Abstract: Formaldehyde can be quantitatively converted to diethoxygemethane by the condensation reaction of ethanol and formaldehyde. Based on the analysis of diethoxygemethane using gas chromatography,a new method was developed for the quantitative determination of trace amount of formaldehyde in the wastewater with low concentrations of salt and formaldehyde from Petro plant. The key derivatization conditions such as temperature,time of derivatization,solvent and catalyst for derivatization were investigated. Thus,the best derivatization conditions were determined as follows:1% of MSA as acid catalyst,ethanol as the solvent and material,optimum reaction temperature of 70 degree and optimum reaction time of 60 min. The percent conversion from formaldehyde to diethylformal reached 99.7%. For formaldehyde,the detection limit was 5.5 μg/g,the quantification limit was 17.9 μg/g,the recovery was within 92.62%- 97.44%,and the RSD was 1.21%.

Key words: ethanol-derivatization, gas chromatography, formaldehyde

摘要： 利用乙醇和甲醛的羟醛缩合反应，将甲醛定量转化为二乙氧基甲烷。研究开发了一种用气相色谱法测定石化装置低盐低醛废水中甲醛含量的方法。对衍生温度、衍生时间、衍生反应的溶剂、催化剂等关键衍生条件进行了研究，确定了最佳衍生条件为：1%的甲磺酸作酸催化剂，乙醇做溶剂，70℃条件下反应60 min。在此条件下，甲醛和二乙氧基甲烷之间的转化率为99.7%。取某石化装置所产废水进行甲醛含量分析，其测定结果的相对标准偏差为1.21%（n=6），二乙氧基甲烷的加标回收率为92.62%~97.44%。该方法对于环氧丙烷废水中甲醛的检出限为5.5 μg/g，定量限为17.9 μg/g。

关键词: 乙醇衍生, 气相色谱, 甲醛

CLC Number: 

• O657.7+1