Laboratory Analysis – The IH Prospective William J. Lowry, CIHEnviroHealth Technologies, Inc.
Overview • Workplace hazard assessment • Selecting a laboratory • Methods of analysis • Quality control • Results interpretation
Your workplace hazard assessment • Determine the airborne hazards • Contact the laboratory
Laboratory Analysis • What you need from the lab • Media • Sampling procedure • What the lab needs from you • Detection limits • Method of analysis
Selecting a laboratory Laboratories performing industrial hygiene analyses should participate in external performance evaluation programs, and be subject to audit by external assessors.
Selecting a laboratory AIHA • offers performance evaluation and accreditation programs for industrial hygiene and environmental lead laboratories. • IHLAP is designed for labs involved in analyzing samples taken in the workplace environment and provides guidance for establishing a comprehensive laboratory quality assurance program.
Selecting a laboratory NVLAP • NIST accredits laboratories for the analysis of asbestos
Selecting a laboratory • Both accreditations are ISO 17025 compliant • Both accreditations specific to Field of Testing (FoT)
Selecting a laboratory Questions for labs • Does the laboratory perform the required analysis? • Does the lab meet your quality assurance requirements? • Are analysis and reports within your required turnaround time? • Does the analytical report contain the information you need? • Are detection limits reported and are they sufficiently low • Are analytical costs acceptable? • Does the laboratory provide the client services needed? • Are you confident in the results provided?
Selecting a laboratory The lab needs your information Chain-of-custody form that includes: • Administrative items such as reporting and billing address, contact name, phone, fax, email • Individual sample numbers • Type of collection media • Sample volume if you would like airborne concentration reported. • Analysis and method requested • Turnaround requested
Method of analysis • Typically use validated methods, i.e. NIOSH or OSHA, sometimes EPA and ASTM
Method of Analysis Analysis and method requested • OSHA – Sampling and Analytical Methods www.osha.gov/dts/sltc/methods/toc.html • NIOSH – Manual of Analytical Methods (NMAM) www.cdc.gov/niosh/nmam/ • EPA - www.epa.gov Method TO-1 Method TO-2 Method TO-3 Method TO-17 Method TO-14A • ASTM – www.astm.org/cgi-bin/SoftCart.exe/index.shtml?E+mystore
Common Laboratory Instrumentation • AAS, Atomic Absorption Spectrophotometer • ICP-AES, Inductively Coupled Plasma – Atomic Emission Spectroscopy • GC, Gas Chromatography (various detectors) • HPLC, High Pressure Liquid Chromatography (various detectors) • Gravimetric • Ion Chromatography
Quality Control • Collect two samples under the same conditions. Remember, when evaluating these samples, that they are not identical. • If bulk material, divide into two portions after thoroughly homogenizing. • Prepare “spiked” samples of known concentration to be submitted blind with field samples. These must be prepared by a skilled individual. Prepare additional spikes at the same time to be verified by a second laboratory if questionable results are reported. (Some may be purchased.)
Results Interpretation • Pay particular attention to units used by laboratory to report data. • Remember that the laboratory results are not exact measurements. Upper and lower confidence limits should be determined.
Confidence Limits CALCULATION METHOD FOR A FULL-PERIOD, CONTINUOUS SINGLE SAMPLE. Obtain the full-period sampling result (value X), the PEL and the Sampling and Analytical Error (SAE). The SAE can usually be obtained from the test method. Divide X by the PEL to determine Y, the exposure severity. That is: Y = X/PEL
Confidence Limits • Compute the UCL95% as follows: UCL95%=Y+SAE
Confidence Limits • Compute the LCL95% as follows: LCL95%=Y-SAE
Confidence Limits Classify the exposure according to the following classification system: • If the UCL < 1, a violation does not exist. • If LCL < 1 and the UCL > 1, classify as possible overexposure. • If LCL > 1, a violation exists.
Summary • More and more laboratory involvement prior to sampling is demanded • Increasing need for interaction of lab and IH field professionals to jointly develop sampling strategies • Laboratories must have professionals with strong IH field and IH lab background • Accreditations compliant with ISO Standards required for laboratories • Laboratory “Scope of Accreditation” specifies FoT • Development of complete laboratory quality programs required