热脱附-气相色谱-质谱法筛查分析溶剂型涂料中挥发性有机化合物

Analysis and Screening of Volatile Organic Compounds in Solvent-Based Coatings by Thermal Desorption-Gas Chromatography-Mass Spectrometry

为检测溶剂型涂料中挥发性有机物(VOCs)的释放量,利用1m3气候箱,在温度(23±2)℃和相对湿度(50±5)%、箱内空气换气率为1次·h-1的条件下,以钢化玻璃板(30cm×30cm)为基材,将涂料样品(约10g)涂覆在玻璃板上,置于气候箱中,关闭箱门并开始计时。此前已将老化的Tenax TA吸附管靠近吸附剂的一端与气候箱连接,另一端与采样连接,调节流量为0.20L·min-1,采集2h时的空气样品。将吸附管放入热脱附-气相色谱-质谱仪器系统中,按工作条件对65种VOCs进行分离和测定。样品经热脱附并流经HP-VOC色谱柱,恒压模式,在35~250℃之间程序升温进行VOCs的分离,进入质谱仪,在电子轰击离子源(EI)全扫描模式进行测定。试验结果表明:二氯甲烷、四氯化碳和乙二醇的信号较弱,标准曲线的线性不佳,其余62种VOCs的标准曲线的线性范围均在0.01~0.20μg之间,其检出限(3S/N)在0.018~0.25μg·kg-1之间,此62种VOCs的加标回收率在85.0%~116%之间。对市售的8种溶剂类涂料,按本方法进行筛查和分析,被检出频次较高的为芳香烃、醇、烷烃、酯醚等4大类;从所检测得到的VOCs的含量可见,其中芳香烃和酯醚类VOCs的释放占大部分,8种涂料第2h采样VOCs的释放总量分别为2.51,2.29,1.54,1.47,1.64,13.01,3.37,17.14mg·kg-1。

To inspect the liberation of volatile organic compounds(VOCs)of solvent-based coating into air of our residence,a climate chamber of 1m3 with its chamber temperature of(23±2)℃and relative humidity of(50±5)%and rate of air ventilation of once an hour was used to simulate actual enviromental condition.And about 10g of coating sample was applied onto the surface of a piece of toughened glass(30cm×30cm),which was placed into the climate chamber.An aged Tenax TA absorption tube was used to collect air sample from the climate chamber by connecting one of its terminal which was nearer to the absorbent to the chamber and the other terminal to the sampler.The sampler was adjusted to work at air flow-rate of 0.20L·min-1 and a sample of 2hflowing was collected for analysis.The absorption tube,by which VOCs in air were absorbed,was placed into the instrumental system of thermal desorption-GC-MS.The analytes on the absorbent were thermodesorbed and separated by passing through the HP-VOC chromatographic column under the mode of constant pressure and programed temperature elevation between 35℃to 250℃,and then determined by MS under the modes of EI and whole scanning.As shown by the results,among the 65VOCs,CH2Cl2,CCl4and glycol gave only weak signals,and linearity of their standard curves were not so good,while linearity of standard curves of the remaider 62VOCs were quite good and were found same between 0.01,0.20μg,with their limits of detection(3S/N)in the range of 0.018-0.25μg·kg-1.Recoveries of the 62VOCs were tested by standard addition method,giving results in the range of 85.0%to116%.8solvent-based coatings obtained in the market were screened and analyzed by the present method,and 4categories of VOCs,i.e.,the aromatic series,alcohols,alkanes,ethers and esters,were inspected with high frequencies;and as shown by the contents of VOCs determined,among the VOCs liberated,the aromatic series,esters and ethers constituted the great majority.Amounts of VOCs liberated from the 2h-samples of the 8coatings were as follows:2.51,2.29,1.54,1.47,1.64,13.01,3.37,17.14 mg·kg-1.