Recent Development of Two-Dimensional Liquid Chromatography in Food Analysis

Modulation optimization when using a splitter pump after the first dimension in comprehensive two- dimensional liquid chromatography

The rapid growth in the use of two dimensional liquid chromatography (2D-LC) applied to the analysis of moderately to highly complex mixtures, has been fueled by continuous improvements in performance and robustness of the instrument components, as well as the ease-of-use of software necessary for controlling the 2D-LC instrument hardware, and analysis of the large data files that result from this type of work. This work has focused on the evaluation of the performance of an online full comprehensive mode (LC×LC), when an active modulation is implemented using a flow splitter pump placed after the 1D effluent. Two different types of splitting pumps were evaluated: a binary ultra-high pressure liquid chromatography (UHPLC) pump and a high precision syringe pump. We analyzed the performance (reproducibility in peak area and retention times and the 2D peak dispersion) as a function of the location of the active pump Before or After the modulation valve, and the influence of connecting tubes (based on internal diameter and length) necessary between the interface, waste, and the splitting pump. The effect on the flow direction on the filling and flushing of the injection loops at the modulation valve was also analyzed for each pump. In this study, we demonstrate that flow-splitting LCxLC assembly can be performed using either a UHPLC binary pump or a simple syringe pump. Flow splitting after the first dimension is a straightforward strategy to: (i) independently select the 1D column and flow rates with respect to the second dimension; (ii) consciously dilute the eluate according to the solvent characteristics of the second dimension, thereby avoiding 2D peak distortions; and (iii) adapt the injected amount to the second column according to the relative concentration of the components in a complex sample. However, careful consideration of the system setup is necessary. It is demonstrated how experimental results can be significantly affected in terms of peak broadening and reproducibility if optimization of the interface is not taken into account. In addition, under the optimized conditions, the reproducibility in peak area and dispersion in the 2D dimension were evaluated as a function of the amount of sample transferred in terms of percentage of filled loop.

Comprehensive and heart-cutting multidimensional liquid chromatography-mass spectrometry and its applications in food analysis

In food analysis, conventional one-dimensional liquid chromatography methods sometimes lack sufficient separation power due to the complexity and heterogeneity of the analyzed matrices. Therefore, the use of two-dimensional liquid chromatography (2D-LC) turns out to be a powerful tool to consider, especially when coupled to mass spectrometry (MS). This review presents the most remarkable 2D-LC-MS food applications reported in the last 10 years, including a critical discussion of the multiple approaches, modulation strategies as well as the importance of the optimization of the different analytical aspects that will condition the 2D-LC-MS performance. The presence of contaminants in food (food safety), the food quality, and authenticity or the relationship between the beneficial effects of food and human health are some of the fields in which most of the 2D-LC-MS applications are mainly focused. Both heart-cutting and comprehensive applications are described and discussed in this review, highlighting the potential of 2D-LC-MS for the analysis of such complex samples.

Comprehensive and heart-cutting multidimensional liquid chromatography-mass spectrometry and its applications in food analysis

In food analysis, conventional one-dimensional liquid chromatography methods sometimes lack sufficient separation power due to the complexity and heterogeneity of the analysed matrices. Therefore, the use of two-dimensional liquid chromatography (2D-LC) turns out to be a powerful tool to consider, especially when coupled to mass spectrometry (MS). This review presents the most remarkable 2D-LC-MS food applications reported in the last 10 years, including a critical discussion of the multiple approaches, modulation strategies as well as the importance of the optimisation of the different analytical aspects that will condition the 2D-LC-MS performance. The presence of contaminants in food (food safety), the food quality and authenticity or the relationship between the beneficial effects of food and human health are some of the fields in which most of the 2D-LC-MS applications are mainly focused. Both heart-cutting and comprehensive applications are described and discussed in this review, highlighting the potential of 2D-LC-MS for the analysis of such complex samples.

Anthocyanins in Different Food Matrices: Recent Updates on Extraction, Purification and Analysis Techniques

Anthocyanins (ANCs), a kind of natural pigments, are widely present in food substrates. Evidence has shown that ANCs can promote health in terms of anti-oxidation, anti-tumor, and anti-inflammation. However, the oxidative stability of ANCs limits accurate quantitation and analysis. Therefore, faster, more accurate, and highly sensitive extraction and determination methods are necessary for understanding the role of ANCs in medicine and food. This review presents an updated overview of pretreatment and detection techniques for ANCs in various food substrates since 2015. Liquid-liquid extraction and various green solvent extraction methods, such as accelerated solvents extraction, deep eutectic solvents extraction, ionic liquids extraction, and supercritical fluid extraction, are commonly used pretreatment methods for extraction and purification of ANCs. Liquid chromatography coupled with different detectors (tandem mass spectrometry and UV detectors) and spectrophotometry methods are some of the determination methods for ANC. This study has updated, compared, and discussed different pretreatment and analysis methods. Moreover, the advanced methods and development prospects in this field are comprehensively summarized, which can provide references for further utilization of ANCs.