The U.S. Geological Survey (USGS) conducts an inter-laboratory comparison study semiannually. This program provides a variety of Standard Reference Samples (SRSs) for laboratory quality assurance testing and are available to purchase for internal quality control. The majority of samples are prepared with water from Colorado streams.
NUTRIENTS * TRACE
ELEMENTS * MAJOR IONS * PRECIPITATION * MERCURY
The program began in 1962 with a single sample containing major constituents that was prepared from distilled water and reagent grade chemicals. Twenty-three USGS laboratories participated in the determinations of six analytes. Since that time, objectives of the program have been to accomplish the following:
Over one hundred and fifty USGS and non-USGS laboratories are participating in the program and six standard reference sample types are available (Trace Element, Major Ion, Precipitation, Mercury, Low-level Nutrient, and Regular-level Nutrient).
This program is not open to international laboratories. U.S. Federal, State, municipal, and university laboratories can participate even though they do not provide data to the USGS. Laboratories can compare their results to other labs based on the deviation (z-value) from the median and percent difference. Laboratories can purchase previously made SRS by calling the number below.
Mark Woodworth U.S. Geological Survey Branch of Quality Systems Denver Federal Center, Bldg. 95 P.O. Box 25046, MS 401 Denver, CO 80225-0046 (303) 236-1875 woodwort@usgs.gov |
Other numbers:
Terry Schertz, Branch Chief, Branch of Quality Systems (303) 236-1835
Brooke Connor, Laboratory Evaluation Project Chief, Branch of Quality Systems
(303) 236-1877
B.J. North, System Administrator, Branch of Quality Systems (303) 236-1820 -
COMPUTER SUPPORT
If you can not fully access the information on this SRS project website, please
contact Mark Woodworth .
All samples are currently $36 (includes shipping). We cannot accept checks or PO's; we can only accept credit cards or USGS standard vouchers. To order samples for the current inter-laboratory comparison, please visit our order page. To order previously prepared SRS, please call (303) 236-1875. View the list of available SRS from our inventory.
All samples are in the dissolved phase (filtered to 0.2 um).
Trace element sample (500 mL): chlorinated with sodium hypochlorite and acidified with nitric acid $36.00 Major ion sample (500 mL): chlorinated with sodium hypochlorite $36.00 Precipitation (low ionic-strength) sample (500 mL): typically non-preserved snowmelt $36.00 Nutrient (low concentration) sample (60 mL; dilute 1:10): concentrations <0.5 mg/L $36.00 Nutrient sample (250 mL): concentrations >0.5 mg/L $36.00 Mercury sample (250 mL): concentration <0.1 ug/L; acidified with hydrochloric acid $36.00
SPRING 2008
|
EVENT | FALL 2008 |
---|---|---|
December 17, 2007
|
invitation to participate in the inter-laboratory comparison | June 16, 2008 |
January 25, 2008
|
sample order deadline for participating laboratories | July 25, 2008 |
Jan 28 to Feb 6, 2008
|
mail out samples to laboratories | August 4-13, 2008 |
April 4, 2008
|
data entry deadline | September 26, 2008 |
April, 2008
|
results made available on the web | October, 2008 |
Answer Sheets and Method Codes
The answer sheets below were created to help laboratories collect analytical results for electronic data entry. These forms are not to be used for data submittal. A listing of the SRS method codes has also been provided for your assistance.Answer sheets for | Trace Sample | Major Sample | Precipitation Sample | Mercury Sample | Nutrient Samples |
SRS Method Codes are used when entering data and are included in the publications.