Quality Control Program
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 can be found here .
The Environmental Analysis Lab (EAL) runs a QC program sending blind samples for the analysis of dissolved oxygen, pH, and alkalinity to volunteer labs the week prior to the third weekend of the month between April and October. We manufacture the blind samples (which we call QC samples) and send the samples by mail. Volunteer analysts analyze the samples and call in their results for verification. Volunteer results are compared to the blinds' expected values and volunteer labs are then notified as to 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, the possible reasons are discussed so that corrective measures can be taken 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. Monitors can request a DO sample, a pH/alkalinity sample, or both. We provides these samples starting in April, monthly through October. To request QC samples, email us a message. A fee of $30 per QC sample covers shipping and handling as well as technical support from EAL.
Supervised Use of Laboratory for Determinations of pH, Alkalinity and Dissolved Oxygen, and for Thermometer Calibration
E-Mail the Lab Technician for more information and to inquire about fees.
|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|