Reduction of blank values in the determination of particulate cyanides.
Perkins-JB; Tharr-DG; Palassis-J; Fannin-DB; Eller-PM
Appl Occup Environ Hyg 1990 Dec; 5(12):836-837
A method for reducing blank values when determining particulate cyanide (57125) concentrations was developed. When analyzing several sets of field samples for particulate cyanide content by NIOSH method 7904 the filter blanks were observed to contain 0.1 to blank readings was interfering material leached out of the mixed cellulose ester (MCE) membrane filters by 0.1 normal potassium- hydroxide. The potassium-hydroxide was used to trap hydrogen- cyanide (74908) that passed through the prefilter. An analysis of several lots of MCE filters showed blank cyanide concentrations of increased when the filters were stored for several days in filter cassettes before treatment with potassium-hydroxide. Polyvinyl- chloride (PVC) and polyvinyl/acrylic copolymer filters were investigated as alternatives. No background cyanide was detected even when the filters had been stored for several days before potassium-hydroxide treatment. The authors conclude that for minimizing blank cyanide values, the MCE filters should be replaced by PVC or polyvinyl/acrylic copolymer membrane filters.
NIOSH-Author; Cyanides; Particulates; Filter-materials; Air-sampling; Air-filters; Membrane-filters; Particulate-sampling-methods
Applied Occupational and Environmental Hygiene