1. Is Your Analytical Result Accurate? Presented By: James S. Smith, Ph.D. Trillium, Inc. GSA North-Central Section 39 th Annual Meeting Minneapolis, Minnesota May 20, 2005

2. Analytical Chemistry 1. Qualitative – Identity of the analyte 2. Quantitative – How much is in the sample

3. Problem Beginning Mr./Ms. Name Plant Manager CompanyAddress Re: Notice of Violation and Assessment of Civil Penalties Dear Mr./Ms. Name:

4. Violation Plant Effluent into the POTW Sewer Maximum amount of mercury (Hg) in the effluent for the plant’s use permit is 150 ng/L (parts per trillion)

5. Results MonthHg Concentration (ng/L) December180 January210 February120 March130 April 10:30 AM810 11:15 AM210

6. Questions 1. Is there an analytical chemistry problem? 2. If there is an analytical chemistry problem then is the problem a. Qualitative? b. Quantitative? c. Both?

7. Analytical Method U.S. EPA Method 1531 Revision E Mercury in Water by Oxidation, Purge and Trap, Cold Vapor Atomic Fluorescence Spectrometry

8. Sampling must be accomplished using U.S. EPA Method 1669: Sampling Ambient Water for Determination of Trace Metals at EPA Water Quality Criteria Levels. MDL is 0.2 ng/L.

9. Laboratory/Samplers 1. Certified by the State for Methods 1669 and 1531. 2. Laboratory has a clean room for the low level mercury analysis. 3. Calibration from 0.5 to 100 ng/L is excellent.

10. Calibration Curve

11. Regression Data ConcentrationArea (ng/L) 016099 0.539979 167789 5255863 10440982R 2 = 0.999 251173163 502194860 1004295252

12. Quality Control Precision Original analysis210 ng/L 1 st replicate210 ng/L 2 nd replicate200 ng/L Each sample was diluted by a factor of 10.

13. Blanks Instrument Blank16,748 16,28917,442 Method Blank21,459 = 0.1 ng/L 23,866

14. Check Standards5.0 ng/L found5.0 ng/L found5.2 ng/L

15. Method of Standard Additions (MSA) U.S. EPA SW-846, Method 7000A, Section 8.7 The standard addition technique involves adding known amounts of standard to one or more aliquots of the processed sample solution. This technique compensates for a sample constituent that enhances or depresses the analyte signal, thus producing a different slope from that of the calibration standards.

16. Standard Addition Plot

17. Mercury Analysis by the Method of Standard Additions Spike Concentration Original Concentration Expected Concentration Measured Concentration 10 ng/L 20 ng/L 30 ng/L 40 ng/L 21 ng/L 21 ng/L 21 ng/L 21 ng/L 31 ng/L 41 ng/L 51 ng/L 61 ng/L 23 ng/L 31 ng/L 33 ng/L 34 ng/L

18. MSA Results

19. Regression Data Spike ConcentrationArea (ng/L) 101088370 201461565R 2 = 0.809 301523412 401588011

20. Conclusion Accuracy of the Hg analysis is wrong. There may not be any Hg in the sample. The MSA can be used for any analysis as a check on its accuracy.