Page:NIOSH Manual of Analytical Methods - 9109.pdf/18

 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