Direct Determination of Potassium in Human Blood Serum by Flow Injection Flame Photometry with Automatic Dilution

Abstract

A method was developed for the automatic quantitative determination of potassium in serum, by flow injection analysis. The serum sample is directly introduced in the flow. The dilution with deionized water stream is done automatically and sequentially in the system to reach the adequate concentration to be introduced in the flame photometer. The results achieved with this method, for serum samples obtained in the Hospital of the University, had been compared with those values of the Hospital laboratory that uses manual dilution and flame photometry. The results obtained by the two methods agree within at least ±5%. About 60 samples/hour can be easily analyzed by the method proposed in this work.     

Simultaneous flow-injection analysis of three components with on-line dialyzers in series. Determination of sodium, potassium and chloride in blood serum

A fast and reliable fully automated three-component flow-injection procedure for the simultaneous determination of sodium, potassium and chloride in blood serum is described. A single sample injection (100-mul blood serum) is directed to two different channels by using two dialyzers in series. To avoid interferences and blocking of the fine jet of the atomizer, sodium and potassium are dialyzed by the first dialyzer before measurement by AES with a flame photometer. A second dialyzer in series is used to eliminate interferences and for automated dilution before the dialyzed chloride is measured by UV/VIS spectrophotometry at 485 nm. The results obtained for the sodium, potassium and chloride in blood serum at a sampling rate of 106 samples per hour compared well with data obtained by standard methods.     

Ion-Selective Electrode Determination of Calcium and Potassium in Bovine Skim-Milk Powder

Abstract

Ion-selective electrode determinations of potassium and calcium have been carried out on skim milk powder and the results compared with data obtained by flame emission spectroscopy for potassium and by atomic absorption spectroscopy for calcium. The data indicate that ion-selective electrodes can be used as an alternative to spectroscopic methods for determining these metals by using a dry-ashing pretreatment procedure. Acid digestion pretreatment is not recommended because of the ensuing high ionic strength and possible interferences. Sodium and magnesium contents obtained by spectroscopy are also quoted for interest. The various percentage metal contents are: potassium: 1.96 ± 0.155 (ISE direct) 1.81 ± 0.144 (ISE Gran) and 1.82 ± 0.076 (flame emission), sodium: 0.511 ± 0.017 (flame emission), calcium: 1.37 ± 0.095 (ISE direct), 1.36 + 0.079 (ISE Gran) and 1.41 ± 0.082 (flame aas), and magnesium 0.119 ± 0.003 (flame aas).     

Simultaneous Determination of Calcium and Magnesium in Human Blood Serum by Atomic Absorption Spectrophotometer

Abstract

Simultaneous determination of calcium and magnesium content in human blood serum has been reported as a routine clinical laboratory method, which is rapid, simple, and requires 50 δ of serum for complete analysis with triplicate runs. This is accomplished using a Model 1250 Varian Techtron Atomic Absorption Spectrophotometer with the stoichiometric nitrous oxide-acetylene flame of 0.2 cm red-cone height. Calcium and magnesium standards and also the serum specimens are prepared in aqueous medium containing 2000 ppm potassium chloride. Serum specimens are ultimately diluted to 1:100 fold. About 40–50 samples can be analyzed per hour of instrument operation, if standard solutions and diluted serum specimens are readily available.     

Studies on Ground and Excited State Prototropic Equilibria Sodium 1,3-Dihydroxy-4-aminoanthraquinone-2-sulphonate

Abstract

The dependence of absorption and fluorescence spectra of sodium 1,3-dihydroxy-4-aminoanthraquinone-2-sulphonate on pH, has been studied. the ground state dissociation constants for the three successive equilibria have been evaluated by photometry and fluorimetry. Also, an estimation of the lowest excited singlet state (pK?₃) dissociation constant, obtained from fluorimetric titration measurements, has been performed.     

An ion-exchange scheme for the determination of the major cations in sea water

A cation-exchange scheme is described for the determination of the principal cations in sea water. The cations are adsorbed onto a column of Amberlite CG 120. Sodium and potassium are eluted together using 0.15 M ammonium chloride and determined gravimetrically as sulphates; potassium is then determined gravimetrically as potassium tetraphenylboron and sodium is determined by difference. Magnesium and calcium are eluted by means of 0.35 M ammonium chloride and 1 M ammonium acetylacetonate (pH 9.6) respectively, and titrated with EDTA. Finally, strontium is eluted with 2 M nitric acid and determined by flame photometry. Tests made using an artificial sea water showed that the method had coefficients of variation of 0.02, o.22, 0.04, 0.08 and 0.8% for sodium, potassium, magnesium, calcium and strontium respectively.     

Determination of Calcium,Phosphorus and Potassium in Leaf Tissues by Extraction with Ethanol-Water Solvent

Abstract

A new method has been developed for the analysis of elements in plant leaves by aqueous-ethanol extraction. The method was initially tested for calcium, potassium and total phosphorus. Very good results were obtained when compared with those of other methods. Extraction is done with a 20% v/v ethanol-water mixture, refluxing the plant material during 15 to 30 minutes. After treatment with activated carbon the solution is filtered through fast quantitative filter paper (Whatman nr. 40). The elements can be analysed as usual, by atomic absorption, flame photometry, etc. The procedure is promising for routine analysis because of its low cost, simplicity of operation, rapidity, safety characteristics and quality of the results. 30 to 40 minutes are sufficient to prepare solution samples from the dried plant material.     

Determination of Surface Silanols of Silica Gels and HPLC Bonded Phases

Abstract

A rapid method determining the surface silanols of silica gels and HPLC bonded phases involves a titration of silica gel with sodium hydroxide, in a medium of any of the following 10% aqueous salts: sodium chloride, sodium nitrate, sodium sulfate, potassium chloride, potassium nitrate and potassium sulfate. The silanols are quantified as m eg/g. It is possible to determine cation exchange capacity of a cation-exchanger due to an acid as an end group and surface silanols separately.     

Studies on bis(crown ether)-based ion-selective electrodes for the potentiometric determination of sodium and potassium in serum

Bis(crown ether)-based ion-selective electrodes for sodium and potassium are described, based on the bis[(12-crown-4)-2-ylmethyl]-2-dodecyl-2-methyl malonate sensor(I) for sodium and the bis[(benzo-15-crown-5)-15-ylmethyl] pimelate sensor(II) for potassium. The best results were obtained when the sensors were used in association with 2-nitrophenyl octyl ether as plasticising solvent mediator and potassium tetrakis(4-chlorophenyl)borate as anion excluder in poly(vinyl chloride) matrices. Electrode slopes were near-Nernstian, with detection limits of less than 10(-5) M. The electrode features are compared with those of a sodium glass membrane electrode, for sensor I, and with a valinomycin-based potassium electrode, for sensor II. The electrodes are also discussed in relation to others reported for sensors I and II and are shown to be superior. However, although the electrodes described offer promising alternatives to glass electrodes for sodium and valinomycin electrodes for potassium, data for sodium and potassium measurements in blood serum indicate a need for further research in order to improve the correlation with flame photometric measurements.     

Simultaneous Determination of Inorganic Cations and Anion in Medical Electrolytes by Capillary Electrophoresis

Abstract

Capillary electrophoresis (CE) was developed in order to effect rapid, specific determination of potassium, calcium, sodium, and magnesium. Ions (4 cations, 1 anion) were measured continuously via shifting of samples from the inlet electrode to the outlet electrode; moreover, samples were subjected to indirect and direct ultraviolet (UV) techniques, respectively. For the measurement of cations, imidazole (5 mM) functioned as a UV absorber of indirect detection at 214 nm. Consequently, anions can be measured directly by UV at 214 nm. Separation times of cations and Cl^? anions were 10 min and 2 min, respectively; the detection limit of each ion (chloride, magnesium, sodium, calcium, and potassium) was 0.1 µmol/L. This approach is very simple; additionally, measurement time is extremely short. As a result, the proposed method is suitable for routine assay of electrolytes in pharmaceutical preparations.     

Sodium quantitation in soft drinks: A rapid methodology by qNMR

High sodium dietary intake has a positive association with an increase in blood pressure and can be correlated with risk factors of disease. Considering that the World Health Organization recommends a sodium intake lower than 2 g day^-1 for adults, the hidden sodium content in processed foods is an important factor that compromises the assessment of a healthy diet. Accordingly, the present paper aimed to quantitate the sodium content of conventional soft drinks and their diet versions using nuclear magnetic resonance spectroscopy as a quantitative analytical technique (²³Na qNMR). The results show one free sodium signal (Na⁺) displayed as a singlet at 0 ppm in the ²³Na NMR spectrum, making its quantitation highly specific. This signal alone was used to directly determine the concentration of sodium in soft drinks. Flame photometry analysis was used to validate the method, and an excellent linearity was found in qNMR analysis (r = 0.9994) in comparison with flame photometry (r = 0.9958). In addition, a good correlation was found between sodium concentrations obtained by ²³Na NMR and flame photometry in the evaluated commercial soft drinks. Since the intensity of the resonance line is directly proportional to the number of nuclei (spins), the concentration of sodium in soft drinks can be determined via this straightforward method without the need for external calibration. The experimental acquisitions are fast (approximately 15 min), allowing the analysis of several samples in a short period of time. This is a novel alternative for sodium quantitation using an efficient NMR methodology.     

A Dedicated Instrument for the Analysis of Blood Urea Nitrogen Using an Immobilized Enzyme Reagent

Abstract

A dedicated instrument for the quantitative determination of urea in blood serum or plasma has been developed. The instrument uses urease immobilized on a porous alumina support and a gas-detecting electrode to measure ammonia resulting from hydrolysis of urea. Reproducibility and recovery studies show a high degree of accuracy, sensitivity, and specificity. Comparison of patient samples (plasma and serum) show no statistical difference when compared to the diacetyl monoxime, Auto Analyzer method.     

Synthesis and potentiometric selectivity study of new spiro-14-crown-4 derivatives

Abstract

Four new compounds with 14-crown-4 attached to spirocyclopentane or spirocyclohexane were synthesized and tested for potentiometric selectivity for lithium ion in polyvinyl chloride membrane electrodes. Four plasticizers were studied and the addition of tri-octylphosphine oxide (TOPO) was investigated. One ionophore exhibited a sodium/lithium selectivity, K^pot _Li,Na by the matched potential method of 0.0028 in the presence of 1% TOPO, using o-nitro-phenylphenyl ether as plasticizer. Selectivities are reported for sodium, potassium, nickel, cobalt, barium and calcium.     

Constantes d'acidite de l'acide pyrophosphorique et constantes de stabilite des complexes avec le potassium et le sodium: en|The acidity constants of pyrophosphoric acid and the stability constants of complexes with potassium and sodium ions

(The acidity constants of pyrophosphoric acid and the stability constants of complexes with potassium and sodium ions)The effect of potassium and sodium ions on the acidity constants of pyrophosphoric acid is studied by potentiometry at 25°C and at an ionic strength of 0.5 mol l^-1. Comparison of the results obtained in potassium chloride or sodium chloride medium with those found in tetramethylammonium chloride medium provides evidence of the formation of potassium and sodium complexes of the type MHP₂O^2-₇ and MP₂O^3-₇. Stability constants of these complexes are calculated and distribution diagrams of the species as a function of pH are given for the three different media utilized.     

Crystal and Molecular Structure of Potassium trans-bis(iminodiacetato)-cobaltate(III)-2H2O

The combination of iminodiacetic acid (H₂ida) with cobalt(II) chloride hexahydrate in the presence of sodium hydroxide, followed by heating, produces the trans-facial isomer of K[Co(ida)₂]·2H₂O. This compound contains extensive intermolecular and intramolecular coordination and hydrogen bonding involving the potassium ions, and results in a complex three-dimensional structure in which each potassium ion is immediately surrounded by six cobalt centers.     

Conductance Studies of Alkali Metal Acetates in Acetic Acid-Acetonitrile Mixtures

Abstract

Conductance behaviour of lithium, sodium and potassium acetates in 20% and 80% acetic acid-acetonitrile mixtures at 35° have been measured. The association constants were evaluated by Fuoss-Hsia equation of 20% acetic acid-acetonitrile mixtures by making use of TDC-12 Computer. Shedlovsky, Fuoss-Kraus extrapolation techniques were also employed to evaluate the association constants for these salts in both the solvent mixtures. The association constants obtained by these three methods were compared. The results were discussed in terms of various theories of ion pair formation i.e., Bjerrum, Fuoss, Denison-Ramsay, and Ebeling, Kraft, Yokoyama and Yamatera. Hydrodynamic radius was also calculated to understand the solvation of ions, in 20% and 80% acetic acid-acetonitrile mixtures.     

Nanoparticles based on gadolinium(iii) and europium(iii) complexes for biovisualization

Complexes Ln(TTA)₃ and [Ln(TTA)₃·1] (Ln = Eu, Gd; ТТА is thenoyltrifluoroacetyl-acetonate; 1 is 2-(5-chlorophenylene-2-hydroxy)-2-phenylethylene-bis(2-methoxy)phosphine oxide) in individual form, and as a part of a core of the polyelectrolyte stabilized colloids have been studied by Mössbauer spectroscopy and X-ray powder diffraction. The photophysical and colloidal characteristics of the solutions of polyelectrolyte nanoparticles were studied in water, artificial cerebrospinal fluid solution, solution of bovine serum albumin, and human blood serum. A stability of a luminescent response of the nanoparticles in solutions of bovine serum albumin and human blood serum at 37 °С for 2 hours has been revealed. This is a prerequisite for the potential application of studied nanoparticles for biovisualization.

     

Thermodynamics of aqueous mixtures of sodium chloride,potassium chloride,sodium sulfate,and potassium sulfate at 25°C

Aqueous solutions of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate can be mixed in six ways to give ternary mixtures. Two of these have already been studied and results are now presented for the remaining four systems: H₂O–NaCl–K₂SO₄, H₂O–Na₂SO₄–K₂SO₄, H₂O–KCl–Na₂SO₄, and H₂O–KCl–K₂SO₄.     

Palladium Biosensor

In this paper we proposed a palladium(II) biosensor. The biosensor is based on determining of interactions between palladium(II) and metallothionein modified hanging mercury drop electrode by means of differential pulse voltammetry. We studied influence of two supporting electrolytes (potassium or sodium chloride) on the signals of the biosensor. Based on the results obtained we found potassium chloride (0.05 M) as the most suitable supporting electrolyte to determine palladium(II). The detection limit of the biosensor for palladium ions was evaluated as 100 nM with RSD about 10%. Moreover, we utilized the biosensor for measurement of the target molecule in the presence of human blood serum and human urine.     

Electrophoretic Behaviour of 34 Organic Acids on Impregnated Strips

Abstract

Electrophoretic behaviour of 34 organic acids on calcium sulphate impregnated papers has been studied. The 19 binary separations in aqueous sodium chloride and sodium sulphate solutions and distilled water have been achieved.