Spectrophotometric determination of total phenolics by solvent extraction and sorbent extraction optosensing using flow injection methodology
Spectrophotometric determination of total phenolics by solvent extraction and sorbent extraction optosensing using flow injection methodology
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DOI：
10.1016/0003-2670(95)00141-l
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发表时间：
1995-07
影响因子：
6.2
通讯作者：
W. Frenzel;S. Krekler
中科院分区：
文献类型：
--
作者：
W. Frenzel;S. Krekler
本文建立了流动注射-吸附剂萃取在线富集分光光度法测定苯酚的新方法。在苯酚和4-氨基安替比林（4-AAP）之间的反应中形成的亚胺产物被萃取到氯仿中（溶剂萃取）或暂时保留在包含在微柱中的C18改性的二氧化硅材料上（吸附剂萃取）。在后一种情况下，使用了两种检测变体，即含有浓缩染料的甲醇洗脱液的分光光度测量和保留的反应产物的柱上光感测，然后甲醇洗脱以保持过程的可逆性。在溶剂萃取程序中，与未进行萃取的常见FIA方法相比，灵敏度提高了10倍，但未观察到检测能力的相应改善。在优化条件下，检测限为8 μg l-1。使用吸附剂萃取方法，当使用大的样品体积时，可以获得高的浓缩因子。获得相应较低检测限的唯一限制是随着采样体积而增加的高且可变的空白值。洗脱液吸光度测量和柱上光传感的检测限分别为11 μg l-1和0.4 μg l-1。使用溶剂和吸附剂萃取的各种苯酚衍生物的可萃取性的研究显示，与未萃取的FIA方法相比，相对响应率较低。具有额外酸性基团的酚类化合物在试验的高pH值下以离子化形式存在，并且根本不可浸提。
Flow injection analysis (FIA) procedures for the Spectrophotometric determination of phenol involving in-line concentration by solvent and sorbent extraction have been developed. The imine product formed in the reaction between phenol and 4-aminoantipyrine (4-AAP) is either extracted into chloroform (solvent extraction) or is temporarily retained on C18-modified silica material contained in a microcolumn (sorbent extraction). In the latter case two variants of detection have been used namely the Spectrophotometric measurement of the methanolic eluent containing the concentrated dye and at-column optosensing of the retained reaction product followed by methanol elution to maintain reversibility of the process. In the solvent extraction procedure a 10-fold increase of sensitivity compared to the common FIA method without extraction is achieved but no corresponding improvement in detectability is observed. Under optimized conditions the detection limit amounts to 8 μg l−1. Using sorbent extraction methodology, high concentration factors can be obtained when large sample volumes are used. The only limitation in getting correspondingly lower detection limits are an increasingly high and variable blank value with sampling volume. The detection limits obtained for measurement of the absorbance in the eluent and on-column optosensing are 11 μg l−1and 0.4 μg l−1, respectively. A study of the extractability of various phenol derivates using both solvent and sorbent extraction revealed lower relative response rates compared to the FIA method without extraction. Phenolics that possess an additional acidic group are present in ionized form at the high pH of the assay and are not extractable at all.