scholarly journals Potentiometric Electronic Tongue for Pharmaceutical Analytics: Determination of Ascorbic Acid Based on Electropolymerized Films

Chemosensors ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 110
Author(s):  
Gabriela Broncová ◽  
Vadim Prokopec ◽  
Tatiana V. Shishkanova
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Coulometric Titration ◽  
Electronic Tongue ◽  
Neutral Red ◽  
Potentiometric Sensors ◽  
Potentiometric Response ◽  
Accuracy Of Measurements ◽  
The Matrix ◽  
The Individual

This work deals with the design of an experimental potentiometric electronic tongue (ET) for the recognition of various samples of effervescent tablets with different ascorbic acid (vitamin C) contents. The ET consisted of twelve potentiometric sensors based on conductive polymers, which were derived from 4-amino-2,1,3-benzothiadiazole, 3,4-diaminobenzoic acid, and neutral red on the surface of the platinum electrode using cyclic voltammetry. The aim of the potentiometric study was to assess the influence of the vitamin C content and the composition of the matrix of commercial samples on the potentiometric response. The results obtained from the sensor array proved that the stability of the potentiometric signal and the accuracy of measurements are affected by individual sensors. The identification of the vitamin C content in the individual samples of effervescent tablets obtained by means of the potentiometric electronic tongue corresponded with the results of the coulometric titration.

A nutritional analysis of the food rations Martin Frobisher's second expedition, 1577

Polar Record ◽  
2002 ◽  
Vol 38 (204) ◽  
pp. 23-38 ◽  
Author(s):  
Conrad E. Heidenreich ◽  
Nancy L. Heidenreich
Keyword(s):  
Ascorbic Acid ◽  
Vitamin A ◽  
Vitamin C ◽  
Nutrient Intake ◽  
Virtual Absence ◽  
Nutritional Analysis ◽  
Food Procurement ◽  
The Subject ◽  
The Individual ◽  
The Cost

AbstractA list of the provisions for the second expedition led by Martin Frobisher was produced on 26 March 1577, for 115 men and 18 months. These plans contain an extraordinarily detailed food procurement list: the quantity of each food, the cost of each item, and how the rations were to be allocated. The subject of this paper is a nutritional analysis of the rations on this list. It is assumed that the March list is simply an 18-month version of what was put in place for the eventual seven-month expedition.The individual foods for the expedition were grouped into four basic meal plans, rotated throughout the journey at four ‘meat days’ and three ‘fast days’ per week. Since the amount of each food allocated per person per day was indicated, the quantities of each were able to be converted into modern measures, based on foods thought to be near equivalents to those in Frobisher's time, and the caloric and nutrient intake calculated. The results show a fairly monotonous diet of about 4000 calories on fast days to 5000 calories on meat days. Except for a virtual absence of vitamin C, the diet seems nutritionally adequate over short runs. Inadequacies could occur quickly if some foodstuffs went bad, or if members of the crew were depleted of crucial nutrients, such as ascorbic acid, before the voyage began. On longer journeys this diet would have been inadequate, as it is doubtful if beer (29% of the calories) or butter and cheese (most of the vitamin A) could have lasted for more than six months. An examination of 18 Arctic voyages between Frobisher's first (1576) and that of James (1631–1632) demonstrates that they had similar foodstuffs on board, and that few suffered appreciable dietary problems unless they were gone for more than six months.

Ascorbic Acid in Chronic Psychiatric Patients —A Controlled Trial

1963 ◽  
Vol 109 (459) ◽  
pp. 294-299 ◽  
Author(s):  
G. Milner
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Clinical Evidence ◽  
Psychiatric Patients ◽  
Normal Population ◽  
Controlled Trial ◽  
Laboratory Findings ◽  
Classical Condition ◽  
The Individual ◽  
Chronic Psychiatric Patients

Anxiety and excitement have been shown by Maas (1961) to increase the rate of breakdown of ascorbic acid, and in schizophrenics this process may be exaggerated by an abnormality of adrenaline metabolism (Briggs, 1962). Schizophrenics receiving “adequate” dietary amounts of vitamin C, as judged by the requirements of the normal population, are commonly found to have low blood ascorbate levels. Evidence of low blood ascorbate levels in most psychiatric patients has been gathered by Horwitt (1942), Leitner and Church (1956) and others. It has been debated whether such laboratory findings are associated with a state of “subscurvy”, where the individual has the complaints of excessive tiredness, depression, irritability and vague ill-health. Many authorities claim that there is no clinical evidence to justify the distinction of a state of “hypovitaminosis C”. They claim that one either absorbs sufficient ascorbic acid to maintain health, or so little that the classical condition of scurvy supervenes.

scholarly journals The relation between gastric vitamin C concentrations, mucosal histology, and CagA seropositivity in the human stomach

Gut ◽  
1998 ◽  
Vol 43 (3) ◽  
pp. 322-326 ◽  
Author(s):  
Z W Zhang ◽  
S E Patchett ◽  
D Perrett ◽  
P H Katelaris ◽  
P Domizio ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Gastric Juice ◽  
Acid Concentration ◽  
High Performance ◽  
Dehydroascorbic Acid ◽  
Human Stomach ◽  
Ascorbic Acid Concentration ◽  
H Pylori ◽  
The Individual

Background—Vitamin C may be protective against gastric cancer though infection withHelicobacter pylori is associated with a reduction in intragastric concentrations of vitamin C.Aims—To examine the effects ofH pylori infection, gastric juice pH, the severity and extent of gastric inflammation, and CagA antibody status of the individual on gastric juice and mucosal vitamin C concentrations.Patients—One hundred and fifteen patients undergoing routine gastroscopy for investigation of dyspepsia.Methods—High performance liquid chromatography was used to determine vitamin C concentrations. CagA antibody was detected by western blot analysis.Results—Gastric juice ascorbic acid concentration was significantly lower in patients infected withH pylori compared with those uninfected (19.3 μmol/l (interquartile range (IQR) 10.7–44.5) versus 66.9 μmol/l (IQR 24.4–94.2), p=0.003). The reduction in gastric juice ascorbic acid concentration was inversely related to the severity of gastritis (p=0.01). CagA positive patients had significantly lower gastric juice ascorbic acid concentrations than CagA negative ones (14.8 μmol/l (IQR 7.9–52.2) versus 39 μmol/l (IQR 19.9–142.2), p=0.05). Decreased gastric juice dehydroascorbic acid concentrations were observed in patients with gastric atrophy and intestinal metaplasia. Mucosal ascorbic acid concentrations were also significantly lower in infected patients than uninfected patients (p=0.04).Conclusions—The reduction in gastric vitamin C concentrations is related to gastric juice pH, the severity and extent of gastritis, the presence of H pylori, and the CagA antibody status of the individual. These findings may have implications in H pyloriassociated carcinogenesis.

Amperometric assay of vitamin C using an ascorbate oxidase enzyme electrode

1979 ◽  
Vol 44 (11) ◽  
pp. 3395-3404 ◽  
Author(s):  
Pavel Posádka ◽  
Lumír Macholán
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Oxygen Electrode ◽  
Ascorbate Oxidase ◽  
Current Response ◽  
Reaction Conditions ◽  
Long Term Storage ◽  
Oxidase Enzyme ◽  
Optimal Reaction

An oxygen electrode of the Clark type, coated by a thin, active layer of chemically insolubilized ascorbate oxidase from squash peelings specifically detects by measuring oxygen uptake 10 to 400 μg of ascorbic acid in 3 ml of phosphate buffer. The record of current response to substrate addition lasts 1-2 min. The ascorbic acid values determined in various samples of fruit juices are in good agreement with the data obtained by titration and polarography. The suitable composition of the membrane and its lifetime and stability during long-term storage are described; optimal reaction conditions of vitamin C determination and the possibilities of interference of other compounds are also examined. Of the 35 phenols, aromatic amines and acids tested chlorogenic acid only can cause a positive error provided that the enzyme membrane has been prepared from ascorbate oxidase of high purity.

scholarly journals Degradation Kinetic Modelling of Ascorbic Acid from Orange Juice

Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 55
Author(s):  
Alina Soceanu ◽  
Nicoleta Matei ◽  
Simona Dobrinas ◽  
Viorica Popescu
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Orange Juice ◽  
Storage Temperature ◽  
Kinetic Modelling ◽  
Activation Parameters ◽  
Graphical Analysis ◽  
State Theory ◽  
Activation Process ◽  
Degradation Kinetic

Vitamin C or ascorbic acid is a basic nutrient, a highly effective antioxidant, widely used as food additive. Therefore, quality control in food industry demands ascorbic acid determination methods. The purpose of this study was to determine vitamin C in natural orange juices by spectrometric and voltammetric methods. Another goal was to determine the kinetic and thermodynamics activation parameters for ascorbic acid degradation in orange juices over time and at different temperatures. It was observed that during storage, ascorbic acid concentrations in orange juices were gradually decreased with time at a rate depending on storage temperature and type of orange juice. The reaction order was determined through integrated graphical analysis where the dependences of ln ct/c0 as a function of time reveals the high values for R2, indicating that the kinetics of the degradation of AA follows first order reaction at both studied temperatures. For studied samples the loss of ascorbic acid was varied between 4.33% and 9.13%. Enthalpy variation (ΔH) and entropy variation (ΔS) of activation process were obtained from the Eyring–Polany model based on transition state theory. The values of activation energy ranged between 7289.24 kJmol−1 and 15689.54 kJmol−1.

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