Determination of coeluted isomers in wine samples by application of MS/MS deconvolution analysis

Abstract

Two organic acids isomers, 3-isopropylmalic acid (3-IPMA) and 2-isopropylmalic acid (2-IPMA), were identified and quantified in wine samples by using an LC-MS/MS method without any chromatographic separation, but processing the MS/MS data with a recently developed deconvolution algorithm (LEDA: linear equations deconvolution analysis), thus decreasing the time necessary for the process. In particular, the LEDA tool processes the MS/MS signals and assigns the relative concentrations (abundances) of the isomers in the sample, at the mg L −1 level. The efficiency of MS/MS signal assignment was improved by introducing five linear equations to define the LEDA matrix. Then, as a novel approach, an overdetermined system of linear equations was applied for the deconvolution of isomers. The use of LEDA to identify and quantify the isomers in wine samples, together with the choice of a short LC column and a fast elution gradient, simplifies the process and shortens the time needed. Furthermore, it was evaluated the quantitative determination of the IPMA isomers by using the calibration curve provided by the precursor ion MRM transition data. The calculated values of accuracy (recovery between 82.6% and 99.8%) and precision (RSD between 0.4% and 4.0%) confirm the validity of this quantitative approach and the ability of LEDA to establish the correct percentage of the MS/MS signal for each isomer. Finally, to compare the conventional LC-MS/MS method and our proposed method of LC-MS/MS coupled with LEDA postprocessing elaboration, a series of real wine samples were analysed by both methods, and the results were compared.

Simultaneous Degradation Study of Isomers in Human Plasma by HPLC-MS/MS and Application of LEDA Algorithm for Their Characterization

“…On the contrary, the slope values obtained from the precursor ion transitions are similar between each pair of isomers. Since the slope value of the calibration curve represents the quantitation sensitivity of the analyte [ 26 ], by comparing the reported slope values, it can obtain similar sensitivities for both isomers by using the precursor ion curves. Naturally, this observation does not consider background noise, isobaric interferences, or other factors due to the sample matrix that effect the precursor ion signal, compromising its value.…”

“…The MS analyzes were obtained in an ion scan by acquiring the m/z range from 250 to 750 with 600 ms of scan time. The ERMS experiments were performed to study the fragmentation of [M + H] + species of each analyte and build its breakdown curves [ 23 , 24 , 25 , 26 , 27 ]. The ERMS experiments were carried out by a series of product ion scan (MS/MS) analyses, increasing the CV stepwise in the range 5–50 V. Each acquired MS/MS spectrum was in the m/z range from 50 to 650, scan time of 600 ms and by using argon as collision gas.…”

“…In regards the topic of the recognition of isomers, our group proposed and developed an MS/MS post-processing mathematical algorithm named LEDA (Linear Equation of Deconvolution Analysis) that allows the recognition of isomer compounds without their chromatographic separation [ 23 , 24 , 25 , 26 ]. Profiting by LEDA features, recently we introduced a methodological approach that simplifies the liquid chromatography (HPLC) parameters, allowing the use of a short column and a fast elution gradient, leading to increased productivity, without losing determination specificity [ 27 ].…”

Differentiation and Quantitation of Coeluting Isomeric Amadori and Heyns Peptides Using Sugar-Specific Fragment Ion Ratios

“…In order to obtain normalized neutral loss ratios for different charge states and collision energies, 45 we included the peak area of the parent ion remaining in the tandem mass spectrum to the sum of the peak areas of the fragment ions in the denominator. Expectedly, the strongest impact occurred for precursor ions with low charge states due to a less efficient fragmentation (Table S9).…”

Tandem mass spectrometry approaches for recognition of isomeric compounds mixtures

“…To overcome these difficulties, the linear equations deconvolution analysis (LEDA) is proposed (Menicatti et al, 2016a(Menicatti et al, , 2016b(Menicatti et al, , 2018(Menicatti et al, , 2020. The LEDA algorithm is based on the same consideration reported above and the MS/MS data acquired by analysis of mixtures of isomers in a postprocessing procedure are elaborated.…”