scholarly journals A Dilute and Shoot Strategy for Determining Alternaria Toxins in Tomato-Based Samples and in Different Flours Using LC-IDMS Separation

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1017
Author(s):  
Ádám Tölgyesi ◽  
Tamás Farkas ◽  
Mária Bálint ◽  
Thomas J. McDonald ◽  
Virender K. Sharma
Keyword(s):  
Matrix Effects ◽  
Internal Standard ◽  
High Sensitivity ◽  
Food Samples ◽  
Standard Samples ◽  
Limit Of Quantification ◽  
Enhanced Sensitivity ◽  
Alternaria Toxins ◽  
Sample Extraction ◽  
Liquid Chromatography Tandem Mass

Alternaria toxins are emerging mycotoxins whose regulation and standardization are in progress by the European Commission and the European Committee for Standardization. This paper describes a dilute and shoot approach to determine five Alternaria toxins in selected food samples using liquid chromatography–tandem mass spectrometry (LC-MS/MS). The strategy involves sample extraction with acidified aqueous methanol, followed by a solvent change accomplished via sample evaporation and reconstitution. The quantification is based on isotope dilution, applying all corresponding isotopically labeled internal standards to compensate possible matrix effects of the analysis. The main advantages of the present method over other existing methods includes simple and effective sample preparation, as well as detection with high sensitivity. The five-fold sample dilution can decrease matrix effects, which were evaluated with both external and internal standard methods. The results demonstrated a limit of quantification lower than 1.0 µg/kg for all five analytes for the first time. The newly presented method showed acceptable accuracy (52.7–111%) when analyzing naturally contaminated and spiked standard samples at the described levels. The method was validated for tomato-based and flour samples (wheat, rye, and maize). The absolute recovery ranged from 66.7% to 91.6% (RSD < 10%). The developed method could be an alternative approach for those laboratories that exclude sample cleanup and pre-concentration of state-of-the-art instruments with enhanced sensitivity.

scholarly journals Ultraperformance Liquid Chromatography–Tandem Mass Spectrometry Assay for Iohexol in Human Serum

2009 ◽  
Vol 55 (6) ◽  
pp. 1196-1202 ◽  
Author(s):  
Thomas M Annesley ◽  
Larry T Clayton
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Human Serum ◽  
Matrix Effects ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
Structural Analog ◽  
Limit Of Quantification ◽  
Iodinated Contrast ◽  
Liquid Chromatography Tandem Mass

Abstract Background: Iohexol is an iodinated contrast dye that has been shown to be useful in the estimation of glomerular filtration rate (GFR) in patients with suspected renal insufficiency. We developed and validated an ultraperformance liquid chromatography (UPLC)–triple quadrupole mass spectrometry (MS/MS) assay for quantifying iohexol in human serum. Methods: Sample preparation involved dilution of 50 μL serum with 400 μL water, followed by protein precipitation with zinc sulfate and methanol containing the structural analog ioversol as the internal standard. After 1:20 dilution of the supernatant with water, 5 μL was injected into the UPLC-MS/MS system. Chromatography was performed using a Waters Oasis HLB 5-μm particle size, 2.1 × 20 mm column maintained at 50 °C. We used a 1-step acetonitrile/0.1% formic acid gradient to elute the compounds of interest at a common retention time of 0.96 min. The multiple reaction monitoring transitions used for integration and quantification were m/z 821.7→803.7 for iohexol and m/z 807.9→589.0 for ioversol in the electrospray positive ionization mode. Results: The assay was linear from 2.5 mg/L (lower limit of quantification) to 1500 mg/L iohexol, with a mean extraction efficiency of &gt;99%. Recovery of nominal target concentrations was 99%–102%. Interassay imprecision ranged from 7.9% at a concentration of 2.5 mg/L to 4.1% at 1000 mg/L. Ion suppression studies showed no matrix effects on the ionization of the 2 compounds. Conclusions: This rapid UPLC-MS/MS method can be successfully used for quantifying iohexol in human serum. .

scholarly journals Quantitation of Benzodiazepines and Metabolites in Urine by Liquid Chromatography–Tandem Mass Spectrometry

2018 ◽  
Vol 3 (3) ◽  
pp. 397-407
Author(s):  
Yu Zi Zheng ◽  
Dustin R Bunch ◽  
Katherine Lembright ◽  
Sihe Wang
Keyword(s):  
Precise Measurement ◽  
High Sensitivity ◽  
Urine Samples ◽  
Limit Of Quantification ◽  
Internal Standards ◽  
Independent Laboratory ◽  
Chromatography Tandem Mass Spectrometry ◽  
Analytical Recovery ◽  
Liquid Chromatography Tandem Mass ◽  
Analytical Time

Abstract Background Benzodiazepines (BZDs) are central nervous system depressants that are prescribed to prevent seizures, manage anxiety, or help sleep. When misused, BZDs can lead to addiction and sometimes cause death. Measurement of BZDs in urine is used to identify their use, especially in pain management settings. LC-MS/MS is preferred for these measurements because of its high sensitivity and specificity. Here, we report an LC-MS/MS assay for measuring 7 BZDs and metabolites in urine. Methods Urine sample was incubated at 60 °C for 30 min after addition of internal standards and a β-glucuronidase solution. After centrifugation, the supernatant was diluted with methanol and water before being injected onto a C18 analytical column in an LC-MS/MS system for quantification. The analytical time between injections was 4.35 min. The analytes included 7-aminoclonazepam, α-hydroxyalprazolam, α-hydroxytriazolam, oxazepam, lorazepam, nordiazepam, and temazepam. Results The lower limit of quantification ranged from 30 ng/mL to 50 ng/mL with an analytical recovery &gt;80% for all 7 analytes. Total CV was &lt;10% for all analytes (3 concentration levels of 100, 2500, and 5000 ng/mL; n = 30 each). This method had 100% agreement with a GC-MS method offered by an independent laboratory for negative urine samples. For the positive urine samples, this method showed a strong correlation (R &gt; 0.96) with the GC-MS method. Conclusions The LC-MS/MS assay allows accurate and precise measurement of 7 BZDs and metabolites in a single analytical run with a short analytical run time and broad measuring ranges.

scholarly journals Rapid and Sensitive Method for Quantitative Determination of Lopinavir and Ritonavir in Human Plasma by Liquid Chromatography- Tandem Mass Specrtometry

2009 ◽  
Vol 6 (1) ◽  
pp. 223-230 ◽  
Author(s):  
G. A. Temghare ◽  
S. S. Shetye ◽  
S. S. Joshi
Keyword(s):  
Liquid Chromatography ◽  
Human Plasma ◽  
Solid Phase ◽  
Internal Standard ◽  
Therapeutic Monitoring ◽  
Tandem Mass ◽  
Limit Of Quantification ◽  
Liquid Chromatography Tandem Mass ◽  
Sensitive Method

A rapid and sensitive liquid chromatography-mass spectrometric (LC-MS-MS) method for the simultaneous determination of lopinavir and ritonavir in human plasma using abacavir as internal standard has been developed and validated. Sample preparation of plasma involved solid phase extraction. Detection was performed using an Applied Biosystems Sciex API 2000 Mass spectrometer. The assay of lopinavir and ritonavir was linear over the range of 50 ng mL-1to 20000 ng mL-1and 20 ng mL-1to 3000 ng mL-1 respectively with a precision of <15% and accuracy in the range of 85-115%. The limit of quantification in plasma for lopinavir and ritonavir was 50 ng mL-1and 20 ng mL-1respectively. The described method has the advantage of being rapid and easy and it could be applied in therapeutic monitoring of these drugs in human plasma

Quantification and Stereochemical Composition of R-(−) and S-(+)-Clenbuterol Enantiomers in Bovine Urine by Liquid Chromatography–Tandem Mass Spectrometry

2019 ◽  
Vol 44 (3) ◽  
pp. 237-244
Author(s):  
Benjamín Velasco-Bejarano ◽  
Jahir Bautista ◽  
Martha E Rodríguez ◽  
Raquel López-Arellano ◽  
Roberto Arreguín-Espinosa ◽  
...  
Keyword(s):  
Extraction Efficiency ◽  
Limit Of Detection ◽  
Internal Standard ◽  
High Specificity ◽  
Wilcoxon Test ◽  
Adrenergic Agonist ◽  
Limit Of Quantification ◽  
Bovine Urine ◽  
Enantiomeric Analysis ◽  
Liquid Chromatography Tandem Mass

Abstract Clenbuterol (4-amino-α-[(tert-butylamino)methyl]-3,5-dichlorobenzylalcohol) is a β2-adrenergic agonist. The consumption of meat contaminated with clenbuterol can lead to increased heart rate, blood pressure, anxiety, palpitations and skeletal muscle tremors. Several analytical methods have been developed to identify and quantify clenbuterol in different biological matrices. In this report, we have developed a specific and sensitive analytical method for quantifying clenbuterol and performed an in-depth enantiomeric analysis in bovine urine. The method was evaluated in accordance with international guidelines, and we used an isotopically labeled analog as an internal standard. The extraction efficiency for clenbuterol in bovine urine was &gt; 98%, the limit of detection was 0.05 ng/mL and the limit of quantification was 0.10 ng/mL. Our assay showed high specificity, no carryover was observed and the assay was linear in the range 0.10–8.0 ng/mL. Fifteen bovine urine samples were analyzed (containing clenbuterol), and an enantiomeric analysis was performed. The clenbuterol concentration range was 0.10–10.56 ng/mL across these samples. The levorotatory enantiomer was detected at greater concentrations than the dextrorotatory enantiomer, the ratio being 1.7 ± 0.6 (n = 15), and a statistical difference was observed (P &lt; 0.05) using the Wilcoxon test.

scholarly journals Quantification of Tau in Cerebrospinal Fluid by Immunoaffinity Enrichment and Tandem Mass Spectrometry

2014 ◽  
Vol 60 (4) ◽  
pp. 683-689 ◽  
Author(s):  
Thomas McAvoy ◽  
Michael E Lassman ◽  
Daniel S Spellman ◽  
Zhenlian Ke ◽  
Bonnie J Howell ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Cerebrospinal Fluid ◽  
Tandem Mass Spectrometry ◽  
Magnetic Beads ◽  
Internal Standard ◽  
Tandem Mass ◽  
Limit Of Quantification ◽  
Total Tau ◽  
Liquid Chromatography Tandem Mass ◽  
Full Scan

Abstract BACKGROUND Cerebrospinal fluid (CSF) tau is a common biomarker for Alzheimer disease (AD). Measurements of tau have historically been performed using immunoassays. Given the molecular diversity of tau in CSF, the selectivity of these immunoassays has often been questioned. Therefore, we aimed to develop an analytically sensitive and selective immunoaffinity liquid chromatography–tandem mass spectrometry (LC-MS/MS) (IA-MS) assay. METHODS IA-MS sample analysis involved the addition of an internal standard, immunoaffinity purification of tau using a tau monoclonal antibody coupled to magnetic beads, trypsin digestion, and quantification of a surrogate tau peptide by LC-MS/MS using a Waters Trizaic nanoTile ultraperformance LC microfluidic device. Further characterization of tau peptides was performed by full-scan MS using a Thermo Orbitrap LC-MS. CSF samples from a cohort of age-matched controls and patients with AD were analyzed by the IA-MS method as well as a commercially available immunoassay. RESULTS The IA-MS assay had intra- and interassay imprecision values of 3.2% to 8.1% CV and 7.8% to 18.9% C, respectively, a mean recovery of 106%, and a limit of quantification of 0.25 pmol/L and was able to quantify tau concentrations in all human specimens tested. The IA-MS assay showed a correlation of R2 = 0.950 against a total-tau immunoassay. In patients with AD, tau was increased approximately 2-fold. CONCLUSIONS Combining immunoaffinity enrichment with microflow LC-MS/MS analysis is an effective approach for the development of a highly selective assay to measure total tau and, potentially, other posttranslationally modified forms of tau in CSF.

scholarly journals Studies on the Stability of Acrylamide in Food During Storage

2005 ◽  
Vol 88 (1) ◽  
pp. 268-273 ◽  
Author(s):  
Katrin Hoenicke ◽  
Robert Gatermann
Keyword(s):  
Milk Powder ◽  
Internal Standard ◽  
Food Samples ◽  
Reaction Products ◽  
Before And After ◽  
Raw Sugar ◽  
Liquid Chromatography Tandem Mass ◽  
Sh Group ◽  
The Stability ◽  
Soluble Coffee

Abstract Acrylamide levels in a variety of food samples were analyzed before and after 3 months of storage at 10°–12°C. The analysis was performed by liquid chromatography tandem mass spectrometry (LC/MS/MS) using deuterium-labeled acrylamide as internal standard. Acrylamide was stable in most matrixes (cookies, cornflakes, crispbread, raw sugar, potato crisps, peanuts) over time. However, slight decreases were determined for dietary biscuits (83–89%) and for licorice confection (82%). For coffee and cacao powder, a significant decrease occurred during storage for 3 or 6 months, respectively. Acrylamide concentrations dropped from 305 to 210 μg/kg in coffee and from 265 to 180 μg/kg in cacao powder. On the contrary, acrylamide remained stable in soluble coffee as well as in coffee substitutes. Reactions of acrylamide with SH group-containing substances were assumed as the cause for acrylamide degradation in coffee and cacao. Spiking experiments with acrylamide revealed that acrylamide concentrations remained stable in baby food, cola, and beer; however, recovery levels dropped in milk powder (71%), sulfurized apricot (53%), and cacao powder (17%). These observations suggest that variations in the acrylamide content of food, especially in coffee and cacao, can vary depending on the storage time because special food constituents and/or reaction products can affect the levels.

Identification of Suvorexant in Blood Using LC–MS-MS: Important Considerations for Matrix Effects and Quantitative Interferences in Targeted Assays

2019 ◽  
Vol 44 (3) ◽  
pp. 245-255 ◽  
Author(s):  
Britni Skillman ◽  
Sarah Kerrigan
Keyword(s):  
Matrix Effects ◽  
Limit Of Detection ◽  
Chemical Properties ◽  
Internal Standard ◽  
Forensic Toxicology ◽  
Calibration Model ◽  
Physico Chemical ◽  
Limit Of Quantitation ◽  
Liquid Chromatography Tandem Mass ◽  
Electrospray Interface

Abstract Suvorexant (Belsomra®) is a novel dual orexin receptor antagonist used for the treatment of insomnia. The prevalence of suvorexant in forensic samples is relatively unknown, which demonstrates the need for robust analytical assays for the detection of this sedative hypnotic in forensic toxicology laboratories. In this study, suvorexant was isolated from whole blood using a simple acidic/neutral liquid–liquid extraction followed by analysis by liquid chromatography tandem mass spectrometry (LC–MS/MS). Matrix effects were evaluated qualitatively and quantitatively using various extraction solvents, proprietary lipid clean-up devices and source conditions. The method was validated in terms of limit of detection, limit of quantitation, precision, bias, calibration model, carryover, matrix effects and drug interferences. Electrospray is a competitive ionization process whereby compounds in the droplet compete for a limited number of charged sites at the surface. As such, it is capacity-limited, and LC–MS-based techniques must be carefully evaluated to ensure that matrix effects or coeluting drugs do not impact quantitative assay performance. In this report, we describe efforts to ameliorate such effects in the absence of an isotopically labeled internal standard. Matrix effects are highly variable and heavily dependent on the physico-chemical properties of the substance. Although there is no universal solution to their resolution, conditions at the electrospray interface can mitigate these issues. Using this approach, the LC–MS/MS assay was fully validated and limits of detection and quantitation of 0.1 and 0.5 ng/mL suvorexant were achieved in blood.

Pattern and distribution of ergot alkaloids in cereals and cereal products from European countries

2014 ◽  
Vol 7 (2) ◽  
pp. 217-230 ◽  
Author(s):  
S.V. Malysheva ◽  
D.A. Larionova ◽  
J. Diana Di Mavungu ◽  
S. De Saeger
Keyword(s):  
Ergot Alkaloids ◽  
Food Samples ◽  
Human Consumption ◽  
Limit Of Quantification ◽  
Cereal Products ◽  
Liquid Chromatography Tandem Mass ◽  
Food And Feed ◽  
Animal Feeding ◽  
Sample Set ◽  
Feed Samples

This paper reports on the occurrence of ergot alkaloids in cereals and cereal products in Europe. It includes occurrence data our group previously submitted to the European Food Safety Authority and new data we gathered afterwards. A total of 1,065 samples of cereals and cereal products intended for human consumption and animal feeding were analysed by liquid chromatography-tandem mass spectrometry for the presence of ergot alkaloids. The sample set included rye-, wheat- and multigrain-based food as well as rye-, wheat- and triticale-based feed. The study revealed that 59% of the analysed food and feed samples were contaminated with ergot alkaloids to some extent. In 55% of the samples, the levels of the -ine isomers were above the limit of quantification (LOQ), while contamination with the -inine isomers was found in 51% of the samples. The median values for the main ergot alkaloids (-ine forms) and the epimers (-inine forms) were 1 and 2 μg/kg, respectively. Ergot alkaloids were present in 84% of rye food, 67% of wheat food, 48% of multigrain food, 52% of rye feed, 27% of wheat feed, and 44% of triticale feed at total alkaloid levels ranging from ≤1 (LOQ) to 12,340 μg/kg. Though the highest frequencies of contamination were observed for food samples, the feed samples, in particular Swiss rye feed, accounted for the highest levels of ergot alkaloids. The frequencies and levels of contamination were significantly lower in organic samples compared to conventional samples. Maximum levels of individual ergot alkaloids up to 3,270 μg/kg (for ergotamine) were observed. Overall, ergosine, ergokryptine and ergocristine were the frequently occurring ergot alkaloids. The co-occurrence of all six ergot alkaloids was noted in 35% of the positive samples. Occurrence of a single ergot alkaloid was mainly observed for ergometrine.

scholarly journals Simultaneous determination and pharmacokinetics studies of five isoflavones in rat plasma by UHPLC-MS/MS after oral administration of Radix Astragali extract

2021 ◽  
Author(s):  
Jianwei Han ◽  
Wenbo Zhu ◽  
Ling Yu ◽  
Yajun Chen ◽  
Gaosong Wu ◽  
...  
Keyword(s):  
Oral Administration ◽  
High Performance ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
Rat Plasma ◽  
Tandem Mass ◽  
Radix Astragali ◽  
Limit Of Quantification ◽  
Liquid Chromatography Tandem Mass ◽  
Mass Spectrometery

AbstractA rapid, sensitive and convenient method based on ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was developed and validated for the simultaneous quantification of calycosin-7-O-β-d-glucoside (CCSG), ononin, calycosin, (6aR,11aR)-9,10-dimethoxypterocarpan-3-O-β-d-glucopyanoside (DPPG), and 7,2′-dihydroxy-3′,4′-dimethoxyisoflavan-7-O-β-d-glucopyanoside (DIFG) in rat plasma after oral administration of the methanol extraction from Radix Astragali. Theophylline played the role of internal standard (IS). Preparation of plasma samples by liquid-liquid extraction method with ethyl acetate after precipitation of protein with methanol. The analytes were detected with a triple quadrupole tandem mass spectrometery (MS) in multiple reaction monitoring (MRM) mode and a positive ion electrospray ionization (ESI). The method was validated with the concentration ranges of 1.96–62.69 ng/mL for CCSG, 1.70–54.5 ng/mL for ononin, 1.85–59.06 ng/mL for calycosin, 2.14–137.24 ng/mL for DPPG and1.96–125.25 ng/mL for DIFG, respectively. The method had the lower limit of quantification (LLOQ) with 0.49, 0.21, 0.92, 1.07, and 0.98 ng/mL for CCSG, ononin, calycosin, DPPG and DIFG respectively, and the precision less than 10%. The RSD of the accuracy was in the range of −4.35–8.91%. The results may be helpful to provide more accurate references to clinical application of this herb.

scholarly journals Electrochemical Applications for the Antioxidant Sensing in Food Samples Such as Citrus and Its Derivatives, Soft Drinks, Supplementary Food and Nutrients

2021 ◽  
Author(s):  
Ersin Demir ◽  
Hülya Silah ◽  
Nida Aydogdu
Keyword(s):  
Antioxidant Capacity ◽  
Analytical Methods ◽  
High Sensitivity ◽  
Differential Pulse ◽  
Food Samples ◽  
Electrochemical Methods ◽  
General Description ◽  
Range Limit ◽  
Healthy Individuals ◽  
Limit Of Quantification

Although there are many definitions of antioxidants, the most general description; antioxidants are carried a phenolic function in their structure and prevent the formation of free radicals or intercept from damage to the cell by scavenging existing radicals. Moreover, they are one of the most effective substances that contain essential nutrients for healthy individuals. The importance of these antioxidants, which have an incredible effect on the body and increase the body’s resistance, is increasing day by day for healthy individuals. Numerous studies have been carried out for antioxidants with excellent properties and however new, reliable, selective, sensitive and green analytical methods are sought for their determination at trace levels in food samples. Along with the latest developments, electrochemical methods are of great interest in the world of science because they are fast, reliable, sensitive and environmentally friendly. Electrochemical methods have been frequently applied to analyze antioxidant capacity in many nutrients samples found in different forms such as solid, liquid without any pretreatment applications in the last decade. Furthermore, these methods are preferred because of the short analysis time, the ability to lower detection limits, reduction in a solvent, high sensitivity, portability, low sample consumption, wide working range, and more economical than existing other traditional analytical methods. The antioxidant sensing applications by modern electrochemical methods such as cyclic, square wave, differential pulse, and combined with stripping voltammetric techniques were used to deduce antioxidant capacity (AC) in critical nutrients. Moreover, this chapter includes a description of the classification of electrochemical methods according to the working electrode type, dynamic working range, limit of determination (LOD), limit of quantification (LOQ), sample type, and using standard analyte and so forth for each voltammetric methods. While many articles applied for the determination of antioxidant sensing by electrochemistry have gained momentum in the last two decades, we focused on the studies conducted over the last 4 years in this chapter.

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