The prominent biological effects of adrenaline (A), noradrenaline (NA) and dopamine (DA) as well as the clinical importance of their metabolites (such as dihydroxyphenylacetic acid (DOPAC), methoxy‑4-hydroxyphenyl glycol (MHPG), dihydroxyphenylglycol (DHPG), metanephrine (M), normetanephrine (NM), vanillylmandelic acid (VMA), homovanillic acid (HVA)) have forced researchers to evaluate new analytical methodologies for their isolation and preconcentration from biological samples. For this reason, the three most popular extraction techniques (dispersive liquid-liquid microextraction (DLLME), solid-phase extraction (SPE), solid-phase microextraction (SPME)) were tested. Micellar electrokinetic chromatography (MEKC) - a mode of capillary electrophoresis - with a diode array detector (DAD) was applied to assess the extraction efficiency. Next, the enrichment factor (EF) of each applied method was calculated in respect to standard mixtures of the analytes at the same concentration levels. The EF results of seven selected metabolites of biogenic amines (BAs) from urine after sample preparation procedures based on twenty-five different protocols (one DLLME, thirteen SPE and eleven SPME) were calculated and compared using hierarchical cluster analysis (HCA). The SPE as well as SPME procedures were proved to be the most effective approaches for the simultaneous extraction of the chosen compounds. Moreover, an ionic liquid (IL) - 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide - added to methanol in SPME additionally could successfully improve the extraction efficiency. It was also confirmed that the HCA approach could be considered a supportive tool in the selection of a suitable sample preparation procedure for that group of endogenous substances.

中文翻译：

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在胶束电动色谱分离之前，从l-酪氨酸代谢途径中提取和预浓缩化合物。

肾上腺素（A），去甲肾上腺素（NA）和多巴胺（DA）的显着生物学作用以及它们的代谢产物（如二羟苯基乙酸（DOPAC），甲氧基-4-羟苯基乙二醇（MHPG），二羟苯基乙二醇（DHPG） ），间苯肾上腺素（M），去甲肾上腺素（NM），香草戊二酸（VMA），高香草酸（HVA））迫使研究人员评估从生物样品中分离和预富集的新分析方法。因此，测试了三种最受欢迎​​的萃取技术（分散液-液微萃取（DLLME），固相萃取（SPE），固相微萃取（SPME））。胶束电动色谱（MEKC）-一种毛细管电泳的模式-具有二极管阵列检测器（DAD）用于评估萃取效率。下一个，相对于相同浓度水平的分析物标准混合物，计算了每种应用方法的富集因子（EF）。在基于25种不同方案（一种DLLME，13种SPE和11种SPME）的样品制备程序后，从尿液中选择的7种生物胺的代谢产物的EF结果进行了计算，并使用层次聚类分析（HCA）进行了比较。SPE和SPME程序被证明是同时萃取所选化合物的最有效方法。此外，将离子液体（IL）-1-乙基-3-甲基咪唑双（三氟甲基磺酰基）酰亚胺添加到SPME中的甲醇中可以成功地提高萃取效率。