Determination of carbonyl compounds in waters using triazine-based hydrazine reagents and liquid chromatography

Triazine-based hydrazine reagents have been developed and applied for the d etermination of aldehydes in waters. N-Methyl-4-N',N'-dimethylamino-6-(4'-m ethoxy-1'-naphthyl)-1,3,5-triazine-2-hydrazine (MDMNTH) and 4-N,N-dimethyla mino-6-(4'-methoxy-1'-naphthyl)-1,3,5-triazine-2-hydrazine (DMNTH) react wi th these carbonyl compounds with very high yields under the formation of th e respective hydrazones, which are separated by reversed-phase liquid chrom atography with binary gradients of acetonitrile and water. Organic modifier s are added to obtain improved peak shapes. UV/vis as well as fluorescence detection has been applied successfully to quantify the hydrazones. The der ivatization of aqueous solutions of the aldehydes has been optimized. Limit s of detection are in the range between 0.1 mu M and 1.0 mu M depending on the analyte and the reagent used for derivatization. Although calibration v ia external standards is possible for higher analyte concentrations, best r esults are obtained by calibration via the derivatization reaction. Compare d to the US EPA method 8315A, the newly developed method is characterized b y very easy sample preparation, lower limits of detection without enrichmen t and excellent reproducibility with an average RSD of 1.5% with DMNTH as r eagent and 3.5% with MDMNTH as reagent for a formaldehyde concentration of 1.0 x10(-5) mol L-1. Aldehyde-spiked mineral water samples were analyzed su ccessfully with the new method.