Abstract

The present work reports the development of a new analytical method for the determination of free glycerol in biodiesel samples using enzymatic-spectrophotometric assay combined with solid phase extraction (SPE) by molecularly imprinted poly(methacrylic acid) (MIP). The spectrophotometric method was performed using a commercial enzyme kit. The enzymatic-spectrophotometric method showed good analytical performance in terms of the linearity (0.998), limit of detection (7.70 × 10⁻⁶% w/w), limit of quantification (2.54 × 10⁻⁵% w/w), repeatability (0.42% to 7.91%), and recovery (99.4% to 112%). The analyses of several biodiesel samples by SPE and enzymatic-spectrophotometric method provided recovery values between 91.4% and 105%. Therefore, the high selectivity of molecularly imprinted polymer (MIP) was successfully applied to isolate free glycerol from biodiesel samples containing acylglycerols and methyl esters, and thereby allow enzymatic-spectrophometric based quantification. The developed method using SPE with MIP was efficient for the determination of free glycerol in biodiesel and the obtained results are in agreement with gas chromatrography (GC) that was used as a reference protocol.

摘要

本工作报告了一种新的分析方法的开发，该方法用于酶联光度法测定并通过分子印迹聚甲基丙烯酸（MIP）固相萃取（SPE）来测定生物柴油样品中的游离甘油。使用市售酶试剂盒进行分光光度法。酶促分光光度法在线性（0.998），检出限（7.70×10 ^-6％w / w），定量限（2.54×10 ^-5）方面表现出良好的分析性能％w / w），重复性（0.42％至7.91％）和回收率（99.4％至112％）。通过固相萃取和酶促分光光度法对几种生物柴油样品进行分析，回收率在91.4％至105％之间。因此，分子印迹聚合物（MIP）的高选择性已成功应用于从含有酰基甘油和甲酯的生物柴油样品中分离出游离甘油，从而实现了基于酶谱法的定量分析。使用SPE和MIP的已开发方法可有效测定生物柴油中的游离甘油，所得结果与用作参考方案的气相色谱（GC）一致。