水样经0.22 μm亲水针筒式过滤器过滤，根据需要进行稀释后，在Acclaim Mixed-Mode WAX-1色谱柱（4.6 mm×150 mm，5 μm）上进行分离，以90 mmol·L^-1磷酸盐缓冲溶液[pH 6.0，溶剂为10%（体积分数）乙腈溶液]为流动相进行等度洗脱，在波长210 nm处进行紫外检测。结果表明：乙醇酸、乙醛酸和草酸的质量浓度分别在3.51~2 500，4.20~8 000，18.0~800 mg·L^-1内与对应的峰面积呈现线性关系，检出限（3S/N）分别为1.00，1.24，4.82 mg·L^-1，测定下限（10S/N）分别为3.32，4.15，16.1 mg·L^-1。对实际样品进行加标回收试验，乙醇酸、乙醛酸和草酸的回收率分别在98.2%~101%，99.6%~103%，99.2%~101%之间，测定值的相对标准偏差（n=6）分别为0.77%，0.65%，1.1%。

The water sample was filtered through a 0.22 μm hydrophilic syringe filter, diluted as needed, and separated on an Acclaim Mixed-Mode WAX-1 column (4.6 mm×150 mm, 5 μm), with 90 mmol·L^-1 phosphate buffer solution ［pH 6.0, 10% (volume fraction) acetonitrile solution as solvent］ as mobile phase for elution. UV detection was performed at the wavelength of 210 nm. The results showed that linear relationships were obtained between peak area and mass concentration of glycolic acid, glyoxylic acid and oxalic acid in the ranges of 3.51-2 500, 4.20-8 000 and 18.0-800 mg·L^-1, respectively. The detection limits (3S/N) were 1.00, 1.24, 4.82 mg·L^-1, and the lower limits of determination (10S/N) were 3.32, 4.15, 16.1 mg·L^-1. Tests for recovery was made by standrard addition method to the actual samples, giving values of recovery of glycolic acid, glyoxylic acid and oxalic acid between 98.2%-101%, 99.6%-103% and 99.2%-101%, respectively. The relative standard deviation of the measured values (n=6) were 0.77%, 0.65% and 1.1%, respectively.