Amoah Enoch, Acharya Santosh Raman, Seth Ayesha, Badu-Tawiah Abraham K
Department of Chemistry and Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, OH, 43210, USA.
Anal Bioanal Chem. 2025 Aug;417(20):4709-4722. doi: 10.1007/s00216-025-05988-9. Epub 2025 Jul 9.
Sucrose, which forms < 2% of the chemical content in honey samples, is known to have five structural isomers each with its own medicinal benefits. Unfortunately, studies characterizing the specific sucrose isomer(s) present in honey samples are limited. Herein, we introduce a contained electrospray ionization (cESI) method that can be coupled between liquid chromatography (LC) and tandem mass spectrometry (MS/MS). This LC-cESI-MS/MS platform leverages chloride adduction to enable sensitive differentiation and characterization of disaccharide isomers in complex honey samples. By integrating retention time and collision-induced dissociation (CID) MS/MS data, we achieved orthogonal analysis of six sucrose isomers. The MS/MS on the chloride adducts showed distinct fragment ions for each isomer. Additional optimization afforded nanomolar (nM) detection limits for all disaccharides analyzed via chloride adduction in negative-ion mode, a feature that showed superior sensitivity compared with conventional sodium adduction methods typically achieved in positive-ion mode. We identified four sucrose isomers (turanose, palatinose, maltulose, and trehalulose) in three mono-floral honey samples, of which turanose was the most abundant isomer. Sucrose itself could not be confirmed in any of the honey samples tested and leucrose was confirmed to be absent. Although the specific amounts of these isomers were not determined, principal component analysis showed that the abundances of the four identified structural isomers significantly differed in the three mono-floral honey samples. The current study forms the first report suggesting turanose to be the main sucrose isomer in the tested mono-floral honey. Such identification was made possible because of our ability to independently optimize LC and cESI spray solvents, and to enable online microdroplet chemistry via chloride adduction, which allowed the conventional CID-MS/MS to yield highly informative fragmentation.
蔗糖占蜂蜜样本化学成分的比例不到2%，已知有五种结构异构体，每种异构体都有其独特的药用价值。遗憾的是，对蜂蜜样本中存在的特定蔗糖异构体进行表征的研究有限。在此，我们介绍一种封闭式电喷雾电离（cESI）方法，该方法可与液相色谱（LC）和串联质谱（MS/MS）联用。这个LC-cESI-MS/MS平台利用氯离子加合作用，能够灵敏地区分和表征复杂蜂蜜样本中的二糖异构体。通过整合保留时间和碰撞诱导解离（CID）MS/MS数据，我们实现了对六种蔗糖异构体的正交分析。氯离子加合物的MS/MS显示，每种异构体都有独特的碎片离子。进一步优化后，在负离子模式下通过氯离子加合分析的所有二糖的检测限达到了纳摩尔（nM）级别，这一特性显示出比通常在正离子模式下实现的传统钠离子加合方法更高的灵敏度。我们在三个单花蜂蜜样本中鉴定出四种蔗糖异构体（松二糖、异麦芽糖、麦芽糖酮和海藻酮），其中松二糖是含量最高的异构体。在所测试的任何蜂蜜样本中均未确认有蔗糖本身，且已确认不存在异麦芽酮糖醇。尽管未确定这些异构体的具体含量，但主成分分析表明，在这三个单花蜂蜜样本中，四种已鉴定的结构异构体的丰度存在显著差异。本研究首次报告表明，松二糖是所测试的单花蜂蜜中的主要蔗糖异构体。能够进行这样的鉴定是因为我们有能力独立优化LC和cESI喷雾溶剂，并通过氯离子加合实现在线微滴化学，这使得传统的CID-MS/MS能够产生信息量丰富的碎片。
