Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284, USA.
Department of Chemistry, Gustavus Adolphus College, St. Peter, MN 56082, USA.
Anal Chim Acta. 2017 Apr 8;961:49-58. doi: 10.1016/j.aca.2017.01.047. Epub 2017 Jan 31.
Comprehensive two-dimensional liquid chromatography (LC × LC) has been gaining popularity for the analysis of complex samples in a wide range of fields including metabolomics, environmental analysis, and food analysis. While LC × LC can provide greater chromatographic resolution than one-dimensional LC (1D-LC), overlapping peaks are often still present in separations of complex samples, a problem that can be alleviated by chemometric curve resolution techniques such as multivariate curve resolution-alternating least squares (MCR-ALS). MCR-ALS has also been previously shown to assist in the quantitative analysis of LC x LC data by isolating pure analyte signals from background signals which are often present at higher levels in LC x LC compared to 1D-LC. In this work we present the analysis of a dataset from the LC × LC analyses of parsley, parsnip and celery samples for the presence and concentrations of 14 furanocoumarins. Several MCR-ALS implementations are compared for the analysis of LC × LC data. These implementations include analyzing the LC x LC chromatogram alone, analyzing the one-dimensional chromatogram alone, as well as two hybrid approaches that make use of both the first and second dimension chromatograms. Furthermore, we compared manual integration of resolved chromatograms versus a simple summation approach, using the resolved chromatographic peaks in both cases. It is found that manual integration of the resolved LC × LC chromatograms provides the best quantification as measured by the consistency between replicate injections. If the summation approach is desired for automation, the choice of MCR-ALS implementation has a large effect on the precision of the analysis. Based on these results, the concentrations of the 14 furanocoumarins are determined in the three apiaceous vegetable types by analyzing the LC × LC chromatograms with MCR-ALS and manual integration for peak area determination. The concentrations of the analytes are found to vary greatly between samples, even within a single vegetable type.
二维液相色谱（LC×LC）在代谢组学、环境分析和食品分析等广泛领域中分析复杂样品时越来越受欢迎。虽然 LC×LC 可以比一维液相色谱（1D-LC）提供更高的色谱分辨率，但在复杂样品的分离中仍然经常存在重叠峰，这个问题可以通过化学计量曲线解析技术（如多变量曲线解析交替最小二乘法（MCR-ALS））来缓解。MCR-ALS 之前也被证明可以通过从背景信号中分离出纯分析物信号来协助 LC x LC 数据的定量分析，而背景信号在 LC x LC 中比在 1D-LC 中通常更高。在这项工作中，我们分析了来自欧芹、欧洲防风草和芹菜样品的 LC×LC 分析数据集，以检测和确定 14 种呋喃香豆素的存在和浓度。比较了几种 MCR-ALS 实现方法来分析 LC×LC 数据。这些实现方法包括单独分析 LC x LC 色谱图、单独分析一维色谱图，以及两种混合方法，同时利用第一维和第二维色谱图。此外，我们比较了对解析色谱图进行手动积分与简单求和方法的差异，在两种情况下都使用解析色谱峰。结果发现，通过对重复进样的一致性来衡量，对解析后的 LC×LC 色谱图进行手动积分可以提供最佳的定量结果。如果需要自动化求和方法，那么 MCR-ALS 实现方法的选择对分析的精度有很大的影响。基于这些结果，通过用 MCR-ALS 分析 LC×LC 色谱图并手动积分进行峰面积测定，来确定三种伞形科蔬菜中 14 种呋喃香豆素的浓度。发现即使在同一蔬菜类型内，分析物的浓度在不同样品之间差异很大。
