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提出了由聚乙二醇(PEG)1500-OP-(NH4)2SO4及少量水组成的双水相萃取体系并应用于从阿司匹林基体中萃取游离水杨酸。对试验条件作了系统试验,取得如下优化条件:①PEG1500(500 g.L-1)溶液及OP(500 g.L-1)溶液的体积(mL)比为PEG∶OP=2.50∶1.50;②固体(NH4)2SO4的加入量为2.0 g;③加入pH 6.0的B-R缓冲溶液至总体积约为10 mL。按此条件测得水杨酸的萃取率为98.6%。萃取后,将上层液(即表面活性剂相)移至10 mL容量瓶中,加B-R缓冲溶液至10.0 mL,在eλx为305 nm,eλm为392 nm波长条件下测定溶液的荧光强度。应用此方法分析了3件阿司匹林试样,每一个试样分析10次,所得结果的相对标准偏差(n=10)在1.7%~2.1%之间。在此样品的基础上加入水杨酸标准溶液进行回收率试验,所测得回收率在93.3%~103.3%之间,其相对标准偏差(n=5)≤2.5%。
A two-phase aqueous extraction system consisting of polyethylene glycol (PEG) 1500-OP- (NH4) 2SO4 and a small amount of water was proposed and applied to the extraction of free salicylic acid from aspirin matrix. The experimental conditions were systematically tested and the following optimization conditions were obtained: ① The volume ratio (mL) of PEG1500 (500 gL-1) and OP (500 gL-1) 2SO4 added 2.0 g; ③ adding BR buffer solution pH 6.0 to a total volume of about 10 mL. According to this condition, the extraction rate of salicylic acid was 98.6%. After the extraction, the supernatant (ie surfactant phase) was transferred to a 10 mL volumetric flask and the B-R buffer solution was added to 10.0 mL. The fluorescence intensity of the solution was measured at eλx of 305 nm and eλm of 392 nm. Three aspirin samples were analyzed using this method. Each sample was analyzed 10 times and the relative standard deviation (n = 10) of the results was between 1.7% and 2.1%. The salicylic acid standard solution was added to the sample for recovery test. The recovery was between 93.3% and 103.3%, and the relative standard deviation (n = 5) was less than or equal to 2.5%.