Headspace analyzers

Low detection limits (low ng/mL) have been achieved using a headspace/gas chromatographic (GC) technique (Seto et al. 1993). The sample is acidified and incubated, and the headspace analyzed by GC with a nitrogen-specific detector (NPD) (Carseal et al. 1993 Levin et al. 1990 Seto et al. 1993). Reported recovery is good (>90%) (Carseal et al. 1993), and precision is good as well (<15% RSD) (Carseal et al. 1993 Levin et al. 1990 Seto et al. 1993). Blood samples may be treated with chloramine T priorto incubation to produce a derivative which can be determined by GC with electron capture detection (ECD). Cyanate and thiocyanate do not interfere in this method (Odoul et al. 1994). The detection limit is 5 pg/L (ppb) precision is good (<15% RSD) (Odoul et al. 1994). 

Various foods (e.g., grains, grain-based foods, fruits, and Ground sampie in water (water-soluble foods or sulfuric acid (water-immiscible foods) and introduce in headspace analyzer GC/MS <0.001 mg/g (wate r-so I u b le foods) 0.01-0.05 mg/g (lipid-containing foods) 90%-100% Entz and Hollifield 1982... 

Uehori and co-workers (1987) developed a retention index in GC to screen and quantify volatile organic compounds in blood. A dynamic headspace analyzer and GC/FID with retention indices were employed for the detection of 1,1-dichloroethane at nanogram levels. Uehori and co-workers noted that this method is simple, reliable and requires little or no sample preparation. 

Dynamic headspace analyzer GC has been used for the analysis and identification of 1,1-dichloroethane in water and fish tissue (Comba and Kaiser 1983 Mehran et al. 1985, 1986 Otson and Williams 1982 Reinert et al. 1983 Trussell et al. 1983). The analytic sample is placed in a... 

Automated Procedures Some of the difficulties associated with manual procedures can be eliminated with an automated headspace sampler. Such a device has been described in the literature (14), and is commercially available. The schematic diagram of such a semi-automatic headspace analyzer is shown in Figure 3. Precise control of times and temperatures, as well as the capability to hold samples at high temperatures, produces better chromatographic reproducibility. We have been able to analyze ppm levels of ethyl dodecanoate in aqueous solution with this system. Significant amounts of water vapor are introduced into the gas chromatographic column under these conditions. For this reason, columns with non-polar liquid phases or bonded Carbowax-type liquid phases... 

Blood Acidify blood sample and introduce into a headspace analyzer GC/FPD 15 pg/F NR Campbell et al. 1985... 

The alcohol concentration in the sample is calculated with the assistance of standard samples containing ethanol in water at known concentrations and the amount of the internal standard added to the samples. A volume of 0.5 ml of the specimen to be analyzed is pipetted into a vessel 0.1 ml of the internal standard (a 0.2% w/v solution of ferf-butanol in water) is added the vessels are sealed with a rubber septum and the covers are secured with aluminum caps to compensate for the eventuality of an excess pressure buildup. For standard samples, instead of the specimen, 0.5 ml of a known ethanol concentration solution is added. Finally, the vessels are placed into the turntable of the headspace analyzer, which is thermo-statted at 60°C. ... 

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