METHAMPHETAMINE . . . on Wipes by SPE: METHOD 9109, Issue 1, dated 17 October 2011 - Page 16 of 33
Table 7. Suggested spiking schedule for calibration standards and quality control samples Add the following to clean shipping containers (e.g., 50-mL polypropylene centrifuge tubes) in the following order.
Name
Number of Wipes(1,2)
Volume(2) of Isopropanol or Methanol(3)
Volume(2) of Internal Standard Spiking Solution(4,5)
Volume of Target Analyte Spiking Solution(5,6)
Volume of Spiking Solution diluted 1/20(5,7)
Volume(2) of Desorption Solution(8)
Resulting µg/sample as Free Base(9)
Calibration Standards(10) CS0
0
3 mL
60 µL
0.0 µL
30 mL
0.00
CS1
0
3 mL
60 µL
2 µL
30 mL
0.02
CS2
0
3 mL
60 µL
5 µL
30 mL
0.05
CS3
0
3 mL
60 µL
10 µL
30 mL
0.1
CS4
0
3 mL
60 µL
20 µL
30 mL
0.2
CS5
0
3 mL
60 µL
60 µL
30 mL
0.6
CS6
0
3 mL
60 µL
10 µL
30 mL
2.0
CS7
0
3 mL
60 µL
30 µL
30 mL
6.0
CS8
0
3 mL
60 µL
100 µL
30 mL
20
CS9
0
3 mL
60 µL
300 µL
30 mL
60
CS10
0
3 mL
60 µL
1000 µL
30 mL
200
30 mL
0.0
Quality Control Samples
(11)
QB (media blank)
1
3 mL
60 µL
0.0 µL
QC (matrix spike)
1
3 mL
60 µL
3-300 µL
or 20-60 µL
30 mL
0.2-60
QD (matrix spike duplicate)
1
3 mL
60 µL
3-300 µL
or 20-60 µL
30 mL
0.2-60
(1) Gauze wipes may be added to the calibration standards but are not necessary if cotton gauze is used. Blank gauze wipes must always be added to the quality control samples, QB, QC, and QD. (2) a. If a sample consists of 2 gauze wipes, the volume of desorption solution must be increased to 40 mL to accommodate the second wipe. The shipping container should be a 50-mL polypropylene centrifuge tube or equivalent to accommodate the extra volume of desorption solution for 2 wipes. It is not critical to know the exact volume of desorption solution and wetting alcohol used per sample. It only needs to be enough to cover the samples and to permit free percolation through the samples. See step 7. b. If a set of samples consists predominantly of 2 gauze wipes, the QB, QC, and QD should also consist of 2 wipes and treated as per the samples. The volume of isopropanol (or methanol) added to the QC samples should be increased to 4 mL for 2 gauze wipes to simulate samples containing 2 gauze wipes. (3) If methanol was used for wipe sampling, it should also be used in the calibration standards, blanks, and QCs instead of isopropanol. (4) Concentration of internal standards in the internal standard spiking solution is approximately 200 µg/mL as the free base. It is critical to know the exact volume of internal standard spiking solution that is added to the calibration standards, samples, blanks, and quality control samples. The volume spiked into the samples may vary with sample size but the volume spiked into each of the calibration standards must not vary. See step 7b. (5) For quality control samples, spike onto wipe media within the shipping container. For liquid calibration standards (in lieu of media calibration standards), spike into the isopropanol (or methanol). (6) Concentration of analytes in the target analyte spiking solution is approximately 200 µg/mL as the free base. (7) Concentration of analytes in the diluted spiking solution for this table is approximately 10.0 µg/mL as the free base and can be prepared by diluting 100 µL of the target analyte spiking solution to 2 mL in methanol. (8) Desorption solution is 0.1 M sulfuric acid in deionized water. (9) This is µg per total sample irrespective of the total desorption solution volume or the area wiped. (10) Select 6 calibration standards from the list to cover the analytical range plus the blank. (11) Prepare one set of quality control samples for every 20 samples or less.
Method rev. 1.1.1
NIOSH Manual of Analytical Methods (NMAM), Fifth Edition
