Analytical Sciences

Simple Ozone Scrubber Using a Glass Fiber Filter Impregnated with Hydroquinone for the Quantitative Analysis of Ambient Air Samples

Hironari SAKAMOTO, Shigehisa UCHIYAMA, Moka SHIMIDZU, and Hironao OGURA

Faculty and Graduate School of Engineering, Chiba University, 1-33 Yayoicho, Inage, Chiba 263-8522, Japan

As a standard method for measuring the concentration of carbonyl compounds in air, 2,4-dinitrophenylhydrazine (DNPH) derivatization followed by high-performance liquid chromatography (HPLC) is widely used. However, the method is often plagued by interference issues related to the ozone content in ambient air samples. Although the use of a potassium iodide (KI) scrubber circumvents these problems, the combination of a DNPH-coated silica cartridge and KI scrubber often performs poorly, particularly in high humidity. The KI in the scrubber becomes wet under these conditions, trapping the carbonyl compounds under investigation before they can reach the DNPH cartridge; this ultimately results in inaccurate readings. In this study, a new type of ozone scrubber consisting of a glass fiber filter coated with hydroquinone (HQF) was developed. The HQF scrubber was placed in front of the DNPH-coated silica cartridge, allowing airborne carbonyl compounds to pass unimpeded through the HQF section before being trapped by the DNPH-coated silica. The subsequent reaction of the trapped carbonyls with DNPH produced carbonyl 2,4-DNPhydrazone derivative that is used as the basis for the quantitative and qualitative analyses of ambient air samples. The hydroquinone in HQF reacts with ozone to form benzoquinone with an efficiency of more than 95% under wide relative humidity range (8 – 95%). The performance of our novel HQF scrubber was compared with those of potassium iodide (KI) and our previously developed trans-1,2-bis(2-pyridyl)ethylene (BPE)-coated silica scrubbers using ambient air samples, and the results showed that both HQF–DNPH and BPE–DNPH cartridges detected carbonyl compounds in the same concentration levels. The proposed method is superior to the KI-based and BPE-based technique for ozone removal because the HQF is very small and can be easily attached to any commercially available DNPH cartridge.

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