Accumulation And Measurement Of Salicylaldehyde And Vanillin By Diffusive Gradients In Thin Films Technique

The diffusive gradients in thin-films (DGT) technique incorporates an ion-exchange resin separated from the solution by an ion-premeable gel membrane and controls the ion exchange for in stiu accumulation and sample acquisition. In this thesis, a polyethyleneimine (PEI) was used for the binding phase of DGT technique and a cellulose acetate dialysis membrane was used for the diffusive layer of DGT technique in order to determine the concentration of salicylaldehyde and vanillin in water.The experiment investigated the ultraviolet spectrometry based on the Schiff base principle for salicylaldehyde and vanillin, and the optimal condition was confirmed:the absorption wave lengths were 383nm for salicylaldehyde and 344 nm for vanillin; the linear concentrations measured were 2.47～238.5μmol/L for salicylaldehyde and 0.431～68.0μmol/L for vanillin; the recoveries of salicylaldehyde and vanillin were respectively in the range of 99.48%～101.8% and 100.6%～102.5%; for salicylaldehyde and vanillin, the relative-standard deviations for the intra-day precision were respectively 1.1%～1.5% and 1.2%～1.6%; the relative-standard deviations for the inter-day precision were respectively 1.8%～4.2% and 3.6%～4.2%. Then, DGT technique was used to determine salicylaldehyde and vanillin in water. The proper concentration (0.050 mol/L for both salicylaldehyde and vanillin) of binding phase, accumulating capacity (the max accumulating capacity were 20.75μmol/mL for salicylaldehyde and 3.91μmol/L for vanillin) and the effect of different conditions (pH, ionic strength) on the accumulating capacity of the binding phase were also confirmed via the experiment. Meanwhile, the diffusive coefficients of salicylaldehyde and vanillin were measured in different ionic strengths, and the proper reaction conditions were found. The accuracy of DGT technique applied to determination of salicylaldehyde and vanillin were also validated in condition of synthetic water (the recovery rate for salicylaldehyde was 90.14%, the recovery rate for vanillin was 85.06%).The result had demonstrated the presumption that the polyethyleneimine and the cellulose acetate dialysis are fit for the technique. It's valuable for the practice.