样品在水、4%（体积分数）乙酸、50%（体积分数）乙醇、95%（体积分数）乙醇等食品模拟物中回流浸泡30 min（在异辛烷中于60℃浸泡30 min，浸泡液经氮气吹干并用50%乙醇溶解），用0.45 μm微孔滤膜过滤。采用超高压液相色谱进行分离，以BEH C₁₈色谱柱为固定相，以不同体积比的乙腈和水的混合液为流动相进行梯度洗脱。检测波长为210 nm。己内酰胺与十二内酰胺的质量浓度在一定范围内与其对应的峰面积呈线性关系，检出限（3S/N）为1.0~2.0 mg·L^-1。按标准加入法进行回收试验，回收率为93.4%~100%，测定值的相对标准偏差（n=6）为1.7%~3.2%。

The sample was immersed for 30min by refluxing in food stimulant[water, 4% (φ) acetic acid, 50% (φ) ethanol or 95% (φ) ethanol], or the sample was immersed for 30 min at 60℃ in isooctane and then dried by N₂-blowing and dissolved in 50% ethanol. The above solution was filtered through the microporous membrane of 0.45 μm, and then separated by UPLC using BEH C₁₈ chromatographic column as stationary phase, and a mixture of acetonitrile and water in various ratios as mobile phase in gradient elution. The detection wavelength was 210 nm. Linear relationships between values of peak area and mass concentration of caprolactam and laurolactam were found in definite ranges, with detection limits (3S/N) in the range of 1.0-2.0 mg·L^-1. Test for recovery was made by standard addition method, giving results in the range of 93.4%-100%, with RSDs (n=6) ranged from 1.7% to 3.2%.