QAQC Considerations for Sampling and Analysis Associated with EPA Method 1631

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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

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Presentation Overview

• General overview of lab QA/QC
• Sampling considerations
• Facility considerations
• Method 1631 QA/QC requirements
• PT requirements
• Summary

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Hardcopy of presentation
www.wibby.com info_at_wibby.com 303-940-0033
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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

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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

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• Sampling

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Sampling considerations

• EPA Method 1669
• Cant be emphasized enough
• The ease of contaminating ambient water
  samplescannot be overemphasized. Section 1.4
• Sample bottles from commercial vendor or produced
  per Section 6.1.2

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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 lt0.15 ng/L.  The analytical report is provided
  with the containers.
•  Bottles double bagged.

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Containers
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Lab considerations

• Ref Hampton Roads Sanitation District Virginia
  Beach, Virginia
• Use a dedicated room
• Doesnt 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 KBrO3 for 8 hours at 250oC prior to using it
  to produce bromine monochloride solution

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Lab considerations

• Disposable tubes on autosampler
• Rinsed with high purity water
• Glassware washing
• Soak in 11 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

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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

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Section 9.0 QC

• Changes to method Section 9.1.2

9.1.2 In recognition of advancesthe 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.
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Method 1631

• QC by batch
• 1 20 samples
• Same 12 hour shift

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Method 1631

• Batch Section 9.1.7
• Three blanks
• Five calibration standards
• Ongoing precision and recovery (OPR)
• Quality control sample
• Method blank
• Seven samples

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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

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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

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Method 1631

• Matrix Spike/Matrix Spike Duplicate Section 9.3
• Spike at 1-5 times the sample concentration
• 71 125 (accuracy)
• 24 RSD (precision)

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Method 1631

• Blanks Section 9.4
• Bubbler blanks
• System blanks
• Reagent blanks
• Method blanks
• Field blanks
• Equipment blanks
• Bottle blanks

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Method 1631

• Ongoing precision and recovery (Section 9.5)
• 77 123 (Accuracy)
• Same source as that used for calibration
• ICV/CCV

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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

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Method 1631

• Field duplicates (Section 9.7)
• May be required to meet project specific
  requirements

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Method 1631

• Calibration (Section 10)
• Very specific requirements that must be met
• Should review and be familiar with requirements

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• Proficiency
• Testing

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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 1631 0.0005 0.100 ug/L
• Acceptance criteria different
• Approximately 24 (WP)
• 30 (WS)

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Thank You!

• Chuck Wibby
• Wibby Environmental
• 6390 Joyce Drive, 100
• Golden, CO 80403
• 303-940-0033
• cwibby_at_wibby.com
• www.wibby.com