Organochlorine pesticides detectors

Qin BH, Yu BB, Zhang Y, Lin XC. Residual analysis of organochlorine pesticides in soil by gas chromatograph-electron capture detector (gc-ecd) and gas chromatograph-negative chemical ionization mass spectrometry (GC-NCI-MS). Environ. Forensics 2009 10 331-335. 

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). 

Gas Chromatograph - A Varian 6000 equipped with two constant-current/pulsed-frequency electron capture detectors, a 30-m x 0.53-mm ID DB-5 fused-silica open-tubular column (0.83-ftm film thickness), and a 30-m x 0.53-mm ID DB-1701 fused-silica open-tubular column (1.0-/ m film thickness), both connected to a press-fit Y-shaped fused-silica splitter (Restek Corporation, Bellefonte, Pennsylvania), was used to analyze for the organochlorine pesticides. The columns were temperature-programmed from 140°C (2.0-min hold) to 270°C (15-min hold) at 2.8°C/min injector temperature 250°C detector temperature 320°C helium carrier gas 6 mL/min nitrogen makeup gas 20 mL/min. 

Highly selective to halogenated and oxygenated compounds Electron capture detector EDB, DBCP (EPA 8011) Acrylamide (EPA 8032) Phenols (EPA 8041) Phthalates (EPA 8061) Organochlorine pesticides (EPA 8081) PCBs (EPA 8082) Nitroaromatics and cyclic ketones (EPA 8091) Haloethers (EPA 8111) Chlorinated herbicides (EPA 8151) CLP SOW for organic analysis Interferences from Elemental sulfur (S8) Waxes, lipids, other high molecular weight compounds Phthalate esters, which are common laboratory contaminants Oil in PCB analysis... 

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... 

The electrolytic conductivity detector has been used to determine organic iodine with excellent success by Westlake (20), as well as chlorine in organochlorine pesticides, operating in the reducing mode to yield HI or HCl as the detected product. The minimum detectability for chlorine is approximately equal to that of the current microcoulometric detection system. Coulson (4, 15) compared the responses of the electrolytic conductivity, microcoulometric, and electron capture detectors for organochlorine compounds in various extractives and found the first two approximately equal and the electron capture detector unsatisfactory because of high background. 

The variety of detectors available range from the universal (flame ionization detector) to the specific (electron-capture, thermionic, flame photometric and atomic emission detectors). For example, the electron-capture detector is specific for halogen-containing compounds, e.g. organochlorine pesticides. 

Abstract. The distribution of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in the environment has not been systematically studied in Bulgaria in spite of their negative effect on the human health. The aim of this study is to develop a cost-effective method for determination of low concentrations of PCBs and OCPs in soils. After extraction with hexane/acetone and column cleaning with silica, the analyses was performed by gas chromatography with electron-capture detector. The limit of detection is between 0.1 and 1 ng g 1, the reproducibility at low environmental levels is about 15% RSD. The analytical recoveries for the individual compounds are between 65% and 100%. The method can be applied to study the sources of pollution, the migration and biogeochemistry of PCBs in the environment. 

Chee, K. K., Wong, M. K., and Lee, H. K., Determination of organochlorine pesticides in water by membranous solid-phase extraction, and in sediment by microwave-assisted solvent extraction with gas chromatography and electron capture detector and mass spectrometric detection, J. Chromatogr. A, 736, 211-218, 1996. 

Jackson, G. P. and Andrews, A. R. J., A new fast screening method for organochlorine pesticides in water by using solid-phase microextraction with fast gas chromatographic and a pulsed-discharge electron capture detector. The Analyst, 123, 1085-1090, 1998. 

Organochlorine pesticides may be determined by GC and GC/MS techniques. ECD and HECD are suitable GC detectors for such analyses. Samples are extracted with hexane and the extracts injected into a GC equipped with an ECD. Alternatively, the solvent extracts (either in hexane or methylene chloride) may be analyzed by GC/MS (a packed or a capillary column) employing electron impact or chemical ionization. Analysis of these substances in potable and wastewaters and solid wastes may be performed by EPA Methods 505,508,515,608,625, 8080, 8250, and 8270. Of these. Methods 625, 8250, and 8270 are based on GC/MS (U.S. EPA 1984, 1986). 

Reversed-phase SPE is applied principally in two areas of TEQA. The first application is in the determination of organochlorine pesticides (OCs) in connection with the determinative technique of GC using a chlorine-selective detector. The second application is in the determination of priority pollutant semivolatile organics that are adequately recovered from drinking water. Off-line RP-SPE coupled to a determinative technique such as GC using an element-selective detector is a very powerful combination with which to achieve the objectives of TEQA. To illustrate, this author s study of various organophosphorous pesticides (OPs) from spiked water using RP-SPE will now be discussed. 

Organochlorine pesticides (OCs) were used widely in agriculture during the first half of the twentieth century in the United States and were subsequently banned from use during the 1970s. Unfortunately, some of the OCs are still in widespread use around the world. Their persistence in the environment was not apparent until Lovelock introduced the electron-capture detector (LCD) in 1960 (1). When combined with high-resolution capillary gas chromatography and appropriate sample preparation methods, the ECD provides the analytical chemist with the most sensitive means by which to... 

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]. 

Organochlorine Pesticides and PCBs Using the Electron-Capture Detector... 

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