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Organochlorine pesticides (OCP) and polychlorinated biphenyls (PCB) are two classes of organic synthetic substances which are globally used. The vast majority of OCP have been released directly in the environment as agricultural insecticides but they have been also used as byproducts for different applications e.g. wood preserver. PCB have been widely used as additives in industrial applications where chemical stability has been required. OCP and PCB are persistent, bioaccumulating and prone to long-range atmosheric transport and deposition. They are ubiquitous in the environment (water, soil, sediment and waste) and their presence is regularly monitored and controlled.
At present determination of OCP and PCB is carried out in these matrices in most of the routine laboratories following the preceding steps for sampling, pre-treatment, extraction, clean-up by measurement of specific OCP and PCB by means of gas chromatography in combination with mass spectrometric detection (GC-MS) or gas chromatography with electron capture detector (GC-ECD).
Considered the different matrices and possible interfering compounds, this draft International Standard does not contain one single possible way of working. Several choices are possible, in particular relating to clean-up. Detection with both Mass Spectrometry and Electron Capture is possible. Three different extraction procedures and nine clean-up procedures are described. The use of internal and injection standards is described in order to have an internal check on choice of the extraction and clean-up procedure.
Polycyclic aromatic hydrocarbons (PAH) are ubiquitous because of the fact that they are released in appreciable quantities every year into the environment through the combustion of organic matters such as coal, fuel oils, petrol, wood, refuse and plant materials. Since some of these PAH compounds are carcinogenic or mutagenic, their presence in the environment (air, water, soil, sediment and waste) are regularly monitored and controlled. At present determination of PAH are carried out in these matrices in most of the routine laboratories following the preceding steps for sampling, pre-treatment, extraction, clean up by measurement of specific PAH by means of Gas chromatography in combination with mass spectrometric detection(GC-MS) or by HPLC in combination with UV-DAD- or Fluorescence-detection(HPLC-UV-DAD/FLD).
At present there two standards for the determination of PAH in soil, sludge and biowaste and in waste valid. The goal is the development of only one standard for solid materials.
Efficiency Evaluation of Extraction Methods for Analysis of OCPs and PCBs in Soils of Varying TOC
(2017)
Organochlorine pesticides and polychlorinated biphenyls are toxic, carcinogenic, and have a high potential for bioaccumulation. Due to their stability, they are still considered an environmental problem even though the use of most of them has been phased out several decades ago. Soil is a matrix which can retain these contaminants to a great extent. This ability is often associated with the total organic carbon content (TOC). In order to judge the pollution status of soil and to make monitoring data more easily comparable a simple, yet robust extraction method is needed. Agitation solid-liquid-extraction is well suited for this purpose. However, the influence of TOC on the analyte recovery has to be known. For the presented study, 12 organochlorine pesticides and 7 polychlorinated biphenyls were spiked into four model soils with organic carbon contents between 1.6% - 13.3%. The matrices were extracted using solid-liquid extraction between 45 minutes and 16 hours. For comparison, all soils were also extracted using pressurised liquid extraction and Soxhlet extraction. After clean-up the extracts were measured using a gas chromatography-mass spectrometry (GC-MS) system. Statistical analysis of the results implied that the TOC content of the soils did not have significant influence on the extraction efficiency. A longer solid-liquid extraction time did not necessarily increase analyte recovery: Extraction for one hour resulted in 88% recovery while 16 hour extraction led to 89%. Thus, the efficiency of all the methods was comparable for all model soils. Additional investigations regarding GC liner performance highlighted the need for isotopically labelled standards during the analysis of thermolabile pesticides.