流动注射光度法测定植物油中的脂肪醛

Determination of aldehydes in vegetable oils by flow injection spectrophotometry

目的建立流动注射法检测植物油中醛类化合物的方法。方法利用醛类物质和间苯三酚在酸催化作用下生成红色单甲川类衍生物的原理,在自制的流动注射分析仪中,以相同摩尔量的甲醛、乙醛、正丙醛、正丁醛、正戊醛、正己醛、正庚醛、正辛醛和正壬醛配成的混合醛为标准物质,通过优化反应中的酸催化剂种类及用量、温度、试剂浓度以及流速等参数,确定最佳的流动注射法检测植物油中的醛类物质方法。结果最佳的流动注射条件为:两个蠕动泵的流速控制在0.5 m L/min,检测波长为455 nm,进样量为100μL,恒温水浴槽的温度为75℃。在该条件下,醛类化合物在0.0006~0.03 mol/L浓度范围内具有良好的线性关系,线性方程为Y=3.19×10~8X+1.12×10~5,r^2=0.998;该方法的相对标准偏差为0.41%~2.1%,回收率在90%以上。结论该方法可用于实际食用油样品中醛类物质的检测,具有方法简单、测试快速、数据准确的特点,可在食品检测领域中获得推广。

Objective To establish a method for the determination of aldehydes content in vegetable oils with flow injection spectrophotometry. Methods The standard substance was made up of mixed aldehydes with the same mole of formaldehyde, acetaldehyde, n-propanal, n-butanal, n-pentanal, n-hexaldehyde, n-heptaldehyde, n-octanal and n-nonanal. The best determination condition of aldehydes was determined by the optimization of acid catalyst, temperature, concentration and flow rate parameters using the reaction of aldehydes and phloroglucinol to produce the red methenyl derivatives under the acid action by home-made flow injection equipment. Results The optimal flow injection conditions for the experiment were as follow： determination wavelength was 455 nm, the flow rates of two peristaltic pumps were 0.5 m L/min, the injection volume was 100 μL, and the temperature of thermostatic water bath was 75 ℃. In optimal conditions, the favourable linear relation of aldehydes was in range of 0.0006-0.03 mol/L, linear equation was Y=3.19×10^8X＋1.12× 10^5（r-2=0.998）, relative standard deviations were 0.41%-2.1%, and recoveries were above 90%. Conclusion The method can be used for the determination of aldehydes in vegetable oils, it is simple, rapid and accurate, which can get promotion in the field of food detection.