Gas Chromatographic Assay

Rajagopalan et al. [72] described an electron-capture gas chromatographic assay method for the determination of primaquine in blood. The method involves deriva-tization with heptafluorobutyric anhydride to form the diheptafluorobutyramide derivative after a single extraction at alkaline pH. The derivatives are quantitated by electron-capture gas chromatography. Blood levels of primaquine as low as 8 ng/mL can be measured with good precision. 

Winston GW, Regoli F, Dugas JR, Fong JH and Blanchard KA. 1998. A rapid gas chromatographic assay for determining oxyradical scavenging capacity of antioxidants and biological fluids. Free Radic Biol Med 24(3) 480 193. 

K3. Karoum, F., Cattabeni, F., and Costa, E., Gas chromatographic assay of picomole concentrations of biogenic amines. Anal. Biochem. 47, 550-561 (1972). 

G1azko 7 reviewed same early studies on the gas chromatographic assay of phenytoin. These included derivatization with diazomethane S, the use of trimethylsilyl derivative /50, on col linn methyl at ion using tetramethyl ammonium hydroxide51 and trimethylanilinium hydroxide5. ... 

Sampson, D. Harasymiv, I., and Hensley, W.J. Gas chromatographic assay of underivatized 5,5-d iphenylhy-dantoin (Dilantin ) in plasma extracts. Clin. Chem. 17 382-385, 1971. 

B. Kolb and P. Pospisil, A gas chromatographic assay for quantitative analysis of volatiles in solid materials by discontinuous gas extraction, Chromatographia, 70 705-711 (1977). 

J. M. Moore and F. E. Bena, Rapid gas chromatographic assay for heroin in illicit preparations, Anal. Chem., 44 385 (1972). 

T. A. Bierimer, N. Asral, and J. A. Albanese, Simultaneous, stability-indicating capillary gas chromatographic assay for benzo-caine and the two principal benzyl esters of Balsam Peru formulated in a topical ointment, J. Chromatogr., 623 395 (1992). 

Miller JR Jr, Fleckenstein L (2001), Gas chromatographic assay of diethylcarbamazine in human plasma for application to clinical pharmacokinetic studies. J Pharm Biomed Anal 26 665-674... 

Note. Spectrophotometric and gas chromatographic assays have been shown to be non-selective due to interference from acid-labile hydrazones—see P. A. Reece et al., J. pharm. Sci., 1978, 67, 1150-1153 and T. M. Ludden et al., Clin. Pharmaco-kinet., 1982, 7, 185-205. 

A gas chromatographic assay allows the determination of diltiazem hydrochloride in tablet formulations. The separation uses a 3% OV-210 on a Chromosorb W 80/100 mesh column with an oven temperature of 260°C (isothermally). A carrier gas flow rate of 50 mL/minute is used. The method allows the quantitation of diltiazem in the concentration range of 0.05 mg/mL to 0.2 mg/mL (67). 

Soleas, G.J., Yan, J., Seaver, T. and Goldberg, D.M. (2002) Method for the gas chromatographic assay with mass selective detection of trichloro compounds in corks and wines applied to elucidate the potential cause of cork taint,/. Agric. Food Chem., 50 (5), 1032-1039. 

Dumas et al. also developed a micro-method for the same determination in urine and blood. Samples of 3 ml blood were treated with ammonium oxalate and filtered. 1 ml plasma was made alkaline and extracted with chloroform three times, the chloroform extract was evaporated and the residue solved in 10 yl of a solution of 5 ng diphenylamine/ul (internal standard) in ethyl acetate. The solution was used for the gas chromatographic assay. A specific N-detector was used and the sensitivity was 0.2 ng for nicotine and 1 ng for cotinine. The recovery is given in Table 5.9. 

In one paper, Isaac and Rand described a method for the determination of nicotine in plasma. By using an alkali flame ionization detector the sensitivity of the method was improved to 1 ng/ml of nicotine in a 2.5 ml sample. Modaline was used as an internal standard. The alkaloid was extracted from the basified plasma (NaOH) with diethyl ether, and this extract was used for the gas chromatographic assay on a packed column with 13 % K0H and 6.5 % Carbowax 20 M as stationary phase on Varaport 30. 

MajlSt worked out a gas chromatographic assay of atropine and phenobarbital in pharmaceutical preparations containing Valeriana liquid extract. After extraction of atropine, it was hydrolyzed and the free tropic acid silylated with N,0-bis(trimethylsilyl(acetamide. The assay was performed on a glass column, 1 m long by 3 mm I.D. packed with 1.5 % OV-101 on silanized Gas Chrom P, 100-120 mesh, at 140°C, using silylated 2-naphtol as an internal standard. 

A simple and rapid method for gas chromatographic assay of the morphine and codeine con-... 

Dechene et al. determined acetyl salicylic acid, phenacetin, caffeine and codeine in tablets. Acetyl salicylic acid and phenacetin were separated and determined on one packed column of DS 200 on Haloport by temperature programming, 100-180°C, whereas caffeine and codeine were separated on a packed column of SE-30 (10 %) on Chromosorb W AW by temperature programming, 195-260°C. Codeine and caffeine were extracted from the powdered tablet material with chloroform after the addition of alkali, and the chloroform solution used for the gas chromatographic assay. Results obtained with the method are listed in Table 20.4. 

In a paper on the gas chromatographic assay of phenacetin, caffeine, antipyrin and di-... 

Pranskevich et al. preferred a packed column of 3 SP 2250 DB as stationary phase because the butyl derivative, which is a weak base, gas chromatographs markedly better on this phase than on the same percentage loadings of other brands of OV-17. After an initial chloroform extraction of 1.0 ml serum sample, a toluene wash and back extraction into 0.5 M ammonium hydroxide, derivatization was accomplished by the addition of 15 yl of an 8 1 mixture of N,N-dimethylacetamide (400 yl) and 2.4 tetramethylammonium hydroxide in methanol (50 yl) to the dried extract. Butyliodide (15 yl) was then added and the gas chromatographic assay... 

To be able to determine theophylline in the ng range, Arbin and Edlund improved their method by derivatizing theophylline and the internal standard theobromine using penta-fluorobenzyl bromide, in connection with an electron capture detector. To 100 ul samples of plasma containing 50-1000 ng theophylline, 100 yl of a solution of the internal standard were added. The extraction was performed by column extraction (cellulose) using dichloro-methane as solvent. After back extraction into an alkaline aqueous phase (NaOH), theophylline and theobromine were alkylated with pentafluorobenzyl bromide by an extractive alkylation technique. The derivatives were extracted with cyclohexane and, after concentration to 3 ml, 2 yl were injected for the gas chromatographic assay. Standard deviation of the method was 2.5 % at a concentration level of 200 ng per sample, and 8 % at 20 ng per sample. The sample amounts were 100 yl plasma and 250 mg rat brain tissue, and the sensitivity limit... 

When this 6-isomer was added to the reaction product of 1,2,6-hexanetriol and acetic acid, the 11.62 peak was enhanced. Thus, the 10.98 and 11.24 peaks in chromatogram 31a are the 1 and 2-isomers. Because the sensitivity of the gas chromatographic assay is such that as little as 0.01% of the 6-isomer can be detected, hydrolysis of this particular polymer proceeds exclusively by the exocyclic cleavage path shown in Scheme 20. This is in very good agreement with a reported hydrolysis study of the closely related model compounds 2-methoxy-l,3-dioxalane (1) and 2-phenyl, 2-methoxy-l,3-dioxalane (2) which have been reported to undergo respectively about 2.5% and less than 0.1% endocyclic cleavage [52]. 

The most useful type of data that can be obtained in these experiments consists of the absolute fractions of the initially produced F atoms corresponding to the various labeled products. Our preferred method for determining the absolute product yields has involved a combination of conventional radiochemical separations, which serve to establish the combined yields of organic and inorganic species, together with radio gas chromatographic assay of the individual organic products (54, 55). 

Pharmacokinetic data related to the volatile anesthetics are sparse, perhaps because of onerous analytical challenges. Recently, a number of sensitive gas chromatographic assays have been published that may enhance our knowledge of the pharmacokinetics of these chiral drugs. 

Extractive alkylation processes utilizing ion-pair distribution have been used in organic synthesis [61], as well as in derivatization for gas chromatographic assay. The technique is suitable for organic compounds containing active hydrogen, which are particularly reactive as ion-pairs in non-polar solvents. 

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