Magnesium analytical method

Magnesium (Mg), 15 320-381. See also Aluminum— magnesium phase diagram Aluminum-magnesium- zinc phase diagram MgB2 entries activated, 12 835 analytical methods for, 15 348 atmospheric exposures of, 15 369 beer as dietary source of, 3 588 behavior on contact with chemicals, 15 372t... 

Magnesium hydroxide (brucite), 5 479t, 75 394-395, 398-407, 425 advantages and disadvantages of, 75 406 analytical methods for, 75 405-406 health and safety factors related to, 75 406... 

Use of dissolved calcium permits the use of simpler correlations, but the accuracy of calcium measurements in the presence of magnesium is dependent upon the analytical method used. 

Analytical methods employed in soil chemistry include the standard quantitative methods for the analysis of gases, solutions, and solids, including colorimetric, titrimetric, gravimetric, and instrumental methods. The flame emission spectrophotometric method is widely employed for potassium, sodium, calcium, and magnesium barium, copper and other elements are determined in cation exchange studies. Occasionally arc and spark spectrographic methods are employed. 

There is no simple algorithm that allows recalculating ionized magnesium into total magnesium, and vice versa. Ionized magnesium may be compared with results by other analytical methods, e.g. measurement by atomic absorption spectroscopy after ultrafiltration, only by employing the relevant recommendations [7]. 

The most important determination is normally the concentration of carbon-magnesium-bonded species in solution. For routine estimation of this concentration for freshly prepared solutions of organomagnesium compounds, an aliquot of the test solution may be added to an excess of standard acid, and then back-titrated with sodium hydroxide. However, this simple determination of total base will give a high estimate of organomagnesium content if products of hydrolysis or oxidation are present. Analytical methods based on the determination of the hydrocarbon formed on hydrolysis of the organomagnesium compound... 

When estimation of the concentration of magnesium, halide, etc., in organomagnesium compounds is required, hydrolysis followed by standard analytical methods is normally satisfactory. 

The environmental scientist has at his disposal a variety of sensitive, multi-elemental analytical methods that can lead to a massive amount of data on airborne metals. Optimum use of these tools for environmental monitoring calls for focusing resources only on those metals that are environmentally important. Considerations of toxicity along with their ability to interact in the air, leading to the formation of secondary pollutants, and their presence in air have led to the identification of 17 environmentally important metals nickel, beryllium, cadmium, tin, antimony, lead, vanadium, mercury, selenium, arsenic, copper, iron, magnesium, manganese, titanium, chromium, and zinc. In addition to the airborne concentration, the particle size of environmentally important metals is perhaps the major consideration in assessing their importance. 

Several analytical methods will differentiate the "free" (hydrated) metal ions from dissolved complexed metal ions. These methods include specific ion electrodes, polarographic, and other amperometric and voltammetric methods and various types of spectroscopy (see Section 7-10). Specific ion electrodes only respond to the free metal ion for which they are "specific." To determine the relative amounts of complexed and uncomplexed metal ion in a solution, we can use a "wet chemical" method to measure the total concentration of "free + complexed" ions, and then an ion-specific electrode to determine the free metal ion concentration (activity). Care must be taken to eliminate interferences that may affect these measurements. We deduce the concentration of the "complexed ions" by the difference between these two measurements. For example, in the EDTA titration method for hardness, free and complexed calcium and magnesium ion s are measured. 

Ammonium Beryllium Phosphate.— Rossler (1878 9) has shown that a crystalline precipitate, similar to ammonium magnesium phosphate can be produced by adding an excess of ammonium phosphate to a beryllium salt, adding hydrochloric acid and just neutralizing with ammonia, but states that this precipitate varies in composition. M. Austin (1899 8) has also worked with this precipitate in an attempt to obtain an analytical method for beryllium, but agrees that the results are inaccurate. 

Recommended Analytical Methods To analyze electrolyzer feed brine after the ion-exchanger, it is advisable to acidify the sample before testing. This will dissolve any magnesium hydroxide precipitates and make it detectable by colorimeter analysis. Such analysis will reveal any magnesium breakthrough because of upsets in the primary treatment. 

Graphite furnace atomic absorption spectrometry (GFAAS) is an excellent method to provide sub-ng/mL minimum detection limits [110]. Continuing advancements such as Zeeman correction, and stabilized temperature platform furnaces, have made GFAAS an effective analytical method for magnesium determination. Depending on the sample matrix, pretreatment can vary from direct analysis of fluids, to wet mineralization, dry ash, acid extraction, and by using PPRs (e.g., Triton X-100). 

Various analytical methods have been used to determine the elemental components of biodegradable magnesium alloys (Mg, Al, Li, Zn, REE) in histological sections, bone, tissue and body fluids (Witte et al., 2008b) (see Table 10.2). The application of these methods for trace and ultra-trace analysis in small sample volumes is hampered by several problems. The typical concentrations of the elements mentioned above range from < 1 p.g/L to about 1 mg/L in serum and from < 1 mg/kg up to about 500 mg/kg for example in liver and bone. Thus, the sensitivity of several analytical methods... 

The Analytical Methods Committee of the S,A,C. has described a method for the determination of traces of magnesium, based on the method of Hunter. In this method, after destruction of organic matter, the magnesium is complexed with Titan Yellow and the excess dye is extracted from the reaction mixture and determined spectrophotometrically. The method is generally applicable but zinc, if present in quantities greater than 10 per cent of the magnesium content, interferes and should be removed. Aluminium, cadmium, cobalt and nickel interfere also. The recommended procedure is as follows ... 

The interference criterion was an error of not more than 3 0 % in the absorbance. To test the efficiency and selectivity of the proposed analytical methods (A-C) to pharmaceutical formulations, we carried out a systematic study of additives and excipients (e.g. lactose, glucose, dextrose, talc, calcium hydrogen phosphate, magnesium stearate and starch) that usually present in dosage forms. Experiments showed that there was no interference from additives or excipients for methods A-C (Table 3). 

Analytical and Test Methods. Many of the procedures for technical analyses of magnesium hydroxide are readily available from the principal producers. These procedures should be carefully reviewed. Site-specific variations in procedure steps and mechanics, especially for chemical activity, can bias results and inadvertantiy disqualify an otherwise acceptable product. 

In most analytical procedures for determining the total phosphoms content (normally expressed in terms of P20 ), the phosphates are converted to the orthophosphate form. Typically, condensed phosphates are hydrolyzed to orthophosphate by boiling in dilute mineral acid (0.1 N). The orthophosphate is then deterrnined by gravimetric or spectrophotometric methods. For gravimetric deterrnination, insoluble phosphomolybdates (or magnesium ammonium orthophosphate) is formed. 

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