Li N, Lee H K
Department of Chemistry, National University of Singapore, Republic of Singapore.
Anal Chem. 2000 Nov 1;72(21):5272-9. doi: 10.1021/ac000663z.
A tandem-cartridge solid-phase extraction system combining reversed-phase separation and dynamic ion exchange followed by GC/MS analysis was studied for measuring partition coefficients (Kdoc) of association of polycyclic aromatic hydrocarbons (PAHs) to humic acid. Time course batch experiments revealed that the association of PAHs to humic acid included a slow stage with equilibrium time of 5-7 days. The disequlibrium and retention of the PAH-humic acid associate during reversed-phase separation lead to systematic negative error for the measured partition coefficients; more accurate results were achieved with a three-cartridge tandem system in which the negative error was assessed and corrected via the PAH analytes measured on the second reversed-phase cartridge. The potential and advantages of use of C18 disk cartridges instead of conventional C18 cartridges to set up the tandem system for measuring the partition coefficients were also studied. With the tandem-cartridge system, the measured partition coefficients did not change with most experimental conditions, but a trend of decreasing partition coefficients with humic acid concentration was observed, implying possible nonlinear association of the PAHs and humic acid.
研究了一种结合反相分离和动态离子交换，随后进行气相色谱/质谱分析的串联柱固相萃取系统，用于测定多环芳烃（PAHs）与腐殖酸缔合的分配系数（Kdoc）。时间进程批次实验表明，PAHs与腐殖酸的缔合包括一个缓慢阶段，平衡时间为5至7天。反相分离过程中PAH-腐殖酸缔合物的不平衡和保留导致所测分配系数出现系统性负误差；使用三柱串联系统可获得更准确的结果，其中通过在第二个反相柱上测定的PAH分析物评估并校正负误差。还研究了使用C18盘式柱代替传统C18柱建立串联系统来测定分配系数的潜力和优势。使用串联柱系统时，所测分配系数在大多数实验条件下不变，但观察到分配系数随腐殖酸浓度降低的趋势，这意味着PAHs与腐殖酸可能存在非线性缔合。
