National Institute for Occupational Safety and Health

“ Refrigerate the remaining solution. 7. Fill another spray bottle with household vinegar or mak e up a 1% (v/v) nitric acid solution, label that bottle #1 or lead extraction solution. NOTE 1: The indicator solution will remain active for 2-3 days (if kept cold) . After a time the indicator solution will begin to turn color (pale yellow) and lose viability, at which time a new solution NIOSH Manual of Analytical Methods (NMAM) , Fourth Edition LEAD IN DU ST W IPES: M ETH OD 9105, Issue 1, dated 1 5 Ma rch 2003 - Page 3 of 3
8. 9. 10. 11. ”

“ The lead disclosing solution should be k ept cold where pos sible (e .g., rec om m end to use a sm all cooler for field storage of indicator solution) . NOT E 2: Alternative solutions and test indicato rs m ay be used, and this can alter the sen sitivity and selectivity of the test for lead. Place sample (wipe) on clean surface. Spray with 3 pumps of bottle #1 (vinegar) extraction solution. Spray wipe with 2 pum ps of bottle #2 (indicator solution) . If sample turns red, lead is present. If no color change, sample is considered negative. ”

“ SAMPLE PREPARATION: NOTE: The following procedure is written for sodium rhodizonate, and can be amend ed us ing potassium rhod izonate. Also , com m ercial spot test k its may be used to test for lead on wipe samples in lieu of the procedure described below, but sk in contac t with the rea gents should be avoided. 5. Prepare a solution of rhod izonic acid us ing the sod ium rhod izonate powder. Dissolve a pre-weighed portion of 0.135 grams (135 mg) in 105 cc of very cold water (~2 oC) . This is the indicator solution. The indicator solution should turn an orange color when mixed. 6. ”