ISO 28540-2011 pdf free download.Water quality — Determination of 16 polycyclic aromatic hydrocarbons (PAH) in water — Method using gas chromatography with mass spectrometric detection (GC- MS)
5 Interferences
5.1 Interferences with sampling, extraction, and concentration Use sampling containers of materials that do not affect the analyte content during the contact time (preferably of stainless steel or glass). Avoid plastics and other organic materials during sampling, sample storage or extraction. Care should be taken when using surfactants for cleaning sample containers, because they may lead to the formation of emulsions during liquid-liquid extraction. If automatic samplers are used, avoid the use of silicone or rubber material for the tubes.
If these materials are present, ensure that the contact time is minimized. Rinse the sampling line with the water to be sampled before taking the test sample. Use ISO 5667-1 and ISO 5667-3 for guidance. Keep the test samples away from direct sunlight and prolonged exposure to light. Store the samples in amber containers. Clear glass bottles are suitable as well, but then the samples shall be kept in a dark place. During storage of the test samples, losses of PAH may occur due to adsorption on to the walls of the containers. The extent of the losses may depend on the storage time.
5.2 Interferences with GC-MS Substances that co-elute with the target PAH may interfere with the determination. These interferences may lead to incompletely resolved signals and may, depending on their magnitude, affect accuracy and precision of the analytical results. Non-symmetrical peaks and peaks broader than the corresponding peaks of the reference substance suggest interferences. Chromatographic separation between dibenzo[a,h]anthracene and indeno[1,2,3-cd]pyrene is most critical. Due to their molecular mass differences, quantification can be made by mass selective detection. When incomplete resolution is encountered, peak integration shall be checked and, when necessary, the baseline corrected. Sufficient resolution (e.g. not less than R = 0,8) between the peaks of benzo[b]fluoranthene and benzo[k]fluoranthene as well as of benzo[a]pyrene and benzo[e]pyrene is to be set as quality criterion for the capillary column. Benzo[j]fluoranthene cannot be separated from benzo[k]fluoranthene and benzo[b]fluoranthene. It is possible that triphenylene is not completely separated from benzo[a]anthracene and chrysene. If this is the case, state this fact in the test report. NOTE Benzo[j]fluoranthene, benzo[e]pyrene, and triphenylene are not part of the 16 target analytes.
6 Reagents WARNING
— The use of this International Standard may involve hazardous materials, operations and equipment. This International Standard does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. During the analysis, unless otherwise stated, use only reagents of recognized analytical grade, “for residue analysis” or “for GC analysis”, where appropriate, and distilled or demineralized water or water of equivalent purity. Otherwise, pay extra attention that each batch of solvents does not contain blank concentrations affecting the results.ISO 28540 pdf download.