Boric acid determination

Fig. 8-35. Boric acid determination in a nickel/iron plating bath. — Separator column IonPac ICE-AS1 eluent 0.001 mol/L octane-sulfonic acid flow rate 1 mL/min detection suppressed conductivity injection 50 pL sample (1 1000 diluted).

Figure 10.164 Boric acid determination in a nickei/iron piating bath. Separator coiumn ionPac ICE-AS1 eluent 1 mmoi/L octanesuifonic acid flow rate 1 mUmin detection suppressed conductivity injection volume 50 pL sample plating bath (1 1000 diluted) peaks (1) borate.

In this experiment phosphate is determined by singlecolumn, or nonsuppressed, ion chromatography using an anionic column and a conductivity detector. The mobile phase is a mixture of n-butanol, acetonitrile, and water (containing sodium gluconate, boric acid, and sodium tetraborate). 

Eluorspar assay may be completed by fluoride determination alone, because the mineralogical grouping rarely iacludes fluorine minerals other than fluorite. Calcium can be determined as oxalate or by ion-selective electrodes (67). SiUca can be determined ia the residue from solution ia perchloric acid—boric acid mixture by measuriag the loss ia weight on Aiming off with hydrofluoric acid. Another method for determining siUca ia fluorspar is the ASTM Standard Test Method E463-72. 

Ammonia and ammonium ions in industrial water streams, including waste-water streams, can be determined by either of two methods (ASTM Procedure D1426). In the first, the sample is buffered to a pH of 7.4 and distilled into a solution of boric acid where the ammonia nitrogen is deterrnined colorimetricaHy with Nessler reagents or titrated using standard sulfuric acid. 

Lower Oxides. A number of hard, refractory suboxides have been prepared either as by-products of elemental boron production (1) or by the reaction of boron and boric acid at high temperatures and pressures (39). It appears that the various oxides represented as B O, B O, B22O2, and B23O2 may all be the same material ia varying degrees of purity. A representative crystalline substance was determined to be rhombohedral boron suboxide, B12O2, usually mixed with traces of boron or B2O3 (39). A study has been made of the mechanical properties of this material, which exhibits a hardness... 

For the most part boric acid esters are quantitated by hydrolysis in hot water followed by determination of the amount of boron by the mannitol titration (see Boron compounds, boric oxide, boric acid and borates). Separation of and measuring mixtures of borate esters can be difficult. Any water present causes hydrolysis and in mixtures, as a result of transesterification, it is possible to have a number of borate esters present. For some borate esters, such as triethanolamine borate, hydrolysis is sufftciendy slow that quantitation by hydrolysis and titration cannot be done. In these cases, a sodium carbonate fusion is necessary. 

Procedure. To determine the purity of a sample of boric acid, weigh accurately about 0.8 g of the acid, transfer quantitatively to a 250 mL graduated flask and make up to the mark. Pipette 25 mL of the solution into a 250 mL conical flask, add an equal volume of distilled water, 2.5-3 g of mannitol or sorbitol, and titrate with standard 0.1 M sodium hydroxide solution using phenolphthalein as indicator. It is advisable to check whether any blank correction must be made dissolve a similar weight of mannitol (sorbitol) in 50 mL of distilled water, add phenolphthalein, and ascertain how much sodium hydroxide solution must be added to produce the characteristic end point colour. 

Determination of borate as nitron tetrafluoroborate Discussion. Boric acid (100-250 mg) in aqueous solution may be determined by conversion into tetrafluoroboric acid and precipitation of the latter with a large excess of nitron [see Section 11.11(E)] as nitron tetrafluoroborate, which is weighed after drying at 110°C. The accuracy is about 1 per cent. 

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. 

For very weak acids however, e.g. boric acid [trioxoboric(III) acid], the initial conductance is very small but increases as the neutralisation proceeds owing to the salt formed. The conductance values near the equivalence point are high because of hydrolysis beyond the equivalence point the hydrolysis is considerably reduced by the excess alkali. To determine the end point, values of the conductance considerably removed from the equivalence point must therefore be used for extrapolation. 

Discussion. Minute amounts of beryllium may be readily determined spectrophotometrically by reaction under alkaline conditions with 4-nitrobenzeneazo-orcinol. The reagent is yellow in a basic medium in the presence of beryllium the colour changes to reddish-brown. The zone of optimum alkalinity is rather critical and narrow buffering with boric acid increases the reproducibility. Aluminium, up to about 240 mg per 25 mL, has little influence provided an excess of 1 mole of sodium hydroxide is added for each mole of aluminium present. Other elements which might interfere are removed by preliminary treatment with sodium hydroxide solution, but the possible co-precipitation of beryllium must be considered. Zinc interferes very slightly but can be removed by precipitation as sulphide. Copper interferes seriously, even in such small amounts as are soluble in sodium hydroxide solution. The interference of small amounts of copper, nickel, iron and calcium can be prevented by complexing with EDTA and triethanolamine. 

Vanadium borophosphates 107-109 that contain cluster anions with different ring sizes can be synthesized by hydrothermal reactions of vanadium(III) oxide, boric acid and an appropriate phosphate salt [145,146]. The ring size of the cluster anion with the composition [(VO)2BP20iol 4-6 is determined by the size of the cation that is, however, included only in the interior of the cages with n = 5 and 6 (Fig. 28). 

C17-0069. Determine the percent ionization of a solution of boric acid that is 75 mM (see AppendixE for K values). 

Recently, several reports of the flame-retardant properties of boron-containing bisphenol-A resins have appeared from Gao and Liu.89 The synthesis of a boron-containing bisphenol-A formaldehyde resin (64 and 65) (Fig. 42) from a mixture of bisphenol-A, formaldehyde, and boric acid, in the mole ratio 1 2.4 0.5, has been reported.893 The kinetics of the thermal degradation and thermal stability of the resins were determined by thermal analysis. The analysis revealed that the resin had higher heat resistance and oxidative resistance than most common phenol-formaldehyde resins. 

Capillary zone electrophoresis coupled with fast cyclic voltammetric detection was developed by Zhou et al. [27] for the separation and determination of OTC, TC, and CTC antibiotics. All compounds were well separated by optimization of pH and complexation with a boric acid sodium tetraborate buffer. The detection limit using fast on-line cyclic voltammetric detection with Hg-film-microm electrode was 1.5 x 10-6 mol/L for OTC (signal to noise ratio > 2). A continuous flow manifold coupled on-line to a capillary electrophoresis system was developed by Nozal et al. [28] for determining the trace levels of OTC, TC, and DC in surface water samples. 

Vinas et al. [46] also determined penicillamine by chemiluminescence - flow injection analysis. The sample was dissolved in water, and a portion of resulting solution was introduced into an FIA system consisting of 5 mM luminol in 0.1 M KOH-boric acid buffer (pH 10.4), 50 pM Cu(II), and 10 mM H202 eluted at 7.2 mL/min. Chemiluminescent detection was used, the calibration graphs were linear from 0.1 to 10 mM of penicillamine, and the coefficients of variation were from 1.2% and 2.1%i. 

Boeseken, J., The Use of Boric Acid for the Determination of the Configuration of Carbohydrates, IV, 189-210 Bonner, William A., Friedel-Crafts and Grignard Processes in the Carbohydrate Series, VI, 251-289 Bourne, E. J., and Peat, Stanley, The Methyl Ethers of D-Glucose, V, 145-190 Bourne, E. J. See also, Barker, S. A. 

Eberlein and Kattner [194] described an automated method for the determination of orthophosphate and total dissolved phosphorus in the marine environment. Separate aliquots of filtered seawater samples were used for the determination orthophosphate and total dissolved phosphorus in the concentration range 0.01-5 xg/l phosphorus. The digestion mixture for total dissolved phosphorus consisted of sodium hydroxide (1.5 g), potassium peroxidisulfate (5 g) and boric acid (3 g) dissolved in doubly distilled water (100 ml). Seawater samples (50 ml) were mixed with the digestion reagent, heated under pressure at 115-120 °C for 2 h, cooled, and stored before determination in the autoanalyser system. For total phosphorus, extra ascorbic acid was added to the aerosol water of the autoanalyser manifold before the reagents used for the molybdenum blue reaction were added. For measurement of orthophosphate, a phosphate working reagent composed of sulfuric acid, ammonium molyb-... 

Marcantoncetos et al. [112] have described a phosphorimetric method for the determination of traces of boron in seawater. This method is based on the observation that in the glass formed by ethyl ether containing 8% of sulfuric acid at 77 K, boric acid gives luminescent complexes with dibenzoylmethane. A 0.5 ml sample is diluted with 10 ml 96% sulfuric acid, and to 0.05-0.3 ml of this solution 0.1ml 0.04 M dibenzoylmethane in 96% sulfuric acid is added. The solution is diluted to 0.4 ml with 96% sulfuric acid, heated at 70 °C for 1 h, cooled, ethyl ether added in small portions to give a total volume of 5 ml, and the emission measured at 77 K at 508 nm, with excitation at 402 nm. At the level of 22 ng boron per ml, hundredfold excesses of 33 ionic species give errors of less than 10%. However, tungsten and molybdenum both interfere. 

The 2nd-order 300°C rates determined by the Arrhenius equation (Table VI) show that the rates are extremely high compared to the control or boric acid treated samples. In addition, the rate of mass loss appears to be unaffected by crystallinity. Ea values were lowered relative to the untreated control samples, except for the amorphous sample, and also appeared to be unaffected by... 

Trace amounts of bromine in sodium diclofenac, sodium (2-[(2, 6-dichlorophenyl)amino] phenyl acetate, have been determined using XRF [82], since the drug substance should not contain more than 100 ppm of organic bromine remaining after the completion of the chemical synthesis. Pellets containing the analyte were compressed over a boric acid support, which yielded stable samples for analysis, and selected XRF spectra obtained in this study are shown in Fig. 7.19. It was found that samples from the Far East contained over 4000 ppm of organic bromine, various samples from Europe contained about 500 ppm, while samples from an Italian source contained less than 10 ppm of organic bromine. 

The effect of those ions most frequently present in soils on the boron determinations is shown in Table 12.1. The interference of iron at concentrations higher than 7xlO 5M can be eliminated as the chloro complex by extraction with methyl isobutyl ketone. The total elimination of iron III was not necessary as the phosphoric acid masked the residual iron III in the boric acid-curcumin reaction. 

The amount of standardized acid needed is proportional to the amount of ammonia that bubbled through. It is an indirect method because the ammonia is determined but not titrated. It is determined indirectly by titration of H2B03. In a direct titration, the analyte would be reacted directly with the titrant, as per the discussion in Section 4.6. The concentration of the boric acid in the receiving vessel does not enter into the calculation and need not be known. Equation (4.40) is used for the calculation. 

Due to the chemical interactions between PVA and boric acid that lead to directly proportionally of the swollen hydrogel shrinking and the boric acid concentration, a sensor for this acid, difficult to determine by classical titration because of its weakness, has been proposed [162],... 

The monograph of levocarbastine has already been revised. The determination of the related substances is performed by means of MEKC using an electrolyte solution composed of sodium dodecyl sulfate as a micelle-forming agent in addition to hydroxypropyl-/ -cyclodextrin in a boric acid buffer of pH 9.0. Due to the very good specificity and robustness the method is able to baseline separate the nine specified and detectable impurities and the drug substance. It is easy to meet the system suitability (Rs>4) the resolution between levocarbastine and impurity D was found to be 6.4 and the content of related substances less than 0.5% (see Figure lA and B). 

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