National Institute for Occupational Safety and Health

“ Gauze in sterile packaging is recommended to minimize the chance for cross-contamination, which can more easily occur with open bulk packaged cotton gauze. 6.
To prevent contamination in the field, another alternative is to pre-wet and insert the gauze wipes into the sample containers off-site. This avoids any possibility of the bottle of methanol or isopropanol becoming contaminated on-site with methamphetamine (or other analytes) . If the wipes were prepared off-site, then remove pre-wetted gauze wipe from sample container, opening only one sample container at a time. ”

“ Care must be exercised in the selection of internal standards for each analyte because of differences in derivatization efficiencies due to structural differences. a. Deuterated analogs of each target analyte may be acceptable as internal standards if they are isotopically pure enough and their ions do not interfere with the quantification ions (usually base peaks) of the target analyte, especially at the limit of detection for the target analyte. ”

“ LODs were calculated on liquid standards using the procedure of Burkart (LODs for linear calibration curves are calculated as 3 times the standard error of the lowest three standards analyzed in replicate divided by the slope of the calibration curve) . [9] (4) MDLs are provided to satisfy regulatory agencies requiring this expression of sensitivity. These MDLs are calculated as the standard deviation of six replicates on spiked media analyzed at the 0.1 μg/sample level (except as noted) times the Student’s t value for 6 replicates (3.365) . ”

“ Set mass spectrometer conditions to manufacturer’s specifications and those given on page 9109-1 for the scan mode or those in Table 6 for the SIM mode. c. Inject sample volume with autosampler or manually. NOTE: After the derivatives are prepared and just before analyzing any samples or standards, inject the highest concentrated standard several times in order to prime or deactivate the GC column and injection port. This will help minimize any drift in the instrument’s response to target analytes relative to their internal standards. ”

“ The more highly deuterated an analog, the more it will chromatographically separate from the target analyte, reducing interference from common ions. c. Phentermine and mephentermine have been used as internal standards. Such use is not advised in this method because of their reported occasional use as adulterants in certain illicit drugs such as MDMA. (2) N-Propylamphetamine and MDEA-D6 are only applicable to MDEA and other hindered amines (e.g., fenfluramine and MBDB) due to similar steric hindrance at the nitrogen (N-ethyl or N-propyl substitution) which affects derivatization efficiency. ”

“ Transfer an aliquot of the derivatization sample mixture from the GC vial to a clean low-volume GC vial and add acetonitrile, MSTFA, and MBHFBA. For example, for a 10:1 dilution transfer 20 μL of sample to a clean vial and add 120 μL of acetonitrile and 30 μL each of MSTFA and MBHFBA, for a total volume of 200 μL. For a 4:1 dilution, transfer 50 μL of sample to a clean vial and add 100 μL of acetonitrile and 25 μL each of MSTFA and MBHFBA, for a total volume of 200 μL. Cap the GC vial, mix by inversion a few times, and analyze diluted sample. ”

“ NIOSH has not established health-based or feasibility-based airborne Recommended Exposure Limits (RELs) or surface contamination guidelines for clandestine drug laboratories. State surface contamination limits are provided as an aid to those seeking additional information and does not constitute endorsement by NIOSH. The National Alliance for Model State Drug Laws (NAMSDL) website (http:// www.namsdl.org/home.htm) periodically summarizes state feasibility-based decontamination limits and proposed state legislative requirements and guidelines. ”

“ 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 [1] . Additional research on surface sample recovery and solvent effectiveness has been reported by Martyny [10, 11] . REFERENCES: [1] Reynolds JM, Siso MC, Perkins JB [2004] . Backup Data Report for NIOSH 9109, Methamphetamine and illicit drugs, precursors, and adulterants on wipes by solid phase extraction, Abridged. ”

“ In this example, an LOD of 0.18 μg/100 cm2 is above the action threshold of 0.1 μg/100 cm2, meaning that this composite sample cannot satisfy the requirement that residual levels be below 0.1 μg/100 cm2. It remains for the regulatory agency and not the laboratory to determine how to apply results for composite samples to the established action levels. ”

“ NIOSH Manual of Analytical Methods (NMAM) , Fifth Edition METHAMPHETAMINE . . . on Wipes by SPE: METHOD 9109, Issue 1, dated 17 October 2011 - Page 3 of 33
SPECIAL PRECAUTIONS: The solvents are flammable and have associated adverse health effects. Phenethylamines target the nervous system at very low concentrations and are easily absorbed through the skin. Avoid breathing vapors. Avoid skin contact. Work should be performed in a hood with adequate ventilation. ”

“ If the area to be wiped remains substantially wet from the first gauze, the second gauze wipe might be used in the dry state to soak up the residual solvent from the first gauze wipe. 8.
Composite sampling: Composite samples are allowed by some regulatory agencies. Their use for quantitative purposes may be subject to the permission and guidance of regulatory agencies. Refer to guidelines of regulatory agency for directions on composite sampling. ”

“ Fold the pad, exposed side in, and place in shipping container and seal with cap. NOTE: Keep samples refrigerated (<6 oC) . While methamphetamine and several related amines are stable on the recommended wipe media for at least 7 days at room temperature, refrigeration is recommended as soon as possible (see Table 5) . 4.
Either clean the template before use for the next sample or use a new disposable template. 5.
Label each sample clearly with a unique sample identifier. 6.
Prepare a minimum of two field blanks with one field blank for every ten samples. ”

“ Suggested ions for other analytes and internal standards are given in Tables 11 and 12. (8) Secondary ions may be used for quantification if the primary ion encounters interference. Secondary ions improve qualitative identification for SIM analyses. The relative abundances given are approximate (±10 to 20%) and depend upon specific instrument tuning and conditions. ”

“ For methamphetamine the range is 0.05 to 60 μg/sample (sample = 100 cm2 or 1000 cm2) . This method was developed for the analysis of selected drugs and precursors on surfaces in clandestine drug labs. [2, 3] Sampling methodology was tested using wipes on smooth, non-porous surfaces. The APPENDIX contains sampling information for other types of surfaces. INTERFERENCES: No chromatographic interferences detected. Water, surfactants and polyols inhibit derivatization. ”

“ Trifluoroacetyl derivatives are not presented. Underivatized compounds are identified as a “parent” compound. Parent compounds that have poor chromatographic peak shapes under the conditions used are not presented. Spectra for the derivatives are given in the Backup Data Report (Appendix-II) . [2] (3) Major and minor peaks are identified where two or more forms are possible. In some cases two major peaks may exist. Pri.deriv. = Primary derivative, a major peak. The major peak or the primary derivative should be used for quantitation. OS artifact = Oversilylation artifact [18] . ”

“ Crystal violet indicator: 2-3 mg/mL in isopropanol. 6. Solid phase extraction (SPE) wash solution: Aqueous 0.1 M hydrochloric acid: Dilute 8.3 mL concentrated hydrochloric acid in about 800 mL water, dilute to 1 liter with ASTM Type II water. 7. SPE elution solution: 80:20:2 CH2Cl2:IPA:NH4OH v/v. Prepare fresh daily. 8. 0.3 M hydrochloric acid in methanol: Dilute 2.5 mL conc. hydrochloric acid in about 80 mL methanol; dilute to 100 mL with methanol. 9. Derivatization diluent solvent: acetonitrile containing 4 μg/mL of 4,4’-dibromo-octafluorobiphenyl (optional) . ”