How should the mercury sample be prepared for analysis?

Follow your normal method SOP, but do an in-bottle oxidation, rather than first taking a subsample, to ensure a representative aliquot.

What is the cost and volume of the samples?

$36 each - this includes shipping (paid with credit card or USGS account number)
Trace: 500 mL
Major: 500 mL
Precip: 500 mL
Mercury: 200 mL
Nutrient (low): 60 mL (dilute 1:10)
Nutrient (reg): 250 mL

How often is the inter-laboratory comparison study performed?

Biannually

Event	SPRING SRS	FALL SRS
invitation to order samples	mid December	mid June
distribution of samples	early February	early August
analytical results due	late March	late September
report generation	mid April	mid October

Who can participate in the Standard Reference Sample Project?

Only those labs that are enrolled in the program can participate. Please contact me at woodwort@usgs.gov.

Why can’t I log into the data entry page?

Your username (lab#) and password, that were assigned to you at enrollment, are to be entered with no spaces and lower case. Your lab number should replace the pound (#) sign.

When will the inter-laboratory comparison results be released?

Results are displayed on the website within a week of the data entry deadline. Publications are no longer produced.

Are the Standard Reference Sample's filtered?

The water has been filtered through a series of filters to 0.2 um.