EN 17322-2020 pdf download.Environmental Solid Matrices – Determination of polychiorinated biphenyls (PCB) by gas chromatography – mass selective detection (GC-MS) or electron-capture detection (GC-ECD).
10.2.2 Extraction procedure 1: Samples using acetone/petroleum ether or hexane-like solvent and agitation or sonication
Place the sample in a bottle (8.1.1). Add a definite volume of the secondary internal standard solution (7.5.3). Add 50 ml of acetone (7.2.1) to the sample and extract by shaking or sonication, thoroughly to break up aggregates for 30 mm. Then add 50 ml of petroleum ether or hexane-like solvent (7.2.3) and shake again or sonicate thoroughly during at least 1 h. Use a horizontal shaking device or an end-over- end shaking device (8.1.2) and have the solvent movement in the sample bottle as long as possible (horizontal position). After the solids have been settled, decant the supernatant. Wash the solid phase with 50 ml of petroleum ether or hexane-like solvent (7.2.3) and decant again. Collect the extracts in a separating funnel (8.1.4) and remove the acetone by shaking twice with 400 ml of water (7.2.5). Dry the extract over sodium sulfate (7.2.4). Rinse the sodium sulfate with petroleum ether or hexane-like solvent (7.2.3) and add the rinsing to the extract.
In case of waste material with a high proportion of plastic, e.g. plastic shredder, extraction with an acetone containing solvent leads to a high amount of co-extractives. In these cases, extraction should be performed twice with 50 ml of petroleum ether or hexane-like solvent (7.2,3).
NOTE 1 Tap water has shown to be applicable for removal of the acetone, because target compounds are not present.
If the sample contains water up to 25 %, the same procedure can be used. If the water content of the sample is greater than 25 % this procedure is less effective and the amount of acetone shall be increased. The ratio acetone: water should be at least 9: 1. The ratio acetone: petroleum ether or hexane-like solvent should be kept constant to 1: 2.
The definite amount of the internal standard added in all extraction methods shall have such a quantity that their concentrations in the final extract are within the working range of the measurement method. Typically, the concentration of the individual internal standards in the final extract is 0,1 tg/ml. To ‘wet’ the complete sample, a minimum amount of 100 iii of internal standard is recommended.
NOTE 2 In matrices with a high organic matter content (e.g. some sludge) longer extraction procedures can be necessary. Extraction procedure 2 (see 10.2.3) can be preferred for these samples.
10.2.3 Extraction procedure 2: Samples using Soxhlet or pressurized liquid extraction
Place the sample in the extraction thimble (8.1.6). Add the definite amount of the secondary internal standard solution (7.5.3) and approximately 70 ml of the extraction solvent (7.2.2 or 7.2.3) to the extraction vessel. Extract the sample with the Soxhlet extraction apparatus (8.1.6). The duration of the extraction should be calculated with a minimum of 100 extraction cycles.
NOTE lithe sample is hygroscopic and is not dried just before analysis, it is advised to add Na2SO4 to the sample to get a free-flowing material.
Add 40 g sodium chloride (7.2.6), 100 ml acetone (7.2.1) and 50 ml petroleum ether or hexane-like solvent (7.2.3) to the moistened preparations, close the sample bottle and shake it with a shaking device (8.1.2) for at least 12 h.
The organic phase shall be separated, if necessary, using a centrifuge with sealable centrifuge cups. Collect the extract in a separating funnel of 1 I capacity. Dry the extract over sodium sulfate (7.2.4) and transfer the dried extract to the concentrator (8.1.9). Rinse the sodium sulfate with petroleum ether or hexane-like solvent (7.2.3) and add the rinsing to the extract.
10.3 Concentration
If necessary, add a boiling chip (8.1.10) to the extract and concentrate the extract to approximately 10 ml by evaporation using a concentrator (8.1.9). Transfer the concentrated extract to a calibrated test tube (8.1.12) and concentrate to 1 ml using a gentle stream of nitrogen or another inert gas at room temperature. If necessary, fill up to the lml. If clean-up method H is used, concentration is not necessary. Record the final volume of the extract.
In heavily contaminated samples, an aliquot is used for further clean-up. Establish the fraction f of the extract used for further clean-up. If non-labelled congeners have been used as internal standard added to the sample, add a definite amount of the secondary internal standard solution containing 13C2- congeners.
To prevent losses of the most volatile PCBs it is not allowed to evaporate till complete dryness. It is advisable to add a small amount (one drop) of keeper substance (7.2.7).
10.4 Clean-up of the extract
10.4.1 General
Clean-up shall be used if compounds are present that can interfere with the PCB congeners of interest in the gas chrornatogram or if those compounds can influence the GC-procedure (i.e. contamination of the chromatographic system). If no or negligible interfering substances are present, no clean-up is necessary. Depending on the substances to be removed, Table S shall be used. If polar compounds shall be removed take special care on the recoveries of the low chlorinated PCBs.EN 17322-2020 pdf download.