Page:NIOSH Manual of Analytical Methods - 9109.pdf/21

 METHAMPHETAMINE. . . on Wipes by SPE: METHOD 9109, Issue 1, dated 17 October 2011 - Page 21 of 33

Table 10b. Recovery of methamphetamine from various surfaces with various solvents; one wipe compared with the sum of two wipes(1) Isopropanol First Wipe Surface Material(3)

Replicates

Plus Second Wipe(2)

Plus Second Wipe(2)

First Wipe

Percent

%RSD

Enamel (lid of washing machine)

(4)

4

58

5.7

68

81

2.4

87

Vinyl veneer on particle board

4 (5)

60

5.2

68

81

4.8

89

Latex painted wall

6(4)

64

7.4

75

87

3.5

94

Refrigerator door

2

65

2.9

76

91

4.0

92

Varnished hardwood panel

(6)

2

72

5.4

76

82

3.7

86

Formica® countertop

4(5)

75

4.9

82

87

3.8

91

(5)

Percent

Methanol

Percent

%RSD

Percent

(1)	 Backup Data Report for NIOSH 9109 [2]. Area of each sample was 100 cm². (2)	 For the serial wipe study, each 100-cm² area was wiped again with a fresh pre-wetted gauze wipe and the amount recovered was determined separately. In practice, a second (serial) wipe is included with the first gauze wipe; both gauze wipes constitute a single sample. The percent recoveries shown in the column represent the sum of the amounts recovered in both the first and second wipes. (3)	 The refrigerator door and the washing machine lid were from used appliances. The vinyl-veneered particle board (a book shelf), the Formica® countertop, and the varnished hardwood paneling were all purchased new. All surfaces of used and new materials were pre-cleaned with multiple rinses of methanol prior to spiking. Each pre-measured 100-cm² square was spiked with 3 µg methamphetamine. (4)	 Samples were taken using the side-to-side and then top-to-bottom wiping technique. (5)	 Half of the samples were wiped using the side-to-side wiping technique and half were wiped using the concentric squares wiping technique. There were no significant differences in recoveries. Percent recoveries and %RSDs are for both techniques combined. (6)	 Samples were taken each time using only top-to-bottom wiping with the grain of the wood in an “N” pattern.

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

Method rev. 1.1.1