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Laboratory requirements Dioxin Workshop, Leon Mexico

Laboratory requirements Dioxin Workshop, Leon Mexico. Richard Turle Analysis and Air Quality Division Environmental Science and Technology Centre Environment Canada. Principle of Methods. Add surrogates (labeled internal standards) or spike a blank sample Extract according to matrix type

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Laboratory requirements Dioxin Workshop, Leon Mexico

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  1. Laboratory requirements Dioxin Workshop, Leon Mexico Richard Turle Analysis and Air Quality Division Environmental Science and Technology Centre Environment Canada

  2. Principle of Methods • Add surrogates (labeled internal standards) • or spike a blank sample • Extract according to matrix type • Clean-up (very critical step) • Fractionate (very critical step) • Concentrate to known volume • Analyze by GC-ECD for screening or GC-HRMS

  3. Requirements for Dioxin Analysis • Clean extraction lab • HRGC-HRMS in EI mode • Low Res NOT acceptable • Labeled dioxin standards • Highly trained staff • A few CRMs available

  4. Reasons for Using HRMS • Sensitivity • Modern HRMS can detect 0.01- 0.02 fg/ul TCDD • Resolution • @ 10000 resolution can separate masses to 4 decimal places • Necessary to eliminate co-eluting fragment ions from other compounds such as PCBs and chlorinated diphenyl ethers • Eliminates the need for even more extreme cleanup procedures to remove matrix effects and interfering compounds

  5. Canadian Reference Methods • P&P dioxin reg under CEPA • Performance based • First use of LOQ • 2,3,7,8 TCCD regulated • Other PCDD/FS requested

  6. Internal QA Requirements for Dioxins in Environmental samples • Compares Hi-Res and Low Res • Applicable to all matrices • Used in monitoring

  7. Cost of labs For dioxins, $500K for instrument, space needed for high-res GC-MS, clean extraction lab, wash-up lab etc ~ cost $0.5 to $1M – main cost due to HVAC needed. • Also need UPS for continuous power supply

  8. How do you know analyses are good? • Use spiked samples to ensure repeatability • Use CRMs to establish accuracy • Proficiency testing ensures comparability with peers • Exchange calibration solutions • Accreditation ensures good procedures; SOPS, quality system, management

  9. Accreditation in Canada • Required by Environment Canada policy • ISO 17025 • CAEAL for environmental labs - Labs have published Scope of accreditation • Labs must participate in PT if available

  10. Quality Assurance Summary – Method EPS RM/19 and PM/23 1)     Before any sample is processed, all pre-cleaned glassware are rinsed with solvents. Contamination levels of individual 2,3,7,8-substituted congeners in glassware proof rinses must not exceed the acceptable limits. 2)     Before and sample is processed, laboratory capability must be demonstrated by conducting triplicate analyses of matrix blanks spiked with natives and surrogates. Criteria for accuracy and surrogate recoveries must be met. 3)     Before extraction, each sample is spiked with native congeners and isotopically-labeled surrogates to assess the degree and analyte loss during sample workup. If the recovery of natives and surrogate is outside the acceptable range, the sample must be re-processed and re-analyzed. 4)     A method blank consisting of blank media (e.g. water, filter, solvents) spiked only with surrogates should be processed along with each batch of test samples.

  11. Quality Assurance Summary – Method EPS RM/19 and PM/23 • 5)Two labeled analogs must be added to each sample extract immediately before GC-MS analysis as recovery (internal) standards to calculate surrogate recoveries • 6)  Verification of MS resolution at 10,000 or better is required • 7) A Window Defining Mixture containing the first and last eluting isomer within each homologous group of PCDD/F must be used to correctly define retention time windows 8)Acceptable chromatographic separation between 2,3,7,8-TCDD/TCDF and its closest neighbouring isomers must be confirmed.

  12. Quality Assurance Summary – Method EPS RM/19 and PM/23 9)The established calibration must be verified daily by analyzing the calibration verification standard. The calculated concentration of analytes and surrogates must be within the acceptable limits. 10)Detection limits must be assessed by analyzing the lowest concentration standard solution. 11)  As a check on accuracy, reference material is periodically analyzed as a sample. 12) Sample results must be fully documented. All QA/QC documentation and raw GC-MS data, must be available for auditing

  13. Limit (Level) of Quantitation • Based on ACS definition of 1983 • ASTM D6259-98 defines procedure • 3* SD of a “blank is LOD (=MDL) • Reasonable certainty substance is present • i.e statistically different from a blank • 10*SD of a “blank” is LOQ • +/-30% uncertainty at 99% CL • 99% confidence substance is measurable • De facto definition of “virtual elimination”

  14. Sampling • Standard trace organic sampling for OCs • Keep equipment for PCBs in oil separate • Special equipment/bottles needed for dioxins (must be proofed) • Need special sampling procedures for dioxins from stacks

  15. GOLDEN RULE • The analysis is only as good as the sample • One dirty sample can contaminate many clean samples • Use standard operating procedures • Stack sampling need special training

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