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

2017 ◽  
Vol 23 (5) ◽  
pp. 245-253 ◽  
Author(s):  
Maarja-Liisa Oldekop ◽  
Riin Rebane ◽  
Koit Herodes
Keyword(s):  
Amino Acids ◽  
Matrix Effect ◽  
Negative Ion ◽  
Herbal Extracts ◽  
Esi Ms ◽  
Ms Analysis ◽  
The Matrix ◽  
Negative Ion Mode ◽  
Positive Ion ◽  
Sample Dilution

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.

scholarly journals Electrospray Ionization Matrix Effect as an Uncertainty Source in HPLC/ESI-MS Pesticide Residue Analysis

2010 ◽  
Vol 93 (1) ◽  
pp. 306-314 ◽  
Author(s):  
Anneli Kruve ◽  
Koit Herodes ◽  
Ivo Leito
Keyword(s):  
Electrospray Ionization ◽  
Matrix Effect ◽  
Matrix Effects ◽  
Residue Analysis ◽  
Commodity Group ◽  
Large Variability ◽  
Esi Ms ◽  
Ms Analysis ◽  
The Matrix ◽  
Peak Areas

Abstract The matrix effects in HPLC/electrospray ionization (ESI)-MS analysis are difficult to compensate for because of their large variability. It is, therefore, often more practical to include uncertainty due to the matrix effect into the uncertainty budget rather than try to compensate. This work presents an empirical approachthe matrix effect graph approachfor estimating the uncertainty due to the matrix effect in HPLC/ESI-MS analysis of pesticide residues in fruits and vegetables. At certain time intervals (1 month), a calibration graph using extracts of different fruits/vegetables as calibration solutions is prepared, and a regression line is fitted through these data. These fruits/vegetables may be either from the commodity group of the samples or from different commodity groups. The relative residuals of the calibration point peak areas are calculated and plotted against the measurement time. We term the resulting graph the matrix effect graph. The root mean square of the relative residuals is calculated and used as the estimate of relative uncertainty of the sample peak areas caused by the matrix effect. The matrix effect graph obtained over fruits/vegetables from different commodity groups can also be used to identify fruits/vegetables with extreme matrix effects. The matrix effect graph approach was used for determination of thiabendazole, aldicarb, imazalil, and methiocarb and was validated with tomato, cucumber, and sweet corn matrixes at the 0.5 mg/kg concentration level. When different commodity groups were used to compile the matrix effect graph, results of analysis of all samples agreed with the spiked concentrations within the expanded uncertainties (at k = 2 level). When the matrix effect graph was compiled using fruits from the same commodity group as the analyzed samples (fruiting vegetables in this case), agreement was found in 98 of the cases.

scholarly journals Pouteria lucuma Pulp and Skin: In Depth Chemical Profile and Evaluation of Antioxidant Activity

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5236
Author(s):  
Milena Masullo ◽  
Antonietta Cerulli ◽  
Cosimo Pizza ◽  
Sonia Piacente
Keyword(s):  
Antioxidant Activity ◽  
Agricultural Waste ◽  
Metabolite Profile ◽  
Careful Analysis ◽  
2D Nmr ◽  
Negative Ion ◽  
Specialized Metabolites ◽  
Esi Ms ◽  
Ms Analysis ◽  
Negative Ion Mode

Pouteria lucuma Ruiz and Pav., known as the ‘Gold of the Incas’ or ‘lucuma’, is a subtropical fruit belonging to the Sapotaceae family, with a very sweet flavor, used to prepare cakes, ice creams as well as in the baking and dairy industries. To date, the content of primary metabolites is known, but little information is reported about the composition in specialized metabolites. Moreover, no study is reported on skin which represent an important agricultural waste due to the high demand for lucuma. In order to have a preliminary metabolite profile of Pouteria lucuma, the extracts of pulp and skin have been analyzed by LC-ESI/LTQOrbitrap/MS/MS in negative ion mode. The careful analysis of the accurate masses, of the molecular formulas and of the ESI/MS spectra allowed to identify specialized metabolites belonging to phenolic, flavonoid and polar lipid classes. The LC-MS/MS analysis guided the isolation of compounds occurring in the pulp extract whose structures have been characterized by spectroscopic methods including 1D- and 2D-NMR experiments and ESI-MS analysis. Furthermore, the phenolic content of the extracts along with the antioxidant activity of extracts and isolated compounds was evaluated.

Should We Think Positive or Negative About Dihydrobenzofuran Neolignans? an ESI-MS/MS Study

2020 ◽  
Author(s):  
Herbert Dias ◽  
Eduardo Crevelin ◽  
Vinicius Palaretti ◽  
Ricardo Vessecchi ◽  
Antônio Eduardo Crotti
Keyword(s):  
Structural Features ◽  
Biologically Active ◽  
Negative Ion ◽  
Esi Ms ◽  
Product Ions ◽  
Sequential Mass Spectrometry ◽  
Negative Ion Mode ◽  
Gas Phase Fragmentation ◽  
Protonated Molecules ◽  
Positive Ion

<p>This study elucidates the gas-phase fragmentation pathways of a series of biologically active benzofuran neolignans (BNs) and dihydrobenzofuran neolignans (DBNs) by means of electrospray ionization accurate-mass tandem and sequential mass spectrometry (ESI-MS/MS and ESI-MS<sup>n</sup>) and thermochemical data estimated by using Computational Chemistry and the B3LYP/6-31+G(d,p) model. In their deprotonated forms, these compounds produced more diagnostic product ions as compared to the corresponding protonated molecules. Moreover, a series of odd-electron product ions (radical anions) were detected, which has not been reported for protonated DBNs. Direct C<sub>2</sub>H<sub>3</sub>O<sub>2</sub>• elimination from the precursor ion (deprotonated molecule) only occurred for the BNs and can help to distinguish these compounds from the DBNs. Although the product ion [M‒CH<sub>3</sub>OH]<sup>‒</sup> emerged in the spectrum of all the DBNs analyzed here, the mechanism through which this ion originates strongly depends on specific structural features, so that further [M‒CH<sub>3</sub>OH]<sup>‒</sup> fragmentation generates important diagnostic product ions. Comparison between the ESI-MS/MS data of these compounds in the negative ion mode (deprotonated molecule) and in the positive ion mode (protonated molecule) revealed that the negative ion mode provides much more information (at least one diagnostic product ion emerged for all the analyzed compounds) and does not require the use of additives to produce the precursor ions (deprotonated molecules). </p>

Should We Think Positive or Negative About Dihydrobenzofuran Neolignans? an ESI-MS/MS Study

2020 ◽  
Author(s):  
Herbert Dias ◽  
Eduardo Crevelin ◽  
Vinicius Palaretti ◽  
Ricardo Vessecchi ◽  
Antônio Eduardo Crotti
Keyword(s):  
Structural Features ◽  
Biologically Active ◽  
Negative Ion ◽  
Esi Ms ◽  
Product Ions ◽  
Sequential Mass Spectrometry ◽  
Negative Ion Mode ◽  
Gas Phase Fragmentation ◽  
Protonated Molecules ◽  
Positive Ion

<p>This study elucidates the gas-phase fragmentation pathways of a series of biologically active benzofuran neolignans (BNs) and dihydrobenzofuran neolignans (DBNs) by means of electrospray ionization accurate-mass tandem and sequential mass spectrometry (ESI-MS/MS and ESI-MS<sup>n</sup>) and thermochemical data estimated by using Computational Chemistry and the B3LYP/6-31+G(d,p) model. In their deprotonated forms, these compounds produced more diagnostic product ions as compared to the corresponding protonated molecules. Moreover, a series of odd-electron product ions (radical anions) were detected, which has not been reported for protonated DBNs. Direct C<sub>2</sub>H<sub>3</sub>O<sub>2</sub>• elimination from the precursor ion (deprotonated molecule) only occurred for the BNs and can help to distinguish these compounds from the DBNs. Although the product ion [M‒CH<sub>3</sub>OH]<sup>‒</sup> emerged in the spectrum of all the DBNs analyzed here, the mechanism through which this ion originates strongly depends on specific structural features, so that further [M‒CH<sub>3</sub>OH]<sup>‒</sup> fragmentation generates important diagnostic product ions. Comparison between the ESI-MS/MS data of these compounds in the negative ion mode (deprotonated molecule) and in the positive ion mode (protonated molecule) revealed that the negative ion mode provides much more information (at least one diagnostic product ion emerged for all the analyzed compounds) and does not require the use of additives to produce the precursor ions (deprotonated molecules). </p>

A Modified QuEChERS Extraction and LC-MS/MS Method for the Determination of Pesticide Residues in Curry Leaves (Murraya koenigii)

2019 ◽  
Vol 6 (1) ◽  
pp. 30-41
Author(s):  
Ranjith Arimboor ◽  
Karunkara Ramakrishna Menon ◽  
Natarajan Ramesh Babu ◽  
Haneesh Chandran
Keyword(s):  
Sample Preparation ◽  
Matrix Effect ◽  
Retention Time ◽  
Pesticide Residues ◽  
Mobile Phase ◽  
Preparation Technique ◽  
Modified Quechers ◽  
Curry Leaves ◽  
Ms Analysis ◽  
The Matrix

Background:Increased consumer demand for curry leaves free from pesticides demands fast and reliable analytical methods for the analysis of pesticide residues.Objective:The optimization of a QuEChERS based sample preparation technique with improved analytical accuracy by removing interfering matrix components for LC-MS/MS analysis of pesticide residues from curry leaves.Methods:A modified QuEChERS solid phase extraction method was developed and validated for the analysis of 26 pesticides in fresh and dried curry leaves. The effects of the sample preparation steps and column retention time on the matrix suppression of analyte ions were also evaluated.Results:Validation parameters were found within an acceptable range. The matrix effect evaluation studies showed that the QuEChERS sample preparation was able to minimize the ion suppression of analytes due to co-eluting matrix of components and that a d-SPE clean up step had major role in reducing matrix effect. The gradient mobile phase with longer retention time for analytes resulted in comparatively lesser matrix effects than the isocratic mobile phase of non-polar nature. Even after the clean up, a considerable number of compounds had more than 20% reduction in their MS response in the gradient mobile phase.Conclusion:This study emphasized the need of proper sample clean up before a LC-MS/MS analysis and the usage of matrix matched standards and mobile phase that ultimately results in an appropriate analyte separation in reasonable retention times.

Serum Lipids Profiling Perturbances in Patients with Ischemic Heart Disease and Ischemic Cardiomyopathy

2020 ◽  
Author(s):  
Lin Yang ◽  
Liang Wang ◽  
Yangyang Deng ◽  
Lizhe Sun ◽  
Bowen Low ◽  
...  
Keyword(s):  
Heart Disease ◽  
Ischemic Heart Disease ◽  
Ischemic Cardiomyopathy ◽  
Serum Lipids ◽  
Ischemic Heart ◽  
Negative Ion ◽  
Serum Samples ◽  
Cross Sectional ◽  
Negative Ion Mode ◽  
Positive Ion

Abstract Background: Ischemic heart disease (IHD) is a common cardiovascular disorder associated with inadequate blood supply to the myocardium. Chronic coronary ischemia leads to ischemic cardiomyopathy (ICM). Despite their rising prevalence and morbidity, few studies have discussed the lipids alterations in these patients. Methods: In this cross-sectional study, we analyzed serum lipids profile in IHD and ICM patients using a lipidomics approach. Consecutive consenting patients admitted to the hospital for IHD and ICM were enrolled. Serum samples were obtained after overnight fasting. Non-targeted metabolomics was applied to demonstrate lipids metabolic profile in control, IHD and ICM patients. Results: A total of 63 and 62 lipids were detected in negative and positive ion mode respectively. Among them, 16:0 Lyso PI, 18:1 Lyso PI in negative ion mode, and 19:0 Lyso PC, 12:0 SM d18:1/12:0, 15:0 Lyso PC, 17:0 PC, 18:1-18:0 PC in positive ion mode were significantly altered both in IHD and ICM as compared to control. 13:0 Lyso PI, 18:0 Lyso PI, 16:0 PE, 14:0 PC DMPC, 16:0 ceramide, 18:0 ceramide in negative ion mode, and 17:0 PE, 19:0 PC, 14:0 Lyso PC, 20:0 Lyso PC, 18:0 PC DSPC, 18:0-22:6 PC in positive ion mode were significantly altered only in ICM as compared to IHD and control. Conclusion: Using non-targeted lipidomics profiling, we have successfully identified a group of circulating lipids that were significantly altered in IHD and ICM. The lipids metabolic signatures shed light on potential new biomarkers and therapeutics for preventing and treating ICM.

scholarly journals Profiling Murchison Soluble Organic Matter for New Organic Compounds with APPI- and ESI-FT-ICR MS

Life ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 48 ◽  
Author(s):  
Jasmine Hertzog ◽  
Hiroshi Naraoka ◽  
Philippe Schmitt-Kopplin
Keyword(s):  
Organic Matter ◽  
Negative Ion ◽  
Ion Cyclotron Resonance ◽  
Ms Analysis ◽  
Major Interest ◽  
Polycyclic Aromatic ◽  
Soluble Organic Fraction ◽  
Negative Ion Mode ◽  
Ft Icr Ms ◽  
Ft Icr

The investigation of the abundant organic matter in primitive meteorite such as carbonaceous chondrites is of major interest in the field of origin of life. In this study, the soluble organic fraction of the Murchison meteorite was analyzed by atmospheric pressure photoionization (APPI) and electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), in both detection modes. Such an approach ensured that we obtained an extensive description of the organic matter of the CM2 meteorite. Indeed, while in total close to 16,000 unique features were assigned, only 4% are common to all analyses, illustrating the complementarity of both the detection modes and the ionization sources. ESI FT-ICR MS analysis, in negative-ion mode, ensured to observe specifically CHOS and CHNOS species, whereas the positive-ion mode is more dedicated to the detection of CHNO and CHN species. Moreover, new organomagnesium components were observed in (+) ESI. Eventually, (+) APPI FT-ICR MS analysis was a preferred method for the detection of less polar or nonpolar species such as polycyclic aromatic hydrocarbons but also heteroatom aromatic species composing the organic matter of Murchison.

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