Dependence of matrix effect on ionization polarity during LC–ESI–MS analysis of derivatized amino acids in some natural samples

Abstract

Matrix effect, the influence of co-eluting components on the ionization efficiency of the analyte, affects the trueness and precision of the LC-ESI-MS analysis. Derivatization can reduce or eliminate matrix effect, for example, diethyl ethoxymethylenemalonate (DEEMM) derivatives have shown less matrix effect compared to other derivatives. Moreover, the use of negative ion mode can further reduce matrix effect. In order to investigate the combination of derivatization and different ionization modes, an LC-ESI-MS/MS method using alternating positive/negative ion mode was developed and validated. The analyses in positive and negative ion modes had comparable limit of quantitation values. The influence of ESI polarity on matrix effect was investigated during the analysis of 22 DEEMM-derivatized amino acids in herbal extracts and honeys. Sample dilution approach was used for the evaluation of the presence of matrix effect. Altogether, 4 honeys and 11 herbal extracts were analyzed, and the concentrations of 22 amino acids in the samples are presented. In the positive ion mode, matrix effect was observed for several amino acid derivatives and the matrix effect was stronger in honey samples compared to the herbal extracts. The negative ion mode was free from matrix effect, with only few exceptions in honeys (average relative standard deviation over all analytes and matrices was 8%; SD = 7%). The matrix effect was eliminated in the positive ion mode by sample dilution and agreement between concentrations from the two ion modes was achieved for most amino acids. In conclusion, it was shown that the combination of derivatization and negative ion mode can be a powerful tool for minimizing matrix effect in more complicated applications.

Synergistic therapeutic effects of Duzhong Jiangya Tablets and amlodipine besylate combination in spontaneously hypertensive rats using 1H‐NMR‐ and MS‐based metabolomics

“…(Elmsjo et al, 2017;Gika, Theodoridis, Plumb, & Wilson, 2014). However, MS has a matrix effect and can only detect ionized substances (Oldekop, Rebane, & Herodes, 2017). Metabolites that are not ionizable can be detected by NMR.…”

High-Throughput Fractionation Coupled to Mass Spectrometry for Improved Quantitation in Metabolomics

“…This is in accordance to other studies, in which was shown that ion suppression is less occurring in negative ionization mode. 24,25 Although the FIA method is faster (1.4 versus 3 min), the findings in Figure 3 emphasize the necessity of online fractionation prior to electrospray ionization.…”

Derivatization-targeted analysis of amino compounds in plant extracts in neutral loss acquisition mode by liquid chromatography-tandem mass spectrometry

“…A UHPLC-MS method was developed for the detection of derivatized amino compounds in neutral loss scan mode, by exploiting the characteristic DEEMM fragmentation pattern. All analyses were performed in positive ionization mode, due to the lower MS intensity of DEEMM derivatives (especially biogenic amines) in negative ESI mode, and because the investigated neutral fragment originates from the positively charged compounds [6,12,31].…”