Organochlorine pesticides HPLC determination

Organochlorine pesticides and OPPs have been determined mainly using GC, because of the stability and volatility that most of them show under chromatographic conditions and, particularly, the availability of element-selective detectors that display high selectivity for OCPs (electron-capture detector, ECD), and OPPs (flame photometric detector, FPD, and nitrogen phosphorus detector, NPD). Mass spectrometry-based detection is also more popular in GC than in HPLC (1,2,12,16). 

The determination of OCP residues in milk has always presented problems, because the most common approach has required the total extraction of fat, together with lipophilic compounds, including organochlorine pesticide residues. Only one procedure for the extraction and separation of OCPs directly into an HPLC system has been described (11). The direct procedure injects the samples into an internal-surface reversed-phase C18 column connected online with the analytical column. 

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]. 

Berset, J.D. Holzer, R. Quantitative determination of polycyclic aromatic hydrocarbons, polychlorinated biphenyls and organochlorine pesticides in sewage sludges using supercritical fluid extraction and mass spectrometric detection. J. Chromatogr., A 1999, 852, 545-558. Gongalves, C. De-Rezende Pinto, M. Alpendurada, MJ. Benefits of a binary modifier with balanced polarity for an efficient supercritical fluid extraction of PAHs from solid samples followed by HPLC. J. Liq. Chromatogr. Relat. Technol. 2001, 24 (19), 2943 -2959. 

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