Page:NIOSH Manual of Analytical Methods - 7605.pdf/4

 CH RO MIUM, HEX AVA LEN T: Me thod 7605, Issue 1 dated 15 M arch 200 3 - Page 4 o f 5 CALCULATIONS: 12. From the calibration graph, determine the mass of C r(VI) in e ach sam ple, W (:g), and in the average blank, B (:g). 13. Ca lculate con cen tration, C (m g/m 3), of Cr(VI) in the air volume sam pled, V (L):

NO TE : :g/L = m g/m 3

EVALUATION OF METHOD: This method was evaluated in the laboratory with spiked filters and a certified reference material containing a known loading of Cr(VI). This c ertified reference material (CRM ) is European Comm ission, Institute for Reference Materials and Measurements EC/IRMM) CRM 545, Cr(VI) and Cr(total) in welding dust loaded on a glass fiber filter [12]. This method was evaluated for extraction efficiency over the concentration range of 0.15 - 5 :g/sample testing two brands of filters, SILICAL® and G LA-5000™[3]. In these experiments, test atmospheres were no t generate d; inste ad, C r(VI) as the dichromate was fortified on the face of the sam ple filters, then 240 L of air with 35% relative humidity was pulled through at 1 L/min. A 30-day storage study using both types of filters was conducted at 1.5 :g/sample (30x LOQ) at ambient room temperature and 4 °C. The average recovery of the sto red sam ples w as 94.8% . The estim atio n of the lim it of detec tion and lim it of quantitation (LO D/LOQ ),were de term ined ana lyzing a se ries of liquid sta nda rds . The LO D and L OQ, 0.02
 * g/sample and 0.07 :g/sa m ple respe ctively were ca lculated by Burk art's m etho d [13].

To fully evalua te this m etho d, a field-stud y was con duc ted in w hich side-by-side sam ples were tak en to m easure exposures to Cr(VI) during spray-painting and electroplating operations. Th ese sam ples were analyzed subsequently by 4 different methods (NIOSH Method 760 5, 7703, 7300 and OS HA ID-215) [1 ]. NIOSH m etho d 73 00 w as u sed to measure total chromium. The results from the other 3 methods correlated very well showing no statistical difference among the 3 methods. Recoveries of 98.4 (+ 3.4) % were obtained for C RM 545 (n = 6) [2].

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Boiano JM, W allace ME, Sieber W K, Groff JH, W ang J, Ashley K [2000]. Com parison of three sampling and analytical methods for the determination of airborne hex avalent ch rom ium. J Environ M onit 2: 329333. Ashley K, Andrews RN, Cavazos L, Dem ang e M [2001]. Ultrasonic extraction as a sample preparation technique for elemental analysis by atomic spectrometry. J Anal At Spectrom 16:1147-1153. Foote P, W ickman DC, Perkins JB [2002]. Back-up data report for determination of hexavalent chromium by HPLC with post-column derivatization, prepared under NIOSH C ontract 2000-95-2955., unpublished, Augus t. Eide ME [2 000]. H exavalent C hrom ium, Meth od No. W 4001. Sa lt Lake City, Utah: US Department of Labor (U SDO L), Occ upational Safety and Health Adm inistration (OSH A), Salt Lake T echnical Cen ter. (Septem ber). Ku JC, Eide M [1998]. Hexavalent chrom ium in the workp lace atm osphere, O SH A ID -215. Sa lt Lake City, Utah: US Departm ent of Lab or (U SD OL ), Oc cup ationa l Safe ty and H ealth A dm inistration (O SH A), Sa lt Lake Tech nical Center (1998). ISO [2003]. Method No. 16740 (Draft International Standar d), M arch, 1999. Reference Num ber ISO/TC146 /SC 2/W G 2N136. Geneva, Switzerland: International Organization for Standardization. Arar EJ, Pfaff, JD, Martin TD [1994]. Method 218.6, Revision 3.3 (199 4). Cincinn ati, Oh io: Environmental Monitoring Systems La boratory, Office of Research and Developm ent, U.S. Environmental Prote ctio n Agency.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition