索氏抽提-柱层析分离-高效液相色谱法测定煤沥青中多环芳烃

以甲苯为溶剂对煤沥青进行索氏抽提,抽提液经过有机滤膜过滤,过滤后的抽提液用二氯甲烷溶解,将样品溶液用硅胶柱分离,然后用体积比为1∶1的石油醚与甲苯混合液以5.0mL/min的流量进行淋洗,将淋洗液旋干后用乙腈定容至10mL,利用ZORBAX Eclipse PAH柱以不同体积比的乙腈-水体系为流动相对样品溶液进行梯度洗脱,建立了煤沥青中16种多环芳烃(PAHs)的高效液相色谱分离检测方法。结果表明,16种PAHs的线性范围为0.50~20mg/L,相关系数(r)不小于0.999,检出限为0.04~0.33μg/L,按照实验方法对湘钢煤沥青实际样品中16种PAHs进行测定,测得结果的相对标准偏差(RSD,n=6)为0.20%~3.5%,回收率为97%~109%。采用实验方法分别测定湘钢、涟钢两种不同煤沥青中16种PAHs的含量,测得结果与湘钢、涟钢两公司提供的推荐值基本一致。结果表明,每1kg湘钢煤沥青中16种致癌性PAHs质量为107.9g,即质量分数为10.79%;每1kg涟钢煤沥青中16种致癌性PAHs质量为104.1g,即质量分数为10.41%;其中苯并[a]芘分别为11.86g/kg和13.82g/kg,即质量分数为1.186%和1.382%。

Determination of polycyclic aromatic hydrocarbons in coal pitch by high performance liquid chromatography after Soxhlet extraction and column chromatographic separation

The Soxhlet extraction of coal pitch was conducted using methylbenzene as solvent. The leaching liquor was filtrated by organic membrane followed by dissolution with dichloromethane. The sample solution was separated with silica gel column, which was then eluted with petroleum ether-methylbenzene mixture (1∶1, V/V) at flow rate of 5.0 mL/min. The leacheate was dried by rotary evaporation and then dissolved with acetonitrile to 10 mL. The sample solution was separated on a ZORBAX Eclipse PAH column by gradient elution using acetonitrile-water with different volume ratios as mobile phases. The separation and detection method of 16 polycyclic aromatic hydrocarbons (PAHs) in coal pitch by high performance liquid chromatography (HPLC) was established. The results showed that the linear range of 16 PAHs was 0.50-20 mg/L. The correlation coefficients (r) were not less than 0.999. The limits of detection were between 0.04 μg/L and 0.33 μg/L. The experimental method was applied to the determination of 16 PAHs in actual coal pitch samples from Hunan Valin Xiangtan Iron & Steel Co.,Ltd. The relative standard deviations (RSD, n=6) of results were between 0.20% and 3.5%, and the recoveries were between 97% and 109%. The proposed method was also applied to the determination of 16 PAHs in two coal pitch samples from Hunan Valin Xiangtan Iron & Steel Co.,Ltd. and Lianyuan Iron & Steel Co.,Ltd. The found results were basically consistent with the recommended values provided by two companies. The results showed that the content of 16 carcinogenic PAHs in 1 kg of coal pitch from Hunan Valin Xiangtan Iron & Steel Co.,Ltd. and Lianyuan Iron & Steel Co.,Ltd. was 107.9 g (10.79%) and 104.1 g (10.41%), respectively. The content of benzopyrene [a] was 11.86 g/kg and 13.82 g/kg (i.e., 1.186% and 1.382%), respectively.