为优化索氏提取法测定烤烟中粗脂肪的工艺条件,在单因素实验的基础上,通过Box-Behnken试验设计,研究称样量、回流时间、烘干时间对粗脂肪提取量的影响,并建立一种快速测量粗脂肪含量的紫外可见吸收光谱方法。结果表明,干燥温度为105 ℃时,预测最佳的粗脂肪提取条件为:称样量3.08 g,回流时间6 h,烘干时间1.5 h,粗脂肪含量为6.27%。在0.276~2.211 g/L(λ=326 nm)或 0.276~2.763 g/L(λ=415 nm)范围内,烟叶粗脂肪溶液的浓度与吸光度有较好的线性关系(R2326 nm=0.9982,R2415 nm=0.9993),检出限分别为0.128和0.093 g/L,定量限分别为0.387和0.281 g/L。利用响应面优化的索氏提取工艺及建立的粗脂肪紫外分光光度测定法,简便省时,且重复性和精密度较好,适合批量烟叶粗脂肪的分析测定。
In order to optimize the determination parameters of crude oil from flue-cured tobacco leaves extracted by Soxhlet extraction,the single factor tests and a Box-Behnken design were applied to study the effects of sample weight,reflow time,and drying time on the extraction rate of crude oil. And a new UV absorption spectroscopic method of determination crude oil was established. The results showed that when the drying temperature was set at 105 ℃,the predictable optimum extraction conditions for crude oil were as follows:Sample weight 3.08 g,reflow time 6 h,and drying time 1.5 h. Under the optimum condition,the total extraction yield was 6.27%. The linear relationships between values of absorption and mass concentration of crude oil at 326 and 415 nm wavelength were good(R326 nm2=0.9982,R415 nm2=0.9993),with linearity ranges of 0.276~2.211 g/L(326 nm wavelength)and 0.276~2.763 g/L(415 nm wavelength). The detection limits were 0.128 and 0.093 g/L,and quantification were 0.387 and 0.281 g/L,respectively. The optimum Soxhlet extraction process and contents determination of crude fat in tobacco were established by response surface methodology and UV spectrophotometry. The method was simple,time-saving,and had good repeatability and precision,which would be suitable for analysis crude fat of batch tobacco sample.