Investigation On Preparation,Accurate Measurement And Reference Materials For Aldehyde And Ketone Dnphs

Recently,the monitoring of oxygenated VOCs pollutants such as aldehydes and ketones has received extensive attention.Aldehydes and ketones,as important precursors of ozone and secondary organic aerosol,are not only highly irritating and toxic to humans,but also can cause serious air pollution problems.Based on the advantages of high performance liquid chromatography(HPLC)for the simultaneous qualitative and quantitative analysis of a variety of aldehydes and ketones,many regulations and standards issued by the Ministry of Ecology and Environment in China use high performance liquid chromatography for the detection of aldehydes and ketones.At present,the equivalence and consistency of China’s monitoring data on aldehydes and ketones still needs to be improved.Therefore,the research on accurate measurement methods and reference materials of aldehyde and ketone compounds has great significance for the implementation of national standards and the prevention and control of environmental pollution.In this thesis,formaldehyde-2,4-dinitrophenylhydrazone was synthesized by the derivatization reaction of formaldehyde with 2,4-dinitrophenylhydrazine(DNPH).The optimal conditions for the derivatization reaction were obtained by optimizing the reaction time,the acidity of the reaction solution and the number of extractions;the qualitative analysis of the derivative was carried out by microinfrared spectroscopy and gas chromatography-mass spectrometry,the derivative was in good agreement with the spectrum of formaldehyde hydrazone in the NIST standard library;the quantitative analysis of the derivative was performed by high performance liquid chromatography and standard curve method,and the purity of the prepared formaldehyde-2,4-dinitrophenylhydrazone could reach 98.5% with a measurement uncertainty of2.1%(k=2).Aldehydes and ketones in e-cigarettes have received extensive attention with the popularity of e-cigarettes.The new GB 41700-2022 electronic cigarette standard clearly specifies the limit values for various types of aldehydes and ketones.In this thesis,the measurement of aldehydes and ketones by high performance liquid chromatography applied to the analysis of formaldehyde,acetaldehyde,acrolein and 2,3-butanedione in e-cigarette liquids,an analytical method with sensitive detection and simultaneous measurement of multiple aldehydes and ketones was established and the uncertainty was evaluated.The results show that the measurement repeatability is good,the standard curve has good linearity( > 0.9999),detection limits were in(0.53 ～ 1.15)μg/L,the recovery rates of adding standard were between 90% and 103%,the uncertainty of the measurement method was better than 4.5%(k=2).The above results demonstrate the feasibility of high performance liquid chromatography for the measurement of aldehydes and ketones in e-cigarette liquids.In response to the lack of reference solutions for aldehydes and ketones DNPHs,reference solutions of formaldehyde-DNPH,acetaldehyde-DNPH,propionaldehyde-DNPH and acetone-DNPH in acetonitrile were prepared by weight-volume method,and the homogeneity and stability research was carried out and uncertainties were evaluated.The results show that the prepared reference solutions have good homogeneity;the short-term(7 days)stability and long-term(12 months)stability have no unidirectional trend changes,the stability is good;the certified values and expanded uncertainties of four reference solutions were(50.0±1.2)mg/L(formaldehyde-DNPH),(50.0±1.7)mg/L(acetaldehyde-DNPH)、(50.0±1.9)mg/L(propionaldehydeDNPH)and(50.0±1.8)mg/L(acetone-DNPH),respectively.The development of aldehydes and ketones reference solutions is beneficial to the prevention and control of aldehydes and ketones pollutants in environment,and it can provide comparable,traceable and reproducible data for the monitoring of aldehydes and ketones pollutants in environment.