Site-Specific Health and Safety Plan (HASP) - Laschools.org

precision range from zero to the historical mean plus three standard deviations. An RPD
within the control limit indicates satisfactory precision in a measurement system.
2.2.2 Accuracy
Accuracy is a measure of the closeness of a reported concentration to the true value.
Accuracy is expressed as a bias (high or low) and is determined by calculating percent
recovery (%R) from MS/MSDs, LCSs, and surrogate spikes. MS/MSD and surrogate
spike recoveries indicate accuracy relevant to a unique sample matrix. LCS recoveries
indicate accuracy relevant to an analytical batch lot, and are strictly a measure of
accuracy conditions in preparation and analysis independent of samples and matrices.
The %R of an analyte, and the resulting degree of accuracy expected for the analysis of
spiked samples for QC, are dependent upon the sample matrix, method of analysis, and
the compound or element being measured. The concentration of the analyte relative to
the detection limit of the method is also a major factor in determining the accuracy of the
measurement.
Accuracy expressed as %R is calculated as follows:
where:
%R = [(A-B)/C] x 100
A = measured concentration in spiked sample,
B = measured sample concentration (without spike), and
C = concentration of spike added.
The laboratory shall have procedures in place for establishing and updating accuracy
control limits. Typical control limits for accuracy are based on the historical mean plus
or minus three standard deviations.
2.2.3 Completeness
Completeness is defined as the percentage of laboratory measurements judged to be valid
on a method-by-method basis. Valid data are defined as all data and/or qualified data
considered to meet the DQOs for this project. Data completeness is expressed as percent
complete (PC) and should be ≥ 90 percent. The goal for meeting analytical holding times
is 100 percent. At the end of each sampling event, the completeness of the data will be
assessed. If any data omissions are apparent, new samples will be collected and
reanalyzed for the parameter in question, if feasible. Laboratory results will be
monitored as they become available to assess laboratory performance and its effect on
data completeness requirements. When appropriate, additional samples will be collected
to ensure that laboratory performance meets PC requirements.
2-3
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