ANALYSIS OF ALDEHYDE COMPOUNDS USING DNPH SAMPLING CARTRIDGES AND HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

Abstract

The use of Florisil cartridges coated with 2,4-Dinitrophenylhydrazine (DNPH) were evaluated for the collection of airborne butyraldehyde and formaldehyde vapor samples. The samples were eluted and analyzed using a High Performance Liquid Chromatographic (HPLC) analysis method utilizing a fixed wavelength ultraviolet detector. Standard solutions containing various concentrations of synthesized butyraldehyde and formaldehyde DNPH adducts were used to establish the calibration curves. The results indicate that a linear relationship exists between the concentration of aldehydes and spectral absorbance within the limits of solutions containing 2.5-20 ug/ml of formaldehyde and butyraldehyde. The desorption efficiency of the method was tested by loading known amounts of butyraldehyde onto the sampling cartridges. The cartridges were solvent desorbed, the eluted solution injected into the HPLC and then the analytical response was compared to the developed calibration curves. It was determined that the sampling cartridges had approximately an 88 percent recovery efficiency for butyraldehyde when the cartridges were spiked with known amounts of the butyraldehyde liquid. Above 200 ug, the greater the amount of butyraldehyde loaded onto the cartridge the lower the recovery efficiency. The sampling efficiency of the cartridges was determined by collection of air samples inside a test chamber containing an unknown concentration of airborne butyraldehyde and formaldehyde vapors. Side-by-side samples were collected using the DNPH-cartridge method, and a second unrelated standard collection method using commercially available ORBO24 tubes. The amount measured with the DNPH cartridges were compared to the ORBO-24 method to determine the relative efficiency of the DNPH-cartridge for collecting butyraldehyde and formaldehyde. Recovery of airborne butyraldehyde by use of cartridges was initially low, but improved dramatically when the cartridges were allowed to stand overnight. The recovery of aldehydes on the cartridges allowed to stand overnight was greater than the amount of butyraldehyde recovered by the ORBO-24 reference method.