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 CARBON MONOXIDE: METHOD 6604, Issue 1, dated 15 May 1996 - Page 3 of 3 at CO concentrations up to 200 ppm and a range of ambient temperatures and relative humidities. Most of the tests were conducted at or near the PEL. For mean recovery studies, six different monitors were used and readings were taken approximately 1 h apart. Recovery at 20 ppm was 105% (n = 42); at 50 ppm, 99.6% (n = 36); and at 100 ppm, 99.9% (n = 30). Thus, the overall mean bias was calculated at - 1.7%. The precision ( r) at 20 ppm was 0.035 (35 readings from 5 monitors over a 7-h period). At 50 ppm,r was 0.012 (30 readings from 5 monitors over a 6-h period), and at 100 ppm, r was 0.008 (36 readings from 6 monitors over a 6-h period). Tests also were conducted to determine response time, zero and span drift, alarm decibel level, battery life, life of the sensors, as well as the effects of selected interferences (gases, vapors, and RF) and the effects of handling and transporting to remote sites.

REFERENCES: [1] [2] [3]

NIOSH [1977]. Backup data report no. S340, prepared under NIOSH Contract No. 210-76-0123. Woodfin WJ, Woebkenberg ML [in preparation]. An evaluation of portable direct-reading carbon monoxide monitors. Ashley K [1994]. Electroanalytical applications in occupational and environmental health. Electroanalysis 6:805-820.

METHOD WRITTEN BY: W. James Woodfin, NIOSH, DPSE, MRB

NIOSH Manual of Analytical Methods(NMAM), Fourth Edition, 5/15/96