HPLC柱前衍生法测THPA游离酸含量的研究

建立柱前衍生化高效液相色谱法测定THPA中游离酸的含量,首先将四氢苯酐(THPA)与甲醇反应,生成以四氢苯二甲酸单甲酯(Mono-ME)为主的混合物,然后以2-溴苯乙酮为衍生化试剂,三乙醇胺为催化剂,将单甲酯转换成单苯酯(Mono-BE),将少量四氢苯二甲酸(THOX)转换成四氢苯二甲酸二苄酯(Di-BE),将采用ODS-C18色谱柱(250 mm×4.6 mm,5μm),以(甲醇-乙腈(58∶27))-水为流动相梯度洗脱,在检测波长235 nm,柱温25℃,流速1.0 mL/min的色谱条件下13 min中内完成的分离检测。结果表明,在10～1 220μg/mL浓度范围内,四氢苯酐(THPA)和四氢苯二甲酸(THOX)衍生物的峰面积与浓度呈现良好的线性关系,相关系数为0.998 17,加样回收率为100.8%,RSD为0.8%。该法重现性好,精确度高,可作为四氢苯酐中游离酸的测量方法。

Study on the Determining Method of Free Acid in THPA by HPLC with Pre-column Derivatization

A method was developed to determine free acid in Liquid Chromatography （ HPLC ） with pre - column derivatization. tetrahydrophthalic anhydride by High Performance Anhydride （THPA） was reacted with methanol to produce to mixture consisting mainly of tetrahydro acid monomethyl ester （Mono -ME） , the Mono -ME were derivatized with 2 - bromoacetophenone as derivative reagent, triethanolamine as catalyst, to convert mono - methyl ester of phenyl （Mono- BE）, a small amount of tetrahydro- phthalic acid （THOX） into tetrahydrophthalic acid dibenzyl ester （Di - BE）, and the BDS C18 column （250 mm ×4.6 mm, 5 μm） was used. The detection wavelength was set at 235 nm, column temperature 25 ℃, with methanol - acetonitrile （58 ：27） - water as eluent, flow rate was 1.0 mL/min, 13 min to complete the separation and detection of the chromatographic conditions. The peak area and concentration of anhydride （THPA） and tetrahydro acid （THOX） derivatives had a good linearity at the concentration of 10 -1220 μg/mL, and the correlation coefficient was 0. 998 17. The average recovery of linoleic acid was 100. 8% and RSD was 0. 8%. This method was reproducible, accurate measurement, which can be used as the determination of the free acid in tetrahydrophthalic anhydride.