高效液相色谱法测定乙醛溶液中的乙二醛和乙醛酸

利用醛基与2,4-二硝基苯肼(DNPH)反应得到的腙产物对紫外-可见光有吸收的特性,采用高效液相色谱法(HPLC)测定乙醛溶液中乙二醛和乙醛酸的含量。结果表明,DNPH衍生乙二醛成腙反应的适宜条件为: 反应温度70 ℃, pH 1.75, DNPH与羰基的物质的量比为6,反应时间150 min。在20 ℃、pH 1.75的乙腈溶液中,乙二醛二腙的溶解度为20.2 mg/L。乙二醛质量浓度在2～20 mg/L范围内,乙二醛二腙的峰面积与乙二醛的质量浓度之间呈良好的线性关系;乙醛酸质量浓度在10～100 mg/L范围内,乙醛酸腙的峰面积与乙醛酸的质量浓度之间呈良好的线性关系。用HPLC测定乙醛硝酸氧化法制乙二醛反应液中乙二醛和乙醛酸的含量,结果的重复性好;对乙二醛的测定结果与应用化学分析法测定结果的平均相对误差为1.77%;对反应液中乙二醛、乙醛酸含量的测定有着较高的加标回收率,分别为99.6%～103.3%和98.1%～102.4%。所建立的方法为醛及二羰基化合物的测定提供了准确、便捷的方法。

Determination of glyoxal and glyoxalic acid in aldehyde solution by high performance liquid chromatography

The hydrazones have the absorption in the ultraviolet-visible (UV-vis) spectral region. The hydrazones can be formed by the reaction of aldehyde group and dinitrophenylhydrazine (DNPH) in acidic solution. The determination of glyoxal and glyoxalic acid in aldehyde solution was performed by high performance liquid chromatography (HPLC). The proper derivatization conditions were as follows: the reaction temperature of 70 ℃, the pH of the system of 1.75; the molar ratio of DNPH to carbonyl of 6, the reaction time of 150 min. The saturated concentration of glyoxal dihydrazone in acetonitrile solution at pH 1.75 and 20 ℃ was 20.2 mg/L. The standard curves for glyoxal and glyoxalic acid both had good linear relations in the ranges of 2-20 mg/L and 10-100 mg/L, respectively. The glyoxal and glyoxalic acid contents in the solution of oxidation of acetaldehyde to glyoxal by nitric acid were determined by this method, the repeatabilities of analysis results were excellent and the relative error compared to chemical analysis of glyoxal was 1.77% . The spiked recoveries of glyoxal and glyoxalic acid were 99.6% -103.3% and 98.1% -102.4% , respectively. The method is simple, accurate and efficient for determining aldehydes and dicarbonyl compounds.