Formaldehyde: A Comparative Evaluation of Four Monitoring Methods

Abstract

The performances of four formaldehyde monitoring devices were compared in a series of laboratory and field experiments. The devices evaluated included the DuPont C-60 formaldehyde badge, the SKC impregnated charcoal tube, an impinger/polarographic method and the MDA Lion formaldemeter. The major evaluation parameters included: concentration range, effects of humidity, sample storage, air velocity, accuracy, precision, interferences from methanol, styrene, 1,3-butadiene, sulfur dioxide and dimethylamine. Based on favorable performances in the laboratory and field, each device was useful for monitoring formaldehyde in the industrial work environment; however, these devices were not evaluated for residential exposure assessment. The impinger/polarographic method had a sensitivity of 0.06 ppm, based on a 20-liter air sample volume, and accurately determined the short-term excursion limit (STEL). It was useful for area monitoring but was not very practical for time-weighted average (TWA) personal monitoring measurements. The DuPont badge had a sensitivity of 2.8 ppm-hr and accurately and simply determined TWA exposures. It was not sensitive enough to measure STEL exposures, however, and positive interferences resulted if 1,3-butadiene was present. The SKC impregnated charcoal tube measured both TWA and STEL concentrations and had a sensitivity of 0.06 ppm based on a 25-liter air sample volume. Lightweight and simple to use, the MDA Lion formaldemeter had a sensitivity of 0.2 ppm. It had the advantage of giving an instantaneous reading in the field; however, it must be used with caution because it responded to many interferences. The method of choice depended on the type of sampling required, field conditions encountered during sampling and an understanding of the limitations of each monitoring device.

Formaldehyde Exposure in U.S. Industries from OSHA Air Sampling Data

“…Although the authors did not find published studies directly, and comprehensively comparing the methods referred to in the OSHA manuals, indirect mentions in two publications suggest absence of any important bias. (25,26) A small OSHA study about validation of a diffusive sampler reported, based on 10 samples, a slight downward bias (5-10%) of the impinger method compared with the XAD-2 method (the standard error of the XAD-2 method is 7%). (27) The authors assumed comparability of the methods in this study's analysis.…”

Real-Time Portable Organic Vapor Sampling Systems: Status and Needs

“…Positive interferences have been reported from methanol, styrene, 1,3-butadiene and so2. (8) Interferences from phenol, resorcinol, formic acid and furfuryl alcohol were reported for an earlier model. (3) A special filter is now available to minimize phenol interferences.…”

“…This instrument has been reported to be linear over the range of 0.4 to Sppm formaldehyde with an accuracy of 99 ± 20% over this range. (8) The lower limit of detection is 0.3 ppm. Positive interferences have been reported from methanol, styrene, 1,3-butadiene and so2.…”