scholarly journals Masking Ability of Various Metal Complexing Ligands at 1.0 mM Concentrations on the Potentiometric Determination of Fluoride in Aqueous Samples

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Sakuni M. De Silva ◽  
Samitha Deraniyagala ◽  
Janitha K. Walpita ◽  
Indira Jayaweera ◽  
Saranga Diyabalanage ◽  
...  
Keyword(s):  
Experimental Data ◽  
Natural Waters ◽  
Ethylenediaminetetraacetic Acid ◽  
Aqueous Samples ◽  
Metal Chelating ◽  
Low Concentrations ◽  
Masking Agents ◽  
Potentiometric Analysis ◽  
Common Anion

Fluoride is a common anion present in natural waters. Among many analytical methods used for the quantification of fluoride in natural waters, potentiometric analysis is one of the most widely used methods because of minimum interferences from other ions commonly present in natural waters. The potentiometric analysis requires the use of ionic strength adjusting buffer abbreviated as TISAB to obtain accurate and reproducible data. In most of the reported literature, higher concentrations of strong metal chelating ligands are used as masking agents generally in the concentration range of 1.0 to 0.01 M. In the present study, effectiveness of the masking agents, phosphate, citrate, CDTA ((1,2-cyclohexylenedinitrilo)tetraacetic acid), EDTA (ethylenediaminetetraacetic acid) HE-EDTA ((hydroxyethyl)ethylenediaminetriacetic acid)), triethanolamine, and tartaric acid at 1.0 mM in TISAB solutions was investigated. The experimental data were compared with a commercially available WTW 140100 TISAB solution as the reference buffer. According to the experimental data, the reference buffer always produced the highest fluoride concentrations and the measured fluoride concentrations were in the range of 0.611 to 1.956 mg/L. Out of all the masking agents investigated, only CDTA performed marginally well and approximately a quarter of the samples produced statistically comparable data to the reference buffer. All the other masking agents produced significantly low concentrations compared to the reference buffer. The most probable reasons for the underestimation of fluoride concentrations could be shorter decomplexing time and lower masking agent concentrations.

FLUORIMETRIC DETERMINATION OF ADRENAL CORTICOSTEROIDS: OBSERVATIONS ON INTERFERING FLUOROGENS IN HUMAN PLASMA

1964 ◽  
Vol 30 (2) ◽  
pp. 255-263 ◽  
Author(s):  
J. R. DALY ◽  
J. SPENCER-PEET
Keyword(s):  
Experimental Data ◽  
Human Plasma ◽  
Plasma Volume ◽  
Fluorescence Intensity ◽  
Plasma Sample ◽  
Accurate Estimation ◽  
Fluorimetric Determination ◽  
Low Concentrations ◽  
Theoretical Considerations

SUMMARY Simple fluorimetric methods for the determination of corticosteroids are not sufficiently specific to allow the accurate estimation of low concentrations in plasma. It has been noted previously and is confirmed here, that the measured fluorescence is not proportional to the volume of plasma used, but includes a component which is relatively independent of the plasma volume extracted. This gives rise to a positive intercept on the fluorescence axis when fluorescence intensity is plotted against volume. The suggestion that the determination of plasma corticosteroids can be made specific by subtracting the value of this intercept from the measured fluorescence intensity of the plasma sample has been examined. In the light of experimental data and certain theoretical considerations presented here, this suggestion is rejected. It is concluded that the inaccuracy due to interfering fluorogens can be reduced by taking fluorimeter readings within 5 min. of extraction into the fluorescence reagent, but that even then specificity is not complete.

scholarly journals The Mathematical Modeling of Ca And Fe Distribution In Peat Layers

2015 ◽  
Vol 2 ◽  
pp. 40
Author(s):  
Ērika Teirumnieka ◽  
Ilmārs Kangro ◽  
Edmunds Teirumnieks ◽  
Harijs Kalis ◽  
Aigars Gedroics
Keyword(s):  
Mathematical Modeling ◽  
Experimental Data ◽  
Mathematical Model ◽  
Trace Elements ◽  
Mathematical Models ◽  
Organic Material ◽  
Low Concentrations ◽  
The Mathematical Model ◽  
Research Show

Bogs have been formed by an accumulation of peat - a light brown-to-black organic material, built up from partial decomposition of mosses and other bryophytes, sedges, grasses, shrubs, or trees under waterlogged conditions. The total peatlands area in Latvia covers 698 918 ha or 10.7% of the entire territory. Knowledge’s of peat metals content are important for any kind of peat using. Experimental determination of metals in peat is very long and expensive work. Using experimental data mathematical model for calculation of concentrations of metals in different points for different layers can help to very easy and fast to find approximately concentration of metals or trace elements. The results of the research show that concentrations of trace elements in peat are generally low. Concentrations differ between the superficial, middle and bottom peat layers, but the significance decreases depending on the type of mire. The mathematical model for calculation of concentration of metals in different points for different 3 layers in peat blocks is developed. As an example, mathematical models for calculation of Ca and Fe concentrations have been analyzed.

Dispersive liquid–liquid microextraction technique combined with UV–Vis spectrophotometry for determination of zirconium in aqueous samples

2020 ◽  
Vol 3 (03) ◽  
pp. 18-24
Author(s):  
Ehsan Zolfonoun
Keyword(s):  
Natural Waters ◽  
Xylenol Orange ◽  
Binary Solution ◽  
Aqueous Samples ◽  
Pure Ethanol ◽  
Extraction Solvent ◽  
Relative Standard ◽  
Dispersive Liquid Liquid Microextraction ◽  
Liquid Microextraction

Dispersive liquid–liquid microextraction coupled with UV–Vis spectrophotometry was applied for the determination of zirconium in aqueous samples. In this method a small amount of chloroform as the extraction solvent was dissolved in pure ethanol as the disperser solvent, then the binary solution was rapidly injected by a syringe into the water sample solution containing Zr(IV), xylenol orange and cetyltrimethylammonium bromide. The formed ion-associate was extracted into the fine chloroform droplets. The detection limit for Zr(IV) was 0.010 µg mL−1. The precision of the method, evaluated as the relative standard deviation obtained by analyzing of 10 replicates, was 2.7 %. The practical applicability of the developed method was examined using natural waters and ceramic samples.

Direct separation of plutonium by thermochromatography from environmental samples

2002 ◽  
Vol 90 (3) ◽  
Author(s):  
L. Wacker ◽  
U. Krähenbühl ◽  
B. Eichler
Keyword(s):  
Experimental Data ◽  
Inductively Coupled Plasma ◽  
Inductively Coupled ◽  
Low Concentrations ◽  
Icp Ms ◽  
Direct Separation ◽  
Plasma Mass Spectrometry ◽  
Quartz Grains ◽  
Reactive Gas

SummaryA thermochromatographic separation was performed on plutonium from environmental soil samples. This procedure was investigated with the goal to measure low concentrations of plutonium by inductively coupled plasma-mass spectrometry (ICP-MS). The soil sample was chlorinated by thionylchloride as reactive gas at a temperature of 1400 K. The volatile chlorides were separated chromatographically and deposited in a temperature gradient tube filled with quartz grains. Results about the deposition behaviour of the elements were obtained. Two different formalisms based on the thermodynamic functions are used to describe the experimental data. One formula is used to describe the deposition behaviour of microscopic amounts of plutonium (adsorption), the other formula for macroamounts of the main matrix elements (desublimation). The calculated values are in a reasonable agreement with the experimental data. A determination of plutonium content was successfully made for a referenced sea sediment (IAEA-135) after the thermochromatographic sample preparation for ICP-MS.

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