GC-atomic emission detection

Ref. [41] describes a procedure developed for the determination of eight organophosphoms insecticides in natural waters using SBSE combined with thermal desorption-GC-atomic emission detection (AED). Optimization of the extraction and thermal desorption conditions showed that an extraction time of 50 min and a desorption time of 6 min were sufficient. Addition of salt and adjustment of the pH were not necessary. Recoveries of seven of the compounds studied between 62 and 88%. For fenamiphos, which is highly water-soluble, recovery was only 15%. The very low detection limits, between 0.8 ng/1 (ethion) and 15.4 ng/1 (fenamiphos), indicate that the SBSE-GC-AED procedure is suitable for sensitive detection of OPPs in natural waters. 

Figure 2.19 Schematic representation of an on-line liquid-liquid extraction-GC/AED system. Reprinted from Journal of High Resolution Chromatography, 18, E. C. Goosens et al, Continuous liquid-liquid extraction combined on-line with capillary gas chromatography- atomic emission detection for environmental analysis , pp. 38-44, 1995, with permission from Wiley-VCH.

The presence of heteroatoms usually provides a convenient feature for improving selectivity by employing selective detection mechanisms. GC may then use flame photometric detection (FPD) for S and P atoms and to a certain extent for N, Se, Si etc. thermoselective detection (TSD) and nitrogen-phosphorus detection (NPD) for N and P atoms electron capture detection (ECD) for halogen atoms (E, Cl, Br, and 1) and for systems with conjugated double bonds and electron-drawing groups or atomic emission detection (AED) for many heteroatoms. 

The most widely regarded approach to accomplish the determination of as many pesticides as possible in as few steps as possible is to use MS detection. MS is considered a universally selective detection method because MS detects all compounds independently of elemental composition and further separates the signal into mass spectral scans to provide a high degree of selectivity. Unlike GC with selective detectors, or even atomic emission detection (AED), GC/MS may provide acceptable confirmation of the identity of analytes without the need for further information. This reduces the need to re-inject a sample into a separate GC system (usually GC/MS) for pesticide confirmation. Through the use of selected ion monitoring (SIM), efficient ion-trap or quadrupole devices, and/or tandem mass spectrometry (MS/MS), modern GC/MS instruments provide LODs similar to or lower than those of selective detectors, depending on the analytes, methods, and detectors. 

A method with LOQ at ppt levels was developed based on LLE followed by GC-AFID for the determination of trace concentrations of nitrobenzene, l-chloro-2-nitrobenzene and synthetic fragrances such as musk xylene (223) and musk ketone (224). The method was applied to study the distribution of these compounds in environmental samples of North Sea waters460. GC with atomic emission detection (AED) has been successfully applied to the determination of nitro musks in human adipose tissues, at ppb concentration levels. A clean-up procedure for nonpolar substances and element-specific detection with AED enabled for the first time target screening analysis for lipophilic nitro aromatic compounds. The lack of sensitivity of AED was compensated by higher concentrations of the extracts... 

Organotin compounds enriched from a diethylether extract of a snow sample collected from the city of Gdansk, Poland and analyzed are shown in Fig. 22 b, c [286]. Gas chromatography with atomic emission detection (GC-AED) run in the chlorine and tin channels, respectively, revealed the presence of tributyltin chloride and this was subsequently confirmed by GC-MS and GC-AED analyses of an internal standard solution (e.g., 1-chlorooctane) of that compound. Quantification was based on the response to chlorine (wavelength 479 nm) in the AED system, and a detection limit of 0.5-1 ng/1 was achieved for all the reference substances. 

Schematic diagram of a gas chromatography atomic emission detection (GC-AED) instrument.

I. Rodriguez Pereiro and A. Carro Diaz, Speciation of mercury, tin and lead compounds by gas chromatography with microwave-induced plasma and atomic-emission detection (GC-MIP-AED), Anal. Bioanal. Chem., 312, 2002, 74-90. 

Fig. 2. Separation and analysis of polyaromatic sulfur-containing compounds (PASC). Oils 3-1, 3-2, and 3-3 were analyzed by gas chromatography-mass spectroscopy (GC-MS) and gas chromatography-atomic emission detection (GC-AED). Reproduced from Ref. 12, with permission.

All alternative detection schemes fail in at least one of the above criteria, and mass spectrometric detection has replaced other detectors even in applications in which they were well established, such as ECD for the gas chromatographic determination of organochlorine pesticides,61 or atomic emission detection (AED) or FPD in the GC analysis of organotin (OT) compounds.62... 

Atomic spectroscopy as a means of detection in gas chromatography is becoming popular because it offers the possible selective detection of a variety of metals, organometallic compounds, and selected elements. The basic approaches to GC-atomic spectroscopy detection include plasma emission, atomic absorption, and fluorescence. 

Jakubowski et al. (36) developed a GC/MS method for CVAA spiked into guinea pig urine using 1,2-ethanedithiol for derivatization, with phenyl arsine oxide as the internal standard. The same group later expanded the method to include atomic emission detection (AED) (37). CVAA was concentrated from urine (adjusted to pH 6 with 1M HC1) by SPE on Cl8. After elution with methanol and concentration to dryness, the residue was reconstituted and derivatized with ethanolic 1,2-ethanedithiol. Detection was by GC combined with arsenic selective AED and by electron impact/mass spectrometry (EI/MS) using SIM. Ions monitored were the moderately intense M+ ion at mlz 228, an intense ion [M — C2H4]+, mlz 200, and a base... 

Cmoja, M., Haberhauer-Troyer, C., Rosenberg, E., Grasserbauer, M. Determination of Sn-and Pb-organic compounds by solid-phase microextraction-gas chromatography-atomic emission detection (SPME-GC-AED) after in situ propylation with sodium tetrapropylborate. J. Anal. At. Spectrom. 16, 1160-1166 (2001)... 

GC/MS and GC with atomic emission detection and Wampler,who used pyrolysis GC/MS to deformu-late rubber, including identification of antioxidants. 

AED = atomic emission detection FI = fluorescence FID = flame ionization detection GC = gas chromatography FIMW= high molecular weight FIPLC = high-performance liquid chromatography LMW= low molecular weight MS = mass spectrometry PAFI = polycyclic aromatic hydrocarbon UV = ultraviolet... 

Carpinterio Botana, J., Rodnguez Pereiro, I., and Cela Torrijos, R., Rapid determination of butyltin species in water samples by multicapiUary GC with atomic emission detection following headspace solid-phase microextraction, J. Chromatogr. A, 963, 195-203, 2002. 

---