Magnesium , concentrations determination

COMBINED APPLICATION OF COMPOSITION AND STRUCTURE ANALYSIS METHODS TO THE DETERMINATION OF MAGNESIUM CONCENTRATION AND LOCATION IN BONE... 

Atomic absorption spectrometry is the method of choice for clinical chemists, with serum usually being analysed to determine magnesium concentration, although in this case synthetic urine is being analysed to assess the amount of magnesium being processed by the kidneys. 

Chen, Y. Wang, T. Helmy, R. Zhou, G.X. etal., Concentration determination of methyl magnesium chloride and other Grignard reagents by potentiometric titration with in-line characterization of reaction species by FTIR spectroscopy /. Pharm. Biomed. Anal. 2002, 29, 393 04. 

The determination of magnesium is so sensitive that there is rarely any reason for attempting to determine the element by AFS or AES. Nevertheless, the element may be determined with good sensitivity at 285.2 nm by AES using a nitrous oxide-acetylene flame, although potassium should then be added as an ionization buffer, especially at very low magnesium concentrations. 

In slower production processes, atomic absorption can be used directly for production control of those processes for which rapid sample preparation techniques have been developed. One such example is the determination of magnesium concentration during the production of cast iron [70]. A further example is the determination of acid soluble aluminium in steel [147], where in large steel companies 100 samples or more per day may be required. (See also section II.A.)... 

The extent of muscle diseases can be followed by the decrease of ATP concentration. Surprisingly, I have one paper, which is a citation classic and that s the one where I showed the effect of metal ions on the NMR chemical shifts of P in ATP. It is now used even in vivo to find out how much magnesium there is by measuring the chemical shift of the phosphorus atoms in ATP. One can determine how saturated ATP is with magnesium. Now it s used to determine magnesium concentration in the brain. 

Experimental results show that turbidity removal by lime coagulation depends both on pH and on the quantity of magnesium precipitated in the form of magnesium hydroxide. Magnesium concentration exerts a significant influence determining... 

For certain sample types, both stray light and recombination eflFects on the analytical results can be largely eliminated by matrix matching. Such an approach is not practical for the determination of trace elements in urine because of the wide ranges of calcium and magnesium concentrations which occur in so-called normal samples. 

Magnesium concentrations as a function of depth (meters below the sea floor) in sediment porewaters from the western flank of the Juan de Fuca Ridge near 48° N in the North Pacific Ocean. The concentration decreases with depth because it is removed from solution by reaction with crustal rocks at the sediment-crustal boundary. The curves are convex upward because of porewater upwelling along the upward-flowing limb of a convection cell. Velocities of the upwelling are determined by using a one-dimensional advection-diffusion model and are indicated by the numbers on the curves. Redrafted from Wheat and MottI (2000). 

Instruments for the measurement of free magnesium in whole blood, plasma, or serum are available commercially. These instruments use ISEs with neutral carrier ionophores, including ETH 5220, ETH 7025, or a proprietary ionophore. Current ionophores or electrodes have insufficient selectivity for magnesium over calcium. Free calcium is simultaneously determined and used chemometrically with the signal from the magnesium electrode to calculate free magnesium concentrations. 

The data in Table 2.3, shown in Figure 2.14, consist of magnesium concentrations as determined from river water samples collected at various distances from the stream mouth. Because of the problems of accessibility to sampling sites, the samples were collected at irregular intervals along the stream channel and the distances between samples were calculated from aerial photographs. To produce regularly spaced data, all methods for interpolation... 

A. Specific ievels. Determination of semm magnesium concentration is usually rapidly available. The normal range is 1.8-3.0 mg/dL (0.75-1.25 mmol/L, or 1.5-2.5 mEq/L) total Mg. Therapeutic levels tor treatment of toxemia of pregnancy (eclampsia) are 5-7.4 mg/dL (2-3 mmol/L, or 4-6 mEq/L) total Mg. Ionized levels correlate with total Mg levels, and are not indicated. 

Magnesium concentration can be determined in physiological samples such as serum and urine by FAAS, FAES, and UV-visible spectrophotometry. Urine must be acidified (pH 1.0) by hydrochloric acid to release magnesium from salts of the sediment. Recently, potentiometry has become available for the measurement of ionized (free) magnesium in serum and blood. 

Potentiometry ISEs for the determination of ionized (free) magnesium are now available. They use membranes with neutral ion carriers (e.g., modified ETH 5220), which, however, lack specificity with respect to calciiun. Therefore, magnesium and calcium must be measured simultaneously in the same analytical portion (with different electrodes) and magnesium concentration is calculated from this. 

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