Conventional GC Detectors

Most of the GC detectors commonly applied to pesticide residue analysis have also been applied to the screening of samples for chemical warfare agents. Detection limits are typically in the nanogram to picogram range. Flame ionization detection (FID) is routinely used for preliminary analyses, as this technique provides a good indication of the complexity of a sample extract. Figure 2 illustrates GC-FID chromatograms obtained using a J&W DB-1 capillary column for three different munitions grade mustard formulations, HT, HS and HQ. HT is typically 60% distilled mustard (H) and 40% bis(2-chloroethyl-

Figure 2 Capillary column GC-FID chromatograms of three munitions grade mustard samples: (A) HT, (B) HS and (C) HQ. Identified compounds include: 1, 1,4-thioxane; 2, 1,4-dithiane; 3, mustard (H); 4, bis(2-chloroethyl)disulfide; 5, 2-chloroethyl (2-chloroethoxy)ethyl sulfide; 6, sesquimustard (Q); 7, bis (2-chloro-ethylthioethyl)ether (T); 8, 1,14-dichloro-3,9-dithia-6,12-dioxatet-radecane; 9, 1,14-dichloro-3,6,12-trithia-9-oxatetradecane; and 10, 1,16-dichloro-3,9,15-trithia-6,12-dioxaheptadecane. (GC column: 15 mx 0.32 mm ID J&W DB-1, temperature programme: 50°C (2 min), then 10°C min"1 to 280°C (5 min), 2 x 10~1° A full scale.)

Figure 2 Capillary column GC-FID chromatograms of three munitions grade mustard samples: (A) HT, (B) HS and (C) HQ. Identified compounds include: 1, 1,4-thioxane; 2, 1,4-dithiane; 3, mustard (H); 4, bis(2-chloroethyl)disulfide; 5, 2-chloroethyl (2-chloroethoxy)ethyl sulfide; 6, sesquimustard (Q); 7, bis (2-chloro-ethylthioethyl)ether (T); 8, 1,14-dichloro-3,9-dithia-6,12-dioxatet-radecane; 9, 1,14-dichloro-3,6,12-trithia-9-oxatetradecane; and 10, 1,16-dichloro-3,9,15-trithia-6,12-dioxaheptadecane. (GC column: 15 mx 0.32 mm ID J&W DB-1, temperature programme: 50°C (2 min), then 10°C min"1 to 280°C (5 min), 2 x 10~1° A full scale.)

Figure 3 Capillary column GC-FID chromatogram of munitions grade tabun (GA) sample. Compounds identified include: 1, tabun (GA); 2, ethyl isopropyl A/,A/-dimethylphosphoramidocyanidate; 3, ethyl N,N,N',N'-tetramethylphosphorodiamidate; 4, N,N,N',N'-tetramethylphosphorodiamidiccyanide; and 5, pyrophosphates. (GC-column: 15 m x0.32 mm ID J&WDB-5, temperature programme: 50°C (2 min), then 10°Cmin~1 to 280°C (5 min), 5x10~"A full scale.)

Figure 3 Capillary column GC-FID chromatogram of munitions grade tabun (GA) sample. Compounds identified include: 1, tabun (GA); 2, ethyl isopropyl A/,A/-dimethylphosphoramidocyanidate; 3, ethyl N,N,N',N'-tetramethylphosphorodiamidate; 4, N,N,N',N'-tetramethylphosphorodiamidiccyanide; and 5, pyrophosphates. (GC-column: 15 m x0.32 mm ID J&WDB-5, temperature programme: 50°C (2 min), then 10°Cmin~1 to 280°C (5 min), 5x10~"A full scale.)

The need for higher specificity and sensitivity has led to the application of element-specific detectors such as flame photometric detection (FPD), thermionic detection (TID), atomic emission detection (AED) and electron capture detection (ECD). The simultaneous use of FID with one or more element-specific detectors has also been demonstrated during dual or tri-channel GC analysis using conventional and thermal desorption sample introduction. While these detectors may provide strong collaborative evidence for the presence of chemical warfare agents, they cannot be used for full confirmation. Use of GC with one or more spectrometric technique such as MS is required to confirm the presence of chemical warfare agents.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook


Post a comment