Fast Quantification Without Conventional Chromatography, The Growing Power of Mass Spectrometry

Abstract

Mass spectrometry (MS) in hyphenated techniques is widely accepted as the gold standard quantitative tool in life sciences. However, MS possesses intrinsic analytical capabilities that allow it to be a stand-alone quantitative technique, particularly with current technological advancements. MS has a great potential for simplifying quantitative analysis without the need for tedious chromatographic separation. Its selectivity relies on multistage MS analysis (MSn), including tandem mass spectrometry (MS/MS), as well as the ever-growing advancements of high-resolution MS instruments. This perspective describes various analytical platforms that utilize MS as a stand-alone quantitative technique, namely, flow injection analysis (FIA), matrix assisted laser desorption ionization (MALDI), including MALDI-MS imaging and ion mobility, particularly high-field asymmetric waveform ion mobility spectrometry (FAIMS). When MS alone is not capable of providing reliable quantitative data, instead of conventional liquid chromatography (LC)-MS, the use of a guard column (i.e., fast chromatography) may be sufficient for quantification. Although the omission of chromatographic separation simplifies the analytical process, extra procedures may be needed during sample preparation and clean-up to address the issue of matrix effects. The discussion of this manuscript focuses on key parameters underlying the uniqueness of each technique for its application in quantitative analysis without the need for a chromatographic separation. In addition, the potential for each analytical strategy and its challenges are discussed as well as improvements needed to render them as mainstream quantitative analytical tools. Overcoming the hurdles for fully validating a quantitative method will allow MS alone to eventually become an indispensable quantitative tool for clinical and toxicological studies.

The foundations and development of lipidomics

“…In the last 20 years, development of lipidomics technologies has vastly improved by the following: i ) extensive characterization of the structures of known lipid classes and subclasses and uncovering both new classes and new molecular species of lipids (e.g., ( 4 , 74 , 134 , 135 , 136 , 137 , 138 )); ii ) sensitive quantification of lipid species at attomole to femtomole levels from a variety of biological samples (e.g., ( 132 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 )); iii ) applications for biomedical and biological studies through pathway/network analysis; iv ) biomarker development that facilitates prediction, diagnosis, and prognosis of disease states (see recent reviews for references ( 83 , 147 , 148 , 149 , 150 , 151 , 152 , 153 , 154 , 155 , 156 )); v ) determining the alterations of lipids in spatial distribution via mapping complex organs by MALDI imaging (see recent reviews for references ( 157 , 158 , 159 , 160 , 161 , 162 )); and vi ) advances in bioinformatics to facilitate real time data processing (e.g., ( 88 , 163 , 164 , 165 , 166 , 167 , 168 , 169 , 170 , 171 , 172 , 173 , 174 )).…”

Quantification of Irinotecan in Single Spheroids Using Internal Standards by MALDI Mass Spectrometry Imaging

“…Quantitative MSI (qMSI) using MALDI remains challenging because of the stability of analytes, inefficient analyte extraction, and ion suppression caused by matrix background signals, which especially impacts the quantification of small molecules in the low m / z range. , Furthermore, sample heterogeneity, mainly caused by matrix crystal dispersity and nonuniform cocrystallized substrate surfaces, can result in signal variations . However, MALDI-MSI has unique advantages in quantification in that it has simplified sample preparation, high tolerance for salts, and much faster analysis speeds compared with the gold standard quantitative MS method, liquid chromatography tandem mass spectrometry (LC-MS/MS) . To capitalize on these advantages, many considerations need to be considered to conduct quantitative MALDI-MSI.…”

“…10 However, MALDI-MSI has unique advantages in quantification in that it has simplified sample preparation, high tolerance for salts, and much faster analysis speeds compared with the gold standard quantitative MS method, liquid chromatography tandem mass spectrometry (LC-MS/MS). 11 To capitalize on these advantages, many considerations need to be considered to conduct quantitative MALDI-MSI. These considerations include appropriate experimental design to optimize matrix selection and application, a normalization method to visualize data, and a suitable method used to generate calibration curves.…”

Simplified Liquid Chromatography–Mass Spectrometry Methods for Gestagen Analysis in Animal Fat and Liver

“…We hypothesized that instead of using time-consuming clean-up steps during sample preparation, shorter, simpler methods to analyze kidney fat and/or liver samples could be used while relying more upon the capabilities of mass spectrometry and its related techniques. 27 In particular, if the simplified sample preparation resulted in an analysis that produced excessive chemical background interference, FAIMS would be used to clean up the samples in the gas phase (after ionization and before entering the mass spectrometer), thereby giving the required sensitivity and selectivity needed to achieve desired levels of quantification.…”