Separation and determination of carbonyl compounds in indoor air using two-step gradient capillary electrochromatography

A method of two-step gradient capillary electrochromatography (CEC) was developed to measure 12 carbonyls (aldehydes and ketones) in indoor air samples. The carbonyls were derivatized with 2,4-dinitrophenylhydrazine (DNPH) and then separated by a two-step gradient CEC on a C8 column. Effects of various instrumental conditions on the separation, including buffer concentration, organic modifiers, voltage, and cassette temperature, were investigated. The method detection limits for the 12 carbonyls ranged from 0.2 mug to 1.6 mug per sample and the recoveries were generally between 90 and 120%. A subset of 30 indoor air samples containing formaldehyde and acetaldehyde from 75 randomly selected homes in the city of Ottawa, Canada were measured using the CEC method. The concentrations of formaldehyde and acetaldehyde in these indoor air samples ranged from 5.8 mug/m(3) to 85 mug/m(3), and from 4.4 mug/m(3) to 38 mug/m(3), respectively. The comparison between CEC and the traditional HPLC method shows a good agreement in measured values.