METHAMPHETAMINE . . .on Wipes by Liquid-Liquid Extraction: METHOD 9106, Issue 1, dated 17 October 2011 - Page 22 of 31
Table 11a. Recovery from latex-painted wall with various solvents; one gauze wipe compared with the sum of two gauze wipes(1,2) Water(3) First Gauze Wipe
Test Compound(5)
Percent
%RSD
Amphetamine
51
14
Cocaine
36
Ephedrine MDMA
Isopropanol Plus Second Wipe(4) Percent
Methanol
Plus Second Wipe(4)
First Gauze Wipe
Percent
First Gauze Wipe
Percent
%RSD
Plus Second Wipe(4)
Percent
%RSD
Percent
56
67
6.0
78
90
4.0
96
22
36
69
22
80
89
9.1
94
48
23
52
76
7.4
85
91
4.4
96
40
20
44
61
9.0
70
88
5.3
94
MDEA
45
22
50
69
12
80
90
11
97
Methamphetamine
46
16
50
64
7.4
75
87
3.5
94
Phencyclidine
27
26
30
64
9.6
73
86
5.2
91
Phentermine
53
9.2
58
78
6.6
91
95
2.9
101
Phenylpropanolamine
58
21
62
80
9.3
95
85
5.0
94
Pseudoephedrine
49
20
53
73
7.0
85
95
3.3
101
(1) Backup Data Report for NIOSH 9109 [8]. Area of each sample was 100 cm . (2) Wall was an existing standard gypsum board wall painted with a latex based paint. Painted surface was at least one year old. There were six replicates for each solvent tested. (3) Water was deionized water (ASTM type II). Note low recovery and high %RSD. (4) 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. (5) Each pre-measured area was spiked with 3 µg of each analyte in methanol and the methanol allowed to dry for several minutes prior to wipe sampling. 2
Table 11b. Recovery from various surfaces with various solvents; one gauze wipe compared with the sum of two gauze wipes(1) Isopropanol First Gauze Wipe
Surface Material(3) Enamel (lid of washing machine) Vinyl veneer on particle board Latex painted wall Refrigerator door Varnished hardwood panel Formica® countertop
Replicates 4(3) 4(4) 6(3) 2(4) 2(5) 4(4)
Percent 58 60 64 65 72 75
%RSD 5.7 5.2 7.4 2.9 5.4 4.9
Methanol
Plus Second Wipe Percent 68 68 75 76 76 82
(2)
First Gauze Wipe
Percent 81 81 87 91 82 87
%RSD 2.4 4.8 3.5 4.0 3.7 3.8
Plus Second Wipe(2) Percent 87 89 94 92 86 91
(1) Backup Data Report for NIOSH 9109 [8]. 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. Method rev. 1.1.1
NIOSH Manual of Analytical Methods (NMAM), Fifth Edition
