Page:NIOSH Manual of Analytical Methods - 3601.pdf/3

 MA NEB, Hand W ash: ME TH OD 3601, Issue 1, dated 1 5 Ma rch 2003 - page 3 of 5

5. 6. 7. 8.

NOT E 2: Preweighing the L-cysteine and the EDTA into small vials is a convenient way of dispensing these chemicals in the field. NOTE 3: The addition of EDTA and L-cysteine to the hand-wash solution before washing the hand is not recomm ended, becaus e these che m icals will mak e the hand-w as h s olu tion very alkaline, slippery, and have a n unpleasan t odor (from the L-cysteine). Shake the bag until all the L-cysteine and EDTA dissolve. Pour the hand-wash solution from the bag into a 75- to 125-m L am ber wide-m outh bottle to overflowing and cap with no headspace. Prepare a blank sample by following all steps above, except step 3. Pack securely for shipment in refrigerant packs to keep at approximately 4 / C, and ship via overnight express.

SAMPLE PREPARATION: 9. On arrival at the laboratory, store the samples at 4 / C. 10. Put capped sam ple bo ttles in the ultrasonic bath for 5 to 10 m inutes. 11. Transfer 1 to 2 mL of each hand-wash solution, standard, and blank to an autosampler vial for analysis. An alyze with in 24 hours. No fu rther sam ple pre paration is necessary.

CALIBRATION AND QUALITY CONTRO L: 12. Calibrate daily with at least six working standards over the range of 0.1 to 100 µg/mL. a. Pipet aliquots of c alibration stoc k solution into 10 -m L volum etric flas ks, and bring to volum e with diluting solution. b. Include a calibration blank of unspiked diluting solution. c. Analyze together with field sam ples, field blanks, and laboratory control samples (steps 14 through 16). d. Prepare a calibration graph (pe ak area vs. concentration, µg/m L). 13. Prepare Lab orato ry Control Sam ples (LC S), in du plicate, with ea ch s am ple se t. a. Ind ependently prepare quality control Maneb L CS s olu tions in aqueous 1% L-cysteine, 3% Na 4EDTA•2H 2O at concentrations within the analytical range. b. Analyze along with the field sam ples, blanks, and liquid standards (steps 14 through 16).

MEASUREMENT: 14. Set liquid chrom atograph to m anufacturer’s recom m endations and the param eters given on page 3601-1. 15. Inject sample aliquots (100 µL) manually or with an autosampler. Rinse and dry syringe after each injection. 16. Mea sure peak areas. If sample peak area exceeds the linear calibration range, dilute with an aqueous 1% L-cysteine, 3% Na 4EDTA•2H 2O solution, reanalyze, and apply the appropriate dilution fa cto r in calculations.

CALCULATIONS: 17. From the calibration graph, read the concentration, C (µg/mL), of Maneb found in the sample. 18. Calculate the m ass of M aneb, M (µg), in the hand wash s am ple volume, V (mL ).

NIOSH Manual of Analytical Methods, Fourth Edition