Anal. Chem. 1986, 58, 1195-1196
1195
Field Comparison of Two Personal Formaldehyde Monitoring Methods Eero Priha* and Ilpo Ahonen Tampere Regional Institute of Occupational Health, P.O. Box 486, SF-33101 Tampere, Finland
Two personal formaldehyde monitoring methods, (2,4-dlnltropheny1)hydrarlne (DNPH) and N-benzylethanolamine (BEA), were evaluated under practical field condltlons. I n both, sampllng is carried out wlth a chemlcally coated solld sorbent and a sampling pump, and the analysis Is done with chromatographic procedures. The chromotroplc acid method, wlth lmpinger sampling, was used slmultaneously as a reference method. The results of both personal sampllng methods and the chromotroplc acid method were of the same magnltude, and the correlations between them were good. Therefore both personal sampllng methods studied can be used In place of the chromotropic acid method. Both also have certain advantages, such as good storage stablllty wlth the BEA method and rapid analysls wlth llquld chromatography wlth the DNPH method.
Formaldehyde is a common air contaminant in industry, dwellings, and outdoor air. In recent years the substance has been the object of increasing concern because of its irritant, sensitizing, and carcinogenic properties. Several sampling and analytical methods are available for the air monitoring of formaldehyde. In industrial environments solid sorbent sampling methods enable personal sampling from the breathing zone. Because of the reactivity of formaldehyde, problems have been encountered with the storage stability of the samples. Recently, sorbent materials coated with chemical reagents (2-3), which react with formaldehyde, have gained increasing use. These methods, being chromatographic procedures, are also more specific than conventional photometric methods (4). The two most promising of these procedures, namely the (2,4-dinitrophenyl)hydrazine (DNPH) and N-benzylethanolamine (BEA) methods, were tested under actual field conditions and compared with the established impinger-chromotropic acid (CTA) method (5). In our study field testing was preferred to laboratory testing for several reasons. Under laboratory conditions environmental factors (humidity, temperature, formaldehyde concentration, etc.) are often standardized. In actual workplace environments a monitoring method is, however, subject to interference from high air humidity, interfering airborne compounds, errors in the measurement of air volume, etc.
EXPERIMENTAL SECTION Sampling Methods. Tubes containing XAD-2 coated with BEA, (ORBO-22, XAD-2 formaldehyde tubes, lot no. 70) were purchased from Supelco, Inc. In these tubes XAD-2 is used instead of Chromosorb 102, but the chemical nature of both sorbents is the same (styrene-divinylbenzene copolymer). Tubes containing XAD-2 coated with DNPH (DNPH tubes) were prepared as described by Andersson et al. (1). The samples were collected with a Sipin 1B personal sampling pump in both methods. In the standard chromotropic acid method (5,6)formaldehyde was collected into a 1% sodium bisulfite solution with an SKC Universal sampler (SKC, Inc.). 0003-2700/86/0358-1195$01.50/0
Analysis of Samples. The BEA tubes were analyzed by capillary gas chromatography as described by Kennedy and Hill ( 3 ) . The gas chromatograph was a HP 5880 A equipped with a HP 7671 autosampler. The injector and detector temperatures were set at 250 and 275 "C, respectively, the column temperature program (for the split injection mode) being 150 "C (7 min), 10 "C/min, 200 "C (0.1 min), 25 "C/min 250 "C (9 min). The split ratio was 1:25. The main difference between the method used and the original one was the column, which was an 0.32 mm X 50 m fused silica capillary column coated with 5% phenyl methyl silicone (Ultra no. 2, Hewlett-Packard Co.). The DNPH tubes were analyzed with a Varian 5000 liquid chromatograph equipped with a Spherisorb ODS column as described by Beasley (2)and Girard and Heurer (7). The CTA method used was that standardized in Finland (6). The analytical procedure included evaporation of interfering solvents for improvement of specificity ( 4 , 6). Field Measurements. Field measurements were carried out in the furniture industry (three plants), in an iron foundry, in a plywood and particleboard factory, and in a paper products factory. Formaldehyde monitoring methods can suffer from interference caused by simultaneously occurring airborne compounds ( 4 ) . Workroom air in the furniture factories contained the following paint solvents during the formaldehyde sampling: xylene (4-17 ppm), toluene (10-81 ppm), butanol (17-60 ppm), butyl acetate (6-24 pprn), 2-ethoxyethanol(
