Liquid chromatography organochlorine determination

As discussed in section 5.6.1.4 a solid phase carbon trap has been used in conjunction with supercritical fluid extraction liquid chromatography for the simultaneous determination of organochlorine insecticides, polychlorobiphenyls, polychlorodibenzo-p-dioxins and polychlorodibenzofurans in soils [19]. 

Headspace analysis has been employed in the extraction of dithiocarbamate insecticide in vegetables [227]. Other techniques occasionally used are vacuum distillation followed by gas chromatography-mass spectrometry in the determination of volatile organic compounds in leaves, steam distillation in the determination of organochlorine insecticides in fruit and vegetables [229], and water distillation followed by high-performance liquid chromatography in the determination of 2-aminobutane in potatoes [102,230]. 

Tn recent years much concern has risen, especially in o Bcial regulatory circles, about the problem of misidentification or uncertain identification in pesticide residue analysis. Since the introduction of the electron-capture detector (EC) in 1960 (i) and its rapid exploitation for the determination of organochlorine residues by gas-liquid chromatography (GLC) (2) the combined EC-GLC system has become, from 1963, the most commonly used end-method for quantitative pesticide residue analysis. It was quickly discovered that even after the application of the more common clean-up techniques (3, 5, 4) EC-GLC interferences occurred not only from peak-overlap of the various pesticides themselves (6, 7) but also from extraneous contamination—e,g, the laboratory or... 

UV detection is used in most chiral analysis by HPLC and other liquid chromatographic modalities. However, some other detectors, such as conductivity, fluorescent and refractive index types, are also used. The choice of detector depends on the properties of the racemic compound to be resolved [41, 144]. Chiroptical detectors, which are based on the principle of polarimetry [145] or circular dichroism [146, 147], are also available. The enantiomer (+)- or (—)-notation is determined by these detectors. Some organochlorine pesticides are not UV-sensitive, and hence they are difficult to detect in liquid chromatography. The detection of these types of pollutant can be achieved by using a mass spectrometry (MS) detector, and therefore LC-MS instruments are now being put on the market for routine use [148, 149]. 

EN Standard, 1996. EN/ISO 6468 19% Water quality - Determination of certain organochlorine insecticides, polychlorinated biphenyls and ehlorobenzenes Gas chromatographie method after liquid-liquid extraction (ISO 6468 1996). 

Msagati TAM, Mamba BB. Determination of persistent cyclic organochlorine residues in sediment slurry by microporous membrane liquid-liquid extraction and gas chromatography-mass spectrometry. Water SA 2011 37 1-6. 

Basheer, C., Lee, H.K., and Obbard, J.P., Determination of organochlorine pesticides in seawater using liquid-phase hollow fibre membrane microextraction and gas chromatography-mass spectrometry, /. Chromatogr. A, 968, 191, 2002. 

Yan, C.H. and Wu, H.F., A liquid-phase microextraction method, combining a dual gauge microsyringe with a hollow fiber membrane, for the determination of organochlorine pesticides in aqueous solution by gas chromatography/ion trap mass spectrometry. Rapid Commun. Mass Spectrom., 18, 3015, 2004. 

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