Page:NIOSH Manual of Analytical Methods - 9109.pdf/15

 METHAMPHETAMINE. . . on Wipes by SPE: METHOD 9109, Issue 1, dated 17 October 2011 - Page 15 of 33

Table 6. Example of mass spectrometer operation parameters for selected ion monitoring mode(1) Heptafluorobutyryltrimethyl-silyl derivatives

Scan window(2)

Acquisition Group 1

8.20 to 10.20

104

118

128

132

210

213

Acquisition Group 2

10.20 to 13.20

179

240

254

282

296

456

Acquisition Group 3

13.20 to 19.00

82

162

182

200

242

254

Acquisition ions (m/z) per group(3) 240

244

Target Analytes and Internal Standards

13

Acquisition Group 1: Amphetamine-D11 (I$)(9)

8.46

244

128

70%

5 92

Amphetamine Phentermine

8.54 8.72

240 254

118 132

70% 12%

81 68 64

N-Methyl phenethylamine (I$)(9) Methamphetamine-D14 (I$)(9) Methamphetamine Acquisition Group 2: Phenylpropanolamine N-Propylamphetamine (I$)(9) Ephedrine Pseudoephedrine

8.54 9.86 9.94

240 261 254

104 213 210

100% 30% 35%

10.49 11.05 11.40 11.68

179 282 179 179

240 240 254 254

18% 85% 17% 15%

Dibromooctafluorobiphenyl(10) Acquisition Group 3: MDMA

12.82

296

456

100%

13.81

254

162

80%

95 97 36 98 32 59

Primary Ion (m/z)(7) (Quantification Ion)

261

268

GC Peak No.(4)

Retention Time(6)(min)

254

Secondary ion and approximate relative abundance(8)(relative to the Primary Ion)

57 MDEA 14.19 268 162 60% 86 Phencyclidine 15.62 200 242 35% 27 Cocaine 18.65 182 82 110% (1)	 In this example, 10 analytes and 5 internal standards are grouped into 3 acquisition groups having no more than 10 primary and secondary ions per acquisition group. For 6 analytes and internal standards or less, one acquisition group may be sufficient. (2)	 Scan window is in minutes. Actual times are dependent upon GC column and instrument conditions. (3)	 Ions (m/z) in bold numbers are suggested primary (quantification) ions. For best signal to noise ratio, do not exceed 10 ions per acquisition group. Dwell time per ion (m/z) is 50 milliseconds. (4)	 GC peak numbers are those in Figures 1 and 2 and Table 11. (5)	 The list of analytes and internal standards shown is an example. Analyte(s) and internal standard(s) must be selected according to analytical objectives. (6)	 Retention times are dependent upon GC column and instrument conditions. (7)	 The better ions for quantification are usually the base peak or those with masses >100 m/z and relative abundances >50% of the base peak. These minimize interference from co-eluting hydrocarbons. The suggested primary ions are not necessarily the base peaks in the mass spectra of the analytes, especially if the base peaks are ions common to aromatics (e.g., m/z 91) and paraffinic or olefinic hydrocarbons (e.g., m/z 42, 57, and 58). 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. They are relative to the primary ion and not necessarily to the base peak in the mass spectrum of each analyte. The relative abundance of secondary ions for each analyte needs to be determined from a mass spectrum acquired on the instrument to be used. (9)	 (I$) = internal standard. Internal standards must be paired with the appropriate analytes. Tables 8a and 8b give precision and accuracy data for various pairings. Other potentially useful internal standards are given in Tables 9 and 11. Highly deuterated analogs of the target analytes are preferred, where available. (10)	 Dibromooctafluorobiphenyl is an optional secondary internal standard useful for monitoring autosampler performance and instrument tuning. A shift in the mass axes or the relative abundance of m/z 296 to that of m/z 456 throughout an analytical sequence will help signal degraded tuning.

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

Method rev. 1.1.1