Split Sample and Blind Sample Programs

Home > Data Hub > Quality Assurance > QA Split Sample/Blind Sample


	• See: Quality Assurance Glossary

Split Sample and Blind Sample Programs

Water Quality Coordinated Split Sample Program
Plankton Split Sample Programs
Nutrient and Chlorophyll Blind Audit Samples
Performance on USGS Nutrient Reference Samples

Water Quality Coordinated Split Sample Program

The Chesapeake Bay Program initiated the Coordinated Split Sample Program (CSSP) in 1988 to assess the comparability of water quality results from Chesapeake Bay Water Quality Laboratories (136 kb). The water quality CSSP has three components, Mainstem, Tidal Tributary, and Fall Line, each representing a different salinity levels in the watershed. Maryland DNR staff collect and split natural water samples four times a year on routine mainstem and tributary monitoring cruises. USGS staff collect Fall Line split samples at the twice per year. In June 1999, CSSP sampling and data analysis protocol (214 kb) were modified to better estimate inter-laboratory variability.

Laboratories report split sample results to the EPA Chesapeake Bay Program Office in Annapolis where they are analyzed, reviewed by quality assurance staff, and discussed quarterly at Analytical Methods and QA Workgroup meetings. When there is poor agreement among the lab results, the group investigates significant differences in methods and recommends corrective actions.

Documentation:

Plankton Split Sample Programs

In 1998, the Chesapeake Bay Program initiated split sample programs for Phytoplankton, Microzooplankton and Mesozooplankton to make plankton counts Maryland and Virginia directly comparable. For phytoplankton and microzooplankton, modifications to existing methods made them comparable but it was necessary to select a single method for mesozooplankton. Plankton split samples continue to be collected each year and the Plankton Methods Workgroup meets once per year to review the results and identify potential differences in methodologies and taxonomic identifications.

Documentation:

Nutrient and Chlorophyll Blind Audit Samples

The Chesapeake Bay QA Program also uses low level blind audit samples to check water quality laboratory performance. The Chesapeake Biological Laboratory prepares dissolved constituents in artificial seawater, particulate samples on filter pads, and distribute them twice per year. Each laboratory's results are compared to the expected values and serve as an external check on the accuracy of data.

Performance on USGS Nutrient Reference Samples

Laboratories that analyze non-tidal water samples in the Chesapeake Bay watershed participate in the semi-annual USGS Reference Sample Program. QA staff review the results (Nutrient Reference Sample Results (2.2 MB) of Chesapeake Bay laboratories and initiate corrective actions if necessary.

To bookmark this page, please use this URL: http://www.chesapeakebay.net/qasample.htm

For more information, contact the Chesapeake Bay Program Office:
410 Severn Avenue, Suite 109, Annapolis, MD 21403 / Tel: (800) YOUR-BAY / Fax: (410) 267-5777.