Buffers lithium carbonate

The lithium carbonate concentration was measured by acidimetric titration with methyl orange indicator. The calcium sulfate and calcium hydroxide concentrations were determined by titration with disodium dihydrogen Versenate [the disodium salt of (ethylenedinitrilo) tetraacetic acid], with added magnesium chloride. A buffer of ammonium chloride in ammonium hydroxide was employed. The indicator was Erio-chrome Black T. A special high purity calcium carbonate in hydrochloric acid was used as a standard. Because of the high concentration of sodium sulfate it was con-... 

Variable volatility of the analyte mixture can also be a problem. Various elements in a sample are removed at different rates, causing the temperature of the flame to vary with time. For this reason, the sample is often mixed with a spectroscopic buffer such as lithium carbonate, in order to prevent the composition and temperature of the arc or spark from changing as the analysis proceeds. This procedure is also effective in lowering the temperature of the discharge to prevent ionization of alkali and alkaline earth metals. 

The addition of a spectroscopic buffer such as lithium carbonate has a stabilizing effect on the flame temperature and decreases the ionization of elements with low ionization potentials as well. At a constant flame temperature, the intensity of a given emission line is directly proportional to the concentration of analyte according to the equations given for emission spectrometry in the theoretical section. In practice, a standard curve is usually prepared in order to assess linearity between intensity and concentration. Alternatively, the method of standard addition (24) can be utilized. 

Amino acids were derlvatlzed with 1-dlmethylamlnonaphthalene-5-sulfonyl chloride (dansyl chloride) according to the procedure of Tapuhl and coworkers (48-50). A 10 M stock solution of twenty common -amlno acids (Sigma Chemical Co., St. Louis, MO) was prepared by dissolving the carefully weighed standards in 0.1 M aqueous hydrochloric acid. Aliquots of this solution were transferred to conical vials, evaporated to dryness, and redlssolved In 500 pL aqueous buffer (0.04 M lithium carbonate, pH 9.5). A 500 jL volume of dansyl chloride solution (5 x 10 3 m in acetonitrile) was added, and the derlvatlzatlon was allowed to proceed In the dark at 35"C for one hour. The reaction was terminated by the addition of 2% methylamlne hydrochloride, and the derlvatlzed sample was analyzed Immediately by mlcrocolumn liquid chromatography with UV-absorbance and LIF detection. 

Harvey has determined values of k for many elements and in different matrices. Use of these data can give semiquantitative results on a wide variety of samples containing many different elements. More recently Harvey (see footnote 7) has extended his original work to include data obtained using lithium carbonate as a buffer. These data permit buffering samples to a common matrix and make possible more uniform results. 

Wang et al have made use of the lithium carbonate-graphite buffer together with controlled-atmosphere excitation to devise another method of semiquantitative analysis. An intensity gain of 1.4-3.7 was observed when the sample was arced in an argon-oxygen atmosphere and the cyanogen bands were eliminated. 

The efficiency of lithium tartrate as a buffer to counteract the effect of potassium on phosphorus is shown in Figure 8-4. The quantity of phosphorus on the electrode was 0.10 mg for all points plotted and the amount of lithium tartrate on the electrode was 2.8 mg. The sample was in liquid form and was placed in the electrode cup and dried before dc arc excitation occurred. One of the most common spectroscopic buffers presently used for a variety of samples is lithium carbonate, which is available in a highly pure form from spectroscopic supply houses. 

In a liquid-carbonate electrolyte, dendrites form on an elemental Lithium anode that can grow across the electrolyte to short-circuit a cell on repeated cycling. Therefore, carbon or an alloy buffered by carbon is used with a liquid electrolyte [8]. 

Golorfastness to Bleaching. In fastness to hypochlorite bleachiag, ISO 10S-N01, the specimen is agitated ia a solution of sodium, calcium, or lithium hypochlorite containing 2 g/L available chlorine buffered to pH 11.0 with sodium carbonate for 1 h at 20°C and 50 1 Hquor-to-goods ratio. The specimen is tinsed ia water, hydrogen peroxide, or sodium bisulfite solution to remove free chlorine, dried, and assessed. 

In media selective for enterobacteria a surface-active agent is the main selector, whereas in staphylococcal medium sodium and lithium chlorides are the selectors staphylococci are tolerant of salt concentrations to around 7.5%. Mannitol salt, Baird-Parker (BP) and Vogel-Johnson (VJ) media are three examples of selective staphyloccocal media. Beside salt concentration the other principles are the use of a selective carbon source, mannitol or sodium pyruvate together with a buffer plus acid-base indicator for visualizing metabolic activity and, by inference, growth. BP medium also contains egg yolk the lecithin (phospholipid) in this is hydrolysed by staphylococcal (esterase) activity so that organisms are surrounded by a cleared zone in the otherwise opaque medium. The United States Pharmacopeia (1990) includes a test for staphylococci in pharmaceutical products, whereas the British Pharmacopoeia (1993) does not. 

The key intermediate 124 was prepared starting with tryptophyl bromide alkylation of 3-acetylpyridine, to give 128 in 95% yield (Fig. 37) [87]. Reduction of 128 with sodium dithionite under buffered (sodium bicarbonate) conditions lead to dihydropyridine 129, which could be cyclized to 130 upon treatment with methanolic HC1. Alternatively, 128 could be converted directly to 130 by sodium dithionite if the sodium bicarbonate was omitted. Oxidation with palladium on carbon produced pyridinium salt 131, which could then be reduced to 124 (as a mixture of isomers) upon reaction with sodium boro-hydride. Alternatively, direct reduction of 128 with sodium borohydride gave a mixture of compounds, from which cyclized derivative 132 could be isolated in 30% yield after column chromatography [88]. Reduction of 132 with lithium tri-f-butoxyaluminum hydride then gave 124 (once again as a mixture of isomers) in 90% yield. 

A solution of hypochlorite is stable in an excess of alkali, whereas in acid there is a slow conversion to chlorate. The minimum stability of hypochlorite solutions is at pH 6.7 (6.68 and 7-7.13 have also been reported - ) and the maximum stability is at pH 13. There is also a region of high stability in strong acid, where the solute is predominantly composed of chlorine and only very little hypochlorous acid. The rate of decomposition at pH 6.7-7.2 is proportional to the chloride concentration and to the square of the hypochlorite concentration. In slightly alkaline solution the rate is proportional to [0C1-][H0C1]. The catalytic effect of chloride ion is well known buffers " such as acetate, borate and carbonate also have an effect. It has been recommended that the concentration of phosphate buffers be kept below 0.25 M to prevent decomposition of hypochlorite solutions. The catalytic effect of heavy metals, especially copper and iron, has been noted. The effect of various cations is shown in the greater stability of lithium hypochlorite in comparison with the sodium and potassium salts. ... 

Uses Buffer mfg. of lithium stearate and other lithium soaps lubricating greases carbon dioxide absorbent (for submarines and space vehicles) esterification catalyst photographic developer stabilizer source of Li-6 isotope (used in prod, of tritium) in alkaline batteries (electrolyte additive) corrosion inhibitor in steam boilers dispersant in water-based alkyd paints leather ceramics buffer in cosmetics hair waving or straightening... 

Huang, X., Chen, Yu, H., Cai, R, Peng, S., Yan, Q.,and Hng, H. H. [2013]. Carbon buffered-transition metal oxide nanoparticle-graphene hybrid nanosheets as high-performance anode materials for lithium ion... 

Uses Buffer mfg. of lithium stearate and other lithium soaps lubricating greases carbon dioxide absorbent (for submarines and space vehicles) esterification catalyst photographic developer stabilizer source of Li-6 isotope (used in prod, of tritium) in alkaline batteries (electrolyse additive) corrosion inhibitor in steam boilers dispersant in water-based alkyd paints leather ceramics buffer in cosmetics hair waving or straightening Manuf./Distrib. AMC Chems. Alfa Aesar http //www.aifa.com] Am. Int l. http //www.aicma.com] BassTech Int l. Chemetall Foote Dastech Int l. FMC/Lithium http //www.fmciithium.com] Integra http //www.integrachem.com] J.T. Baker http //www.jtbaker.com] Pacific West Spectrum Quality Prods. http //www.spectrumchemicai.com] VWR Int l. http //www.vwrsp.com] Varsal Instruments http //www.varsai.com] Vopak USA http //WWW. vopakusa. com... 

CE with end-column amperometric detection (33 pm diameter carbon fibre electrode, +0.65 V vs Ag/AgCl) has also been used to detect isoprenaline enantiomers in microdialysates of rat plasma. Analyses were performed at 20 kV in fused-silica capillaries (65 cm x 50 mm i.d.). The analysis buffer consisted of aq. lithium acetate (100mmolpH 4.75), methyl-O-P-cyclodextrin (100gL ) and disodium EDTA (0.5 mmolL ). Samples were introduced by electrokinetic injection (18 kV, 3 s) or by pH-mediated stacking (electrokinetic injection, 18kV 15 s, followed by electrokinetic injection of 0.1 mol L aq. hydrochloric acid, 18kV, 20 s). Inclusion of DHBA as the internal standard was claimed to increase the precision of the analysis from 3.2 to 1.4% RSD. The LoD was 600ngL (S/N = 3, 1 pL sample). 

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