METHAMPHETAMINE . . . on Wipes by SPE: METHOD 9109, Issue 1, dated 17 October 2011 - Page 18 of 33
Table 8b. Precision and accuracy in scan mode for AlphaWipe®(1) Internal Standard(2)
Compound
Bias
Range(3) µg/ sample
Accuracy
Overall Precision
Average
Range
(D)-Amphetamine
D14-Met
0.1-30
17.2
0.0611
-0.0712
-0.1066 to -0.0468
Cocaine
D14-Met
0.3-30
17.7
0.0901
-0.0014
-0.0246 to +0.0252
(L)-Ephedrine
D14-Met
0.1-30
10.7
0.0432
-0.0362
-0.0638 to -0.0039
MDEA
N-PAmp
0.3-29
9.6
0.0425
-0.0240
-0.0453 to +0.0416
MDMA
D14-Met
0.3-27
11.4
0.0498
-0.0297
-0.0612 to +0.0095
(D)-Methamphetamine
D14-Met
0.1-30
8.7
0.0430
-0.0114
-0.0483 to +0.0625
Phencyclidine
D14-Met
0.3-30
13.0
0.0391
+0.0658
+0.0216 to +0.1418
Phentermine
D14-Met
0.3-30
10.4
0.0295
-0.0560
-0.0917 to -0.0266
(±)-Norephedrine(4)
D14-Met
0.1-30
12.6
0.0577
+0.0282
-0.0220 to +0.0937
Pseudoephedrine
D14-Met
0.1-30
13.5
0.0592
-0.0352
-0.1001 to -0.0020
(1)
Backup Data Report [1]. Values are for the heptafluorobutyryl and mixed heptafluorobutyryl-trimethylsilyl and analysis by GC-MS in scan mode (see p 9109-1 for GC and MS conditions). Each sample consisted of a pair of 3” x 3” 12-ply cotton gauze pads. There were 6 replicate samples per concentration level and six concentration levels evaluated from approximately 0.1 to 30 µg/sample. (2) Internal Standards: D14-Met = Methamphetamine-D14, N-PAmp = N-Propyl amphetamine. (3) Range used for calculation of precision, accuracy, and bias. The entire range studied for all analytes was approximately 0.1 to 30 µg/sample (1xLOQ to 300xLOQ). (4) (±)-Norephedrine = (±)-phenylpropanolamine.
Table 9a. Recommended internal standards(1) and best application COMPOUND NAME
CAS
MW as free base
Quant. Ion
Secondary Ion
COMMENTS
(±)-Amphetamine-D11
not available
146.12
244
128
Preferred analog for amphetamine
(±)-Amphetamine-D8
145225-00-9
143.15
243
126
Alternate for amphetamine-D11
(±)-Amphetamine-D6
not available
141.16
244
123
Alternate for amphetamine-D11
(±)-Methamphetamine-D14
not available
163.12
261
213
Preferred methamphetamine analog
(±)-Methamphetamine-D11
152477-88-8
160.15
260
213
Alternate for methamphetamine-D14
(±)-Methamphetamine-D9
not available
158.16
261
213
Alternate for methamphetamine-D14
N-Methylphenethylamine
589-08-2
135.23
240
104
Alternate for methamphetamine-D14
Phencyclidine-D5
60124-86-9
248.35
205
96
Use only for phencyclidine
160227-44-1
213.22
268
162
Use only for MDEA
not available
177.29
282
240
Alternate for MDEA-D6
MDEA-D6
(2)
N-Propylamphetamine
(2)
(1)
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. Conversely it is also important that ions in the target analyte, especially at high concentrations, do not interfere with the quantification ion (usually base peaks) of any deuterated analog used as the internal standard. b. 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.
Method rev. 1.1.1
NIOSH Manual of Analytical Methods (NMAM), Fifth Edition
