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Quality Assurance

The ESER Quality Assurance Program consists of five ongoing tasks which measure:

1. method uncertainty;
2. data completeness;
3. data accuracy, using spike and laboratory control samples;
4. data precision, using split samples, duplicate samples, and recounts; and
5. the presence of contamination in samples, using blanks.

The following discussion briefly summarizes the results of the quality assurance program for the period from April 1 to June 30, 2004.

METHOD UNCERTAINTY

The Quality Assurance Project Plan (QAPP) establishes data quality and method quality objectives for the ESER surveillance program (Stoller 2002). Since the primary concern is with detection, the lower bound for the method uncertainty is set at zero. The upper bound is established as the average maximum concentration from the past seven years of applicable data. Each individual result is checked for acceptance on the basis of the result, whether it is below the lower limit (i.e., a negative value), greater than the upper limit, or between the lower and upper limit (the most common occurrence). The calculated method uncertainty is then compared to the 1s measured uncertainty. A sample is deemed acceptable when the measured 1s uncertainty is less than the calculated uncertainty. Those results that did not meet this requirement are shown in Table 5.

 Table 5.                    Analytical results determined to be unacceptable. 

DATA COMPLETENESS

The Quality Assurance Project Plan (QAPP) specifies a 98 percent completeness goal for all regularly scheduled sample types (Stoller 2004). Data completeness for sample collection and delivery was 100 percent during the second quarter for all sample types with one exception: a number of precipitation samples were not collected due to lack of precipitation.

Two air samples were determined to invalid due to insufficient volume collected because of equipment failure (Dubois on June 30 and FAA Tower on June 23). The completeness of air filter data is thus considered to be 99.2%.

DATA PRECISION

Data precision is measured using duplicate samples, split samples, and recounts. The QAPP specifies that sample results should agree within ± 20 percent or 3s, whichever is greater. For environmental samples at levels that are within the normal range found by the ESER, the 3s criterion is the one that applies in nearly all cases.

SUMMARY

In summary the quality assurance and data quality objectives for analyses were met in the fourth quarter of 2004 with the following exceptions:

• The FAA Tower air samples for the week ending June 23 and the June 30 air samples from Dubois were invalid due to insufficient volume collected;

• ¹³¹I in charcoal cartridges;
• ²⁴¹Am and ⁹⁰Sr in quarterly composites;
• Gross alpha and tritium in drinking and surface water;
• ⁹⁰Sr in milk.

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