Langenfeld J J, Hawthorne S B, Miller D J
Energy and Environmental Research Center, P.O. Box 9018, University of North Dakota, Grand Forks, North Dakota 58202.
Anal Chem. 1996 Jan 1;68(1):144-55. doi: 10.1021/ac950862w.
Solid-phase microextraction (SPME) parameters were examined on water contaminated with hydrocarbons including benzene and alkylbenzenes, n-alkanes, and polycyclic aromatic hydrocarbons (PAHs). Absorption equilibration times ranged from several minutes for low molecular weight compounds such as benzene to 5 h for high molecular weight compounds such as benzo[a]pyrene. Under equilibrium conditions, SPME analysis with GC/FID was linear over 3-6 orders of magnitude, with linear correlation coefficients (r(2)) greater than 0.96. Experimentally determined FID detection limits ranged from ∼30 ppt (w/w hydrocarbon/sample water) for high molecular weight PAHs (e.g., MW > 202) to ∼1 ppb for low molecular weight aromatic hydrocarbons. Experimental distribution constants (K) were different with 100- and 7-μm poly(dimethylsiloxane) fibers, and poor correlations with previously published values suggest that K depends on the fiber coating thickness and the sorbent preparation method. The sensitivity of SPME analysis is not significantly enhanced by larger sample volumes, since increasing the water volume (e.g., from 1 to 100 mL) has little effect on the number of analyte molecules absorbed by the fiber, especially for compounds with K < 500. Water sample storage should utilize silanized glassware, since hydrocarbon losses up to 70% could be attributed to unsilanized glassware walls when samples were stored for 48 h. Hydrocarbon losses at part-per-billion concentrations also occurred with surface waters due to partitioning onto part-per-thousand concentrations of suspended solids. Quantitative determinations of aromatic and aliphatic hydrocarbons (e.g., in gasoline-contaminated water) can be performed using GC/MS with deuterated internal standard or standard addition calibration as long as the target components or standards had unique ions for quantitation or sufficient chromatographic resolution from interferences. SPME analysis gave good quantitative performance with surface waters having high suspended sediment contents, as well as with coal gasification wastewater which contained matrix organics at 10(6)-fold higher concentrations than the target aromatic hydrocarbons. Good agreement was obtained between a 45-min SPME and methylene chloride extraction for the determination of PAH concentrations in creosote-contaminated water, demonstrating that SPME is a useful technique for the rapid determination of hydrocarbons in complex water matrices.
在被包括苯和烷基苯、正构烷烃以及多环芳烃（PAHs）在内的碳氢化合物污染的水中，对固相微萃取（SPME）参数进行了研究。吸收平衡时间从低分子量化合物（如苯）的几分钟到高分子量化合物（如苯并[a]芘）的5小时不等。在平衡条件下，使用气相色谱/火焰离子化检测器（GC/FID）的SPME分析在3至6个数量级范围内呈线性，线性相关系数（r(2)）大于0.96。实验测定的FID检测限范围从高分子量PAHs（如分子量>202）的约30 ppt（重量比碳氢化合物/样品水）到低分子量芳烃的约1 ppb。100μm和7μm聚二甲基硅氧烷纤维的实验分配常数（K）不同，且与先前公布的值相关性较差，这表明K取决于纤维涂层厚度和吸附剂制备方法。更大的样品体积并不会显著提高SPME分析的灵敏度，因为增加水的体积（如从1 mL增加到100 mL）对纤维吸收的分析物分子数量影响很小，尤其是对于K<500的化合物。水样储存应使用硅烷化玻璃器皿，因为当样品储存48小时时，高达70%的碳氢化合物损失可能归因于未硅烷化的玻璃器皿壁。由于分配到千分之一浓度的悬浮固体上，地表水中十亿分之一浓度的碳氢化合物也会发生损失。只要目标成分或标准物具有用于定量的独特离子或与干扰物有足够的色谱分辨率，就可以使用带有氘代内标或标准加入校准的GC/MS对芳香烃和脂肪烃进行定量测定（如在受汽油污染的水中）。SPME分析对于悬浮沉积物含量高的地表水以及煤气化废水中的目标芳香烃浓度测定具有良好的定量性能，煤气化废水中含有的基质有机物浓度比目标芳香烃高10^6倍。在对杂酚油污染水中PAH浓度的测定中，45分钟的SPME与二氯甲烷萃取之间取得了良好的一致性，这表明SPME是一种用于快速测定复杂水基质中碳氢化合物的有用技术。
