Comprehensive two‐dimensional liquid chromatography for polyphenol analysis in foodstuffs

Abstract

Polyphenols are a class of plant secondary metabolites that are recently drawing a special interest because of their broad spectrum of pharmacological effects. As they are characterized by an enormous structural variability, the identification of these molecules in food samples is a difficult task, and sometimes having only a limited number of commercially available reference materials is not of great help. One-dimensional liquid chromatography is the most widely applied analytical approach for their analysis. In particular, the hyphenation of liquid chromatography to mass spectrometry has come to play an influential role by allowing relatively fast tentative identification and accurate quantification of polyphenolic compounds at trace levels in vegetable media. However, when dealing with very complex real-world food samples, a single separation system often does not provide sufficient resolving power for attaining rewarding results. Comprehensive two-dimensional liquid chromatography is a technique of great analytical impact, since it offers much higher peak capacities than separations in a single dimension. In the present review, we describe applications in the field of comprehensive two-dimensional liquid chromatography for polyphenol analysis in real-world food samples. Comprehensive two-dimensional liquid chromatography applications to nonfood matrices fall outside the scope of the current report and will not be discussed.

Optimizing separations in online comprehensive two‐dimensional liquid chromatography

“…Where applicable, we refer the reader to useful applications and reviews which offer a great deal additional information [63]. Applications in life sciences [64,65], food [66][67][68][69], polymers [70][71][72], and traditional Chinese medicine [73] are covered by recent reviews.…”

Evaluation of matrix effect in one‐dimensional and comprehensive two‐dimensional liquid chromatography for the determination of the phenolic fraction in extra virgin olive oils

“…As viable alternative for enhancing the overall separation capability, comprehensive 2D‐LC (LC × LC) has been far employed for phenol determination in many food and natural products as witnessed by several recent research and review articles [21–34]. It was already reported that LC × LC minimize matrix interferences at the detector, because of the higher resolving power, viz .…”

Online high‐pH reversed‐phase liquid chromatography × low‐pH reversed‐phase liquid chromatography tandem electrospray ionization mass spectrometry combined with pulse elution gradient in the first dimension for the analysis of alkaloids in Macleaya cordata (willd.) R. Br

“…Unlike the traditional linear gradient, PE gradient provide a new modulation strategy for separation and cut the complex sample in 1st D [15]. According to the results of our previous work, the parameters of pulse width and step height play key role in PE gradient separation.…”

“…However, due to the diverse structure and complex chemical composition of alkaloids, such 1D LC technology faces enormous challenges [11]. Comprehensive 2D LC (LC×LC) has attracted increasing attention in complex samples such as herb medicine, food additives, and so on for much higher peak capacity compared to 1D LC [12][13][14][15]. For dissociable compounds like alkaloids, they could be well separated by IEC, HILIC, normal phase LC (NPLC), and RPLC according to the difference in hydrophobicity and dissociation [16].…”