Page:NIOSH Manual of Analytical Methods - 9109.pdf/14

 METHAMPHETAMINE. . . on Wipes by SPE: METHOD 9109, Issue 1, dated 17 October 2011 - Page 14 of 33

Table 5. Limit of detection (LOD), method detection limit (MDL), and sample storage stability(1) Estimated LOD(3)

Estimated MDL(4)

µg/sample liq. stds(6)

µg/sample liq. stds(7)

µg/sample cotton gauze

D11-Amp

0.1

0.1

0.02

D14-Met

0.1

0.05

0.02

NMPhen

0.1

0.04

D11-Amp

0.6

0.2

(9)

D14-Met

0.4

0.1

(9)

NMPhen

0.4

0.1 (9)

D11-Amp

0.2

0.2

0.02

D14-Met

0.1

0.1

0.02

NMPhen

0.1

0.02

MDEA

N-PAmp

0.1

0.06

MDMA

D11-Amp

0.1

0.02

D14-Met

0.1

0.02

NMPhen

0.1

0.03

D11-Amp

0.2

0.07

0.02

D14-Met

0.1

0.05

0.02

NMPhen

0.1

0.02

D11-Amp

0.6

0.1

(9)

D14-Met

0.4

0.1

(9)

NMPhen

0.4

0.1

(9)

D11-Amp

0.2

0.03

D14-Met

0.1

0.03

NMPhen

0.1

0.04

D11-Amp

0.1

0.05

0.03

D14-Met

0.1

0.05

0.03

NMPhen

0.1

D11-Amp

0.2

D14-Met

0.1

NMPhen

0.1

Compound (D)-Amphetamine

Cocaine

(L)-Ephedrine

(D)-Methamphetamine

Phencyclidine

Phentermine

(±)-Norephedrine

(8)

Pseudoephedrine

Int. std.(2)

Storage Stability(5) µg/sample AlphaWipe® 0.02

0.1

(9)

0.02 0.1 0.04

0.02

0.5

(9)

30 days 4 ºC

7 days 22 ºC

100.5

94.5

99.7

87.9

-

-

99.3

98.8

98.5

91.9

-

-

95.6

97.2

94.8

90.5

-

-

98.9

102.1

99.7

111.1

98.9

103.2

-

-

98.7

100.6

98.0

93.5

-

-

103.7

105.2

102.9

97.7

-

-

102.0

101.5

101.1

94.3

-

-

94.3

92.7

93.6

86.2

0.03

-

-

0.2

0.02

100.4

97.9

0.1

0.02

99.6

91.1

-

-

0.02

0.03

0.03

0.02

(1)	 Backup Data Report [1]. (2)	 Internal standards: D11-Amp = Amphetamine-D11, D14-Met = Methamphetamine-D14, NMPhen = N-Methyl phenethylamine, N-PAmp = N-Propyl amphetamine. (3)	 LODs vary according to individual GC columns, instrument conditions and cleanliness, media interferences, and internal standards used. 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). (Normally 7 replicates are required.) (5)	 Cotton gauze samples were spiked at 3 µg/sample per analyte. Six samples were analyzed immediately after preparation. Six samples were stored at room temperature (about 22 ºC) for 7 days and then analyzed. Eighteen samples were stored at >6 ºC. Of the 18 samples stored at >6 ºC, six each were analyzed at 7 and 21 days and three each were analyzed at 14 and 30 days. (Backup Data Report [1].) Apparent recoveries vary according to internal standard used. (6)	 These LODs are conservative since the lowest calibration standard for these determinations was 0.1 µg/sample. Lower LODs are achievable with lower concentration calibration standards and operation of the mass spectrometer in the SIM mode. (7)	 Typical LODs for a five point calibration curve with single standards at each concentration level. The lowest calibration standard for these determinations was 0.05 µg/ sample. (8)	 (±)-Norephedrine = (±)-phenylpropanolamine. (9)	 MDLs for cocaine and phencyclidine were determined from the 0.3 µg/sample level because the GC peaks for the 0.1 µg/sample level were un-measurable. Precisions at the 0.3 µg/sample level were such that the MDLs calculated to 0.1 µg/sample anyway. This value may be realistic since the 0.1 µg/sample level samples had been stored for one month prior to analysis which may have affected stability.

Method rev. 1.1.1

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition