微波萃取-气相色谱-质谱法测定固体废物中丙烯酸的含量

Determination of Acrylic Acid in Solid Waste by Gas Chromatography-Mass Spectrometry with Microwave Extraction

参照HJ/T 20-1998采集样品后,参照HJ 765-2015剔除样品中杂质,将易研磨的样品研磨或粉碎,并全部通过1mm筛,不易研磨的样品剪碎或撕碎,使样品能被萃取溶剂充分浸泡。分取样品5.000g,加入2.000g无水硫酸钠、2.000g硅藻土,混匀后加入丙酮20mL,于80℃微波萃取15min。冷却至室温,加入5.000g无水硫酸钠脱水,用定性滤纸过滤,滤液置于氮吹管中,在低于35℃条件下氮吹浓缩溶液体积至约1mL,快速过硅酸镁固相萃取小柱。用1mL丙酮分3次洗涤氮吹管,洗涤液全部过柱,用15mL体积比1∶1的三氯甲烷-丙酮混合溶液洗脱。收集洗脱液,继续在小于35℃条件下氮吹浓缩溶液体积至约0.5mL,加入1 000mg·L^(-1)1,4-二氯苯-d4内标溶液5μL,用丙酮定容至1.0mL,所得溶液进入气相色谱-质谱仪,在DB-FFAP色谱柱上以程序升温条件分离其中丙烯酸,用电子轰击电离(EI)源电离,选择离子监测(SIM)模式检测,内标法定量。结果表明:丙烯酸的质量浓度在0.5~20.0mg·L^(-1)内与质谱(MS)响应值比值呈线性关系,检出限(3.143s)为0.08mg·L^(-1);对阴性工业灰渣和生化污泥进行3个浓度水平的加标回收试验,回收率为68.5%~90.1%,测定值的相对标准偏差(n=6)为2.6%~9.1%。

After the sample was collected refer to HJ/T 20-1998,impurities in which were removed.Refering to HJ 765-2015,easily ground sample was ground or crushed,and passed through sieve with pore diameter of 1mm,and the sample that was not easy to grind was cut and torn,so that it could be fully soaked in the extraction solvent.An aliquot(5.000g)of sample was taken,and 2.000g of anhydrous sodium sulfate and 2.000g of diatomaceous earth were added.After mixing well,20mL of acetone was added,and microwave extraction was made at 80℃ for 15min.The digestion solution was cooled to room temperature,and 5.000g of anhydrous sodium sulfate was added to remove water.The mixture was filtered using qualitative filter,and the filtrate was place into a nitrogen blowing tube,and its volume was concentrated to about 1mL below 35℃.The solution was quickly passed through the magnesium silicate solid phase extraction column.Using 1mL of acetone to wash the nitrogen blowing tube 3times,all the washing solution was passed through the column,and 15 mL of trichloromethane-acetone mixed solution at volume ratio of 1∶1 was added for elution.The eluate was collected,and its volume was continually concentrated to about 0.5 mL under nitrogen blowing conditions below 35℃.An aliquot(5μL)of1000mg·L^(-1)1,4-dichlorobenzene-d_4internal standard solution was added into the above concentrate,and the mixed solution was diluted to 1.0 mL by acetone,and introduced into gas chromatograph-mass spectrometer.Acrylic acid was separated under temperature programmed conditions on the DB-FFAP chromatographic column,ionized by the EI source,detected by the SIM mode,and quantified by internal standard method.It was shown that linear relationship between values of the mass concentration of acrylic acid and the respective MS response value ratio was kept in the range of 0.5-20.0 mg·L^(-1),with detection limit(3.143s)of 0.08 mg·L^(-1).The spiked recovery test was made on negative industrial ash and biochemical sludge at the 3concentration levels,giving recoveries ranging from 68.5%to 90.1%,and RSDs(n=6)of the determined values were in the range of 2.6%-9.1%.