RESUMO
In the present study, a novel and reliable analytical method was developed and validated for the simultaneous determination of 1,3,5-tris(2,3-dibromopropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TDBP-TAZTO) and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) in environmental samples using high-performance liquid chromatography coupled to a tandem mass spectrometer. Firstly, for optimization of the liquid chromatography separation, mobile phases, oven temperatures, modifiers, and buffers were varied. Afterwards, the extraction efficiency of sediment and fish samples was tested with different techniques (pressurized liquid, solid-liquid, ultrasound-assisted, and Soxhlet extraction). Additionally, cleanup using modified multilayer silica gel (sediment) and gel permeation chromatography as well as Florisil® columns (fish) with several solvent mixtures were performed. The best results were obtained with the pressurized liquid extraction (optimal conditions: extraction solvent 100% toluene, extraction time 20 min, cycles two, extraction temperature 100 °C, and flushing volume 60%) compared to other solvent extraction methods. On the basis of this optimized analytical procedure, the method was validated with satisfactory values of correlation coefficient (R2) between 0.998 and 0.999 for both matrices in the calibration range of 2.0-502.0 µg kg-1 for TDBP-TAZTO and 16.6-770.6 µg kg-1 for TTBP-TAZ in sediment samples as well as 4.8-303.5 µg kg-1 and 47.4-742.5 µg kg-1 in fish samples (bream), respectively. Mean recoveries (n = 5) were calculated for both analytes with spiked matrices at one concentration level (100 µg kg-1) between 98 and 114% with intra-day relative standard deviations less than 11%. The inter-day precision (n = 15) was also acceptable for both compounds < 11%. It was found that the limit of detection and limit of quantification were in the range of 0.4-1.3 µg kg-1 for TDBP-TAZTO and 10-28 µg kg-1 for TTBP-TAZ in surface sediment samples and 7-25 µg kg-1 and 22-80 µg kg-1 in fish samples (bream), respectively. The results indicated that these analytical methods could provide reliable and efficient approaches for quantification of TDBP-TAZTO and TTBP-TAZ in sediment and fish samples. Graphical abstract.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Retardadores de Chama/análise , Hidrocarbonetos Bromados/análise , Espectrometria de Massas em Tandem/métodos , Triazinas/análise , Poluentes Químicos da Água/análise , Animais , Monitoramento Ambiental/métodos , Peixes/metabolismo , Sedimentos Geológicos/análise , Halogenação , Limite de DetecçãoRESUMO
Because of the high number of possible pesticide residues and their chemical complexity, it is necessary to develop methods which cover a broad range of pesticides. In this work, a qualitative multi-screening method for pesticides was developed by use of HPLC-ESI-Q-TOF. 110 pesticides were chosen for the creation of a personal compound database and library (PCDL). The MassHunter Qualitative Analysis software from Agilent Technologies was used to identify the analytes. The software parameter settings were optimised to produce a low number of false positive as well as false negative results. The method was validated for 78 selected pesticides. However, the validation criteria were not fulfilled for 45 analytes. Due to this result, investigations were started to elucidate reasons for the low detectability. It could be demonstrated that the three main causes of the signal suppression were the co-eluting matrix (matrix effect), the low sensitivity of the analyte in standard solution and the fragmentation of the analyte in the ion source (in-source collision-induced dissociation). In this paper different examples are discussed showing that the impact of these three causes is different for each analyte. For example, it is possible that an analyte with low signal intensity and an intense fragmentation in the ion source is detectable in a difficult matrix, whereas an analyte with a high sensitivity and a low fragmentation is not detectable in a simple matrix. Additionally, it could be shown that in-source fragments are a helpful tool for an unambiguous identification.
Assuntos
Cromatografia Líquida de Alta Pressão/normas , Análise de Alimentos/métodos , Análise de Alimentos/normas , Frutas/química , Praguicidas/análise , Verduras/química , Bases de Dados Factuais , Limite de Detecção , Resíduos de Praguicidas/análise , SoftwareRESUMO
Reported food-related symptoms of patients may sometimes be misleading. A correct delineation of food-induced symptoms is often difficult and various differential diagnoses have to be considered. We report on two cases of food-induced, predominantly respiratory symptoms (in one case life-threatening) in children with food allergy. First, a two-year-old boy with no history of allergies and suspected foreign body aspiration which was finally diagnosed as an anaphylactic reaction to fish, and secondly a six-year-old girl with multiple food allergies and allergic asthma who during an electively performed oral food challenge developed severe respiratory distress, drop in blood pressure, and asphyxia not due to an anaphylactic reaction but due to choking on an unnoticed sweet. These two cases represent challenging, life-threatening symptom constellations involving food-induced reactions in food allergic children, reminding us to question first impressions.
Assuntos
Obstrução das Vias Respiratórias/diagnóstico , Anafilaxia/diagnóstico , Hipersensibilidade Alimentar/diagnóstico , Corpos Estranhos/diagnóstico , Aspiração Respiratória/diagnóstico , Síndrome do Desconforto Respiratório/diagnóstico , Obstrução das Vias Respiratórias/etiologia , Anafilaxia/complicações , Broncoscopia , Criança , Pré-Escolar , Diagnóstico Diferencial , Feminino , Hipersensibilidade Alimentar/complicações , Corpos Estranhos/complicações , Humanos , Masculino , Aspiração Respiratória/complicações , Síndrome do Desconforto Respiratório/etiologiaRESUMO
The reaction behaviour of monosaccharides in the Maillard reaction is well investigated. Amadori compounds, for instance, form deoxyhexosuloses which are responsible for the formation of volatile flavour substances and melanoidins. These intermediates can be quantified by a trapping reaction with o-phenylendiamine as stable quinoxalines. However the reaction behaviour of oligo and polymeric carbohydrates in non-enzymatic browning reactions are hardly known. Therefore maltooligosaccharides and in some cases starch were used together with glycine as model substances to investigate the Maillard reaction mechanism of oligo and polysaccharides. In quasi waterfree reaction systems oligosaccharides form alpha-dicarbonyl compounds via a "peeling off" mechanism. The Maillard reaction with the amino compound starts at the reducing end of an alpha-glucane residue and results in the formation of 1,4-dideoxyhexosulose. This is the main alpha-dicarbonyl compound found by trapping reaction with o-phenylendiamine during thermally induced degradation of maltooligosaccharides. The thermal reaction of maltooligosaccharides is accompanied by transglycosylations leading to formation of branched carbohydrate structures and by dehydrations forming anhydrosugars. The reaction mechanism which is responsible for degradation of oligomeric carbohydrates in aqueous model systems differs significantly from pathways mentioned above for water free reaction conditions. As the main alpha-dicarbonyl compound 3-deoxypentosulose is formed which can be proved also by trapping reactions. Under aqueous reaction conditions the formation of other alpha-dicarbonyls plays only a marginal role in the Maillard reaction of oligomeric carbohydrates. In an aqueous system transglycosylation and dehydration of maltooligosaccharides are not important.
Assuntos
Reação de Maillard , Oligossacarídeos/metabolismo , Polissacarídeos/metabolismo , Temperatura Alta , Isomerismo , Oligossacarídeos/química , Polissacarídeos/química , Volatilização , ÁguaRESUMO
The formation of alpha-dicarbonyl-containing substances and Amadori rearrangement products was studied in the glycine-catalyzed (Maillard reaction) and uncatalyzed thermal degradation of glucose, maltose, and maltotriose using o-phenylenediamine as trapping agent. Various degradation products, especially alpha-dicarbonyl compounds, are formed from carbohydrates with differing degrees of polymerization during nonenzymatic browning. The different Amadori rearrangement products, isomerization products, and alpha-dicarbonyls produced by the used carbohydrates were quantified throughout the observed reaction time, and the relevance of the different degradation pathways is discussed. In the Maillard reaction (MR) the amino-catalyzed rearrangement with subsequent elimination of water predominated, giving rise to hexosuloses with alpha-dicarbonyl structure, whereas under caramelization conditions more sugar fragments with an alpha-dicarbonyl moiety were formed. For the MR of oligosaccharides a mechanism is proposed in which 1,4-dideoxyosone is formed as the predominating alpha-dicarbonyl in the quasi-water-free thermolysis of di- and trisaccharides in the presence of glycine.
Assuntos
Dissacarídeos/metabolismo , Reação de Maillard , Oligossacarídeos/metabolismo , CinéticaRESUMO
Amylolytic enzymes are only slightly inhibited by thermal treated alpha-glucans (10-15%). The addition of glycine to the thermolysis mixture produces no increase of the inhibition. The inhibition of the enzyme activity is probably caused by short-chain alpha-glucans that the secondary binding places of the active centre coat and therefore the hydrolysis is reduced. Glucoamylase and alpha-amylase are not inhibited by non-dialysed melanoidines from the reaction of D-glucose and glycine, but there is a strong inhibition of alpha-glucosidase by these melanoidines (up to 45%). Strongly coloured, low molecular compounds that are formed during the Maillard-reaction and are soluble in ethyl acetate cause no inhibition of Glucoamylase and alpha-amylase.
Assuntos
Glucana 1,4-alfa-Glucosidase/antagonistas & inibidores , Glucanos/metabolismo , Glucanos/farmacologia , Inibidores de Glicosídeo Hidrolases , Reação de Maillard , Polímeros/farmacologia , alfa-Amilases/antagonistas & inibidores , Temperatura Alta , CinéticaRESUMO
The enzymatic degradation of thermal treated alpha-glucans with amylolytic enzymes depends on the reaction environment (T, pH, moisture), the degree of polymerisation (DP) and the branch of the substrates as well as on the presence of amino compounds. The chemical changes of the alpha-glucans due to thermolysis at 180 degrees C are characterized by means of the amount of reducing substances and the amount of maltooligosaccharides (HPLC). In general the enzymatic degradability of the thermal treated alpha-glucans is decreased with increasing time of thermolysis, temperature and moisture content. The enzyme activity with the thermal treated alpha-glucans is diminished in the same way. The addition of amino compounds reduces the enzymatic degradability only at the beginning of the reaction. With increasing time of thermolysis the thermolysates without glycine addition are hardly degraded. As reason for these differences in the enzymatic degradation transglycosylation and non-enzymatic browning reactions (caramalisation/Maillard-reaction) are assumed.
Assuntos
Glucanos/química , Glucosidases/metabolismo , Reação de Maillard , Oligossacarídeos/análise , Cromatografia Líquida de Alta Pressão/métodos , Glucana 1,4-alfa-Glucosidase/metabolismo , Glucanos/metabolismo , Temperatura Alta , Cinética , Termodinâmica , alfa-Amilases/metabolismo , alfa-Glucosidases/metabolismoRESUMO
In this article current knowledge about the Maillard reaction in vivo is described first, especially the glycosylation reactions of various tissues and the identification of different final products and intermediates of Maillard reaction. The influence of MRP on digestion is of significant importance. These products are absorbed in different ways and are excreted in various amounts. Hence, the organism is variably influenced by MRP. The influence of defined MRP, of glycosylated proteins and of melanoidins on glycosidases and proteases is described. The effects produced depend on the enzyme and on the used MRP. Reactive alpha-dicarbonyl compounds play an important role in the organism. Further possible reactions of these compounds caused by reductases are discussed. The protein structure of enzymes is changed by Maillard reaction. Thereby the enzyme activity is influenced by covalent modifications of different amino acids and by inter- and intramolecular crosslinking. Finally, the use of enzymes and monoclonal antibodies for detection of MRP is discussed.
Assuntos
Endopeptidases/metabolismo , Glicosídeo Hidrolases/metabolismo , Reação de Maillard , Oxirredutases/metabolismo , Animais , Endopeptidases/química , Glicosídeo Hidrolases/química , Glicosilação , Humanos , Oxirredutases/química , Polímeros/metabolismo , Conformação Proteica , Proteínas/metabolismoRESUMO
The well known enzymatic method for the determination of glucose in aqueous solution with the system glucose oxidase/peroxidase/o-dianisidine was modified in a way that enables the quantitative determination of glucose in various reverse micellar systems. For instance in the 0.1 M sodium-bis-(2-ethylhexyl)-sulfosuccinate/n-octane system the useable glucose measuring range is between 10 and 70 micrograms glucose per 3 ml micellar solution. Investigations concerning the influence of the pH-value and the wo-value on the enzyme activity of glucose oxidase in the system 0.1 M sodium-bis-(2-ethylhexyl) sulfosuccinate/n-octane led to a shift of the pH-optimum from pH 5.5-6.0 in aqueous solution, to pH 4.0, in reverse micellar solution. The bell-shaped wo-dependence of the enzyme activity, typical for many other enzymes, was not found for glucose oxidase at pH 4.0, and was less clearly visible at the other investigated pH-values with an optimum at wo = 5.6.
Assuntos
Aspergillus niger/enzimologia , Glucose Oxidase/metabolismo , Glucose/análise , Micelas , Tensoativos/química , Água/química , Fenômenos Químicos , Físico-Química , Ácido Dioctil Sulfossuccínico , Concentração de Íons de Hidrogênio , Cinética , Métodos , Octanos , Concentração OsmolarRESUMO
The influence of Amadori-compounds (fructosyl-, maltulosyl- and maltotriulosylglycin) on the activity of the enzymes alpha-glucosidase (from Saccharomyces cerevisiae), glucoamylase (from Aspergillus niger) and alpha-amylase (from porcine pancreas) was studied. Fructosylglycin was not hydrolyzed by all three enzymes. alpha-Glucosidase hydrolyzes maltulosylglycin 10 times slower than maltotriulosylglycin. Glucoamylase and alpha-amylase catalyze only the cleavage of maltotriulosylglycin to form glucose and maltulosylglycin. The activities of alpha-glucosidase and glucoamylase are inhibited through the Amadori-compounds fructosyl- and maltulosylglycin. These Amadori-compounds don't influence the activity of alpha-amylase. Electronic effects or interactions between the secondary amino function of Amadori-compounds and the carboxyl- or carboxylate groups of active centres could be responsible for such an inhibition.
Assuntos
Glucana 1,4-alfa-Glucosidase/antagonistas & inibidores , Inibidores de Glicosídeo Hidrolases , Reação de Maillard , Oligossacarídeos/metabolismo , alfa-Amilases/antagonistas & inibidores , Animais , Aspergillus niger/enzimologia , Dissacarídeos/metabolismo , Enzimas Imobilizadas , Glucana 1,4-alfa-Glucosidase/metabolismo , Glicina/análogos & derivados , Glicina/metabolismo , Pâncreas/enzimologia , Saccharomyces cerevisiae/enzimologia , Suínos , Trissacarídeos/metabolismo , alfa-Amilases/metabolismo , alfa-Glucosidases/metabolismoRESUMO
The thermally induced decomposition of disaccharide Amadori compounds has been compared to those of monosaccharide ones under almost water-free conditions. The structure of the synthesized maltulosyl compound has been proved to be 4C1-alpha-D-glucopyranosyl- (1----4)-2C5-beta-D-fructopyranosylglycine by 1H- and 13C-NMR spectroscopy. The decomposition of Amadori compounds has been used to study the kinetics of the browning reaction. Compared to fructosylglycine and maltotriulosylglycine, the browning of the disaccharide is faster. Curie point pyrolysis at 300 degrees C and investigation of the pyrolysate by gas chromatography/mass spectrometry have shown that the disaccharide component influences the thermal process. Furanes and furanones have been detected as predominant degradation products, the main one being 2(5H)-furanone. For the first time, we suggest a reaction pathway for the formation of these products via the Maillard reaction which includes 1,6-anhydroglucose.
Assuntos
Dissacarídeos/metabolismo , Temperatura Alta , Reação de Maillard , Glicina/análogos & derivados , Glicina/química , Glicina/metabolismo , Cinética , Maltose/análogos & derivados , Maltose/química , Maltose/metabolismoRESUMO
Glucosylthiazolidine-4-carbonic acid, an intermediate of the Maillard reaction between D-glucose and L-cysteine, was given in doses of 0, 25, 50 or 100 mg/kg b.w. by oral intubation to male and female rats for 21 days. General appearance, growth, food consumption, haematology, urine analysis and serum chemistry including determinations of enzyme activities, organ weights and macroscopic and microscopic pathology were used as criteria for adverse effects. Effects on the kidneys were indicated by oliguria and decreased specific gravity of the urine in males and histopathological changes of the proximal tubules in females. The no-effect dose established from this study is 25 mg/kg b.w.
Assuntos
Glucosídeos/toxicidade , Rim/efeitos dos fármacos , Reação de Maillard , Tiazóis/toxicidade , Animais , Contagem de Células Sanguíneas/efeitos dos fármacos , Análise Química do Sangue , Relação Dose-Resposta a Droga , Ingestão de Alimentos/efeitos dos fármacos , Feminino , Masculino , Tamanho do Órgão/efeitos dos fármacos , Ratos , Urina , Aumento de Peso/efeitos dos fármacosRESUMO
ESR spectroscopic investigations on the mechanism of Maillard-reactions using the model D-glucose/glycine show radical formation in some of the reaction steps. These are possibly due to competitive reactions against ionic mechanism. The formation of radicals depends on the concentration of reactants and reaches a maximum in thermically induced browning reactions. The addition of L-cysteine leads to a decrease in the radical concentration to about 60%. It can be indirectly proven that the radicals are involved in the formation of browning products. The hyperfine structures of ESR spectra are supposed to be similar to pyrazine cation radicals.
Assuntos
Cisteína/farmacologia , Glucose , Glicina , Reação de Maillard , Sulfitos/farmacologia , Espectroscopia de Ressonância de Spin Eletrônica , Modelos BiológicosRESUMO
Glucose can be extracted from the carbohydrates of pig liver by water, but glycogen only by boiling alkalies. The last one can be precipitated with ethanol. The boiling of an aqueous liver suspension causes a decrease in glucose quantity as expected. Thereby the influence of the liver proteins on carbohydrate concentration becomes apparent as well as the interaction between both substances within the reaction of non-enzymatic browning. A series of storing experiments confirmed that neither freezing nor boiling temperatures can completely stop this reaction.
Assuntos
Carboidratos da Dieta/análise , Manipulação de Alimentos , Fígado/análise , Animais , Glucose/análise , Temperatura Alta , Glicogênio Hepático/análise , SuínosRESUMO
The influence of thermical treatment of pig liver on the concentration of water-soluble proteins was investigated. The latter can be partly separated by preparative thin-layer chromatography and characterized by UV-spectroscopy. The initial decrease in measurable protein content as a result of the denaturation was followed by a light increase. The latter was caused by an easier accessibility of the hydrophobe protein areas and by hydrolytical splitting of the proteins. The same assessment of quality is also valid for the model protein (bovine-serum albumin). The addition of glucose causes in both cases an intensive reaction between proteins and sugars--the result is in every case an increase in browning intensity.
Assuntos
Proteínas Alimentares/análise , Manipulação de Alimentos , Glucose/análise , Fígado/análise , Animais , Cromatografia em Camada Fina , Culinária , Solubilidade , Espectrofotometria Ultravioleta , Suínos , ÁguaRESUMO
The storage life of industrial-made tinned liver sausage has more effect on the decrease in glucose and total carbohydrate content than the corresponding sterilisation program. The addition of glucose and casein shows greater effect as respects the Maillard-reaction on tinned model than on minced liver.