硬脂酰乳酸钠对铜皂络合比色法测定酸价干扰的 固相萃取清除工艺Solid phase extraction elimination of interference of sodium stearyl lactate on acid value determination by cupric-pyridine colorimetric method

Abstract

为清除合成乳化剂硬脂酰乳酸钠（SSL）对铜皂络合比色技术测定油脂酸价过程的正向干扰，开发了一种固相萃取（SPE）清除SSL的技术。用含2%异丙醇的环己烷为固相萃取流动相和油脂样品溶解液，通过离子排斥色谱检测油脂皂化水解后释放的游离乳酸的含量，间接评估SPE净化处理前后油脂中的SSL含量,并结合铜皂络合比色技术测定的酸价变化，评价所建立的SPE技术对去除油脂中SSL的效果。结果表明：SPE技术可有效去除油脂中的SSL，明显消除油脂中SSL对铜皂络合比色法测定酸价的干扰，不会导致油脂样品脂肪酸含量损失。对于含SSL的食用油脂试样，经SPE技术净化处理后，铜皂络合比色法测定酸价过程的干扰明显降低。To eliminate the positive interference of synthetic emulsifier sodium stearyl lactate (SSL) in the determination of acid value by cupric-pyridine colorimetric method,a solid-phase extraction (SPE) technique for cleaning SSL was developed. Using cyclohexane containing 2% isopropyl alcohol as mobile phase of SPE and oil sample solution, the content of SSL in oils before and after SPE was indirectly evaluated by detecting the content of free lactic acid released after saponification and hydrolysis of oils by ion exclusion chromatography. The effect of the established SPE technique on the removal of SSL from oils was evaluated by combining the acid value change measured by cupric-pyridine colorimetric method.The results showed that the SPE method could effectively remove SSL from oil, and obviously eliminate the interference of SSL on the determination of acid value by cupric-pyridine colorimetric method, without causing the loss of fatty acid content in oil samples.After purification by SPE, the interference of the acid value determination by cupric-pyridine colorimetric method is significantly reduced for the samples containing SSL edible oils.

Keywords

• 酸价；铜皂络合比色法；硬脂酰乳酸钠；离子排斥色谱；固相萃取
• acid value; cupric-pyridine colorimetric method; sodium stearyl lactate; ion exclusion chromatography; solid-phase extraction