GC-FID Analysis

Fiber 85 (xm polyacrylate used in headspace mode Desorption 250°C for 2 min Analysis GC-FID and GC-MS. 

Gas chromatography was first applied to analyse cuticular waxes in the early 1960s, and its use has progressed with the introduction of capillary columns. Many of the more recently published papers deal with gas chromatography analysis (GC-FID or GC-MS) rather than with liquid chromatography (LC, TLC or PIPLC). The aim of GC is to resolve the individual constituents of the complex wax mixture in order to obtain information on their qualitative and quantitative composition. This can be done in the following ways ... 

GC is typically used conventionally for simultaneous analysis for trichothecene mycotoxins and ZEN but requires trimethylsilyl derivatization before analysis. GC-FID produced good results in a validation of the EU Standards, Measurements and Testing Programme [107]. However, the GC method requires a derivatization procedure, which generally causes a loss of time and recovery. 

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). 

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... 

Table 7.87 shows the main features of on-line micro LC-GC (see also Table 7.86). The technique allows the high sample capacity and wide flexibility of LC to be coupled with the high separation efficiency and the many selective detection techniques available in GC. Detection by MS somewhat improves the reliability of the analysis, but FID is certainly preferable for routine analysis whenever applicable. Some restrictions concern the type of GC columns and eluent choice, especially using LC columns of conventional dimensions. Most LC-GC methods are normal-phase methods. This is partly because organic solvents used as eluents in NPLC are compatible with GC, making coupling simpler. RPLC-GC coupling is demanding water is not a suitable solvent for GC, because it hydrolyses the siloxane bonds in GC columns. On-line RPLC-GC has not yet become routine. LC-GC technology is only applicable to compounds that can be analysed by GC, i.e. volatile, thermally stable solutes. LC-GC is appropriate for complex samples which are difficult or even impossible to analyse by a single chromatographic technique. Present LC-GC methods almost exclusively apply on-column, loop-type or vaporiser interfaces (PTV).

On-line NPLC-GC-FID and/or FUR analysis has been used in discriminating between paraffin waxes and paraffin oils present in, or migrating between, food packaging and food simulants FID was used for quantitation [967]. In a typical application, online coupled LC-GC-F1D has also been used for the analysis of food contamination by mineral oil from printed cardboard [968]. The technique has revealed that many foods are contaminated with mineral oil products. Grob et al. [969] have determined mineral oil in canned food by on-line LC-LC-GC-F1D. DEHP was determined in salad oil by means of conventional LC-GC [970]. HPLC-GC-MS/MS (ion trap) can serve highly useful purposes in areas of applications such as impurity... 

Coupled LC-LC can separate high-boiling petroleum residues into groups of saturates, olefins, aromatics and polar compounds. However, the lack of a suitable mass-sensitive, universal detector in LC makes quantitation difficult SFC-SFC is more suitable for this purpose. Applications of multidimensional HPLC in food analysis are dominated by off-line techniques. MDHPLC has been exploited in trace component analysis (e.g. vitamin assays), in which an adequate separation for quantitation cannot be achieved on a single column [972]. LC-LC-GC-FID was used for the selective isolation of some key components among the irradiation-induced olefinic degradation products in food, e.g. dienes and trienes [946],... 

SEC-GC-FID, according to Figure 7.40, has been used to carry out the simultaneous determination of the polymer average molecular masses and molar mass distribution and the concentration of additives [984]. The effluent was split and adsorbed on PTV packing material before GC analysis. The choice of PTV... 

Breath Connect Teflon sampling probe to analyzer and syringe through a sampling valve and loop insert probe 4 cm into mouth between closed lips withdraw 20 mL over 6 seconds into syringe flush and fill the sample loop with 10 mL mouth air carry sample to analysis in nitrogen gas. GC/FID 7ppb NR Blanchette and Cooper 1976... 

Lidocaine Direct immersion PDMS (100) GC-FID (LOD 5 ng/mL) Analysis of free, protein-bound, and total amount of lidocaine in human plasma Koster et al., 2000 (14)... 

Some methods are available for determining -hexane in urine and tissues. A modified dynamic headspace extraction method for urine, mother s milk, and adipose tissue has been reported (Michael et al. 1980). Volatiles swept from the sample are analyzed by capillary GC/FID. Acceptable recovery was reported for model compounds detection limits were not reported (Michael et al. 1980). A solvent extraction procedure utilizing isotope dilution followed by GC/MS analysis has been reported for tissues (White et al. 1979). Recovery was good (104%) and detection limits are approximately 100 ng/mL (White etal. 1979). 

Boyd-Boland and Pawliszyn [77] pioneered the SPME analysis of APEOs by SPME-HPLC using normal-phase gradient elution with detection by UV absorbance at 220 nm. The Carbowax-template resin (CW-TR) and Carbowax-divinylbenzene (CW-DVB) fibres allowed the analysis of APEO with a linear range of 0.1-100 mg L 1. The former coating produced the best agreement between the distribution of ethoxymers before and after extraction. This CW-TR fibre provided a limit of detection for individual AP ethoxamers at the low ppb level. The determination of NP in water by SPME-GC (FID) was accomplished by Chee et al. [78] using a polydimethylsiloxane (PDMS) fibre. The linear range was between 1 and 15 mg L 1 with an estimated detection limit of 0.1 mg L-1. 

McLeese et al. [10] studied the accumulation of AP in aquatic fauna including salmon. Fish were mixed with anhydrous sodium sulphate and Soxhlet extracted with ethyl acetate. Lipids were removed by GPC on Biobeads using cyclohexane/dichloromethane (1 1, v/v). The final analysis was performed with GC-FID. The recovery of p-NP was reported as 86%. 

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