Magnesium measurement

A growing interest in ionized magnesium measurements indicates that further improvements in the analytical properties of the Mg-ISSs, regarding the selectivity as well as the response time and lifetime, are needed, to facilitate wider clinical application of this method [31]. 

Peroxide Value, Fats and Oils (PV) (Cd 8-53) determines all substances, in terms of milliequivalents of peroxide per 1000 g of sample, that oxidize potassium iodide (KI). These substances generally are assumed to be peroxides or products of fat oxidation. Phosphorus in Oils (Ca 13-55) estimates the phospholipid content of crude, degummed, and refined vegetable oils in terms of phosphorus. Refineries often use induction coupled plasma (ICP) spectrographs to analyze divalent cations rapidly in aspirated crude oil. The calcium and magnesium measured are mainly responsible for nonhydratable phosphatides (NHP) and are determined directly. An AOCS method for analysis by ICP is being developed. 

Patients at risk for electrolyte disturbances (e.g., patients on diuretic therapy) should have baseline and periodic serum potassium and magnesium measurements... 

EN89 Cheung, K., Price, L., Lynch, S., Hickman, P.E. and Dwyer, K.P. (1992). Magnesium measurement interference in a liver-transplant patient. Clin. Chem. 38, 440. 

As with calcium, AAS methods provide greater accuracy and precision for magnesium measurements than do photometric methods however, they are not frequently used for routine determination of magnesium by clinical laboratories. AAS is used as a reference method for magnesium. 

Discordance between total and free magnesium measurements has been reported in selected patient populations, including those with cardiovascular disorders, diabetes meUitus, alcoholism, migraine headaches, asthma, renal transplants, head trauma, and in pregnant women. Interferences, such as that from thiocyanate, in measurement of fr ee magnesium may explain some of these discrepencies. Free magnesium determinations may be helpfiil in others of these disorders and in critically ill patients and during cardiopulmonary bypass, preeclampsia, neonatal distress, and therapy with a number of... 

More recently, a PVC ISE based on the [4-(l,l,3,3-tetramethylbutyl) phenyl] phosphate/decan-l-ol system in conjunction with a chemometric technique has facilitated magnesium measurements (35). Attempts to make magnesium sensors with magnesium adducts of poly(propylene glycol) in conjunction with tributyl phosphate, di-octylphenyl phosphonate, its 3-nitrophenyl derivative, 2-nitroethyl benzene and 2-nitrophenyl phenyl ether solvents produced instead calcium sensors with = 0.06-0.08. 

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