Use of a total ionic strength adjustment buffer for electrode determination of fluoride in water supplies

1968 ◽  
Vol 40 (7) ◽  
pp. 1169-1171 ◽  
Author(s):  
Martin. Frant ◽  
James W. Ross
Keyword(s):  
Ionic Strength ◽  
Water Supplies ◽  
Total Ionic Strength

SERUM TRIIODOTHYRONINE DETERMINATION BY SATURATION ANALYSIS

1973 ◽  
Vol 72 (4) ◽  
pp. 714-726 ◽  
Author(s):  
A. Burger ◽  
B. Miller ◽  
C. Sakoloff ◽  
M. B. Vallotton
Keyword(s):  
Ionic Strength ◽  
Limit Of Detection ◽  
Improved Method ◽  
Accuracy Of Measurement ◽  
Tracer Amount ◽  
The Mean ◽  
Physiological Values ◽  
Hyperthyroid Patients ◽  
Solvent Blank

ABSTRACT An improved method for the determination of serum triiodothyronine (T3) has been developed. After addition of a tracer amount of the hormone, T3 was extracted from 1 ml serum under conditions of pH and ionic strength which favoured T3 extraction (89%) over thyroxine (T4) extraction (58%). Chromatography of the extracted material on Sephadex LH-20 separated T3 completely from residual T4. The T3 eluate was dried, then re-dissolved in 0.5 ml NaOH 0.04 n. To 0.2 ml duplicate aliquots, a standard amount of TBG was added for the competitive protein analysis. After one hour incubation at 4°C, separation of bound from free T3 was achieved on small Sephadex G-25 columns. Overall recovery was 67 ± 10.8% and correction for the loss was made. The solvent blank was 37 ± 27 (sd) ng/100 ml. Accuracy of measurement of known quantities of T3 added to serum was 98.4%. The coefficient of variation within the assay was 6.2% and between the assays it was 11.4%. The limit of detection (0.1 ng) corresponded to a concentration of 25 ng/100 ml. T4 added to serum did not interfere with T3 determination until high non-physiological values were reached. The mean ± sd serum T3 in 54 euthyroid subjects was 153 ± 58 ng/100 ml and in 24 hyperthyroid patients it was 428 ±186 ng/100 ml; 4 out of the 24 hyperthyroid values were within 2 sd of the mean euthyroid group. All the values found in the euthyroid group were well above the limit of detection of the method.

Optimization of Extraction Parameters of Reverse Iontophoretic Determination of Blood Glucose in an Artificial Skin Model

2020 ◽  
Vol 16 (6) ◽  
pp. 722-737
Author(s):  
Cigdem Yengin ◽  
Emrah Kilinc ◽  
Fatma Gulay Der ◽  
Mehmet Can Sezgin ◽  
Ilayda Alcin
Keyword(s):  
Ionic Strength ◽  
Body Fluids ◽  
Extraction Time ◽  
Artificial Skin ◽  
Dialysis Membrane ◽  
Skin Model ◽  
Non Invasive ◽  
Electrode Distance ◽  
Experimental Parameters

Background: Reverse İontophoresis (RI) is one of the promising non-invasive technologies. It relies on the transition of low magnitude current through the skin and thus glucose measurement becomes possible as it is extracted from the surface during this porter current flow. Objective: This paper deals with the development and optimization of an RI determination method for glucose. CE dialysis membrane based artificial skin model was developed and the dependence of RI extraction on various experimental parameters was investigated. Method: Dependence of RI extraction performance on noble electrodes (platinum, silver, palladium, ruthenium, rhodium) was checked with CA, CV and DPV, in a wide pH and ionic strength range. Optimizations on inter-electrode distance, potential type and magnitude, extraction time, gel type, membrane MWCO, usage frequency, pretreatment, artificial body fluids were performed. Results: According to the optimized results, the inter-electrode distance was 7.0 mm and silver was the optimum noble metal. Optimum pH and ionic strength were achieved with 0.05M PBS at pH 7.4. Higher glucose yields were obtained with DPV, while CA and CV achieved almost the same levels. During CA, +0.5V achieved the highest glucose yield and higher potential even caused a decrease. Glucose levels could be monitored for 24 hours. CMC gel was the optimum collection media. Pretreated CE membrane with 12kD MWCO was the artificial skin model. Pretreatment affected the yields while its condition caused no significant difference. Except PBS solution (simulated as artificial plasma), among the various artificial simulated body fluids, intestinal juice formulation (AI) and urine formulation U2 were the optimum extraction media, respectively. Conclusion: In this study, various experimental parameters (pretereatment procedure, type and MWCO values of membranes, inter-electrode distance, electrode material, extraction medium solvents, ionic strength and pH, collection medium gel type, extraction potential type and magnitude, extraction time and etc) were optimized for the non-invasive RI determination of glucose in a CE dialysis membrane-based artificial skin model and various simulated artificial body fluids.

Titration of sulphates and lead using lead ion selective electrode

1981 ◽  
Vol 46 (2) ◽  
pp. 368-376 ◽  
Author(s):  
Josef Veselý
Keyword(s):  
Ionic Strength ◽  
Electrode Surface ◽  
Salt Content ◽  
Ion Selective Electrode ◽  
Lead Ion ◽  
Selective Electrode ◽  
Limit Of Determination ◽  
Total Salt Content ◽  
Automatic Titration

Titration of sulphates with lead perchlorate employing lead ion selective electrode indication was studied using additions of various organic solvents at different pH' and ionic strength values. As the optimum emerged systems with 60-70% 1,4-dioxane, pH' 5.3-5.6. After dehydration with sodium hydroxide, dioxane must be freed from the electrode surface-oxidizing impurities by their reduction with sodium metal and subsequent distillation. The method was applied to determination of sulphates in mountain spring waters. Units of ppm can be determined; the limit of determination, however, depends considerably on the content of dioxane, total salt content in the sample, and speed of the semi-automatic titration. Lead can be determined with EDTA in concentrations down to c(Pb2+) = 5 . 10-6 mol l-1.

GC-MS determination of volatile organic compounds in drinking water supplies in Mexico

2000 ◽  
Vol 15 (2) ◽  
pp. 131-139 ◽  
Author(s):  
Silvia Gelover ◽  
Erick R. Bandala ◽  
Teresa Leal-Ascencio ◽  
Sixto P�rez ◽  
Evaristo Mart�nez
Keyword(s):  
Drinking Water ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Water Supplies ◽  
Volatile Organic

NaCl and CaCl2 activity coefficients in mixed aqueous solutions

1965 ◽  
Vol 20 (6) ◽  
pp. 1332-1336 ◽  
Author(s):  
Edward W. Moore ◽  
James W. Ross
Keyword(s):  
Ionic Strength ◽  
Activity Coefficients ◽  
Technical Assistance ◽  
Osmotic Coefficients ◽  
Electrode System ◽  
Glass Electrode ◽  
Concentration Data ◽  
Harned's Rule ◽  
Potentiometric Measurement

In the investigation of numerous physiological phenomena it is the activity of an ion species which is desired, rather than stoichiometric concentration. The calculation of mean ionic activity from known concentration data requires accurate activity coefficients (ggr). This report concerns the determination of ggrNaCl and ggrCaCl2 in mixed NaCl-CaCl2 solutions by potentiometric measurement with a sodium-selective glass electrode-Ag/AgCl electrode system over the ionic strength range 0.05–0.5 m. Log ggrNaCl varied linearly, at constant total ionic strength, with the ionic strength of CaCl2 in the mixture, in accordance with Harned's rule. From data thus obtained, ggrCaCl2 coefficients in such mixed solutions have been calculated and compared with values calculated from published osmotic data. Resulting activity coefficient curves for ggrCaCl2 are presented over the concentration range encountered in serum and other extracellular fluids. Note: (With the Technical Assistance of Leonard Kaye and Leonard L. Anderson) glass electrodes; ion interaction; electrolyte metabolism; Harned's rule; membrane transport; osmotic coefficients Submitted on March 11, 1965

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