ISO 23646:2022 pdf – Soil quality — Determination of organochlorine pesticides by gas chromatography with mass selective detection (GC-MS) and gas chromatography with electron-capture detection (GC-ECD).
The limit of detection and the limit of application depends on the determinants, the sample intake, the equipment used, the quality of chemicals used for the extraction of the sample and the clean-up of the extract. Under the conditions specified in this document, lower limits of application from 1 μg/kg (expressed as dry matter) for soils to 10 μg/kg (expressed as dry matter) for sediments can be achieved. The necessity to achieve these lower limits of application depends on the analyses order and the current limit values. Soils and sediments can differ in properties as well as in the expected contamination levels of OCPs and the presence of interfering substances. These differences make it impossible to describe one general procedure. Based on the properties of the samples, this document contains decision tables regarding drying-, extraction- and clean-up procedures. This method is performance based. The method can be modified if all performance criteria given in this method are met. The method can be applied to the analysis of other chlorinated compounds not specified in the scope in cases where suitability has been proven by proper in-house validation experiments. NOTE The validation data are shown in Annex A. This document is validated only for α-HCH, β-HCH, γ-HCH, δ-HCH, o,p′-DDE, p,p′-DDE, o,p′-DDD, p,p′-DDD, o,p′-DDT and p,p′-DDT. For sediments, data are displayed measured using an ECD detection. The comparability of ECD and MS data in terms of the approach of this document was demonstrated on additional matrices. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
3.1 calibration standard solution of organochlorine pesticides (OCPs) prepared from a secondary standard and/or stock solutions of native OCPs and used to calibrate the response of the instrument with respect to analyte concentration 3.2 internal standard labelled organochlorine pesticide (OCP) or other OCP that is unlikely to be present in the sample, added to the sample prior to extraction and used for quantification of OCP content 3.3 extraction standard chemical substance which is only used for checking the extraction efficiency and not used for quantification purposes 3.4 injection standard labelled organochlorine pesticide (OCP) or other OCP that is unlikely to be present in the sample, added to the extract before injection into the gas chromatograph, and used to monitor variability of instrument response and the recovery of the internal standards (3.2) 3.5 performance standard one calibration solution used for the determination of performance criteria (3.6), which contains the same amount of internal, extraction and injection standards (3.4) used in the samples 3.6 performance criterion value for the recovery of standards which describes the capacity of the analytical method or parts of the analytical method 4 Principle Due to the multi-matrix character of this document, different procedures for different steps (modules) are allowed. Which modules should be used depends on the sample. A recommendation is given in this document. Performance criteria are described and it is the responsibility of the laboratories applying this document to show that these criteria are met. Use of spiking standards (internal standards) allows an overall check on the efficiency of a specific combination of modules for a specific sample. But it does not necessarily give the information regarding the extensive extraction efficiency of the native OCPs bonded to the matrix. After pre-treatment, the test sample is extracted with a suitable solvent or solvent-mixture.