METHAMPHETAMINE . . .on Wipes by Liquid-Liquid Extraction: METHOD 9106, Issue 1, dated 17 October 2011 - Page 8 of 31
better than cotton gauze. Some media (TOPPER® and SOF-WICK®) did not perform well, possibly due to co-extracted nonionic (polyethoxyethylene type) surfactants that are not removed using hexane and incompletely removed using methylene chloride in the cleanup step. Precision and accuracy were determined by analyzing 6 replicates at each of 6 concentration levels (nominally 0.1, 0.3, 1, 3, 10, and 30 μg/sample). Results are presented in Tables 8a and 8b for cotton gauze. The best precision and accuracies were dependent upon the use of carefully chosen internal standards, especially where there is steric hindrance of the amine (e.g. having N-ethyl and N-propyl groups). 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). Results are given in Table 5. The precision and accuracy and long term storage stability evaluations were conducted using isopropanol as the wetting solvent. A second precision and accuracy study using methanol confirmed that methanol is an acceptable substitute for isopropanol. Recovery of amphetamines from six different types of surfaces using cotton gauze was evaluated (see Tables 11a and 11b). 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 made on a latex painted wall. Recoveries and precisions are given in Table 11a. The recoveries with 5% distilled white vinegar were better than for distilled water, but not as good as for isopropanol. Methanol is superior to isopropanol. Recoveries with isopropanol are greatly improved with a repeat (serial) wipe (11% improvement compared to only about 6% improvement with methanol). The study and results are reported in the Backup Data Report for NIOSH 9109 [9]. Additional research on surface sample recovery and solvent effectiveness has been reported by Martyny [11, 12]. REFERENCES: [1] Reynolds JM, Siso MC, Perkins JB [2004]. “Backup data report for NIOSH 9106, Methamphetamine and illicit drugs, precursors, and adulterants on wipes by liquid-liquid extraction, Abridged,” prepared under NIOSH Contract 200-2001-0800, (Unpublished, 2004). [2] Martyny JW, Arbuckle SL, McCammon CS Jr., Esswein EJ, Erb N [2003]. Chemical exposures associated with clandestine methamphetamine laboratories. http://www.njc.org/pdf/chemical_ exposures.pdf [2005]. [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] NIOSH [2011]. Methamphetamine on Wipes by Liquid Chromatography/Mass Spectrometry: Method 9111. 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/]. [5] Baum RM [1985]. New variety of street drugs poses growing problem. Chemical and Engineering News, 63(63):7-16. [6] Buchanan JF, Brown CR [1988]. Designer drugs, a problem in clinical toxicology. Medical Toxicology 3:1-17. [7] NIOSH [1994]. Chapter C: Quality Assurance. In: Eller PM, Cassinelli ME, eds. NIOSH Manual of Analytical Methods, 4th ed. Cincinnati, OH: Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 94-113. [www.cdc.gov/niosh/nmam/]. [8] Burkart JA [1986]. General procedures for limit of detection calculations in the industrial hygiene chemistry laboratory. Applied Industrial Hygiene 1(3):153-155. Method rev. 1.1.1
NIOSH Manual of Analytical Methods (NMAM), Fifth Edition
