Inorganic Blind Sample Project

Blind-sample Matrix Descriptions

 

A variety of blind-sample types are used to quality-assure the NWQL. The designation for the sample type is assigned by the project that produces them—the Standard Reference Sample (SRS) Project. Currently the SRS project produces five types of samples (shown below). The Inorganic Blind Sample Project (IBSP) uses these natural-matrix reference samples* as the source for its blind samples. Efforts are made to produce these samples with concentrations that are similar to the concentration ranges of environmental samples that are submitted to the National Water Quality Laboratory.

If you know the Reference Material ID of the IBSP blind-sample for which you want matrix information, access the master list here. At the master list, look for the reference sample of interest, then click on that line and you'll have all available information for that round; such as, information specific to the reference sample of interest, a compiled list of MPVs (Most Probable Values), how the sample was made, the water source used, statistics for all parameters measured, etc.

If you don't know the Reference Material ID of the IBSP blind-sample for which you want the matrix information, it's easy to find. In the legend of each IBSP "control chart" (the IDs are not listed on the other six chart types) is listed a Reference Material ID followed by the expected concentration for that analyte in that reference material. So, for example, a symbol might be identified as "T217/191.0." This is simply Reference ID "T-217" with an MPV of 191 µg/L. For mixed solutions (FY16 and earlier), a symbol might be identified as "25213-75211/349.0." This means 25% of the solution is T-213 and 75% of the solution is T-211 with a resultant MPV of 349.0 µg/L. In addition, all chart types contain an "Open Data Set" button which pulls up a spread sheet describing the data in the chart. Look for the column called "Ref Soln ID" (or something similar). Once the Reference Material ID is determined, access the master list here, look for the reference sample of interest, click on that line, and then you'll have all available information for that round; such as, information specific to the reference sample of interest, a compiled list of MPVs, how the sample was made, the water source used, statistics for all parameters measured, etc.

T-Series ("Trace") - Primarily used to measure performance of trace metal/major cation methods
M-Series ("Majors") - Primarily used to measure performance of major anion and physical property methods and specific conductance
P-Series ("Precip") - Primarily used to measure performance at low concentration and in low ionic strength of major cation/anion methods and specific conductance
Hg-Series ("Mercury") - Use to measure performance of the mercury methods
N-Series* ("Nutrients") - Used to measure performance of nutrient methods
NS-Series** ("Nutrients") - Used to measure performance of nutrient methods (purchased from an alternative source)

*Odd-numbered N-series samples are synthetic.
** All NS-series samples are synthetic.