title: Use of inductively coupled plasma-mass spectrometry in boron-10 stable isotope experiments with plants, rats, and humans.
abstract: The commercial availability of inductively coupled plasma-mass spectrometry technology (ICP-MS) has presented the opportunity to measure the boron concentrations and isotope ratios in a large number of samples with minimal sample preparation. A typical analytical sequence for fecal samples consists of 25 acid blanks, 1 digestion blank, 5 calibration solutions, 4 standard reference material solutions, 10 samples, and 4 natural abundance bias standards. Boron detection limits (3 x 1 sigma) for acid blanks are 0.11 ppb for 10B, and 0.40 ppb for 11B. Isotope ratios were measured in fecal samples with 20 to 50 ppb boron with < 2% relative standard deviation. Rapid washout and minimal memory effects were observed for a 50 ppb beryllium internal standard, but a 200 ppb boron biological sample had a 1.0 ppb boron memory after a 6-min washout. Boron isotope ratios in geological materials are highly variable; apparently this variability is reflected in plants of a fixed natural abundance value for boron requires that a natural abundance ratio be determined for each sample or related data set. The natural abundance variability also prevents quantitation and calculation of isotope dilution by instrument-supplied software. To measure boron transport in animal systems, 20 micrograms of 10B were fed to a fasted rat. During the 3 days after a 10B oral dose, 95% of the 10B was recovered from the urine and 4% from the feces. Urinary isotope ratios, 11B/10B, changed from a natural abundance of 4.1140 to an enriched value of 0.95077, a 77% change.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Grand Forks, North Dakota 58202-7166.
authors.forename: R A
authors.initials: RA
authors.lastname: Vanderpool
authors.forename: D
authors.initials: D
authors.lastname: Hoff
authors.forename: P E
authors.initials: PE
authors.lastname: Johnson
mesh_terms: D000818:Animals; D001895:Boron / Q000032:analysis*; D005243:Feces / Q000737:chemistry; D006801:Humans; D007554:Isotopes; D008099:Liver / Q000737:chemistry; D013058:Mass Spectrometry; D010944:Plants / Q000737:chemistry*; D051381:Rats
chemical_list: D007554:Isotopes; D001895:Boron