GC/FID

Further more, the essential oils of the plant were isolated by hydrodistillation in Clevenger-type apparatus for 5 hours. The chemical compositions of the SFE extract and hydrodistillation were identified by GC-MS and determined by GC-FID. 

Figure 11.13 (a-c) Immunoaffinity exti action-SPE-GC-FID ti aces of (a) HPLC-grade water (b) urine (c) urine spiked with /3-19-noitestosti one (0.5 p.g/1) or norethindrone and norgestrel (both 4 p.g/1) (d) SPE-GC-FID ti ace of urine. Reprinted from Analytical Chemistry, 63, A. Faijam et al., Direct inti oduction of large-volume urine samples into an on-line immunoaffinity sample pretreatment-capillary gas cliromatography system, pp. 2481-2487,1991, with permission from the American Chemical Society. 

Figure 13.16 LC separation of urban air particulate exrtact (a), along with the GC/FID cliro-matogram (b) of an oxy-PAC fraction (transfeired via a loop-type interface). Reprinted from Environmental Science and Technology, 29, A. C. Lewis et al., On-line coupled LC-GC-ITD/MS for the identification of alkylated, oxygenated and nirtated polycyclic aromatic compounds in urban air particulate exti acts , pp. 1977-1981, copyright 1995, with permission from the American Chemical Society.

Figure 13.20 GC-FID chromatograms of an exuact obtained by (a) SPE and, (b) lASPE of 10 ml of municipal waste water, spiked with 1 p.g 1 of seven s-triazines (c) represents a blank mn from lASPE-GC-NPD of 10 ml of EIPLC water. Peak identification is as follows 1, ati azine 2, terbuthylazine 3, sebuthylazine 4, simetiyn 5, prometiyn 6, terbutiyn 7, dipropetiyn. Reprinted from Journal of Chromatography, A 830, J. Dalliige et al, On-line coupling of immunoaffinity-based solid-phase exUaction and gas chi-omatography for the determination of 5-triazines in aqueous samples , pp. 377-386, copyright 1999, with permission from Elsevier Science.

J. Beens and R. Tijssen, The characterization and quantitation of sulfur-containing compounds in (heavy) middle distillates by FC-GC-FID-SCD , J. High Resolut. Chromatogr. 20 131-137 (1997). 

Field Tests. Recently we conducted a field test at a site contaminated with fuel oil. Our measurements were 0.0625 0.0212 mA for the well water and 0.0189 0.0119 mA for distilled water (showing errors of one standard deviation). From calibration curves, these numbers can be reported as equivalent to 50 ppb phenol or 34 ppb xylenes. Nine-month-old laboratory results (EPA method 624 and GC/FID) for this site indicated concentrations of 25 ppb for benzene, toluene, and xylenes combined and 100 ppb for fuel oil. The important result is the significant difference between the distilled-water and well-water measurements. We are very encouraged by these results and are planning future field tests. 

Methyl parathion was determined in dog and human serum using a benzene extraction procedure followed by GC/FID detection (Braeckman et al. 1980, 1983 DePotter et al. 1978). An alkali flame FID (nitrogen-phosphorus) detector increased the specificity of FID for the organophosphorus pesticides. The detection limit was in the low ppb (pg/L). In a comparison of rat blood and brain tissue samples analyzed by both GC/FPD and GC/FID, Gabica et al. (1971) found that GC/FPD provided better specificity. The minimum detectable level for both techniques was 3.0 ppb, but GC/FPD was more selective. The EPA-recommended method for analysis of low levels (<0.1 ppm) of methyl parathion in tissue, blood, and urine is GC/FPD for phosphorus (EPA 1980d). Methyl parathion is not thermally stable above 120 °C (Keith and Walters 1985). 

Soil Equilibrated in sealed vial headspace gas injected into GC GC/FID NR 80 Pavlostathis and Mathavan 1992... 

Purification of bile acids extracted from human stool quantitation by GC/FID 75... 

Niki and Kuwatsuka reported a method involving trifluoroacetylation of the amino derivatives of chlornitrofen, nitrofen and chlomethoxyfen. A 1-mL volume of 10 M NaOH solution was added to 50 g of soil and the mixture was extracted with 100 mL of benzene. After separation and drying over anhydrous Na2S04, the benzene solution was trifluoroacetylated by adding successively 1 mL of 0.1% trifluoroacetic anhydride in benzene and 1 mL of 0.1% triethylamine in benzene. The mixture was shaken for 30 s and diluted to 10 mL with benzene. To remove the excess of trifluoroacetic anhydride, about 2 mL of water were added to the mixture and shaken for 30 s. The benzene layer was dried over anhydrous Na2S04 and injected for gas chromatography/flame ionization detection (GC/FID). 

The GC/FID conditions were as follows column, 1.5% OV-17 (2 m x 3-mm i.d.) glass column N2 carrier gas flow rate, 45mLmin temperature of injection port, column and detector, 240,235 and 235 °C, respectively. The recoveries of these amino derivatives with fortification level ranging from 0.5 to lO.Omgkg" were 62-101% for chlornitrofen, 62-101% for nitrofen and 58-101% for chlomethoxyfen, and satisfactory recoveries from soil were obtained at high concentrations, but the recoveries at lower concentration averaged about 66% for the least recovered compound. Interference from other substances in the soil extracts derived from the acetylation reaction was negligible. 

We monitored the percent conversion of epichlorohydrin and enantiomeric excess of the recovered S-epichlorohydrin with time by using GC-FID. Approximately 54% conversion and >99% ee were obtained in about 4 h reaction time. After 4 h, the epichlorohydrin was removed under vacuum at room temperature and diol was removed at a temperature of 329 K. The recovered catalyst was further treated in the HKR of racemic mixture of fresh epichlorohydrin. In the second run, we observed a decrease in the conversion and ee compared to the fresh catalyst. The Co-salen was again recovered after the second run by removing all the products under vacuum and recycled two more times. With each subsequent HKR reaction, the conversion and ee were found to decrease with time (22). Table 43.1 summarizes the initial rates and ee s determined from the four runs without intermediate catalyst regeneration. Interestingly, the initial catalyst activity was resumed when the catalyst was regenerated with acetic acid prior to recycle. 

Many standard compendium methods (ASTM, EPA, FAAM) are based on GC analysis. Examples are the GC-FID determination of fatty acid methyl esters (FAME ... 

Solution SHS-GC-FID was used for the determination of dichloromethane (DCM) in PC [222] and solid SHS-GD for the analysis of residual solvents in transdermal drug-delivery systems [223] and rest... 

SFC has played an important role in the extraction and isolation of fatty acids [355,356]. Underivatised fatty acids and methyl esters of fatty acids are surprisingly easy to elute using a bonded phase or a silica based packed column and pure C02, probably due to the long hydrocarbon tails on the molecules [357]. On the other hand, most aromatic and polysubstituted acids will not elute. Triglycerides with saturated fatty acids can be analysed faster with pSCF-ELSD than with GC-FID and do not require sample preparation [358]. Using... 

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