Monitoring of POPs in the ambient air Jana Klánová The objectives of the POPs Global Monitoring Plan To evaluate whether the POPs actually were reduced or eliminated as requested in Articles 3 and 5 of the Convention, information on environmental levels of the chemicals listed in the annexes should enable detection of trends overtime. Therefore focus is upon monitoring of background levels of POPs at locations not influenced by local sources. Reliable identification of trends will require that statistical evaluation is carried out on the design of each national monitoring programme contributing to the Global Monitoring Plan, to ensure that it is powerful enough to detect trends in time. Air is a key medium - responds quickly to sources Air concentrations fluctuate widely in the space and time Various concentrations in the gas/particulate phases - compromise over the sample time/volume/technique Short-term sampling/bulking Air sampling Air sampling - ambient air - permanent gases - volatile/semivolatile compounds - particules - indoor air - working environment - emissions - imissions Sampling and sampling preparation methodology Experimental design Sample matrices - choice of equipment All sampling procedures have to be agreed upon and documented Representativeness and integrity of the sample during the entire sampling process has to be assured Quality requirements (equipment, transportation, pre-analytical treatment, storage, GPS referencing, standardization, documentation) Personal protection, waste management Sample handling High volume samplers for active POPs sampling P1011633 P1011667 Dust aerosols samplers P1011641 P1011643 P1011637 P1011636 Dust aerosols samplers Passive Air Samplers nfilter (polyurethane foam) – captures pollutants from the surrounding air n nsampler body – filter protecting chamber (wind, rainwater, solar radiation) pasiv_sampler_whole pasiv_PUF_0 Analytical methodology Extraction and clean-up POPs analysis Organization of quality control Data treatment Basic requirements • Competence for infrastructure, instrumentation, and trained staff • • Validation of the analytical methods including in-house methods • • Standard operating procedures (SOPs) for the validated methods • • Quality criteria for quality assurance and quality control (QA/QC) Recommended analytes Chemical Parent POPs Transformation products Aldrin Chlordane cis- and trans-chlordane (cis- and trans-nonachlor, oxychlordane) DDT 4,4’-DDT, 2,4’-DDT (4,4’-DDE, 2,4’-DDE, 4,4’-DDD, 2,4’-DDD) Dieldrin Endrin HCB Heptachlor (Heptachlor, heptachlorepoxide) Mirex Polychlorinated PCBs (7 congeners: 28, 52, 101, 118, 138, 153, and 180) PCB with TEFs* (12 congeners: 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, and 189) Polychlorinated 2,3,7,8-PCDD/PCDF (17 congeners) Toxaphene Congeners P26, P50, P62 Extraction The appropriately prepared sample can be extracted by any of a number of techniques (Soxhlet, automatic extraction, pressurized extractions, MAE, SFE). The main points to consider are to allow adequate time of exposure of the solvent system in the sample matrix. Cross contamination from residues left behind by high levels of POPs in other samples is a concern at this stage and equipment must be thoroughly cleaned and checked from batch to batch. Purity of extraction solvents is also a major consideration. Only high purity glass distilled solvents should be used. Standards should be added to the sample as early as possible in the process. If the results are reported on a lipid weight basis, the determination of the lipid content in the sample is critical. Standards should be added before extraction to control the extraction efficiency (the recoveries differ with POP and matrix, for PCB and pesticides: 80 % - 120 %, for tetra- and penta-chlorinated PCB, recoveries down to 60 % can be accepted, for PCDD/PCDF: 50 % - 130 % (for hepta- and octa-chlorinated PCDD/PCDF 40 % - 150 % can be accepted). For PCB analysis and ECD detection, a minimum of two standards - one eluting at the beginning and one at the end of the chromatogram – should be used. Concentration (evaporation under vacuum or with nitrogen – control of temperature, flow of nitrogen, drying of the extract should be avoided - keeper) Elimination of water (sodium sulphate), lipids (sulphuric acid or permeation in gels), proteins (denaturation with oxalate), and sulfur (activated copper) Clean-up is performed with various combinations of adsorbents and solvents depending on selectivity, conditioning and column flow in order to remove interfering substances/materials from the analyte. Sample clean-up procedures should be efficient to prevent contamination of the detector. Separation of POPs is conducted using gas chromatography with electron capture detector (ECD), mass selective detector (MS detector) or, if available, high-resolution mass spectrometry (HRMS). Other separation techniques, such as high pressure liquid chromatography (HPLC), have not been found adequate. An appropriate stationary phase has to be selected and enough peak separation must be achieved to allow accurate quantification (capillary columns lengths of 30-60 m, internal diameters of 0.15-0.25 mm, a film thickness of 0.1-0.3 µm, helium or hydrogen as a carrier gas, cleanliness of injector - deactivated glass insert). Verification of chromatographic conditions include resolution, symmetric peak shape, reproducibility of retention times; verification of the linear range of the instrument. Identification The information available to identify the compounds eluted from the gas Chromatographic column depends on the type of detector being used. Retention time should match between sample and internal standard; Confirmation of peaks can be performed on a second column with different polarity; Matrix spikes are recommended to verify components; For GC-MS detection combinations, positive identification should be done on isotopic ratios within 20 % of theoretical value; The retention time of the labeled internal standard to the native compound should be within 3 seconds ; The use of MS libraries is useful if using full scan. Quantification In general, quantification of the analyte should be done according to the internal standard methodology; At least one standard representative for the POPs analyte group analyzed should be added at the normal level of quantification ; Verification that the concentration of blanks is significantly lower than the samples (recommendation < 10%). Calibration: Multi-point calibrations should be carried out, labeled internal standards are an added value; Daily calibration checks in connection with analyzing a series of samples should be done ; Suitable laboratory reference material should be used to verify the performance. The maintenance of the analytical equipment is considered as one of the most important aspects in POPs analysis. Quality assurance and quality control are important factors in sampling and analysis; Internal and recovery stds have to be used; Any method performance must be verified through control tables where optimal operational ranges are defined ; Periodical analysis of blank samples and certified reference materials; Own laboratory reference materials, and blind or divided samples should be included in routine QA/QC; The inter-calibration exercises are an essential component in quality assurance of the results and are deemed indispensable in the implementation of a regional laboratory network; A recommendation would be that at least once a year such an intercalibration study is performed for each matrix and persistent organic pollutant of interest to the Region. Data treatment There are a number of parameters that have to be reported together with the analytical results. These include the efficiency of the extraction and clean-up, and the blank values, but the results should not be compensated for these parameters. The uncertainty of the results should also be at least estimated, but preferably determined, using results from inter- or intralaboratory comparisons. Terminology Calibration Linearity Sensitivity and specificity Robustnes and repeatibility Limit of detection and quantification Accuracy, trueness, precision S Ri2 2n s2 = RSD = 100 s X Standard deviation Regulation diagram – Warning interval X ± 2 σ (95.5% results) Regulation interval X ± 3 σ (99.7% results) Confidence interval R = 2,8 σ Z-score -2