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Michael Rychlik - One of the best experts on this subject based on the ideXlab platform.
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microalgae a superior source of folates quantification of folates in halophile microalgae by stable isotope Dilution Assay
Frontiers in Bioengineering and Biotechnology, 2020Co-Authors: Dirk Volker Woortman, Tobias Fuchs, Monika Fuchs, Nadine Weber, Thomas Bruck, Lisa Striegel, Michael RychlikAbstract:A multitude of human nutritional supplements based on Chlorella vulgaris biomass has recently been introduced to the specialty food market. In this study, an analysis of total folate contents in Chlorella sp. and a series of marine microalgae was conducted to evaluate folate content in alternative algae-based food production strains. For the first time, total folate content and vitamer distribution in microalgae were analyzed by stable isotope Dilution Assay (SIDA) using LC-MS/MS, which has demonstrated its superiority with respect to folate quantification. Consistently, high folate contents were detected in all examined microalgae samples. High folate concentrations of 3,460 +/- 134 mu g/100 g dry biomass were detected in freshly cultivated Chlorella vulgaris, notably also in other well-researched microalgae strains. To that end, the highest folate content currently documented for any algae sample was measured in the marine microalgae Picochlorum sp. isolate with values of 6,470 +/- 167 mu g/100 g dry biomass. This calls for alternative products based on other algae biomass. Our data indicate that freshwater and marine microalgae provide extremely high concentrations of folates, which warrant further studies on the regulation of pteroylpolyglutamates in algae as well as on bioaccessibility, absorption, and retention in humans.
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Biosynthesis of seven carbon-13 labeled Alternaria toxins including altertoxins, alternariol, and alternariol methyl ether, and their application to a multiple stable isotope Dilution Assay
Analytical and Bioanalytical Chemistry, 2015Co-Authors: Yang Liu, Michael RychlikAbstract:An unprecedented stable isotope Dilution Assay for the genotoxic altertoxins along with exposure data of consumers is presented to enable a first risk assessment of these Alternaria toxins in foods. Altertoxins were produced as the most abundant Alternaria toxins in a modified Czapek–Dox medium with a low level of glucose as the carbon source and ammonium sulfate as the sole nitrogen source. Labeled altertoxins were synthesized in the same way using [^13C_6]glucose. Moreover, labeled alternariol, alternariol methyl ether, altenuene, and alternuisol were biosynthesized in another modified medium containing [^13C_6]glucose and sodium [^13C_2]acetate. A stable isotope Dilution LC–MS/MS method was developed and used for food analysis. For altertoxin I, altertoxin II, alterperylenol, alternariol, and alternariol methyl ether, the limits of detection ranged from 0.09 to 0.53 μg kg^−1. The inter-/intra-day ( n = 3 × 6) relative standard deviations of the method were below 13 %, and the recoveries ranged between 96 and 109 %. Among the various commercial food samples, some of the organic whole grains revealed low-level contamination with altertoxin I and alterperylenol, and paprika powder, which was heavily loaded with alternariol, alternariol methyl ether, and tentoxin, showed higher contamination level of altertoxin I and alterperylenol. Altertoxin II and III and stemphyltoxin III were not detectable. In addition, if the food was contaminated with altertoxins, it was likely to be co-contaminated with the other Alternaria toxins, but not necessarily vice versa. Maximum concentrations of altertoxin I and alterperylenol were detected in sorghum feed samples containing 43 and 58 μg kg^−1, respectively. This was significantly higher than that in the measured food samples.
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Determination of tenuazonic acid in human urine by means of a stable isotope Dilution Assay
Analytical and bioanalytical chemistry, 2013Co-Authors: Stefan Asam, Katharina Habler, Michael RychlikAbstract:The content of tenuazonic acid in human urine was determined by a stable isotope Dilution Assay (SIDA) that was recently developed for the analysis of food commodities and extensively re-validated for urine matrix in this study. Linearity of the response curve was proven between molar ratios n(labeled standard)/n(analyte) of 0.02–100. The limits of detection and determination were 0.2 and 0.6 μg/L, respectively. The mean recovery of the stable isotope Dilution Assay was 102 ± 3 % in the range between 1.0 and 100 μg/L. InterAssay precision was 6.7 % (relative standard deviation of three triplicate analyses of a human urine sample during 3 weeks). The method was applied to two studies dealing with urinary excretion of tenuazonic acid: In the first study, tenuazonic acid was quantified in the 24-h urine of six volunteers from Germany (three female, three male) in a concentration range of 1.3–17.3 μg/L or 2.3–10.3 ng/mg−1 creatinine, respectively. In the second study, two volunteers (one female, one male) ingested 30 μg tenuazonic acid by consumption of naturally contaminated whole meal sorghum infant cereals and tomato juice, respectively. The urinary excretion of the ingested tenuazonic acid was 54–81 % after 6 h, depending on matrix and volunteer. After 24 h, 87–93 % of the ingested amount of tenuazonic acid was excreted, but the fate of the remaining about 10 % is open. Thus, it is not possible to exclude potential health hazards for the consumer, completely.
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Content of the Alternaria mycotoxin tenuazonic acid in food commodities determined by a stable isotope Dilution Assay
Mycotoxin Research, 2012Co-Authors: Stefan Asam, Martina Lichtenegger, Michael RychlikAbstract:The Alternaria mycotoxin tenuazonic acid (TA) was quantified in fruit juices ( n = 50), cereals ( n = 12) and spices ( n = 38) using a recently developed stable isotope Dilution Assay (SIDA). [^13 C_6,^15 N]-TA was used as the internal standard. Method validation revealed low limits of detection (LODs) of 0.15 μg/kg (fruit juices), 1.0 μg/kg (cereals) and 17 μg/kg (spices). The respective limits of quantitation were about three times higher. Recovery was about 100% for all matrices. The precision (relative standard deviation of replicate analyses of naturally contaminated samples) was 4.2% (grape juice; 1.7 μg/kg), 3.5% (whole wheat flour; 36 μg/kg) and 0.9% (curry powder; 215 μg/kg). The median content of TA in the analyzed samples was 1.8 μg/kg (fruit juices), 16 μg/kg (cereals) and 500 μg/kg (spices). Positive samples amounted to 86% (fruit juices), 92% (cereals) and 87% (spices).
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Determination of ochratoxin A in food: comparison of a stable isotope Dilution Assay, liquid chromatography-fluorescence detection and an enzyme-linked immunosorbent Assay
Mycotoxin Research, 2011Co-Authors: Michael Lindenmeier, Peter Schieberle, Michael RychlikAbstract:Quantitative results for the mycotoxin ochratoxin A (OTA), obtained by a stable isotope Dilution Assay (SIDA) were compared with two commonly used analytical methods for OTA quantitation. For this, different types of food, such as wheat, coffee, sultanas, and blood sausages, were analyzed. Because results obtained by the SIDA method were closest to the certified contents of an OTA reference material, data obtained by this method were considered as reference data. For liquid chromatography-fluorescence detection, a clean-up by solid phase extraction on silica was found to be necessary, and a correction for recovery had to be performed to match the data from the SIDA experiments. The enzyme-linked immunosorbent Assay (ELISA) strongly overestimated the OTA content in coffee and nutmeg therefore an extract clean-up by immunoaffinity chromatography had to be used to match the SIDA results. Following this sample preparation, ELISA gave correct qualitative and semiquantitative results, and proved to be a suitable screening method. SIDA was also established as a valuable tool to quantify OTA in meat products, when using a clean-up procedure developed recently for blood samples.
Peter Winterhalter - One of the best experts on this subject based on the ideXlab platform.
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synthesis of deuterium labeled 1 1 6 trimethyl 1 2 dihydronaphthalene tdn and quantitative determination of tdn and isomeric vitispiranes in riesling wines by a stable isotope Dilution Assay
Journal of Agricultural and Food Chemistry, 2019Co-Authors: Pia Bechtloff, Hans-georg Schmarr, Michael Ziegler, Ulrich Fischer, Peter WinterhalterAbstract:The C13-norisoprenoid aroma compounds 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and isomeric 2,10,10-trimethyl-6-methylene-1-oxaspiro[4.5]dec-7-enes, so-called vitispiranes, are considered to be biosynthetically related. They occur at higher concentrations in bottle-aged Riesling wines especially and are important contributors to the varietal aroma of Riesling wines. Because of the variation of the quantitative methods and data reported in the literature, a redetermination of concentration levels for both free and total TDN and isomeric vitispiranes, especially in German Riesling wines, was performed using a stable-isotope-Dilution Assay (SIDA). For this purpose, a novel six-step synthetic route to TDN and deuterium-labeled TDN was developed. A standardized sample preparation for TDN and vitispiranes and a rapid acid-hydrolysis method at genuine wine-pH conditions for the conversion of the precursors into TDN and vitispiranes were also developed. Automated HS-SPME was applied to 250 wine samples from t...
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synthesis of deuterium labeled 1 1 6 trimethyl 1 2 dihydronaphthalene tdn and quantitative determination of tdn and isomeric vitispiranes in riesling wines by a stable isotope Dilution Assay
Journal of Agricultural and Food Chemistry, 2019Co-Authors: Recep Gok, Hans-georg Schmarr, Pia Bechtloff, Michael Ziegler, Ulrich Fischer, Peter WinterhalterAbstract:The C13-norisoprenoid aroma compounds 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and isomeric 2,10,10-trimethyl-6-methylene-1-oxaspiro[4.5]dec-7-enes, so-called vitispiranes, are considered to be biosynthetically related. They occur at higher concentrations in bottle-aged Riesling wines especially and are important contributors to the varietal aroma of Riesling wines. Because of the variation of the quantitative methods and data reported in the literature, a redetermination of concentration levels for both free and total TDN and isomeric vitispiranes, especially in German Riesling wines, was performed using a stable-isotope-Dilution Assay (SIDA). For this purpose, a novel six-step synthetic route to TDN and deuterium-labeled TDN was developed. A standardized sample preparation for TDN and vitispiranes and a rapid acid-hydrolysis method at genuine wine-pH conditions for the conversion of the precursors into TDN and vitispiranes were also developed. Automated HS-SPME was applied to 250 wine samples from two wine competitions, and analysis was performed by gas chromatography-mass spectrometry with selected-ion monitoring (GC-SIM-MS) as well as selected-reaction monitoring (GC-SRM-MS).
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folate content in sea buckthorn berries and related products hippophae rhamnoides l ssp rhamnoides lc ms ms determination of folate vitamer stability influenced by processing and storage assessed by stable isotope Dilution Assay
Analytical and Bioanalytical Chemistry, 2008Co-Authors: Derek Gutzeit, Peter Winterhalter, Sabine Monch, Gerold Jerz, Michael RychlikAbstract:A stable isotope Dilution Assay was adopted for quantitation of folate vitamers in sea buckthorn berries, juice, and concentrate using fourfold labeled folate isotopologues of the folate derivatives as the internal standards and reversed-phase liquid chromatography–tandem mass spectrometry with electrospray ionization (LC-ESI-MS/MS). Processing effects and storage stability were investigated during juice and concentrate production from sea buckthorn berries (Hippophae rhamnoides). The technological processing of the berries caused a total degradation of tetrahydrofolate and 5-formyltetrahydrofolate in the generated juice. The content of the main folate vitamer 5-methyltetrahydrofolate remained approximately unchanged during the whole processing from the berries to the concentrate. Sea buckthorn juice was stored under two household storage conditions (6 °C, 25 °C), and also under accelerated aging conditions (40 °C) for up to 7 days to determine the effects of storage temperature on the stability of 5-methyltetrahydrofolate. The content of 5-methyltetrahydrofolate was nearly unchanged during the storage at 6 °C after 7 days. The juice showed almost identical degradation of 5-methyltetrahydrofolate of about 17–20% at 25 °C and 40 °C after 7 days of storage.
Hans-georg Schmarr - One of the best experts on this subject based on the ideXlab platform.
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synthesis of deuterium labeled 1 1 6 trimethyl 1 2 dihydronaphthalene tdn and quantitative determination of tdn and isomeric vitispiranes in riesling wines by a stable isotope Dilution Assay
Journal of Agricultural and Food Chemistry, 2019Co-Authors: Pia Bechtloff, Hans-georg Schmarr, Michael Ziegler, Ulrich Fischer, Peter WinterhalterAbstract:The C13-norisoprenoid aroma compounds 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and isomeric 2,10,10-trimethyl-6-methylene-1-oxaspiro[4.5]dec-7-enes, so-called vitispiranes, are considered to be biosynthetically related. They occur at higher concentrations in bottle-aged Riesling wines especially and are important contributors to the varietal aroma of Riesling wines. Because of the variation of the quantitative methods and data reported in the literature, a redetermination of concentration levels for both free and total TDN and isomeric vitispiranes, especially in German Riesling wines, was performed using a stable-isotope-Dilution Assay (SIDA). For this purpose, a novel six-step synthetic route to TDN and deuterium-labeled TDN was developed. A standardized sample preparation for TDN and vitispiranes and a rapid acid-hydrolysis method at genuine wine-pH conditions for the conversion of the precursors into TDN and vitispiranes were also developed. Automated HS-SPME was applied to 250 wine samples from t...
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synthesis of deuterium labeled 1 1 6 trimethyl 1 2 dihydronaphthalene tdn and quantitative determination of tdn and isomeric vitispiranes in riesling wines by a stable isotope Dilution Assay
Journal of Agricultural and Food Chemistry, 2019Co-Authors: Recep Gok, Hans-georg Schmarr, Pia Bechtloff, Michael Ziegler, Ulrich Fischer, Peter WinterhalterAbstract:The C13-norisoprenoid aroma compounds 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and isomeric 2,10,10-trimethyl-6-methylene-1-oxaspiro[4.5]dec-7-enes, so-called vitispiranes, are considered to be biosynthetically related. They occur at higher concentrations in bottle-aged Riesling wines especially and are important contributors to the varietal aroma of Riesling wines. Because of the variation of the quantitative methods and data reported in the literature, a redetermination of concentration levels for both free and total TDN and isomeric vitispiranes, especially in German Riesling wines, was performed using a stable-isotope-Dilution Assay (SIDA). For this purpose, a novel six-step synthetic route to TDN and deuterium-labeled TDN was developed. A standardized sample preparation for TDN and vitispiranes and a rapid acid-hydrolysis method at genuine wine-pH conditions for the conversion of the precursors into TDN and vitispiranes were also developed. Automated HS-SPME was applied to 250 wine samples from two wine competitions, and analysis was performed by gas chromatography-mass spectrometry with selected-ion monitoring (GC-SIM-MS) as well as selected-reaction monitoring (GC-SRM-MS).
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headspace solid phase microextraction and gas chromatographic analysis of low molecular weight sulfur volatiles with pulsed flame photometric detection and quantification by a stable isotope Dilution Assay
IEEE Journal of Solid-state Circuits, 2018Co-Authors: Sebastian Ullrich, Sylvia Neef, Hans-georg SchmarrAbstract:Low-molecular-weight volatile sulfur compounds such as thiols, sulfides, disulfides as well as thioacetates cause a sulfidic off-flavor in wines even at low concentration levels. The proposed analytical method for quantification of these compounds in wine is based on headspace solid-phase microextraction, followed by gas chromatographic analysis with sulfur-specific detection using a pulsed flame photometric detector. Robust quantification was achieved via a stable isotope Dilution Assay using commercial and synthesized deuterated isotopic standards. The necessary chromatographic separation of analytes and isotopic standards benefits from the inverse isotope effect realized on an apolar polydimethylsiloxane stationary phase of increased film thickness. Interferences with sulfur-specific detection in wine caused by sulfur dioxide were minimized by addition of propanal. The method provides adequate validation data, with good repeatability and limits of detection and quantification. It suits the requirements of wine quality management, allowing the control of oenological treatments to counteract an eventual formation of excessively high concentration of such malodorous compounds.
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Optimization in multidimensional gas chromatography applying quantitative analysis via a stable isotope Dilution Assay.
Analytical and bioanalytical chemistry, 2013Co-Authors: Hans-georg Schmarr, Petra Slabizki, Charlotte LegrumAbstract:Trace level analyses in complex matrices benefit from heart-cut multidimensional gas chromatographic (MDGC) separations and quantification via a stable isotope Dilution Assay. Minimization of the potential transfer of co-eluting matrix compounds from the first dimension (1D) separation into the second dimension separation requests narrow cut-windows. Knowledge about the nature of the isotope effect in the separation of labeled and unlabeled compounds allows choosing conditions resulting in at best a co-elution situation in the 1D separation. Since the isotope effect strongly depends on the interactions of the analytes with the stationary phase, an appropriate separation column polarity is mandatory for an isotopic co-elution. With 3-alkyl-2-methoxypyrazines and an ionic liquid stationary phase as an example, optimization of the MDGC method is demonstrated and critical aspects of narrow cut-window definition are discussed.
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Analysis of 2-aminoacetophenone in wine using a stable isotope Dilution Assay and multidimensional gas chromatography-mass spectrometry.
Journal of chromatography. A, 2006Co-Authors: Hans-georg Schmarr, Sebastian Ganss, Wei Sang, Theodoros PotouridisAbstract:The key compound in the wine off-flavor phenomenon "Untypische Alterungsnote" (UTA) is 2-aminoacetophenone (AAP). A new method for its quantitative analysis in wine is described. The analysis is based on solid phase extraction with LiChrolut EN as sorbent material followed by multidimensional gas chromatography coupled to mass spectrometry (MDGC-MS). Matrix effects due to the complex wine aroma composition could be overcome by an alkaline washing step of the extract and the use of selected ion monitoring as detection mode. Quantification is based on a stable isotope Dilution Assay using deuterated 2-aminoacetophenone as internal standard.
Mirko Paiardini - One of the best experts on this subject based on the ideXlab platform.
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A Tat/Rev Induced Limiting Dilution Assay to Measure Viral Reservoirs in Non-Human Primate Models of HIV Infection
Scientific Reports, 2019Co-Authors: Ines Frank, Arpan Acharya, Nanda K. Routhu, Meropi Aravantinou, Justin L. Harper, Stephanie Maldonado, Maria Sole Cigoli, Stanka Semova, Svetlana Mazel, Mirko PaiardiniAbstract:The establishment of latent infection and poorly characterized viral reservoirs in tissues represent major obstacles to a definitive cure for HIV. Non-human primate (NHP) models of HIV infection are critical to elucidate pathogenic processes and an essential tool to test novel therapeutic strategies. Thus, the availability of novel Assays to measure residual viral replication and reservoirs in NHP models may increase their utility in the search for an HIV cure. We developed a tat/rev induced limiting Dilution Assay to measure the frequency of CD4^+ T cells that express multiply-spliced(ms)_SIV RNA in presence and absence of stimulation. We validated the Assay using cell lines and cells from blood and lymph nodes of SIV infected macaques. In vitro , SIV/SHIV TILDA detects only cells expressing viral proteins. In SIV/SHIV-infected macaques, CD4^+ T cells that express msSIV/SHIV RNA (TILDA data) were detected also in the setting of very low/undetectable viremia. TILDA data were significantly higher after stimulation and correlated with plasma viral load (pVL). Interestingly, TILDA data from early cART initiation correlated with peak and AUC pVL post-cART interruption. In summary, we developed an Assay that may be useful in characterizing viral reservoirs and determining the effect of HIV interventions in NHP models.
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a tat rev induced limiting Dilution Assay to measure viral reservoirs in non human primate models of hiv infection
Scientific Reports, 2019Co-Authors: Ines Frank, Arpan Acharya, Nanda K. Routhu, Meropi Aravantinou, Justin L. Harper, Stephanie Maldonado, Stanka Semova, Svetlana Mazel, Maria Sole Cigoli, Mirko PaiardiniAbstract:The establishment of latent infection and poorly characterized viral reservoirs in tissues represent major obstacles to a definitive cure for HIV. Non-human primate (NHP) models of HIV infection are critical to elucidate pathogenic processes and an essential tool to test novel therapeutic strategies. Thus, the availability of novel Assays to measure residual viral replication and reservoirs in NHP models may increase their utility in the search for an HIV cure. We developed a tat/rev induced limiting Dilution Assay to measure the frequency of CD4+ T cells that express multiply-spliced(ms)_SIV RNA in presence and absence of stimulation. We validated the Assay using cell lines and cells from blood and lymph nodes of SIV infected macaques. In vitro, SIV/SHIV TILDA detects only cells expressing viral proteins. In SIV/SHIV-infected macaques, CD4+ T cells that express msSIV/SHIV RNA (TILDA data) were detected also in the setting of very low/undetectable viremia. TILDA data were significantly higher after stimulation and correlated with plasma viral load (pVL). Interestingly, TILDA data from early cART initiation correlated with peak and AUC pVL post-cART interruption. In summary, we developed an Assay that may be useful in characterizing viral reservoirs and determining the effect of HIV interventions in NHP models.
Stefan Asam - One of the best experts on this subject based on the ideXlab platform.
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Determination of tenuazonic acid in human urine by means of a stable isotope Dilution Assay
Analytical and bioanalytical chemistry, 2013Co-Authors: Stefan Asam, Katharina Habler, Michael RychlikAbstract:The content of tenuazonic acid in human urine was determined by a stable isotope Dilution Assay (SIDA) that was recently developed for the analysis of food commodities and extensively re-validated for urine matrix in this study. Linearity of the response curve was proven between molar ratios n(labeled standard)/n(analyte) of 0.02–100. The limits of detection and determination were 0.2 and 0.6 μg/L, respectively. The mean recovery of the stable isotope Dilution Assay was 102 ± 3 % in the range between 1.0 and 100 μg/L. InterAssay precision was 6.7 % (relative standard deviation of three triplicate analyses of a human urine sample during 3 weeks). The method was applied to two studies dealing with urinary excretion of tenuazonic acid: In the first study, tenuazonic acid was quantified in the 24-h urine of six volunteers from Germany (three female, three male) in a concentration range of 1.3–17.3 μg/L or 2.3–10.3 ng/mg−1 creatinine, respectively. In the second study, two volunteers (one female, one male) ingested 30 μg tenuazonic acid by consumption of naturally contaminated whole meal sorghum infant cereals and tomato juice, respectively. The urinary excretion of the ingested tenuazonic acid was 54–81 % after 6 h, depending on matrix and volunteer. After 24 h, 87–93 % of the ingested amount of tenuazonic acid was excreted, but the fate of the remaining about 10 % is open. Thus, it is not possible to exclude potential health hazards for the consumer, completely.
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Content of the Alternaria mycotoxin tenuazonic acid in food commodities determined by a stable isotope Dilution Assay
Mycotoxin Research, 2012Co-Authors: Stefan Asam, Martina Lichtenegger, Michael RychlikAbstract:The Alternaria mycotoxin tenuazonic acid (TA) was quantified in fruit juices ( n = 50), cereals ( n = 12) and spices ( n = 38) using a recently developed stable isotope Dilution Assay (SIDA). [^13 C_6,^15 N]-TA was used as the internal standard. Method validation revealed low limits of detection (LODs) of 0.15 μg/kg (fruit juices), 1.0 μg/kg (cereals) and 17 μg/kg (spices). The respective limits of quantitation were about three times higher. Recovery was about 100% for all matrices. The precision (relative standard deviation of replicate analyses of naturally contaminated samples) was 4.2% (grape juice; 1.7 μg/kg), 3.5% (whole wheat flour; 36 μg/kg) and 0.9% (curry powder; 215 μg/kg). The median content of TA in the analyzed samples was 1.8 μg/kg (fruit juices), 16 μg/kg (cereals) and 500 μg/kg (spices). Positive samples amounted to 86% (fruit juices), 92% (cereals) and 87% (spices).
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Development of a Stable Isotope Dilution Assay for Tenuazonic Acid
Journal of agricultural and food chemistry, 2011Co-Authors: Stefan Asam, Yang Liu, Katharina Konitzer, Michael RychlikAbstract:A stable isotope Dilution Assay (SIDA) for the Alternaria mycotoxin tenuazonic acid was developed. Therefore, [13C6,15N]-tenuazonic acid was synthesized from [13C6,15N]-isoleucine by Dieckmann intramolecular cyclization after acetoacetylation with diketene. The synthesized [13C6,15N]-tenuazonic acid was used as the internal standard for determination of tenuazonic acid in tomato products by liquid chromatography tandem mass spectrometry after derivatization with 2,4-dinitrophenylhydrazine. Method validation revealed a limit of detection of 0.1 μg/kg and a limit of quantitation of 0.3 μg/kg. Recovery was close to 100% in the range of 3−300 μg/kg. Determination of tenuazonic acid in two samples of different tomato ketchups (naturally contaminated) was achieved with a coefficient of variation of 2.3% and 4.7%. Different tomato products (n = 16) were analyzed for their content of tenuazonic acid using the developed SIDA. Values were between 15 and 195 μg/kg (tomato ketchup, n = 9), 363 and 909 μg/kg (tomato p...