Column, capillary environment

Pankow JF, Rosen ME. 1988. Determination of volatile compounds in water by purging directly to a capillary column with whole column cryotrapping. Environ Sci Technol 22 398-405. 

MacDonald, S. J., G. B. Jarvis, and D. B. Wheeler. 1998. Ultra fast GC systems using directly resistively heated capillary columns. Int. Environ. Technol. 8 30-32. 

Method 1613 of US Environmental Protection Agency (US EPA) was used for the PCDD detection in the objects of environment (water, soil etc.). PCDD detection was done with the help of Polaris Q gas chromatograph/ mass spectrometer on mass-spectrum of electronic impact in the MS-MS mode. Division of isomer PCDD was carried out on a capillary column from the sintered quartz DB-5 MS (60 m x 0,25 mm, thickness of tape 0,25 p.m). The same device was used for detection of fungicides formulations active ingredients in soil. 

Nitrophenols in fog and atmospheric particles were determined by GC of the underiva-tized compounds and their corresponding acetate esters. Four fused-silica columns were used with three alternative detection modes, namely mass-selective detection, nitrogen-specific detection and ECD. GC-ECD of the acetate derivatives gave the best results501. A capillary GC-UVD method was developed for the determination of small amounts of nitrophenols present in the environment. The method was compared with HPLC-UVD from the point of view of selectivity and sensitivity. LOD for GC were about one-tenth of those for HPLC502. 

Figure 2. Chromatograms typical of a, an urban environment. GC conditions 30-m DB-1 fused silica capillary column oven temperature -50 to 100 °C at 4 °C/min. Continued on next page.

In recent years, many of the technologically outdated methods of 40 CFR Part 136 have been upgraded to incorporate the latest advances in instrumental analysis. For example, capillary chromatographic columns with superior compound resolution replaced obsolete packed columns in gas chromatography (GC) and GC/MS analytical methods Freon 113, a chlorofluorocarbon harmful to the environment, was phased out as the extraction solvent in oil and grease analysis and replaced with hexane in Method 1664 (EPA, 1999b). 

In thermospray interfaces, the column effluent is rapidly heated in a narrow bore capillary to allow partial evaporation of the solvent. Ionisation occurs by ion-evaporation or solvent-mediated chemical ionisation initiated by electrons from a heated filament or discharge electrode. In the particle beam interface the column effluent is pneumatically nebulised in an atmospheric pressure desolvation chamber this is connected to a momentum separator where the analyte is transferred to the MS ion source and solvent molecules are pumped away. Magi and Ianni (1998) used LC-MS with a particle beam interface for the determination of tributyl tin in the marine environment. Florencio et al. (1997) compared a wide range of mass spectrometry techniques including ICP-MS for the identification of arsenic species in estuarine waters. Applications of HPLC-MS for speciation studies are given in Table 4.3. 

Most of the applications of FDCD that have been reported have been concerned with the use of this technique as a probe of specific aspects of the chiral environment of biochemical systems. Although, as indicated above, this technique is basically a probe of the molecular ground state, it uses the sensitivity and selectivity of luminescence measurements. FDCD has also been applied to highly scattering and optically dense samples for which polarized absorption measurements are not possible [58,59]. Some of the more recent applications of this technique include its use for on-column detection of chiral molecules in capillary electrophoresis [60], and in a modified phase-modulation spectrofluoremeter [61,62]. The purpose of the latter application is to develop a procedure to determine the distribution of chiral molecules in multicomponent samples [62],... 

Gas chromatography is the most widely used analytical technique for studying organic chemicals that are hazardous to the environment and that may potentiaUy have adverse human health effects. The conventional packed column systems used by the majority of analysts are valuable for certain analyses. However, along with other problems, packed columns have limited separation ca )abilities, therefore they do not meet the demands of todays s analytical requirements. The very recent developments in the manufacture of open tubular, large bore fused silica columns (0.53 mm ID) and more conventional capillary columns ( 0.35 mm ID) are significant and provide the analyst with superior... 

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