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
