Environmental Laboratory Certification Program (ELCP) Utah Department of Health

ELCP Staff Kristin Brown – Program Manager, Certification Officer Robert Aullman – Certification Officer Max Patterson – Certification Officer Alia Rauf – Certification Officer, Quality Assurance Keith Henderson – Certification Officer Cathy Mitchell – Administrative Support

Proficiency Testing All tests results need to be sent by the provider to the ELCP contact. Please make sure all information is included and correct. EPA ID Method Identification

The NELAC Institute (TNI) Standard TNI Status of 2017 TNI Standard

Standards Development TNI Voting Member TNI Conference August 7-11, 2017 TNI Committee Member

40 CFR 136 – Method Update Rule Pending Final Rule. Review tables in 136.3, additions and deletions have been made. Updates to the MDL procedure.

Revised MDL

The Goal Current MDL assumes that blank are Zero and constant variance over time (if they aren’t then a lower MDL and false positives) The true goal is to find the value at which you are positive your results are not the background Make the Quantitation limit meaningful Risk assessment

Current MDL Method 8270 4 preps, 3 spikes, 2 levels each, 2 instruments, 7 replicates = 504 runs

MDL definition Appendix B to part 136 TNI The method detection limit (MDL) is defined as the minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero and is determined from analysis of a sample in a given matrix containing the analyte. TNI The method detection limit (MDL) is defined as the minimum measured concentration of a substance that can be reported with 99% confidence that the measured concentration is distinguishable from the method blank results.

Current MDL Estimate MDL Signal to noise 3-5 3 X standard deviation of blanks plus the mean 3 X standard deviation of spikes Change in slope of standard curve Instrument limitations Previously determined MDL

Current MDL Procedure Spike at 2-10 X MDL (estimate) Process 7 spikes and 7 blanks in 3 or more batches Multiple instruments must analyze a minimum of 2 spikes and 2 blanks MDL = large of MDLs = t(n-1,1-α=0.99) S MDLb = Ẍ + t(n-1,1-α=0.99) Sb

MDL revision One procedure Start with 7 spikes and 7 blanks (initial determination) MDLs = t(n-1,1-α=0.99) Ss (Std Dev of Spikes) MDLb = X + t(n-1,1-α=0.99) Sb (std Dev of blanks) Use the highest as the MDL At least 2 samples per instrument Requires ongoing spikes Minimum 2 spikes per quarter Collect blank data

Verification Recalculate MDLs and MDLb Set MDLb to highest blank if there are non-detects in blank data set and n<100 Set MDLb to 99th percentile if n>100 If MDLrecalculated is within 0.3 -3 times existing, and <2% of method blanks are >MDL, then optionally leave MDL unchanged

Spike concentration Evaluate spike concentration once per year If >5% of spikes are not detected, then raise spike concentration and re-determine MDL

Summary Assessment of blanks Collection of spikes over time Multi-instrument direction

Implementation 7 low level spike 7 Blanks Verification (most labs have this from current yearly MDL) 7 Blanks (routine method blanks) Verification Requires some spikes each quarter, (yearly full study is removed)

MDL revision Initial 7 replicates across at least 3 batches Multiple instruments with the same assigned MDL Spikes results meet qualitative ID criteria Ongoing quarterly spikes Recalculate yearly (but do not redo)

Questions