Masking as a mechanism for evaporative loss of trace analyte, especially after solid-phase extraction.
Masking as a mechanism for evaporative loss of trace analyte, especially after solid-phase extraction.
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掩蔽是痕量分析物蒸发损失的一种机制，尤其是在固相萃取之后。
DOI：
10.1016/0021-9673(95)00052-o
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Giese,RW
中科院分区：
文献类型：
--
作者：
Crowley,XW;Murugaiah,V;Naim,A;Giese,RW
使用巴斯德吸管塞硅烷化玻璃棉和填充C18-二氧化硅颗粒，我们试图从乙腈水溶液中除去K2 CO 3。尽管在上样后用水充分洗涤色谱柱，但用乙腈洗脱，然后蒸发，得到可见的白色残留物。发现残留物来自样品和填料，包括来自后者的颗粒。用塑料柱/聚乙烯玻璃料代替巴斯德移液器/玻璃棉，得到更一致的残留物，显然是因为这改善了颗粒的保留。随后的实验在塑料硬件中进行。当测试来自不同制造商的C18-二氧化硅颗粒时，观察到残留物的量变化多达19倍，并且当在实验室中制备柱时，与使用相当的预填充柱相比，残留物的量可以减少多达9倍。水本身也会产生一些残留物：即使是常规可用的“最纯”水，在适当蒸发1.0 ml时（例如，在微波炉中的萨兰包装上）也会留下可见残留物。任意痕量分析物和内标物（低pg水平的五氟苄基化核碱基）的回收率在乙腈中蒸发时比在未经处理的乙腈中蒸发时低32%，乙腈已通过含有C18-Si的乙腈和水洗柱。总的来说，这些结果表明，蒸发可能会有一些损失的分析物从掩蔽甚至微妙的溶剂污染物。这往往会抵消通过使用良好溶剂来重新溶解痕量分析物的常见策略。
Using a Pasteur pipette plugged with silanized glass wool and packed with C18-silica particles, we attempted to remove K2CO3from an aqueous acetonitrile solution. In spite of extensive washing of the column with water after the sample was applied, elution with acetonitrile followed by evaporation gave a visible, white residue. It was found that the residue was derived from both the sample and the packing, including particles from the latter. Substitution of a plastic column/polyethylene frit for the Pasteur pipette/glass wool gave a more consistent residue, apparently because this improved the retention of particles. Subsequent experiments were conducted in the plastic hardware. The amount of the residue was observed to vary as much as 19-fold when C18-silica particles were tested from different manufacturers and the residue could be reduced in amount as much as 9-fold when a column was prepared in the laboratory vs. the use of a comparable, pre-packed column. The water itself contributed some of the residue: even the “purest” water routinely available left a visible residue when 1.0 ml was appropriately evaporated (e.g. on Saran Wrap in a microwave oven). The recovery of an arbitrary trace analyte and internal standard (pentafluorobenzylated nucleobases at the low pg level) was 32% less when they were evaporated in acetonitrile that had been passed through an acetonitrile and water-washed cartridge containing C18-Si vs. evaporation in untreated acetonitrile. Collectively these results reveal that an evaporation can risk some loss of an analyte from masking by even subtle solvent contaminants. This tends to counteract the common strategy of redissolving a trace analyte by using a good solvent for it.