Lima Diana L D, Duarte Armando C, Esteves Valdemar I
CESAM and Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
Chemosphere. 2007 Sep;69(4):561-8. doi: 10.1016/j.chemosphere.2007.03.025. Epub 2007 May 1.
Alkaline CuO oxidation has been used on molecular-level analyses of phenols from organic matter in the last decades. This method, originally developed by Hedges and Ertel [Hedges, J.I., Ertel, J.R., 1982. Characterization of lignin by gas capillary chromatography of cupric oxide oxidation products. Anal. Chem. 54, 174-178] has several drawbacks that have limited is wider utilization. In this paper, we propose a modification of the method using a solid-phase extraction (SPE) instead of a liquid-liquid extraction. The SPE procedure using C18 cartridges was optimized to obtain high recoveries. The sequential elution with acetonitrile and methanol was found to be the most appropriate procedure. Recoveries of the 12 phenols in individual standard solutions ranged from 84% to 113% with relative standard deviation (RSD) lower than 12%. Experiments with a mixed standard solution highlighted the competition between the different phenols for the adsorbing sites. Recoveries decreased with polarity, reaching 30% for p-hydroxybenzoic acid when present at a concentration of 2.5 x 10(-3)M. A sample soil subjected to a CuO oxidation was used to test the reproducibility of the SPE method and good results were achieved, RSD ranged between 0.4% and 28.3%. The performance of the CE method was also evaluated by correlation coefficients (higher than 0.9920), linearity (higher than 99.902%) and limit of detection (ranging from 2.64 x 10(-6) to 1.25 x 10(-5)M). SPE procedure presents several advantages such as fast sample preparation, good recoveries, good accuracy, low sample handling and safety improvement due to reduced solvent/sample exposure and glassware management.
在过去几十年中，碱性氧化铜氧化法已用于对来自有机物的酚类进行分子水平分析。该方法最初由赫奇斯和厄特尔开发[赫奇斯，J.I.，厄特尔，J.R.，1982年。通过氧化铜氧化产物的气相毛细管色谱法表征木质素。分析化学。54，174 - 178]，存在一些缺点，限制了其更广泛的应用。在本文中，我们提出了该方法的一种改进，使用固相萃取（SPE）代替液 - 液萃取。使用C18柱的SPE程序经过优化以获得高回收率。发现用乙腈和甲醇顺序洗脱是最合适的程序。单个标准溶液中12种酚类的回收率在84%至113%之间，相对标准偏差（RSD）低于12%。混合标准溶液的实验突出了不同酚类对吸附位点的竞争。回收率随极性降低，当对羟基苯甲酸浓度为2.5×10⁻³M时，回收率降至30%。对经过氧化铜氧化的土壤样品进行测试，以检验SPE方法的重现性，结果良好，RSD在0.4%至28.3%之间。还通过相关系数（高于0.9920）、线性（高于99.902%）和检测限（范围为2.64×10⁻⁶至1.25×10⁻⁵M）对CE方法的性能进行了评估。SPE程序具有几个优点，如样品制备快速、回收率高、准确性好、样品处理量低以及由于减少了溶剂/样品暴露和玻璃器皿管理而提高了安全性。
