scholarly journals An LC-MS/MS Method to Measure S-Methyl-l-Cysteine and S-Methyl-l-Cysteine Sulfoxide in Human Specimens Using Isotope Labelled Internal Standards

Molecules ◽  
2019 ◽  
Vol 24 (13) ◽  
pp. 2427 ◽  
Author(s):  
Tharsini Sivapalan ◽  
Antonietta Melchini ◽  
Jack Coode-Bate ◽  
Paul W. Needs ◽  
Richard F. Mithen ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Correlation Coefficients ◽  
Sulphur Compounds ◽  
Internal Standards ◽  
Limits Of Detection ◽  
Naturally Occurring ◽  
Plasma And Urine Samples ◽  
Quantification Accuracy ◽  
Cysteine Sulfoxide

This is the first report describing an analytical method for quantitative analysis of two naturally occurring sulphur compounds, S-methyl-l-cysteine (SMC) and S-methyl-l-cysteine sulfoxide (SMCSO), in human body fluids using isotope-labelled internal standards and liquid chromatography-mass spectrometry (LC-MS)/MS techniques. This method was validated according to the guideline of the Royal Society of Chemistry Analytical Methods Committee. It offers significant advantages including simple and fast preparation of human biological samples. The limits of detection of SMC were 0.08 µM for urine and 0.04 µM for plasma. The limits of detection of SMCSO were 0.03 µM for urine and 0.02 µM for plasma. The calibration curves of all matrices showed linearity with correlation coefficients r2 > 0.9987. The intra and inter day precisions in three levels of known concentrations were >10% and >20%, respectively. The quantification accuracy was 98.28 ± 5.66%. The proposed method would be beneficial for the rapid and accurate determination of the SMC and SMCSO in human plasma and urine samples using by isotope labelled internal standards.

Direct Determination of Glyphosate and its Metabolite AMPA in Soil Using Mixed-Mode Solid-Phase Purification and LC-MS/MS Determination on a Hypercarb Column

2019 ◽  
Vol 102 (3) ◽  
pp. 952-965 ◽  
Author(s):  
Pei Zhang ◽  
Mick Rose ◽  
Lukas Van Zwieten
Keyword(s):  
Mixed Mode ◽  
Crop Production ◽  
Solid Phase ◽  
Direct Determination ◽  
Correlation Coefficients ◽  
Grain Production ◽  
Internal Standards ◽  
Aminomethylphosphonic Acid ◽  
Lc Tandem Ms

Abstract Background: Although glyphosate is widely used in agriculture, information on its residue level in soils remains scarce partly because of the difficulty in its analysis. Objective: Develop and validate a method to directly analyze glyphosate and its metabolite aminomethylphosphonic acid (AMPA) in soil. Method: Soils were extracted with 0.6 M KOH solution, and coextracted interferences were removed using a mixed-mode Bond Elut Plexa PAX®. The extracts were analyzed by LC-tandem MS fitted with a Hypercarb column and isotope-labeled (13C,15N) glyphosate and AMPA were used as internal standards. Results: LOQs were 0.05 mg/kg for both glyphosate and AMPA in soils. Correlation coefficients were ≥0.99, residuals were below 20%, and calibrations were linear in the range 0.02–1.0 μg/mL. The method was validated on five contrasting soils (Vertosol, Calcarosol, Chromosol, Sodosol, and Tenosol) commonly used for grain production in Australia. The recoveries for glyphosate and AMPA in the soils were 96–121 and 91–118%, respectively, with RSD in the range of 3–16%. Conclusions: This paper presents using the validated method in analysis glyphosate and AMPA in soils collected from crop production paddocks in Australia. The survey data showed that glyphosate and AMPA were detected in all collected soils, with concentrations ranging between 0.05 and 1.2 mg/kg. Highlights: The study demonstrates that the mixed-mode solid-phase extraction is effective in removing interferences and validates the use of Hypercarb as an alternative stationary phase for glyphosate and AMPA analysis from soils.

scholarly journals IMPROVED HPLC RESOLUTION AND QUANTIFICATION OF ELLAGIC ACID FROM STRAWBERRY, BLACKBERRY, AND CRANBERRY

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1078c-1078 ◽  
Author(s):  
S. Y. Wang ◽  
J. L. Maas ◽  
E. M. Daniel ◽  
G. J. Galletta
Keyword(s):  
Ellagic Acid ◽  
Accurate Determination ◽  
Ammonium Phosphate ◽  
Solvent System ◽  
Animal Nutrition ◽  
Genetic Studies ◽  
Naturally Occurring ◽  
Chemically Induced ◽  
Improved Methods

Ellagic acid (EA) a naturally occurring polyphenol in many fruit and nut crops, is a putative inhibitor of certain chemically-induced cancers. Improved methods of extraction, detection and quantification are essential for accurate determination of EA for plant physiological and genetic studies and animal nutrition and chemopreventative studies. Column (C18) preconditioning significantly reduced column retention of EA. An ammonium phosphate/methanol solvent system was used in preference to sodium phosphate/methanol. Fruit sample determinations were 10-100 times higher than previously reported, due to the improvements in efficiency of these methods. EA levels (mg/g dry wt) were: strawberry pulp (1.55), achene (8.46), root (1.55), crown (3.32) and leaf (14.27); blackberry pulp (,2.43) and seed (3.37); and cranberry skin (1.06), pulp (0.31), seed (0.69), leaf (4.10).

Determination of Fatty Acid Methyl Esters in Biodiesel Produced from Pistacia Chinensis Oil by GC

2013 ◽  
Vol 291-294 ◽  
pp. 253-256
Author(s):  
Xiang Hua Liu ◽  
Chao Xing ◽  
Ying Ruan ◽  
Qiu Long Hu ◽  
Wen Hui Shen ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Methyl Esters ◽  
Methyl Esters ◽  
Accurate Determination ◽  
Internal Standard ◽  
Correlation Coefficients ◽  
Good Precision ◽  
Acid Methyl ◽  
Standard Calibration

An accurate determination method of fatty acid methyl esters (FAMEs) in biodiesel produced from pistacia chinensis oil by gas chromatography (GC) was developed, with methyl tridecanoate used as an internal standard. The results show that the standard calibration curves for the FAMEs have good linearity over the concentration range, the linearity correlation coefficients (R2) are more than 0.99 for all the components. The average recoveries are from 95.26% to 99.66%. The method has good precision with the RSD ranging from 1.03% to 3.40%.

scholarly journals Improved Protocol for an Oxygen Electrode Method for Determining Hydrogen Peroxide in Foods

1997 ◽  
Vol 80 (3) ◽  
pp. 681-687 ◽  
Author(s):  
Fumio Miyamoto ◽  
Masanobu Saeki ◽  
Takumi Yoshizawa
Keyword(s):  
Hydrogen Peroxide ◽  
Standard Method ◽  
Present Method ◽  
Accurate Determination ◽  
Oxygen Electrode ◽  
Nitrogen Gas ◽  
Naturally Occurring ◽  
Residual Hydrogen ◽  
Electrode Method

Abstract An oxygen electrode method for determining residual hydrogen peroxide in foods has been further improved. Pretreatment, which includes extraction and neutralization, is done in a hydrogen peroxide extraction apparatus with nitrogen gas bubbling. The hydrogen peroxide concentration of the sample is corrected by subtracting the sample blank value, obtained for the sample through catalase treatment. Bubbling with nitrogen gas effectively minimized the sample blank value, making this method suitable for accurate determination of trace amounts of hydrogen peroxide in foods. Recoveries of hydrogen peroxide added at 1-10 μg/g were 77.8-107.1% by the present method. These recoveries are similar to or higher than those by the Japanese standard method and by another modified oxygen electrode method. Concentrations of naturally occurring hydrogen peroxide in solid foods were <0.87 μg/g by the present method, lower than those by either the standard method or another modified oxygen electrode method.

scholarly journals Natural isotope correction improves analysis of protein modification dynamics

2021 ◽  
Author(s):  
Jörn Dietze ◽  
Alienke van Pijkeren ◽  
Anna-Sophia Egger ◽  
Mathias Ziegler ◽  
Marcel Kwiatkowski ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Protein Modification ◽  
High Resolution Mass Spectrometry ◽  
Accurate Determination ◽  
Mass Spectrometry Data ◽  
Stable Isotope Labelling ◽  
Isotope Labelling ◽  
Naturally Occurring ◽  
Correct Estimation

AbstractStable isotope labelling in combination with high-resolution mass spectrometry approaches are increasingly used to analyze both metabolite and protein modification dynamics. To enable correct estimation of the resulting dynamics, it is critical to correct the measured values for naturally occurring stable isotopes, a process commonly called isotopologue correction or deconvolution. While the importance of isotopologue correction is well recognized in metabolomics, it has received far less attention in proteomics approaches. Although several tools exist that enable isotopologue correction of mass spectrometry data, the majority is tailored for the analysis of low molecular weight metabolites. We here present PICor which has been developed for isotopologue correction of complex isotope labelling experiments in proteomics or metabolomics and demonstrate the importance of appropriate correction for accurate determination of protein modifications dynamics, using histone acetylation as an example.

scholarly journals Development and validation of HPLC-MS2 methodology for the accurate determination of C4–C8 B-type flavanols and procyanidins

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ugo Bussy ◽  
Yusuf Olanrewaju ◽  
Alan Crozier ◽  
Javier Ottaviani ◽  
Catherine Kwik-Uribe
Keyword(s):  
High Performance ◽  
Accurate Determination ◽  
Potential Health ◽  
Internal Standards ◽  
Analytical Protocol ◽  
Liquid Chromatography Tandem Mass ◽  
Primary Standards ◽  
Development And Validation ◽  
Reliable Methods

AbstractCocoa flavanols and procyanidins (CFs), natural dietary bioactives, have been studied extensively over the past two decades for their potential health benefits. Research on their safety and efficacy is critically dependent upon on the ability to reliably characeterize the research materials that are utilized, and with growing consumer availability of CF-based products, reliable methods for the detection of potential adulteration are of increasing importance. This research focused on the development of a high performance liquid chromatography-tandem mass spectrometry method (HPLC-MS2) using primary standards and 13C-labelled procyanidins as internal standards. The ability of MS2 detection to discriminate A- and B-type procyanidins was demonstrated. Method performances were validated for degrees of polymerization up to four in seven model food matrices. Accuracy ranged from 90.9 to 125.4% and precision was < 10% at lower concentrations. Finally, the method was applied to cocoa-based samples and compared to the AOAC 2020.05 analytical protocol, supporting the use of NIST 8403 as reference material for HPLC-MS2 analysis.

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