Absolute Chronoamperometric Determination with Cylindrical Semimicroelectrode

1993 ◽  
Vol 58 (2) ◽  
pp. 281-290 ◽  
Author(s):  
Štefan Mesároš ◽  
Miroslav Rievaj ◽  
Dušan Bustin
Keyword(s):  
Ascorbic Acid ◽  
Analytical Application ◽  
Current Component ◽  
Cylindrical Electrode ◽  
Linear Diffusion ◽  
Absolute Method ◽  
Method Of Determination ◽  
Determination Error ◽  
Electroactive Species

An analytical application of chronoamperometry for determination of electroactive species not requiring standardization is described in this paper. It is based upon the separation of current component limited by linear diffusion from that limited by cylindrical contribution to the total flux of determined substance to the cylindrical (wire) Pt-semimicroelectrode (radius 0.02 mm and length 15 mm). The absolute method of determination was verified with o-dianizidine, ferrocyanide, ascorbic acid and dopamine. The optimalization of radius of the cylindrical electrode to minimize the determination error is also presented.

Simple HPLC method of determination of an ascorbic acid in plasma of blood

2016 ◽  
pp. 6-11
Author(s):  
A. A. Dutov ◽  
A. V. Ermolina ◽  
N. A. Shemyakina ◽  
J. L. Lukianova ◽  
D. A. Nikitin
Keyword(s):  
Ascorbic Acid ◽  
Hplc Method ◽  
Method Of Determination

Study on Spectrophotometric Determination of Trace Copper after Flotation Separation Using Microcrystalline Adsorption System Loaded with CuI

2013 ◽  
Vol 726-731 ◽  
pp. 516-522
Author(s):  
Xin Rong Wen ◽  
Chang Qing Tu ◽  
Qi Feng Liang ◽  
Hong Wei Guo
Keyword(s):  
Ascorbic Acid ◽  
Environmental Water ◽  
Ammonium Bromide ◽  
Separation Mechanism ◽  
Adsorption System ◽  
Optimum Conditions ◽  
Method Of Determination ◽  
Novel Method ◽  
Aas Method

The paper presents a novel method for the flotation separation of Cu2+ using microcrystalline adsorption system loaded with CuI prior to the determination by spectrophotometry. The effects of different parameters,such as the dosages of KI, ascorbic acid and octadecyl trimethyl ammonium bromide (OTMAB),various salts and acidity etc. on the flotation yield of Cu2+ have been investigated. The possible flotation separation mechanism of Cu2+ was discussed.The results showed that under the optimum conditions,octadecyl trimethyl ammonium bromide cation (OTMAB+) reacted with I- to produce the microcrystalline matter (Ms-M) of (OTMAB+·I-), Cu2+ could be reduced to Cu+ by ascorbic acid,and then Cu+ reacted with I- to form the precipitation of CuI.The precipitation of CuI was quantificationally adsorbed on the surface of Ms-M of (OTMAB+·I-) and was floated above water phase, the liquid-solid phases were formed with clear interface. In this condition, K+,Na+,Ca2+,Mg2+, Zn2+,Co2+,Al3+,Mn2+,Ni2+ and Fe2+ could not be floated.Therefore, Cu2+ was separated completely from the above metal ions.A new spectrophotometric method of determination of trace copper by flotation separation using microcrystalline adsorption system loaded with CuI was established.The proposed method has been successfully applied to the determination of Cu2+ in various environmental water samples, and the results agreed well with those obtained by AAS method.

Fluorometric determination of ascorbic acid in the absence of the oxidant in juices of common citrus

Planta Medica ◽  
2010 ◽  
Vol 76 (12) ◽  
Author(s):  
A Copra-Janicijevic ◽  
E Sofic ◽  
L Klepo ◽  
A Topcagic ◽  
I Tahirovic ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Fluorometric Determination

The Effect of Stress and Warfarin on the Adrenal Gland in Relation to Spontaneous Hemorrhage, as Judged by Measurement of Adrenal Ascorbic Acid and Serum Corticosterone

1971 ◽  
Vol 26 (02) ◽  
pp. 275-288 ◽  
Author(s):  
S Chattopadhyay ◽  
D. D Johnson ◽  
G. J Millar ◽  
L. B Jaques
Keyword(s):  
Ascorbic Acid ◽  
Acid Concentration ◽  
Ascorbic Acid Concentration ◽  
Corticosterone Concentration ◽  
Serum Corticosterone ◽  
Spontaneous Hemorrhage ◽  
Combined Action ◽  
Series Of Experiments ◽  
Pituitary Adrenal Axis

SummaryRats were subjected to the following procedures: No treatment, Stressor (10% NaCl i.p.), Warfarin for 7 days, Stressor followed by Warfarin; and groups were sacrificed at intervals for assessment of spontaneous hemorrhage and of adrenal ascorbic acid concentration. There was no hemorrhage in the no treatment and stressor groups; some hemorrhage in the warfarin group; profound hemorrhage with Warfarin + Stressor. The adrenal ascorbic acid concentration was found to be lower, 8 h and again 5 days after stress, and remained lower in the warfarin + stress animals. Warfarin had no effect on adrenal ascorbic acid level.In another series of experiments in which the stress consisted of an electric current to the cage floor for 6 sec over 15 min, rats were sacrificed daily for determination of serum corticosterone concentration and occurrence of spontaneous hemorrhage. There was a statistically significant increase of serum corticosterone concentration with stress, warfarin and combined warfarin and stress treatments (P< 0.001 for all three variables). There was a significant correlation (r = 0.96 and 0.89, P< 0.01) for serum corticosterone concentration with hemorrhage score and incidence of hemorrhage in stressed rats receiving warfarin, but not in those receiving only warfarin. The results indicate an activation, rather than an exhaustion, of the pituitary-adrenal axis during the combined action of anticoagulant and stress, which results in the development of spontaneous hemorrhage.

ADENOHYPOPHYSEAL LH CONTENT IN NORMAL, ANDROGEN-STERILIZED AND PROGESTERONE-PRIMED STERILE FEMALE RATS

1962 ◽  
Vol 39 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Roger A. Gorski ◽  
Charles A. Barraclough
Keyword(s):  
Ascorbic Acid ◽  
Electrical Stimulation ◽  
Quantitative Determination ◽  
Median Eminence ◽  
Hypothalamic Stimulation ◽  
Female Rats ◽  
Rat Pituitary ◽  
Gland Content ◽  
Stimulation Of

ABSTRACT We have previously suggested that the failure of the androgen-sterilized, persistent-oestrous rat to ovulate, following electrical stimulation of the median eminence structures of the hypothalamus, is due to an insufficiency in adenohypophyseal LH concentration. Using the ovarian ascorbic acid technique for quantitative determination of pituitary LH content, the present studies have demonstrated that the sterile rat pituitary gland contains one-third the LH content of the normal prooestrous gland. Furthermore, not only does progesterone priming of this persistent-oestrous rat result in a 75 % increase in LH concentration, but on hypothalamic stimulation sufficient LH is released to induce ovulation. The decrease in LH concentration which accompanies ovulation in the progesterone-primed, sterile rat is approximately 45 % of the total gland content as compared with a 51 % decrease in pituitary content in the normal cyclic rat.

Development of a method for multielemental determination in water by EDXRF with radioisotopic source of 238Pu.

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Camilo Fuentes Serrano ◽  
Juan Reinaldo Estevez Alvares ◽  
Alfredo Montero Alvarez ◽  
Ivan Pupo Gonzales ◽  
Zahily Herrero Fernandez ◽  
...  
Keyword(s):  
Thin Layer ◽  
Expanded Uncertainty ◽  
Considerable Decrease ◽  
X Ray ◽  
Precipitation Efficiency ◽  
Method Of Determination ◽  
Sensitivity Curves ◽  
Order Of Magnitude ◽  
Metrological Parameters

A method for determination of Cr, Fe, Co, Ni, Cu, Zn, Hg and Pb in waters by Energy Dispersive X Ray Fluorescence (EDXRF) was implemented, using a radioisotopic source of 238Pu. For previous concentration was employed a procedure including a coprecipitation step with ammonium pyrrolidinedithiocarbamate (APDC) as quelant agent, the separation of the phases by filtration, the measurement of filter by EDXRF and quantification by a thin layer absolute method. Sensitivity curves for K and L lines were obtained respectively. The sensitivity for most elements was greater by an order of magnitude in the case of measurement with a source of 238Pu instead of 109Cd, which means a considerable decrease in measurement times. The influence of the concentration in the precipitation efficiency was evaluated for each element. In all cases the recoveries are close to 100%, for this reason it can be affirmed that the method of determination of the studied elements is quantitative. Metrological parameters of the method such as trueness, precision, detection limit and uncertainty were calculated. A procedure to calculate the uncertainty of the method was elaborated; the most significant source of uncertainty for the thin layer EDXRF method is associated with the determination of instrumental sensitivities. The error associated with the determination, expressed as expanded uncertainty (in %), varied from 15.4% for low element concentrations (2.5-5 μg/L) to 5.4% for the higher concentration range (20-25 μg/L).

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