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APPENDIX A
MERC Data Quality Objectives
Table A. MERC Data Quality Objectives for Physical/Chemical Analyses
Data Quality
Indicator
Evaluation Process
Performance Measure
MERC DQO
Precision
Analyze at least 10 % of samples
in duplicate.
Relative Percent
Difference (RPD).
< 20 % average RPD.
Bias
Experiment Bias:
Analysis of
spike-recovery samples; ensure
proper calibration/verification and
maintenance of
equipment/analytical
instrumentation; ensure proper
sample handling to avoid
contamination.
Percent Spike Recovery
(SPR)
75%-125% average SPR.
Accuracy
Where applicable, use a certified
reference standard to determine
differences between the measured
and nominal reference standard
concentrations.
Percent Difference (%D).
< 20 % average %D.
Representativeness Ensure pre-treatment/control and
post-treatment/treatment samples
are handled and analyzed in the
same manner.
N/A – Qualitative term.
N/A – Qualitative term.
Comparability
Routine procedures are conducted
according to appropriate SOPs to
ensure consistency between tests.
Ensure correct implementation of
SOPs.
N/A – Qualitative term.
N/A – Qualitative term.
Completeness
Calculate percentage of valid
samples analyzed out of the total
number of samples collected.
Percent Completeness
(%C)
Greater than 90 %C.
Sensitivity
Determine the method detection
limit and limit of quantification for
each analyte and analytical method
utilized.
Method Detection Limit
(MDL) and Limit of
Quantification (LOQ)
Dependent upon the
analyte and
instrumentation.