An analytical method was developed for the determination of formaldehyde in liquid samples and leachates of solid samples. After a review of the current literature, five candidate methods involving chemical derivatization were chosen for evaluation. Methods involving both liquid and gas Chromatographic procedures were considered. The derivatization method which satisfied all performance criteria was reaction with 2,4-dinitrophyenylhydrazine (DNRH) at pH 5, followed by quantification using liquid chromatography with absorbance detection. Mildly acidic derivatization conditions were employed to avoid unwanted generation of formaldehyde from ubiquitous precursors. Optimized experimental procedures include a 30 minute reaction time, followed by extraction using methylene chloride or a solid sorbent method. The derivatization of formaldehyde proceeded in high yield with excellent reproducibility. Laboratory blank levels were in the 10–15 ug/L range. The method satisfied performance criteria over the range of 15–1400 ug/L. Several authentic sample matrices were used to evaluate the method. The method was subjected to a single laboratory validation protocol.
An analytical method was developed for the determination of formaldehyde in samples of environmental origin. After a review of the current literature, five candidate methods involving chemical derivatization were chosen for evaluation. The five derivatization reagents studied were 2,4-dinitrophenylhydrazine (DNPH), 3-methyl-2-benzothiazolinone hydrazone, 2,4-pentanedione, pentafluorophenylhydrazine, and pentafluorobenzyloxyamine. The instrumental techniques used included either high performance liquid chromatography or gas chromatography, based on the nature of the derivative. After determining that the DNPH derivatization could be efficiently performed under mild reaction conditions, this method was chosen as the most appropriate of the five considered and was extensively evaluated. Optimized experimental procedures included a 1-h reaction time, followed by methylene chloride extraction and concentration of the extract. Quantification was best achieved by reverse phase liquid chromatography using absorbance detection at 360 nm. The derivatization of formaldehyde proceeded in high yield with excellent reproducibility and recovery. With the procedures employed, concentrations in the low parts per billion (ppb) range could be determined. Laboratory blank levels were in the 10- to 15-ppb range. An optimized procedure was utilized in studying several matrices, including two samples originating from the pulp and paper industry: a phenol/formaldehyde sludge and a wood dust sample containing urea/formaldehyde glue. The solid samples were extracted using the toxicity characteristic leaching procedure (TCLP) extraction method. Both matrices showed formaldehyde levels that were statistically higher than laboratory blanks. Recovery and reproducibility were excellent for the solid samples. Matrix and derivative storage problems were also evaluated.
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