1. Environmental Laboratory Certification Program (ELCP)
Utah Department of Health

2. 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

3. 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

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

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

6. 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.

7. Revised MDL

8. 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

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

10. 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.

11. 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

12. 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

13. 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

14. 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 times existing, and <2% of method blanks are >MDL, then optionally leave MDL unchanged

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

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

17. 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)

18. 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)

19. Questions