Rapid speciation of Se(IV) and Se(VI) by flow injection-capillary electrophoresis system with contactless conductivity detection

A flow injection-capillary electrophoresis system with contactless conductivity detection and hydrostatic-pressure-generated flow was used for the fast and sensitive speciation of Se(IV) and Se(VI). The sample throughput was 25samples per hour using a background electrolyte solution containing 8.75mM l-histidine (His) adjusted to pH4.00 with acetic acid. The repeatability of peak areas (n=8) was better than 1.41% and the limits of detection were 190μgL−1 and 7.5μgL−1 for Se(IV) and Se(VI), respectively. The interference from carbonate, typically present in water samples, was eliminated by using a low-pH electrolyte in which carbonate is uncharged and migrates at the EOF front. The method was applied to the analysis of Se(IV) and Se(VI) in soil samples that were spiked with both selenium species and the results for recovery of both selenium species were in good agreement with their introduced concentration

A PORTABLE CAPILLARY ELECTROPHORESIS SYSTEM FOR INORGANIC ARSENIC DETERMINATION

Joint Research on Environmental Science and Technology for the Eart

Factors affected decarboxylation activity of Enterococcus faecium isolated from rabbit

  Biogenic amines (BA) are basic nitrogenous compounds formed mainly by decarboxylation of amino acids. There are generated in course of microbial, vegetable and animal metabolisms. The aim of the study was to monitor factors affected production of biogenic amines by Enterococcus faecium, which is found in rabbit meat. Biogenic amines were analyzed by means of UPLC (ultrahigh performance liquid chromatography) equipped with a UV/VIS DAD detector. Decarboxylation activity of E. faecium was mainly influenced by the cultivation temperature and the amount of NaCl in this study. E. faecium produced most of the monitored biogenic amines levels: tyramine ˂2500 mg.l-1; putrescine ˂30 mg.l-1; spermidine ˂10 mg.l-1 and cadaverine ˂5 mg.l-1

Effects of the lactation period, breed and feed on amino acids profile of mare's milk

The effects of the lactation period, breed, and feed on amino acids profile of mare's milk were investigated. The feed contained two major essential amino acids (EAAs) leucine (7.31-10.3 g. kg-1) and arginine (6.37-9.59 g. kg-1); it also included minor EAAs methionine (2.11-3.05 g. kg-1) and histidine (2.48-3.60 g. kg-1). Glu+Gln, Asp+Asn, and proline, major nonessential amino acids (NEAAs), constituted approximately 60% of total NEAAs (TNEAAs). The ratio of total EAAs to NEAAs ranged from 1:1.2 to 1:1.4. Amino acids (AA) content throughout all milk samples varied due to mare's different conditions and lactation days. Except for the 1P milk sample, total AA content in the 2-8Ps specimens caused by differences in breed oscillated from the 2nd to 28th day of lactation within the following limits: 21.9-54.6 g. kg-1, 33.6-70.7 g. kg-1, 38.1-71.2 g. kg-1, 29.46-74.2 g. kg-1, 52.2-87.1 g. kg-1, 37.9-70.3 g. kg-1 and 26.4-64.5 g. kg-1, respectively. In relation to TEAAs in milk, the highest EAAs levels were reached in arginine, leucine and lysine ranging between 2.41-4.35 g. kg-1, 3.36-5.59 g. kg-1 and 2.72-4.80 g. kg-1, respectively, while the lowest AAs amounts were indicated in histidine and methionine, 0.91-1.58 g. kg-1 and 1.23-2.04 g. kg-1 respectively. Total NEAAs content was slightly higher than that of EAAs; the TNEAAs to TEAAs ratio was 1:0.9 proximately. Glu+Gln, Asp+Asn and proline were determined as major NEAAs of milk ranging between, 6.77-11.0 g. kg-1, 3.21-5.60 g. kg-1 and 1.25-2.18 g. kg-1, respectively; levels of NEAAs such as cysteine and glycine oscillated between 0.89-1.52 g. kg-1 and 0.64-1.15 g. kg-1, respectively. The average TAAs contents caused by breed differences were 62.8 g. kg-1, 42.8 g. kg-1, 44.7 g. kg-1 and 44.8 g. kg-1, respectively, on the 2nd, 5th, 10th, and 28th lactation days. © 2020 Potravinarstvo Slovak Journal of Food Sciences

Liquid chromatographic determination of polyphenenols in Czech beers during brewing proces

High performance liquid chromatographic (HPLC/UV) method was adapted for simultaneous determination of seven polyphenols, including derivatives of benzoic (gallic and vanillic acids) and cinnamic acids (p-coumaric, ferulic and sinapic acids), flavan-3-ols (catechin) and flavonols (rutin) in worts and beers at the various stages of the brewing process. Based on the semi-quantitative HPLC analysis, total polyphenols chromatographic index (TPCI) was in the ranges of 5.18 - 19.4 mg/L and 7.37 - 20.7 mg/L for all worts and beers, respectively. The HPLC analyses showed that relatively high levels of (+)-catechin and gallic acid were in all the worts and the beers, while the values were much lower for ferulic acid, rutin, vanillic acid, sinapic acid and p-coumaric acid. Polyphenols with relatively high concentrations, that were detected in all tested worts and beers, were gallic acid (1.29 - 4.75 mg/L resp. 2.59 - 4.97 mg/L), (+)-catechin (1.66 - 7.95 mg/L resp. 4.70 - 10.0 mg/L) and ferulic acid (0.41 - 4.53 mg/L resp. 1.05 - 2.87 mg/L). On the other side, the sinapic acid (0.72 - 1.59 mg/L resp. 0.72 - 2.5 mg/L), rutin (1.17 - 2.03 mg/L resp. 1.16 - 2.85 mg/L), p-coumaric acid (ND - 4.73 mg/L resp. ND - 1.44 mg/L) and vanillic acid (ND - 1.52 mg/L resp. 0.75 - 1.81 mg/L) were detected in lowest concentrations. In both, worts and beers investigated in this study, the changes in the contents of individual polyphenols were not uniform. In the case of some polyphenols, a decrease in the content was observed after boiling the worts with hops or after the main fermentation until maturation and filtration, but with some polyphenols, the concentrations were constant until the end of the process or even increased. © 2015 Potravinarstvo. All rights reserved

SONDEO ARQUEOLÓGICO SECTOR 35 [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201

Chemical composition of buckwheat plant parts and selected buckwheat products

Chemical composition plant parts (roots, stalks, leaves, blossoms) of common buckwheat (Fagopyrum esculentum Moench) and selected products made from its seeds (peels, whole seed, wholemeal flour, broken seeds, crunchy products Natural and Cocoa, flour, and pasta) was determined. Samples were dried and ground to a fine powder. All analyses were performed according to the Commission Regulation no. 152/2009, while rutin concentration was determined by the modified HPLC method. The lowest content of moisture was found in roots (4.3%) and in peels (almost 8%) and the highest moisture (nearly 11%) was discovered in seeds. The lowest amount of crude protein (3.5%) was found in peels, the highest crude protein amount (>13%) in both flours and leaves (23%). The starch content (>50% in dry matter) differs from one sample to another. Only in peels the content of starch was about 3.5%. From all examined samples, the lowest content of fat was found in crunchy products Cocoa, 1.7%. The lowest amount of histidine was determined in all studied samples, except peels, the highest content of glutamic acid was determined in almost all samples, except peels. Whole-meal flour is very rich source of Ca and Fe. The content of these elements was 1172 mg.kg-1 and 45.9 mg.kg-1, respectively. On the other hand, the highest content of Pb (>1 mg.kg-1) was found in broken seeds. The greatest concentration of rutin was determined in blossoms and leaves (83.6 and 69.9 mg.g-1), respectively. On the other hand, the lowest concentrations of rutin were found in buckwheat products (generally less then 1 mg.g-1, i.e. in wholemeal flour, 702 μg.kg-1, the lowest (almost 10 μg.kg-1) in pasta

Content of 4(5)-methylimidazole, caffeine and chlorogenic acid in commercial coffee brands

Content of 4(5)-methylimidazole (4-MeI), caffeine and chlorogenic acid in commercial coffee brands were determined using high-performance liquid chromatography (HPLC) with UV DAD and MS detectors. Positive ion ESI mass spectra of the 4-MeI standard yielded intense signals corresponding to [M+H]+ (83.0604) and [2M+H]+ ions (165.1115). Also, adducts of 4-MeI with acetonitrile from mobile were detected - [M+ACN]+ ions (124.0849). The LOD of 2.5 ng mL-1 and LOQ of 8.4 ng.mL-1 were calculated according to the following formulas: LOD = 3.SD/S, and LOQ = 10.SD/S, where S is the slope of the calibration curve and SD is the standard deviation of the noise. The caffeine content was compared to the results of the standard addition, 1st derivative and liquid-liquid extraction spectrophotometry. 4-MeI was in tens μg g-1 in the Vietnamese coffees while in units μg.g-1 in all Czech and Brazilian coffees (<2.4 μg.g-1 and <4.9 μg.g-1, respectively). The results for caffeine were within the documented range (0.31 - 2.20%) in all coffee samples. The lower content of caffeine and chlorogenic acid was observed in Vietnamese coffees. All the methods used for determination of caffeine in the Czech and Brazilian coffees gave acceptable precision and accuracy. However, there were significant differences in the results in Vietnamese coffees. The caffeine extractability (100 °C, 3 min brewing) almost reached 100% in Czech and Brazilian coffees, while it was less than 90% in Vietnamese coffees. The Czech and Brazilian coffees tend to produce more caffeine in brews than the Vietnamese coffee because of the different composition of blends and the particle size degree. © 2015 Potravinarstvo