| Separation and determination methods of trace boron in various samples, especially in uranium were reviewed. Several methods of separation and preconcentration of boron from aqueous solutions have been reported. These include solvent extraction, ion-exchange separation, boron specific resins, chromatographic separation, and separation of boron as gaseous methyl borate. A variety of analytical techniques for the determination of boron have been developed, such as spectrophotometry, ionometry, atomic spectrometry, mass spectrometry.Difficulties and drawbacks in boron determinations were discussed. Boron is vulnerable to contaminations. There are very highly level boron blanks in water and reagents. Many analytical procedures suffer from serious memory effects. And boron is difficult to be excited and ionized. A series of studies were carried out to overcome these drawbacks. Various water, reagents and containers were compared. It was found that many high-pure waters, reagents and containers were commercial available now days, and they were preferred to the self-made ones because they took the advantages of lower and constant boron blanks, conveniences, lower costs and easy to be applied, high-pressure acid dissolution method was selected to digest the samples and standard materials to avoid the contamination and volatilization losses of boron.ICP-MS was used to measure the boron. The operating parameters were optimized and the interferences were corrected. The instrument was calibrated with mass, detector and response. The interferences was studied in the measurement of boron by ICP-MS, such as oxide interference, double- charge ion, multi-atom ion interference, overlap interference, the matrix effects and memory effects. The calibration curve in the boron measurement by ICP-MS was compared. It was y=0.0083x (y: the concentrations of boron, ng/ml; x: response count CPS, R2=0.9989) with no internal standard calibration and y=9.7876x (y: the concentrations of boron, ng/ml; x: instrument response count after the calibration with internal standard, R2=0.9999) with internal standard calibration. It was indicated that the linear relation of calibration curve was modified with internal standard. Boron standard material GBW 04202 was measured with cation ion-exchange separation standard calibration. The average quantity of sample was less than 0.35g, and the result was 0.165|4,g/gU3Og with the relative standard bias of 12%, the detect limit was 1.1 ng/ml. Compared with the reference value O.lSug/gUaOg of standard materials, the relative error was 10%.The cation ion exchange chromatography on-line ICP-MS determination was used to analysis boron in uranium, thus reducing the procedure contamination and operation time. The regeneration of ion-exchange resin columns weresemi-automatically modified, greatly improving the efficiency. On-line determination calibration equation was y=2556.1x (y: peak area, x: the concentrations of boron, correlation coefficient R2=0.9939). The stability of ICP-MS instrument was studied, and the effects of the stability on the method were discussed. Isotope dilution method was applied to the cation ion exchange chromatography on-line ICP-MS analysis procedure. The method was simple and convenient, accurate and reliable. The principle isotope dilution method was introduced in detail. The accuracy of the method was verified with boron standard materials GBW 04204. The measured result was 0.54|ag/gU3O8, thus the relative error was 8% compared with the reference valve of0.50ng/gU308. |
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