Evaluating Self-Monitoring Reports

1. Evaluating Self-Monitoring Reports Alan K. Bingham QA/QC Coordinator Clean Water Services Water Quality Lab (503) 681-5140 Binghama@cleanwaterservices.org 9/14/05

2. Factors that can affect your self-monitoring results: • Sampling • Sample variability • Interferences • Intra- and Inter-lab variability

3. Sampling • Location and Set-up What the hey?

4. Sampling • Sample splitting, mixing and sub-sampling: • Stop! Do you know where that bottle’s been? BYOB • Proper mixing is critical.

5. Sampling • Preservation and storage

6. Sample Variability • Many industries are unpredictable from sampling to sampling. Different industries, same day. Same industry, different days.

7. Sample Variability • Example: Doh!

8. Sample Variability • Example:

9. Interferences • Color: • Turbidity: Suspensions, precipitates, floaties

10. Interferences • High concentrations of almost anything • Heavy metals: e.g. Al, Fe • Complex matrices: e.g. CN

11. Interferences • Result? • Positive and negative biases • Raised reporting limits (dilution) • Saturation of chemistry • Sample masking and carryover

12. Intra- and Inter-Lab Variability • Digestion methods: acids used, hot plate vs microwave, total vs total recoverable vs soluble, etc.

13. Intra- and Inter-Lab Variability • Analytical methods: colorimetric, probe, IC, etc. • Example: NH3 - 3 methods/3 chemistries Alpkem RFA - salicylate Alpkem FSA - phenate Probe - electrometric

14. Intra- and Inter-Lab Variability • Example: NO23 - 4 methods/3 chemistries Astoria - NED Dionex - IC TrAAcs - hydrazine Manual Chem - NED

15. Intra- and Inter-Lab Variability • Reporting limits • MDLs vs IDLs vs MRLs vs PQLs vs RLs, etc. • MDLs and IDLs clearly defined by regulators and instrument manufacturers. • MRLs, PQLs and RLs more flexible and depend upon the lab.

16. Intra- and Inter-Lab Variability • Reporting limits • However, labs have some freedom to adjust reporting limits according to their comfort level (i.e. a “CYA” factor). • All should be driven by good science, not by customer desires.

17. Intra- and Inter-Lab Variability • Reporting limitsmay be different for different labs: • By choice: CYA factor. • Different methods and chemistries. • Concentration of MDL standard. • Analyst skill levels. • Normal background noise or error. • Abnormal noise or error: i.e. bad hair day.

18. Intra- and Inter-Lab Variability • Examples:

19. Intra- and Inter-Lab Variability Different labs have different test methods and instrumentation and may report different units for the same analyte. • Know your units: • mg/L = parts/million (ppm) • mg/Kg = parts/million, dry wt. (ppm) • µg/L = parts/billion (ppb) • ng/L = parts/trillion (ppt) • pg/L = parts/quadrillion (ppq)

20. Intra- and Inter-Lab Variability • Know your units: • cfu/100 mL = colony-forming units/100 mL (Mico) • S.U. = Standard Units (pH) • µS/cm = microSiemans (Conductivity)

21. Intra- and Inter-Lab Variability • Know your contract lab! • Is it using approved methods? • Does it have a good QA program? • $$$? Quality work costs more. • What is its reputation? Bad reputations are often earned, just like good ones. • Conformity to accepted practices minimizes variability.

22. Intra- and Inter-Lab Variability • Case study: • Industrial sample Zn concentration in sample splits:

23. Intra- and Inter-Lab Variability • Case study: • Preservation:

24. Intra- and Inter-Lab Variability • Case study: • Investigation: It was found that after Split 1 was left with the industry... • Strike 1: Sample was not preserved. Yer out! • Strike 2: Sample was not refrigerated. • Strike 3: Sample was not sent to the lab for a month.

25. Parting shots: Don’t forget the details! • Cross the T’s...

26. More Details: • “If it isn’t documented, it never happened.”

27. Example Lab Report

34. Mmmmm... Lunch! Media Auditor Watchdogs Lawyer DEQ Public EPA IM Industry Someone’s always watching...

35. Questions? I’ll be okay… just let me catch my breath.