羟肟酸法快速测定食用油主要营养必需脂肪酸

建立了用ＨＰＬＣ简便快速测定食用油主要营养必需脂肪酸的羟肟酸法。样品一步衍生成羟肟酸上机分析，不需分离纯化。线性范围为０．０５～０．６０ｇ／Ｌ，回收率９６．９３％，ＲＳＤ＝１．８０％（ｎ＝４），日内和日间ＲＳＤ分别为１．２４％和１．６２％（ｎ＝６）。比较１８∶３，１８∶２和１８∶１的甲酯与相应的三脂肪酸甘油酯标准品衍生的标准曲线，发现二者转化率均相差近一倍，回收率实验和样品实测结果亦证实，选取甲酯标准品衍生作标准曲线用于油脂定量是不合理的。

Rapid Determination of Essential Fatty Acids of Edible Oils by Conversion to Their Hydroxamic Acids

A simple and rapid HPLC method for the determination of essential fatty acids of edible oils was established. Oil samples were converted to their hydroxamic acids in a single step and analyzed without prior separation and purification. The chromatographic conditions were: Shim-pack CLC ODS, 5 microns, 150 mm x 6.0 mm i.d. column, 40 degrees C; MeOH: 0.02 mol/L NaH2PO4(pH 3.0) (81:19, V/V) as eluent and UV-213 nm detector. The linear range was 0.05-0.6 g/L, recovery was 96.93% and RSD was 1.80%(n = 4). The relative standard deviations for intra-day and inter-day assays were 1.24% and 1.62% respectively (n = 6). For 18:3, 18:2, 18:1, the difference between the derivatization yields from triglycerides and their methyl esters was almost one fold. That was confirmed by our recovery and determination results. The calibration curves for the oil samples should not be obtained from the derivatization of their methyl ester standards.