Determination Of Boron Concentration Research Articles

Accurate and efficient determination of boron content in volcanic rocks by neutron induced prompt gamma-ray analysis

An accurate and efficient analytical method using neutron-induced prompt γ-ray was developed for the determination of boron contents in volcanic rocks. We corrected the effect of sample geometry and flux fluctuation by using silicon as an internal standard. However, we found that the slopes of the calibration line vary among volcanic samples with different matrix. Because the increase of boron activity correlates positively with γ-ray count rate of hydrogen (water), we call this as the hydrogen effect. The hydrogen effect was confirmed by our experiment in which the boron activities showed systematic increase with the amount of added hydrogen (water). Most volcanic rocks, however, contain little water (<2 wt.%) to show this effect. We determined boron contents in various volcanic rocks in order to confirm the validity of the procedure that we established. The analyzed boron contents agreed well with the previous reported values. For efficient PGA of boron in volcanic rocks, we recommend JB-2 (GSJ standard rock) as a single geochemical standard, because of its high boron content (31.2 ppm).

Determination of trace amounts of boron in rainwater by ICP-IDMS and NTI-IDMS and the dependence on meteorological and anthropogenic influences

Two different mass spectrometric methods, inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) and negative thermal ionisation isotope dilution mass spectrometry (NTI-IDMS), were applied to the determination of trace concentrations of boron in rainwater samples. After carrying out the isotope dilution step, ICP-MS was directly used for the measurement of the 11 B/ 10 B ratio. For NTI-IDMS, the isotope diluted boron was first separated by a boron selective ion exchanger and then the boron isotope ratio was determined by measuring negative BO 2 – thermal ions. Boron concentrations of 21 rainwater samples from different parts of Germany and from the Jungfraujoch in Switzerland at an altitude of about 3600 m were determined to be in the range 0.3-7 ng ml –1 . The detection limits were 0.2 and 0.3 ng ml –1 for ICP-IDMS and NTI-IDMS using 3 and 50 ml sample volumes, respectively. NTI-IDMS determinations were about a factor of 2.5 more time-consuming compared with ICP-IDMS. However, the boron concentrations determined by ICP-IDMS often showed slightly higher values than those determined by NTI-IDMS, which was due to contributions of relatively high 12 C + ion intensities to the 11 B + intensity when using a quadrupole ICP-MS instrument with insufficient mass resolution. ICP-IDMS is a fast and reliable method for the determination of boron concentrations down to <1 ng ml –1 in aquatic systems if mass resolution between mass numbers 11 and 12 is under control, whereas NTI-IDMS can be best applied as an accurate reference method at these low concentration levels. Significant dependence of the boron concentration in rainwater on the meteorological conditions, but not on the season of sampling, as well as anthropogenic influences, especially on the altitude of the sample collection place, was found by applying both mass spectrometric methods.

Boron Determination—A Review of Analytical Methods

This paper reviews published methods of sample preparation, determinand purification, and the determination of boron concentration and isotopic composition in a sample. The most common methods for the determination of B concentration are spectrophotometric and plasma-source spectrometric methods. Although most spectrophotometric methods are based on colorimetric reactions of B with azomethine-H, curcumin, or carmine, other colorimetric and fluorometric methods have also been used to some extent. These methods, in general, suffer from numerous interferences and have low sensitivity and precision. Application of nuclear reaction and atomic emission/absorption spectrometric (AES/AAS) methods has remained limited because these methods have poor sensitivity and suffer from serious memory effects and interferences. Among a large number of published nuclear reaction methods only prompt-γ spectrometry has been of practical use. The prompt-γ method can determine B concentration in intact samples, which makes this method especially useful for some medical applications, including boron neutron capture therapy. However, this is a time-consuming method and not suitable for detection of low levels of B. Inductively coupled plasma optical emission spectrometry (ICP-OES) created a new dimension in B determination because of its simplicity, sensitivity, and multielement capability. However, it suffers interferences and is not adequately sensitive for some nutritional and medical applications involving animal tissues that are naturally low in B. All methods involving the measurement of B isotopic composition require a mass spectrometer. Thermal ionization mass spectrometry (TIMS) and secondary ion mass spectrometry (SIMS) have been used to measure isotopic composition of B; however, these methods are time consuming and require extensive sample preparation and purification. Development of inductively coupled plasma mass spectrometry (ICP-MS) not only overcame most of the drawbacks of earlier methods, but also its capabiltiy of measuring B isotopes made possible (1) B concentration determination by isotope dilution, (2) verification of B concentration by isotope fingerprinting in routine analysis, and (3) determination of total B concentration and B isotope ratio for biological tracer studies in the same run. Therefore, plasma source MS appears to be the method of choice among present-day technologies.

Analysis of boron by charged particle bombardment

The determination of boron concentration in thin films, semiconductors or other materials requires techniques providing good depth resolution and high sensitivities. For this purpose nuclear analysis techniques can be powerful tools and this paper presents a review of the nuclear reactions essentially with charged particles (p, α, d) that have been used (including charge particle activation analysis). Irradiation with neutrons is also considered, in particular with the very sensitive 10B(n, α) 7Li reaction due to the strong absorption of neutrons is boron. With the aim to search for reactions producing better depth resolutions, elastic recoil detection based technique (ERDA, ERCS) on boron are discussed. The performances of these nuclear reactions are compared with other methods, in particular with SIMS, AES, XPS and, using recent developments, the electronic microprobe.

Prompt-gamma neutron activation analysis using an isotopic neutron source

This paper describes an experimental set up using an isotopic neutron source with graphite, preferably to a hydrogen-rich compound, as moderator. This low thermal flux source has been employed in PGNAA experiments. Only those elements having a high cross section can be quantitatively analyzed at low concentration levels, mainly, Gd, Cd, Sm, B and Hg; the other elements can only be probed at macroscopic levels. An application to the determination of boron content in collyria examplifies the possibilities of the technique.

Boron determination by thermal neutron capture prompt gamma analysis

One of the long-standing applications of neutron capture gamma ray spectrometry is the determination of boron concentrations by in-beam prompt gamma analysis utilizing thermal neutrons. In this, the matrix-dependent shape variability of the Doppler-broadened gamma line has previously not been taken into account. The method described here recognizes the basic symmetry of the line and is of special significance in the frequent case of sodium interference, when it allows a better quantitative separation of the boron and sodium prompt gamma peaks.

Determination of trace concentration of boron in ADU by the nuclear track technique

A method for the determination of boron concentration in extracted (NH4)2 U2O7·H2O (ADU) has been used. One ml of the aqueous solution is irradiated with thermal neutrons from a 10 Ci Am/Be neutron source with a flux of 0.2·105 n·cm−2·s−1 and thermal column in the IRT-5000 with a flux of about 107 n·cm−2·s−1. The alpha-activity due to the reaction10B(n, α)7Li is recorded by a CR-39 alpha track detector. After the exposure, the alpha tracks are made visible in an optical microscope at magnification of 800X by etching the detector in 6N NaOH, and the track density is determined using calibration curves of known concentrations of boron. The boron concentration of the extracted ADU was found to be 5 ppm.

Determination of Boron Content and Boron Isotopic Ratio of Seawater Samples

Determination of Boron Content and Boron Isotopic Ratio of Seawater Samples