Lithium metaborate

Lithium Borates. Lithium metaborate [13453-69-5], LLBO2 2H20, is prepared from reaction of lithium hydroxide and boric acid. It is used as the fluxing agent for the matrix for x-ray fluorescence analytical techniques and in specialty glasses and enamels. The anhydrous salt melts at 847°C. 

The commercial ores, beryl and bertrandite, are usually decomposed by fusion using sodium carbonate. The melt is dissolved in a mixture of sulfuric and hydrofluoric acids and the solution is evaporated to strong fumes to drive off siUcon tetrafluoride, diluted, then analy2ed by atomic absorption or plasma emission spectrometry. If sodium or siUcon are also to be determined, the ore may be fused with a mixture of lithium metaborate and lithium tetraborate, and the melt dissolved in nitric and hydrofluoric acids (17). 

Lithium metaborate octahydrate, LiB02 8H2O or Li20 20 46H2O, hexagonal d = 1.825 g/mL has the stmctural formula Li[B(OH)4 -6H20 (127). On heating to 70°C six waters are lost the last two waters are lost between 140 and 280°C (128). 

The octahydrate is the stable soHd phase ia contact with its solution below 36.9°C. Above this temperature lithium metaborate dihydrate,... 

Fusions with (a) sodium carbonate or fusion mixture, (b) borax and lithium metaborate, (c) alkali bifluorides, and (d) alkali hydrogensulphates (slight attack in the last case above 700 °C, which is diminished by the addition of ammonium sulphate). 

Substances which are insoluble or only partially soluble in acids are brought into solution by fusion with the appropriate reagent. The most commonly used fusion reagents, or fluxes as they are called, are anhydrous sodium carbonate, either alone or, less frequently, mixed with potassium nitrate or sodium peroxide potassium pyrosulphate, or sodium pyrosulphate sodium peroxide sodium hydroxide or potassium hydroxide. Anhydrous lithium metaborate has found favour as a flux, especially for materials containing silica 12 when the resulting fused mass is dissolved in dilute acids, no separation of silica takes place as it does when a sodium carbonate melt is similarly treated. Other advantages claimed for lithium metaborate are the following. 

Fusions with lithium metaborate are usually quicker (15 minutes will often suffice), and can be performed at a lower temperature than with other fluxes. 

The loss of platinum from the crucible is less during a lithium metaborate fusion than with a sodium carbonate fusion. 

For the preparation of samples for X-ray fluorescence spectroscopy, lithium metaborate is the preferred flux because lithium does not give rise to interfering X-ray emissions. The fusion may be carried out in platinum crucibles or in crucibles made from specially prepared graphite these graphite crucibles can also be used for the vacuum fusion of metal samples for the analysis of occluded gases. 

Fusions with lithium metaborate, 112 with sodium carbonate, 113 with sodium hydroxide, 113... 

Lithium-magnesium alloys, 15 135 Lithium manganate(V), 15 592 Lithium-manganese dioxide cells, 3 461 characteristics, 3 462t Lithium metaborate, 15 137 Lithium metaborate octahydrate, 4 277 Lithium metal, 15 132 uses for, 15 134 Lithium metal films, 15 128 Lithium methoxide, 15 148 Lithium nickelate, 15 142 Lithium niobate, 15 141 17 153... 

Lithium metaborate (LiB02) fusion for glass, rocks, and soils. 

Accurately weigh c. 0.1 g powdered sample and c. 0.5 g anhydrous lithium metaborate in platinum, graphite, or pure aluminum oxide crucible, and mix (platinum rod)... 

Are there any alternative chemicals which can be used to eliminate hazards (e.g., the use of lithium metaborate fusion rather than hydrofluoric acid as a dissolution procedure) The protocol should include details of any required checks on the control measures to be adopted, and their frequency (e.g., cleaning of protective clothing, washing down of fume cupboards). 

Probably the most common fluxes are sodium carbonate (Na2C03), lithium tetraborate (Li2B407), and lithium metaborate (LiB02). Fluxes maybe used by themselves or in combination with other compounds, such as oxidizing agents (nitrates, chlorates, and peroxides). Applications include silicates and silica-based samples and metal oxides. 

The presence and concentration of various metallic elements in petroleum coke are major factors in the suitability of the coke for various uses. In the test method (ASTM D5056), a sample of petroleum coke is ashed (thermally decomposed to leave only the ash of the inorganic constituents) at 525°C (977°F). The ash is fused with lithium tetraborate or lithium metaborate. The melt is then dissolved in dilute hydrochloric acid and the resulting solution is analyzed by atomic absorption spectroscopy to determine the metals in the sample. However, spectral interferences may occur when using wavelengths other than those recommended for analysis or when using multielement hollow cathode lamps. 

The <0.063 mm fraction of till was analyzed by aqua regia and lithium metaborate fusion-nitric acid digestions ICP/ES and MS. 

Trace element analysis was carried out on the ash by fusing with lithium metaborate, followed by dissolution in 10 % hydrochloric acid. The resulting solution was analysed using atomic emission and absorption spectrometry (AA). The method has been described previously (9). 

Van Loon, J. C., and Parlssis, C. M., Scheme of silicate analysis based on the lithium metaborate fusion followed by atomic absorption spectrophotometry. The Analyst, 1969, 1057-1062. 

Most fusions use lithium tetraborate (Li2B407, m.p. 930°C), lithium metaborate (LiB02, m.p. 845°C), or a mixture of the two. A nonwetting agent such as KT can be added to prevent the flux from sticking to the crucible. For example, 0.2 g of cement might be fused with 2 g of Li2B407 and 30 mg of KI. 

The introduction of atomic absorption spectroscopy has resulted in major advances in the rapid analysis of many elements. Initially, atomic absorption was applied only to aqueous systems or to materials that could be readily solubilized. There are methods to analyze major elements in such complex materials as silicates and vitreous siliceous coal ashes (1-5). More recently, lithium metaborate has been reported to be a good fluxing agent (6) and has also been used in conjunction with atomic absorption analysis in silicate analysis (7). This paper describes a lithium tetraborate-atomic absorption analytical technique which is being used to analyze coal ash. 

Ingamells, C. O., Lithium Metaborate Flux in Silicate Analysis, Anal. 

Copper, Chromium, Manganese, and Nickel. The analytical method for determining copper, chromium, manganese, and nickel involves digesting the coal with nitric and perchloric acids, fusing the residue with lithium metaborate, and determining the combined digestion and leach solutions by atomic absorption spectrophotometry. Since there is no standard material to analyze for the construction of calibration curves, the standard additions method is used for the assay. While this method increases the time required for analysis, it helps to eliminate the effect of the matrix. 

The total content of sediment base cations (Ca2+, Mg2+, K+, and Na+), as determined by lithium metaborate fusion (16), decreased down-core in both basins from 190 38 mequiv/100 g in the 0-2-cm interval to 160 32 mequiv/100 g in the 12-14-cm interval (Figure 7a). For any depth interval the difference between the basins was less than 5%, and the analysis of sediments for total base cations was not precise enough to confirm the differences between basins detected by other analyses. In contrast, the analyses... 

Typically, these will be alloys, rocks, fertilisers, ceramics, etc. These materials are taken into solution using suitable aqueous/acid media, according to solubility hot water, dilute acid, acid mixtures, concentrated acids, prolonged acid digestion using hydrofluoric acid if necessary, alkali fusion (e.g. using lithium metaborate), Teflon bomb dissolution. Fusion and bomb methods are usually reserved for complex siliceous materials, traditionally reluctant to yield to solubilisation. 

E. Lithium metaborate fusion attack for silicon determination in rock, soil or sediment... 

This method is useful when silicon determinations are required on samples which are not decomposed by hydrofluoric—boric acids at 95°C. The finely ground sample is fused with lithium metaborate in a graphite crucible and the melt is dissolved in dilute nitric acid [12]. 

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