化妆品样品用甲醇提取使苯甲酸及山梨酸溶于溶剂中,经离心分离,取上层清液,通过反相C18固相萃取小柱纯化。取其流出液经过滤和脱气后,用于高效液相色谱法分析。取20 μL进样,在Hypersil C18反相色谱柱(柱温30 ℃)上进行分离,所用流动相为甲醇与0.02 mol·L-1乙酸铵(15+85)混合溶液,流量为0.8 mL·min-1。采用紫外检测,检测波长为221 nm,测得苯甲酸和山梨酸的检出限(3S/N)分别为0.04,0.08 mg·L-1。用5 mg·L-1的苯甲酸和山梨酸标准溶液作精密度试验,测得两者的相对标准偏差(n=7)分别为2.8%及2.5%,向实际样品中加上述两种酸的标准溶液作回收试验,测得回收率在85.0%~106.7%之间。

The cosmetic sample was treated with methanol to dissolve benzoic acid and sorbic acid. After centrifugation, the supernatant was purified by passing through the RP C18 SPE microcolumn. The eluent from the column, after filtering and de-gassing, was used for HPLC analysis. Tweenty μL of the eluent were introduced into the instrument and separated on the Hypersil C18 RP chromatographic column (column temp. 30 ℃), using a mixed solution of methanol and 0.02 mol·L-1 NH4OAc solution (mixed in the ratio of 15+85) as mobile phase (with flow rate of 0.8 mL·min-1). UV detection at 221 nm was adopted in the determination. Values of detection limits (3S/N) for benzoic acid and sorbic acid was found to be 0.04 mg·L-1 and 0.08 mg·L-1, respectively. Precision was tested by using 5 mg·L-1 standard solutions of the 2 acids, giving values of RSD (n=7) 2.8% (for benzoic acid) and 2.5% (for sorbic acid). Recovery was tested by addition of standard solutions of the 2 acids, giving results of recovery in the range of 85.0%-106.7%.