of total cholesterol in multicomponent foods.

A method is described for the determination of total cholesterol in multicomponent foods and also other products such as nonfat dry milk, dried whole egg solids, and certain candy bars. The lipid is extracted from the sample by a mixed solvent and saponified. The unsaponifiable fraction which contains the cholesterol and other sterols is extracted with benzene. An aliquot is evaporated to dryness and the residue is dissolved in dimethylformamide. The sterols are derivatized to form trimethylsilyl (TMS) ethers. The TMS-cholesterol derivative is quantitatively determined by gas-liquid chromatography, using 5alpha-cholestane as an internal standard. Nine laboratories participated in a collaborative study of the determination of total cholesterol in deviled ham sandwich spread, vegetable beef stew, corned beef hash, frozen chicken pot pie, pizza pepperoni, fish sticks, breaded shrimp, chocolate-covered candy bars, dried whole egg solids, and nonfat dry milk and the results are reported here. The coefficient of variation ranged from 5.64 to 23.2%, with an average coefficient of variation of 14.8%.     

Gas-liquid chromatographic determination of 3,6-dichloropicolinic acid in soils.

A gas-liquid chromatographic (GLC) method has been developed for the determination of the experimental herbicide 3,6-dichloropicolinic acid (Dowco 290) in soils. The method involves extraction of 1 g soil samples with 1N NaCl at approximately pH 7, methylation with diazomethane utilizing a microgenerator, and detection by electron capture GLC. Interferences are small, so that a cleanup step is not necessary even at the 6 ppb level. The procedure is rapid, requiring only 45 min/sample. Recoveries range from 84 to 94% at the 6-1000 ppb level with a minimum detectable limit of 6 ppb. Standard deviations for the percentage recovery values vary from 10.9 to 2.3 for the tested range of 6.7-670 ppb, respectively.     

Gas-liquid chromatographic determination of individual sugars in confectionery products.

A gas-liquid chromatographic (GLC) procedure is presented for the separation and quantitative determination of sucrose, lactose, maltose, and glucose in commercial confectionery products. By converting reducing sugars to oximes and then forming trimethylsilyl ethers of these compounds and separating them on a 6 ft X 4 mm id glass column packed with 2% OV-17 on 100--120 mesh Supelcoport, single peaks were obtained for each of the sugars. Results for sugars present in samples at levels of 5% or more are within 2.8%, on the average, of results obtained by polarization measurements. The data also compare favorably with others in the literature on similar products analyzed by other GLC procedures that do not involve oxime formation.     

Gas-liquid chromatographic determination of ethopabate in feed premixes

A gas-liquid chromatographic method is presented for determining ethopabate in 0.8 and 8.0% premixes. A sample is extracted with tetrahydrofuran containing an internal standard, by sonication or overnight soaking. The extract is clarified by centrifugation, diluted if necessary, and injected into a gas chromatograph equipped with a flame ionization detector. Average per cent recoveries for spiked blank samples were 100.6 at the 0.8% level and 100.4 at the 8.0% level. Precision, as indicated by replicate analyses of several premixes, ranged from 0.5 to 1.7% relative standard deviation.     

Gas-liquid chromatographic determination of permethrin in bovine tissues

A method is presented for the determination of permethrin (m-phenoxybenzyl cis,trans-(+/-)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate) in bovine tissues. Fat and muscle samples were cleaned up first by liquid-liquid partition on a bonded phase chromatographic column. Final cleanup of fat and muscle was performed on a short Florisil column. Liver, kidney, spleen, and heart tissues only required cleanup on a Florisil column before quantitation of permethrin by electron capture gas-liquid chromatography.