Quality Assurance/Quality Control (QA/QC) is a very important part of Volunteer Monitoring. Without it, a monitoring program has no documentation to prove that the data they have gathered are usable.
MassWWP suggests that each group have
a QA/QC program that fits their individual program. An excellent guiding document
on how to develop your own study design available from the Volunteer
Environmental Monitoring Network, and MassWWP staff is happy to consult
with you on this topic. The Study Design document is
also available here in pdf format.
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The Environmental Analysis Lab (EAL) runs a QC program where they send blind samples for the analysis of dissolved oxygen, pH, and alkalinity to volunteer labs during the second week of the month. EAL manufactures the blind samples (which we call QC samples) and sends the samples in the mail. Volunteer analysts analyze the samples and call in their results to EAL to check their results. EAL compares volunteer results to the blinds' expected values and tells the volunteer labs how close they came to the expected values. To "pass" a QC sample, volunteer labs need to come within 0.3 units for pH, 3 mg/l for alkalinity, and 10% of the expected value for dissolved oxygen. If a volunteer lab fails the QC, EAL will discuss the possible reasons with them, so they may have a chance to take corrective measures before they analyze their own samples.
Some groups do not call their results ahead of the sampling weekend, but report them later. In this case, the QC information is applied by the volunteer groups to decide whether to keep or discard their monthly data.
You can request a DO sample, a pH/alkalinity sample, or both. EAL provides these samples starting in April, monthly through October. This year due to lack of funding, those QC samples will cost $25 per bottle, which covers shipping and handling as well as teechnical support.
To request QC samples, call (413)545-2936 or send a message to Dr. Peter Kerr
SOME COMMON QUALITY ASSURANCE SAMPLES
|Field Blank||Deionized water treated as a sample||Used in estimating contamination from sample collection and processing|
|Field Duplicate||Duplicate lake or stream sample||Used in estimating combined sampling and lab precision|
|Audit Sample||Synthetic sample prepared by QC officer from outside source||Used in estimating accuracy and precision of lab|
|Calibration Blank||Reagent-grade deionized water used to zero the instrument||Used in identifying instru- ment signal drift; can be compared to field blank to detect contamination of sample|
|Quality Control Check Sample||Standard solution (source other than calibration standard)||Used in determining accuracy and consistency of instrument calibration|
|Laboratory Duplicate (split sample)||Sample split in two at the lab||Used to test precision of lab measurements|
|Matrix Spike||Subsample spiked with known concentration of analyte (substance being measured)||Used in determining interference effects in the sample|
updated 1/12/04 by MF Walk - MWWP Home - Contact MassWWP