SILICA, CR YST ALLINE : MET HO D 760 1, Issue 3, dated 15 M arch 200 3 - Page 5 o f 6 EVALUATION OF METHOD: Th is m etho d is ba sed on the we ll-characte rized T alvitie m etho d [1,8,9,10].
REFERENCES: [1]
[2] [3] [4]
[5]
[6] [7]
[8] [9] [10]
NIOSH [1977]. Silica, crystalline, Method P & CAM 106. In: Taylor DG, ed., NIOSH M anual of Analytical Methods, 2nd ed., Vol. 1. Cincinnati, OH: U.S. Department of Health, Education, and W elfare, Publ. (NIOSH) 77-157-A. Sweet DV, W olowicz FR, Crable JV [1973]. Spectrophotometric determination of free silica, Am Ind Hyg Assoc J 34:500-506. Eller PM, Feng HA, Song RS, Key-Schwartz RJ, Esche CA, Groff JH [1999]. Proficiency analytical testing (PAT) silica variability, 1990-1998. Am Ind Hyg Assoc J 60: 533-539. Key-Sch wartz RJ, Baron PA, Bartley DL, Rice FL, Schlecht PC [2003]. Chapter R, Determination of airborne crystalline silica. In: NIOSH M anual of Analytical M etho ds, 4 th ed., 3 rd Suppl. Cincinnati, OH: U.S . Departm ent of He alth an d Hum an S ervices, P ublic H ealth Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2003-154. NIOSH [1974]. Criteria for a recomm ended standard: Occupational exposure to crystallin e s ilica. Cincinnati, OH: U.S. Department of Health, Education, and Welfare, Health Services and Mental He alth Adm inistration , National Ins titute for O ccu pation al Safety and Health, DHEW (NIOSH) Publication No. 75-120. Inhaled Particles and Vapours [1961]. Pergamon Press, Oxford, U.K. HSE [2000]. General m eth ods for sam pling and gra vim etric analysis of resp irable a nd inh alable dus t: MDHS 14-3. In: Methods for the determination of haza rdou s su bsta nce s. Londo n: Health a nd S afety Executive. Talvitie NA, Hyslop F [1958]. Colorimetric determination of siliceous atmospheric contaminants, Am Ind Hyg Assoc J 19(1):54-58. Talvitie NA [1964]. Determination of free silica: Gravimetric and spe ctrophotometric procedures applicable to airborne and settled dust, Am Ind Hyg Assoc J 25:169-178. Talvitie NA [1951]. Determination of quartz in presence of silicates using phosphoric acid, Anal Chem, 23(4):623-626.
METHOD REVISED BY: Issue 1: Jensen Groff, NIOSH/DART Issue 2: Rosa Key-Schwartz, Ph.D. and Paul Schlecht, NIOSH/DART.
APPE ND IX A: INTERFERENCES S om e silicate s m ay be re sistan t to p hosphoric acid digestio n [8]. An y silicate s not rem oved by the phosphoric acid treatment will give a positive interference. A m orphous silica, if not c om pletely rem oved by phosphoric acid treatm ent, will give a positive interference . Phosphate ion complexes molybdic acid to produce a yellow pho sph om olybda te color which is dissipated by lowering the pH of the solution with 10 N sulfuric acid. Excess ferric ion (more than 1 mg) will consume the reducing agent and inhibit the reduction of silicom olybda te to molybdenum blue. If more than 1 mg ferric ion is present, it should be rem oved by pretreatm ent w ith 10:1 HCl:HNO 3.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition
