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 METHAMPHETAMINE on Wipes by LC/MS : METHOD 9111, Issue 1, dated 17 October 2011 - Page 6 of 12

maintenance. The cleanliness and performance of the mass spectrometer must be maintained such that at a minimum of 0.1 µg/sample a signal of at least 5 to 10 times the baseline noise is achievable. Precision and accuracy were determined by analyzing 6 replicates at each of 4 concentration levels (nominally 0.44, 1.8, 4.4, and 18 µg/sample). Accuracy was calculated using equations and methodology found in the NIOSH Technical Report “Guidelines for Air Sampling and Analytical Method Development and Evaluation” [5]. Using all data, method precision was 0.06663. Accuracy was 20.7% and mean bias was -0.09753. Long term sample storage stability was determined for periods up to 30 days under refrigeration (4 °C ± 2 °C) and for up to 7 days at room temperature (22-24 °C). Since long term storage measures only the viability of analytes on a particular media over time, this determination was not repeated for this particular method; the reader is directed to NIOSH 9106 [2] for more detail. All recoveries were found to be 93.5% or better. Recovery of amphetamines from six different types of surfaces using cotton gauze was evaluated. The study and results are reported in NIOSH 9109 [3]. The practice of serial wiping (wiping the same surface area a second time with a second gauze wipe and combining both wipes as a single sample) was evaluated. Four solvents for wetting the gauze were tested (distilled water, 5% distilled white vinegar, isopropanol, and methanol). Six replicate samples were taken on a latex painted wall. Recovery and precision results are presented in the previously mentioned Backup Data Report. In summary, the effectiveness of the various solvents using a single wipe on a latex painted wall were as follows: water, 46% recovery; 5% distilled white vinegar, 55% recovery; isopropanol, 64% recovery and methanol, 87% recovery. Average recoveries with isopropanol from all the surfaces tested were greatly improved with a repeat (serial) wipe (11% improvement compared to only about 6% improvement with methanol). The serial wipe is added to the first wipe and constitutes a single sample. REFERENCES: [1]	 Siso MC, McKay TT, Reynolds JM, Wickman DC [2005]. Backup data report for NIOSH 9111, Methamphetamine on wipes by liquid chromatography-mass spectrometry. Unpublished. Prepared under NIOSH Contract 200-2001-0800. [2]	 NIOSH [2011]. Methamphetamine and illicit drugs, precursors, and adulterants on wipes by liquid-liquid extraction: Method 9106. In: Ashley KA, O’Connor PF, eds. NIOSH manual of analytical methods. 5th ed. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, [www.cdc. gov/niosh/nmam/]. [3]	 NIOSH [2011]. Methamphetamine and illicit drugs, precursors, and adulterants on wipes by solid phase extraction: Method 9109. In: Ashley KA, O’Connor PF, eds. NIOSH manual of analytical methods. 5th ed. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, [www.cdc. gov/niosh/nmam/]. [4]	 Burkart JA [1986]. General procedures for limit of detection calculations in the industrial hygiene chemistry laboratory. Applied Industrial Hygiene 1(3):153-155, (1986). [5]	 NIOSH [1995]. NIOSH Technical Report: Guidelines for air sampling and analytical method development and evaluation. By Kennedy ER, Fischbach TJ, Song R, Eller PM, Shulman SA. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 95-117. [6]	 Martyny JW. Decontamination of building materials contaminated with methamphetamine [http://health.utah.gov/meth/html/Decontamination/ DecontaminationofBuildingMaterialsContaminatedwithMeth.pdf ]. Date accessed: May, 2007.

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NIOSH Manual of Analytical Methods (NMAM), Fifth Edition