QA/QC Considerations for Sampling and Analysis Associated with EPA Method 1631 Chuck Wibby Wibby Environmental Seminar on Low Level Mercury Data and Analyses Boulder, Colorado September 23, 2004

Presentation Overview  General overview of lab QA/QC  Sampling considerations  Facility considerations  Method 1631 QA/QC requirements  PT requirments  Summary

Hardcopy of presentation

Basic QA/QC Approach  Ref: John Taylor, “Quality Assurance of Chemical Measurements” Lewis Publishers, 1987  Artisan  Based on expertise of person completing the task  Academic research  Chef  Good approach in a non-regulatory situation  Small one, two person laboratories

Basic QA/QC Approach  Systematic  Dependent on Quality System  Independent of person performing task  Cook book approach  Documentation – lots of it  Results can be reviewed  Usually required in regulatory situation

Sampling considerations  EPA Method 1669  Can’t be emphasized enough  “The ease of contaminating ambient water samples…cannot be overemphasized.” – Section 1.4  Sample bottles from commercial vendor or produced per Section 6.1.2

Sample bottle considerations  Example: ESS  Glass (Hg only) or Teflon containers washed per the method with detergent, trace grade nitric acid and Milli Q DI rinsing with drying in a “Low Particle” oven.  Bottles available with preservation; HCl or Bromine monochloride.  Analyze these containers by lot by method 1631 to <0.15 ng/L. The analytical report is provided with the containers.  Bottles double bagged.

Containers

Lab considerations  Ref: Hampton Roads Sanitation District – Virginia Beach, Virginia  Use a dedicated room  Doesn’t have to be a clean room  Simply dedicated to low level Hg  Use a Class 100 clean bench to produce reagents, standards and samples  Bake KBrO 3 for 8 hours at 250 o C prior to using it to produce bromine monochloride solution

Lab considerations  Disposable tubes on autosampler  Rinsed with high purity water  Glassware washing  Soak in 1:1 nitric for at least 24 hours  Rinse with high purity water  Use immediately  Bubble argon though stannous chloride for 30 minutes prior to starting  Continue to bubble argon through stannous chloride during analysis

Method 1631 QA/QC  Contamination Control  Section 4.3  Interferences  Section 4.4  Reagents and Standards  Section 7.0  Sample Collection, Preservation and Storage  Section 8.0

Section 9.0 QC  Changes to method – Section “ In recognition of advances…the analyst is permitted certain options to improve results or lower the cost of measurements. These options include automation of the dual-amalgamation system, single-trap amalgamation (Reference 14), direct electronic data acquisition, calibration using gas-phase elemental Hg standards, changes in the bubbler design (including substitution of a flow-injection system) to maximize throughput, or changes in the detector (i.e., CVAAS), where less sensitivity is acceptable or desired. Changes in the principle of the determinative technique, such as the use of colorimetry, are not allowed. If an analytical technique other than the CVAFS technique specified in this method is used, that technique must have a specificity for mercury equal to or better than the specificity of the technique in this method.”

Method 1631  QC by batch  1 – 20 samples  Same 12 hour shift

Method 1631  Batch – Section  Three blanks  Five calibration standards  Ongoing precision and recovery (OPR)  Quality control sample  Method blank  Seven samples

Method 1631  Batch (continued)  Method blank  Three samples  Matrix spike/Matrix spike duplicate  Four samples  Method blank  Six samples  Matrix spike/Matrix spike duplicate  Ongoing Precision and Recovery

Method 1631  Initial Demonstration of Capability - Section 9.2  Method Detection Limit – equal to or less than 0.5 ng/L (Section 9.2.1)  Initial precision and recovery (Section 9.2.2)  79 – 121% (Accuracy)  21% RSD (Precision)  Four replicates

Method 1631  Matrix Spike/Matrix Spike Duplicate – Section 9.3  Spike at 1-5 times the sample concentration  71 – 125 % (accuracy)  24% RSD (precision)

Method 1631  Blanks – Section 9.4  Bubbler blanks  System blanks  Reagent blanks  Method blanks  Field blanks  Equipment blanks  Bottle blanks

Method 1631  Ongoing precision and recovery (Section 9.5)  77 – 123% (Accuracy)  Same source as that used for calibration  ICV/CCV

Method 1631  Quality control sample (Section 9.6)  No limits specified in method  Suggestion is to use OPR limits  Different source than that used for calibration, external to lab or made internally from second source  Wibby Environmental  QC-UTM-WP, $95  QC-UHG-WP, $65

Method 1631  Field duplicates (Section 9.7)  May be required to meet project specific requirements

Method 1631  Calibration (Section 10)  Very specific requirements that must be met  Should review and be familiar with requirements

PT Requirements  Necessary for accreditation  Once a year or twice a year  Levels much higher than trace levels  0.5 – 30 ug/L (WP)  0.5 – 10 ug/L (WS)  Method – ug/L  Acceptance criteria different  Approximately + 24% (WP)  + 30% (WS)

Thank You! Chuck Wibby Wibby Environmental 6390 Joyce Drive, #100 Golden, CO