Study On The Determination Formaldehyde In Indoor Air By The Collection And On-acf Derivatization And Thermal Desorption/capillary Gas Chromatography

In this dissertation, a research has been made on the sample pretreatment and chromatographic analysis technique of formaldehyde in indoor air, based on the review of the previous work, the original creative research is as follows:First, based on the derivatization agent of O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) coated on activated carbon fibers (ACF) sorbent, the reaction mechanism, the processes of the derivative reaction kinetics of PFBHA with formaldehyde on the ACF fibers, and the quantitative relationship between the PFBHA-HCHO oxime in derivative reaction of formaldehyde in indoor air were researched.Second, in order to establish the rapidly and accurately analysis method of chromatography of the formaldehyde in indoor air, we first put forward the method of PFBHA coated on ACF carrier, the derivative reaction of formaldehyde with PFBHA at the same time when air samples collected, the derivatization products were adsorbed on ACF fiber and then ACF sample tube were directly determined by thermal desorption/capillary gas chromatography.This dissertation is divided into four parts.In theory section, after the study on the surface characteristic of ACF and the principle of its adsorption/desorption, the characteristics of the nano pore structure and the special carrier of ACF was pointed out. In the following, the derivative reaction kinetics and the quantitative relationship of PFBHA-HCHO oxime with formaldehyde after PFBHA loaded on ACF fiber. The reaction of formaldehyde with PFBHA and it's quantitative relationship was described by Langmuir-Rideal mechanism. The linear equation of the formaldehyde concentration CHCHO and the reaction rate v of the PFBHA-HCHO oxime has been derived.In the experiment section, the conditional experiments of the ACF coated by PFBHA derivative agent the experiments of the purification of PFBHA derivatization agent, preparation of sampling tubes, the processing method of ACF, sample collection efficiency, the sample analysis operation parameters, calibration curves and minimum detection limits, method precision, the contrast test of analysis method with the national standard method of phenol reagent spectrophotometric have been put emphasis on researching.Under the optimal conditions, using formaldehyde standard samples and directly thermal desorption/capillary GC analysis, the calibration curve of the formaldehyde concentration and the chromatographic peaks area of PFBHA-HCHO oxime has been draw, the linear regression equation is Y= 33238X+758, linear regression coefficient R2 is 0.9998. The minimum detection limit (MDL) of formaldehyde is 0.0018μg. The relative standard deviation of the 6 times repeated measurement for formaldehyde standard sample is 0.70%, the relative standard deviation of the formaldehyde concentration(RSD) is 0.72%. The contrast experiment shows that the method is better accuracy than of phenol reagent spectrophotometric. The experimental datas show that the method can accurately been measured the formaldehyde content in indoor air in 0.000368 mg/m3-0.409 mg/m3 range.The study has improved the deficiency the previous methods of the formaldehyde sample pretreatment, thermal desorption/gas chromatography cannot directly determined of formaldehyde, many interfering substances leading to variation of results in the phenolic reagent spectrophotometric.The analysis method that by ACF coated PFBHA derivatives, collected formaldehyde in indoor air, thermal desorption/gas chromatography under the results of our experiment was established...