Robust Analysis of Fatty Acids in Milk: An Independent Lifetime Evaluation of Rt-2560 GC Columns

Published By: Restek Corporation

Year of Publication: 2019

Link: https://www.restek.com/Technical-Resources/Technical-Library/Foods-Flavors-Fragrances/fff_FFAR3047-UNV

Abstract:

The analysis of fatty acids in milk fat is an important test and this challenging matrix was used by Eurofins Analytik GmbH to evaluate the stability of Rt-2560 columns. Consistent retention times and separations were achieved even after 225 injections, demonstrating the column’s robust performance.

Differential metabolic signatures in naturally and lactic acid bacteria (LAB) fermented ting (a Southern African food) with different tannin content, as revealed by gas chromatography mass spectrometry (GC–MS)-based metabolomics

Author(s): Oluwafemi Ayodeji Adebo1, Eugenie Kayitesi1, Fidele Tugizimana2,3, Patrick Berka Njobeh1

1. Department of Biotechnology and Food Technology, University of Johannesburg

2. Research Centre for Plant Metabolomics, Department of Biochemistry, University of Johannesburg

3. International R&D, Omnia Group, Ltd

Published By: Food Research International

Issue: Vol. 121, July 2019

Year of Publication: 2019

Link: https://www.sciencedirect.com/science/article/pii/S0963996919302017

Abstract: Fermented whole grain (WG) sorghum food products including WG-ting can be obtained from different sample sources and fermentation conditions, leading subsequently to variations in the molecular composition of the products. There is however, a lack of detailed understanding and description of differential molecular profiles of these food products. Thus, the current study is a nontargeted gas chromatography-mass spectrometry (GC–MS)-based metabolomics approach to descriptively elucidate metabolic profiles of two WG-sorghum types [high tannin (HT) and low tannin (LT)] and their derived WG-ting products obtained via fermentation. Metabolites were extracted with 80% aqueous methanol and analyzed on a gas chromatography high resolution time of flight mass spectrometry (GC-HRTOF-MS) system. Chemometric methods such as principal component analysis (PCA) and orthogonal partial least square-discriminant analysis (OPLS-DA) were applied to mine the generated data. Our results showed that tannin contents influenced the composition of the raw sorghum and derived WG-ting samples. Metabolite signatures that differentiated raw HT- and LT-sorghum included cyclic compounds, pesticides, 2,4-di-tert-butylphenol, fatty acid esters, and sugar derivatives. Furthermore, fermentation of the HT- and LT-sorghum into WG-ting led to an increase in the levels of fatty acids, fatty acid esters and some other compounds which are vital from a dietary and health context. Equally observed were reduction of some phenols, cyclic compounds, a pesticide and ketone. Thus, the results demonstrated that the inherent metabolic composition of raw sorghum would lead to differential metabolic changes in the fermented products such as WG-ting, with subsequent dietary and health implications. Fermenting ting with Lactobacillus fermentum FUA 3321 was most desirable as relevant metabolites were observed in both HT- and LT-ting samples. Furthermore, the study highlights the applicability of GC–MS metabolomics in understanding WG-ting fermentation.

Note(s): The study was done using the Rxi-5ms column.

Can Nonmatching Mycotoxin SIDA Internal Standards Be Used for Stable Isotope Dilution Assay Calibration?

Published By: Restek Corporation

Year of Publication: 2019

Link: https://www.restek.com/Technical-Resources/Technical-Library/Foods-Flavors-Fragrances/fff_FFAR3036-UNV

Abstract:

Stable isotope dilution assay (SIDA) is a calibration technique that can be used to offset matrix effects. However, care must be given to choosing appropriate internal standards. This article demonstrates the importance of using a labeled internal standard that matches the target analyte for mycotoxins analysis.

Faster GC-MS Analysis of 3-MCPD and Glycidyl Esters in Edible Oils

Published By: Restek Corporation

Year of Publication: 2019

Link: https://www.restek.com/Technical-Resources/Technical-Library/Foods-Flavors-Fragrances/fff_FFSS3027-UNV

Abstract:

The analysis of 3-MCPD and glycidyl esters using AOCS Cd 29c-13 is time consuming and exposes the GC-MS to harsh derivatization reagents that can limit column lifetime and increase maintenance costs. Here, we optimized the method using split injection, resulting in a time savings of 8 minutes, less damage from derivatization reagents, and the flexibility to use either PTV or split/splitless inlets.

Comparison of extraction techniques for polycyclic aromatic hydrocarbons from lichen biomonitors

Author(s): Leandri Van der Wat and Patricia B. C. Forbes
Department of Chemistry, University of Pretoria, Hatfield, South Africa

Published By: Environmental Science and Pollution Research

Issue: 26

Year of Publication: 2019

Link: https://link.springer.com/article/10.1007%2Fs11356-019-04587-3

Abstract: Lichens are useful biomonitors for atmospheric polycyclic aromatic hydrocarbons (PAHs). Different sample preparation techniques were explored in this regard, including ultrasound-assisted solvent extraction, microwave-assisted extraction, Soxhlet, and the quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique. It was found that a QuEChERS technique using hexane:acetone (1:1, v/v), never reported before for application to lichens, provided the best recoveries of internal standards, the highest total peak area for all PAHs of interest, and %RSDs comparable with the other preparation techniques tested. The optimized sample preparation technique was found to be a comparatively fast method (45 min), with good recoveries (96%), using less solvents and minimal energy consumption. Strong matrix effects were found: both strong enhancement (for the lighter PAHs) and strong suppression (for the heavier PAHs). The use of matrix-matched standards is thus imperative for the accurate determination of PAH concentrations in the lichen samples.

Acknowledgment(s): Restek Corporation and Wirsam Scientific are
thanked for their support of this research.

Quantitation of Mycotoxins in Four Food Matrices Comparing Stable Isotope Dilution Assay (SIDA) with Matrix-Matched Calibration Methods by LC–MS/MS

Author(s): Dan Li; Justin A. Steimling; Joseph D. Konschnik, Scott L. Grossman; Ty W. Kahler
Restek Corporation

Published By: Journal of AOAC International

Year of Publication: 2019

Link: https://www.ingentaconnect.com/content/aoac/jaoac/pre-prints/content-jaoac_190028

Abstract: Background: Mycotoxins are big concerns in food safety. Analytical methods are important for the evaluation of mycotoxins in different food commodities. Objective: In this study, stable isotope dilution assay (SIDA) was compared with a matrix-matched calibration method for the quantification of mycotoxins in four different commercially available commodities and two reference materials. Methods: All samples were extracted with water–acetonitrile (50+50, v/v), followed by filtration and LC–tandem MS analysis. Results: SIDA calibration accuracies ranged from 78.6 to 112% with relative SDs (RSDs) ≤16% across all four matrices. The majority of the recoveries across all matrices ranged from 70 to 120% with RSDs <11%. Of the four mycotoxins in the reference materials analyzed, only three had 13C-internal standard (IS), whereas the fourth was quantified using a closely eluting 13C-IS for a different mycotoxin. Mycotoxins paired with their corresponding 13C-IS had accuracies >90%, whereas accuracies for the mismatched mycotoxin/13C-IS were <14%. Conclusions: When 13C-IS are not available, matrix-matched calibration was also evaluated as an alternative to quantitating target mycotoxins. The use of 13C-IS is the best way to dynamically account for prevalent matrix effects, but matrix matching provides a viable alternative. Highlights: The study compared SIDA and matrix-matched calibration methods in terms of recovery, efficiency, advantages, and limitations for LC-MS based mycotoxin analysis

Evaluation of a Simple Method for Methylmalonic Acid Analysis in Human Plasma by LC-MS/MS

Author: Justin Steimling and Frances Carroll

Published By: Restek Corporation

Year of Publication: 2019

Link: https://www.restek.com/Technical-Resources/Technical-Library/Clinical-Forensic-Toxicology/cft_CFAN3010-UNV

Abstract:

A new LC-MS/MS method for methylmalonic acid (MMA) analysis was developed that provides complete chromatographic resolution from isobaric succinic acid in plasma samples. Excellent chromatographic results were obtained from the direct injection of a protein crash sample supernatant onto a Force C18 column, providing a much simpler sample preparation compared to typical methods.

Eliminate the Impact of Instrument-Related PFAS Interferences by Using a Delay Column

Published By: Restek Corporation

Year of Publication: 2019

Link: https://www.restek.com/Technical-Resources/Technical-Library/Environmental/enviro_EVAR3001-UNV

Abstract:

Using a PFAS delay column is an effective way to separate target PFAS in samples from interferences caused by PFAS contamination in the LC system. This article explains how the PFAS delay column can improve trace-level PFAS analysis by removing the impact of system-related interferences.

Method Evaluation: Analysis of Phosphatidylethanol (PEth) in Human Whole Blood by LC-MS/MS

Author: Shun-Hsin Liang and Frances Carroll

Published By: Restek Corporation

Year of Publication: 2019

Link: https://www.restek.com/Technical-Resources/Technical-Library/Clinical-Forensic-Toxicology/cft_CFAN3009-UNV

Abstract:

The method established in this study provides accurate analysis of phosphatidylethanol (PEth) using a simple protein precipitation procedure and a fast 3.5 minute LC-MS/MS gradient run. Specific, sensitive analysis of PEth 16:0/18:1 in whole blood was obtained due to the unique selectivity and retention of the Raptor FluoroPhenyl column.

A GC in Your Laptop

Author: Jaap de Zeeuw

Restek Corporation

Published By: The Analytical Scientist

Year of Publication: December 2018

Volume, Issue: Volume 71

Link: https://theanalyticalscientist.com/fileadmin/tas/pdf-versions/TAS_Issue_1218.pdf

Abstract:

Very few students get hands-on experience with a working gas chromatography system. In this article, Jaap de Zeeuw explains how we can overcome this problem using ProEZGC software. By simulating separations, this free, web-based software allows users to change any GC parameter and see how the separations are affected.