A calibration system for producing known concentrations of mercury vapor in air.
Scheide EP; Hughes EE; Taylor JK
Am Ind Hyg Assoc J 1979 Mar; 40(3):180-186
A modified system was developed to produce calibration mixtures of mercury (7439976) vapor in air by saturating the air with mercury at an elevated temperature and condensing the mercury vapor at a lower and accurately controlled temperature. The resulting mixture was further diluted with air to produce the desired concentration. Mixtures within 2 percent of the calculated theoretical value were obtained. Mercury monitoring instruments were calibrated using this system to verify the usefulness of periodic recalibration. Curves obtained from mercury samples were reproducible and easily compared with standards to determine mercury content. Response time was about 5 minutes when changing from one concentration to another at concentrations not different by more than 100 percent, and about 10 minutes when larger concentration changes were made. Temperature effects were observed due to a difference between water bath and condenser temperatures, but when a correction factor was applied the calculated and observed values were the same. Positive and negative errors were considerable in many of the instruments tested against the system. The authors conclude that the new system can provide a means of calibrating instruments for mercury analysis, may be useful in the evaluation of new and existing analytic methods, and can be constructed from readily available components. The authors suggest that mercury monitoring instruments be periodically recalibrated.
NIOSH-Publication; NIOSH-Contract; Airborne-contaminants; Measurement-instrumentation; Air-monitoring; Air-pollution; Atomic-absorption-spectrometry; Analytical-methods; Research-laboratories
American Industrial Hygiene Association Journal