NEW YORK STATE DEPT. OF HEALTH WADSWORTH CENTER ENVIRONMENTAL LABORATORY APPROVAL PROGRAM...
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Transcript of NEW YORK STATE DEPT. OF HEALTH WADSWORTH CENTER ENVIRONMENTAL LABORATORY APPROVAL PROGRAM...
NEW YORK STATE DEPT. OF HEALTHWADSWORTH CENTER
ENVIRONMENTAL LABORATORY APPROVAL PROGRAM
PROFICIENCY TESTING
HISTORY
1985 NYS ELAP established, with PT as an integral part.
1989 Program expanded to include full-volume solid waste samples
Current Status All analytes offered for accreditation by NY ELAP are proficiency tested if they are on the NELAC PT FOT list (except CN in SW)
Restricted to Potable and Non-Potable Water. All WS and WP analytes tested + many more
ANALYTES OFFERED TWICE YEARLY
POTABLE WATER: 137 (Asbestos by TEM is available to laboratories that are not NY ELAP
accredited)
NON-POTABLE WATER: 173
WATER BACTERIOLOGY: 4
AIR: 4
STATISTICAL TECHNIQUES FOR SAMPLE VERIFICATION
1. Verification of Prepared Value
• 5 samples for each parameter are analyzed in duplicate • Mean and standard deviation calculated• Prepared value verified if mean and standard deviation are within prescribed limits
[NIST Handbook 150.19, June 1999, 285.33(h)(5)]
STATISTICAL TECHNIQUES FOR SAMPLE VERIFICATION
2. Verification of Homogeneity
• 1 sample is collected at the beginning, ¼, ½, ¾, and finish of each prep. run• Each sample is analyzed in duplicate • One-tailed ANOVA applied: between sample set and within sample variances are compared
[NELAC Chapter 2, B.3.2]
STATISTICAL TECHNIQUES FOR SAMPLE VERIFICATION
3. Verification of Stability
• After the close of the study, 5 samples for each parameter are analyzed• Stability verified if mean is within prescribed limits of pre-distribution prepared value
[NELAC Chapter 2, B.5]
STATISTICAL TREATMENT OF PT DATA
All scoring conforms with NELAC requirements:
• Regression equations• Fixed acceptance limits • Statistical evaluation of study data
REPORTING
Report forms contain the following information:
• Matrix• Analyte Name• Concentration Units • Sample id• Method• Result• Mean/Target• Warning Limits (+/- 2 sd)• Acceptance Limits• Score (Satisfactory or Unsatisfactory)• X labs passed out of Y reported results
ADDITIONAL INFORMATION AVAILABLE TO ALL LABS AND ACCREDITING AUTHORITIES
Summary data:
• Matrix• Analyte Name• Concentration Units • Sample id• Target• Reported limits• Robust Mean• Standard Deviation• Median• Number of labs passing/ Number of labs failing• Histogram of no. of labs vs. result reported