Determination of boron in biological samples

Two sample treatment methods are evaluated to provide accurate boron determ ination at low concentrations in biological and botanical samples. The firs t approach is a hot 1M nitric acid extraction of baron from the sample The second technique uses wet digestion with concentrated sulfuric acid. The ac curacy of the procedures was demonstrated with botanical and animal referen ce materials (Corn Bran RM 8433 and Whole Egg Powder RM 8415). At least thr ee results are given for each reference material. Two are direct measuremen ts of B using independent B-10 and B-11 calibration curves with a Be intern al reference, and the third is obtained by isotope dilution mass spectromet ry (IDMS). The B-10 and B-11 values are consistent for both acid treatment procedures. The IDMS results also are consistent. Overall results for Whole Egg Powder and Corn Bran RM's match the best-estimate values within their confidence intervals. These results demonstrate the ability to measure B ac curately at the 0.3 mu g/g concentration range Thus, low-level B samples ca n be analyzed with accuracy and precision by the two approaches. These meth ods introduce very little dissolved organic carbon (DOC) in the final solut ion and allow the use of large (2 g) sample aliquots. Direct introduction o f biological fluids including whole blood serum also was evaluated critical ly for the determination of B.