Ketones and aldehydes in polluted air are analyzed as their DNPH derivatives. No traditional C18 column can resolve the list of compounds in CARB Method 1004. Here, coupling the Acclaim^® PA to the Acclaim 120 C18 provides a unique selectivity that resolves all the components of the mixture. The minor peaks in this chromatogram are not impurities. They are minor isomers of the derivatives.