Determination of boron

The method has been applied to the determination of boron in river water and sewage,16 the chief sources of interference being copper(II) and zinc ions, and anionic detergents. The latter interfere by forming ion-association complexes with ferroin which are extracted by chloroform this property... 

Fluoride ion, and weak acids and bases do not interfere, but nitrate, nitrite, perchlorate, thiocyanate, chromate, chlorate, iodide, and bromide do. Since analysis of almost all boron-containing compounds requires a preliminary treatment which ultimately results in an aqueous boric acid sample, this procedure may be regarded as a gravimetric determination of boron. 

An alternative method for the determination of boron is given under Section 6.9. 

In situ densitometry has been the most preferred method for quantitative analysis of substances. The important applications of densitometry in inorganic PLC include the determination of boron in water and soil samples [38], N03 and FefCNfg in molasses [56], Se in food and biological samples [28,30], rare earths in lanthanum, glass, and monazite sand [22], Mg in aluminum alloys [57], metallic complexes in ground water and electroplating waste water [58], and the bromate ion in bread [59]. TLC in combination with in situ fluorometry has been used for the isolation and determination of zirconium in bauxite and almnimun alloys [34]. The chromatographic system was silica gel as the stationary phase and butanol + methanol + HCl -H water -n HF (30 15 30 10 7) as the mobile phase. 

Various chromogenic reagents have been used for the spectrophotometric determination of boron in seawater. These include curcumin [108,109], nile blue [110], and more recently 3,5 di-tert butylcatechol and ethyl violet [111]. Uppstroem [108] added anhydrous acetic acid (1 ml) and propionic anhydride (3 ml) to the aqueous sample (0.5 ml) containing up to 5 mg of boron per litre as H3BO3 in a polyethylene beaker. After mixing and the dropwise addition of oxalyl chloride (0.25 ml) to catalyse the removal of water, the mixture is set aside for 15-30 minutes and cooled to room temperature. Subsequently, concentrated sulfuric-anhydrous acetic acid (1 1) (3 ml) and curcumin reagent (125 mg curcumin in 100 ml anhydrous acetic acid) (3 ml) are added, and the mixed solution is set aside for at least 30 minutes. Finally 20 ml standard buffer solution (90 ml of 96% ethanol, 180 g ammonium acetate - to destroy excess of protonated curcumin - and 135 ml anhydrous acetic acid diluted to 1 litre... 

Atomic absorption spectrometry has been used for the rapid determination of boron in seawater [113]. 

Tsaikov [ 114] has described a coulometric method for the determination of boron in coastal seawaters. This method is based on the potentiometric titra-... 

This technique has been applied to the determination of boron, total phosphorus and arsenic in soil, antimony and organosilicon compounds in non-saline sediments, arsenic in saline sediments and silicon and arsenic in sludges. 

Aznarez et al. [2] have described a Spectrophotometric method using curcumin as chromopore for the determination of boron in soil. Boron is extracted from the soil into methyl isobutyl ketone with 2-methylpentane-2,4-diol. In this method 0.2-lg of finely ground soil is digested with 5ml concentrated nitric-perchloric acid (3 + 1) in a polytetrafluoroethylene lined pressure pump for 2h at 150°C. The filtrate is neutralized with 6M sodium hydroxide and diluted to 100ml with hydrochloric acid 1+l.This solution is triple extracted with 10ml of methyl isobutyl ketone to remove iron interference. This solution is then extracted with 10ml 2-methyl pentane-2,4 diol and this extract dried over anhydrous sodium sulphate. 

Table 12.2 Determination of boron in soils by the spectrophotometric method...

SpivackAJ, Edmond JM (1986) Determination of boron isotope ratios by thermal ionization mass spectrometry of the dicesium metaborate cation. Anal Chem 58 31-35 Spivack AJ, Kastner M, Ransom B (2002) Elemental and isotopic chloride geochemistry and fluid flow in the Nankai Trough. Geophys Res Lett 29 1-4... 

For the routine determination of analytes in the quality control of the production of speciality chemicals, a combination of direct current plasma emission spectroscopy (DCP-OES) with flow injection analysis (FIA) has been used. Results obtained for the determination of boron, copper, molybdenum, tungsten and zinc in non-aqueous solutions have been published by Brennan and Svehla [3], The principle has been extended to other analytes, carrier liquids, and solvents, and the details of a fully automatic system have been described by Brennan et al. [4]. 

Whatman No. 2 filter paper, collecting the filtrate in a boron-free tube inside the filter flask. Terminate the filtration after 5 min, and retain the filtered extract for the determination of boron. Carry out a blank determination. 

Triazoles have been used extensively in analytical chemistry. Nitron (182) has been used for the determination of boron, rhenium, and tungsten. Nitron has been bonded to a polymer and used for the removal of nitrate from water <79Mi 402-oi >. Other triazoles have been used for the spectrophoto-metric assay of cobalt, rhodium, and platinum <68Mi 402-01,72ZAK2209). Hydroxyphenylazotriazoles form brilliant lakes with a number of metal ions <73AJC1585>. 5-" C-3-Diazotriazole couples only to tryptophane below pH 6.8 and can used for the specific determination of tryptophane in proteins <84M1 402-02). 

Domenech A, Sanchez S, Yusa DJ, Moya M, Gimeno JV, Bosch F (2004) Electrochemical determination of boron in minerals and ceramic materials. Anal Chim Acta 501 103-111. 

Boron isotope ratios have been studied in ageothermal system from New Zealand (Ngawha) by MC-ICP-MS (Axiom with eight movable Faraday collectors, from Thermo Electron).188 The 8nB values range between — 3.1 %o and —3.9%e, which does not indicate any marine input into the system. A direct determination of boron isotopes (8nB) on natural and synthetic glass samples at < %o precision at the ng level has been proposed using LA-ICP-MS with multiple electron multipliers.129... 

I. E. Vasilyeva, E. V. Shabanova, Y. V. Sokolnikova, O. A. Proydakova and V. I. Lozhkin, Selection of internal standard for determination of boron and phosphorus by ICP-MS in silicon photovoltaic materials,... 

D. Pollmann, J. A. C. Broekaert, F. Leis, P. Tschoepel and G. Tdlg, Determination of boron in biological tissues by induetively eoupled plasma optical emission spectrometry (ICP-OES), Fresenius J. Anal. Chem., 346(4), 1993, 441 445. 

The Determination of Boron. After dry ashing in the manner used in the lithium, beryllium, etc., procedure, the ash is fused with sodium carbonate, leached in water, and acidified with sulfuric acid. The colorimetric carminic acid method is then used to determine the boron. 

We present here the initial modeling efforts and experimental determinations of boron speciation in solution with a reactive polymer. Also, the speciation model is applied to the ultrafiltration process and compared with data obtained from PAUF of a synthetic boron-contaminated feed. 

Mass spectral data have frequently been used in the structural determination of boron heterocycles. One paper has been devoted to the mass spectra of some six-membered boron-nitrogen systems. It was concluded that the spectra could be interpreted analogously to their hydrocarbon counterparts. In all cases the molecular peak was the base peak of the spectrum (68T6755). Doubly charged molecular ions, a feature typical of aromatic compounds, are often encountered. It should be noted, however, that some certainly non-aromatic aminoboranes give such doubly charged ions as well. 

D. Logie (83) described a new analytical separation technique by applying ion-exchange membranes, which can be used for the determination of boron in sodium metal. By treatment with water, the Na is converted to NaOH, borate being formed from the boron. When the solution is introduced in the anode chamber of a two-cell apparatus fitted with a negative membrane, the Na+ ion is transported to the cathode chamber, whereas the borate anion remains in the anode chamber. In general this method can be applied, if the trace element yields an ion with a charge which opposite to that of the main component. 

Although AA is a very capable technique and is widely used worldwide, its use in recent years has declined in favor of ICP and XRF methods of analysis. The most common application of AA is for the determination of boron and magnesium in oils. 

Miwa, T., T. Yoshimori, and T. Takeuchi Determination of Boron in ceramic Materials by Pyrohydrolytic Separation and Coulometric Titration. J. Chem. Soc. Japan, Ind. Chem. Sect. 64, 2045 (1964). 

Ogner [1] has described an automated analyser method for the determination of boron-containing anions in plants. This is based on the formation of a fluorescent complex between these anions and carminic acid at pH 7. The plant tissues are ashed at 550 °C and the residue dissolved in 0.5 N hydrochloric acid prior to adjustment to pH 6-7 with sodium carbonate solution. The solution is excited at 470 nm and fluorescence intensities measured at 585 nm. Interferences by the reaction of some cations with carminic acid are overcome by passing the solution through an ion exchange column to exchange the cations for sodium ions. Analytical recoveries of boron anions were in the range 98-104%. The detection limit of the method was 5 xg/l boron. 

Lopez Garcia et al. [2] have described a rapid and sensitive spectrophotometric method for the determination of boron complex anions in plant extracts and waters which is based on the formation of a blue complex at pH 1 - 2 between the anionic complex of boric acid with 2,6-dihydroxybenzoic acid and crystal violet. The colour is stabilised with polyvinyl alcohol. At 600 nm the calibration graph is linear in the range 0.3-4.5 xg boron per 25 ml of final solution, with a relative standard deviation of 2.6% for xg/l of boron. In this procedure to determine borate in plant tissues, the dried tissue is treated with calcium hydroxide, then ashed at 400 °C. The ash is digested with 1N sulfuric acid and heated to 80 °C, neutralized with cadmium hydroxide and then treated with acidic 2,6-dihydroxybenzoic acid and crystal violet, and the colour evaluated spectrophotometrically at 600 nm. Most of the ions present in natural waters or plant extracts do not interfere in the determination of boron complex anions by this procedure. Recoveries of boron from water samples and plant extracts were in the range of 97 -102%. 

Dyrssen, D.W., Novikov, Y.P. and Uppstrdm, L.R. (1972) Studies on the chemistry of the determination of boron with curcumin. Analytica Chimica Acta 60, 1 39-1 51. 

G. V. Iyengar, W. B. Clarke, R. G. Dawing, Determination of boron and lithium in diverse biological matrices using neutron activation - mass spectrometry (NA-MS), Fresenius J. Anal. Chem., 338 (1990), 562-566. 

Far more difficult, however, is the atomic absorption analysis of some other elements typically found in steel, for example Nb, As, Sb, Se, Te, or Bi. The determination of boron in steel in the range between 10 3 to 10 s weight percent has been practically impossible until recently. 

Cases have been observed where the isotopic line absorption profiles completely overlap, e.g. boron-10 and -11 in a krypton-filled lamp at 249.7 nm [244]. Hannaford and Lowe [245] later showed that this was caused by an unusually large Doppler half-width induced by the fill-gas, and, if neon is used, the 208.9 and 209.0 nm lines can allow the determination of boron-10 and boron-11 isotope ratios. The 208.89/208.96 nm doublet was found to be more useful than the 249.68/249.77 nm doublet. Enriched isotope hollow-cathode lamps were used as sources. A sputtering cell was preferred to a nitrous oxide/acetylene flame as the atom reservoir, as it could be water-cooled to reduce broadening and solid samples could be used, thus avoiding the slow dissolution in nitric acid of samples of boron-10 used as a neutron absorber in reactor technology. 

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