Development and validation of a single collector SF-ICPMS procedure for the determination of boron isotope ratios in water and food samples

Boron isotope studies on technical materials and geological and environmental samples are one hot topic in nowadays isotope research. Provenance studies of artefacts, food and other products might become another one, as several recent studies demonstrate. Typically boron isotope determinations have been carried out by TIMS. To open up this research field to a broader scientific community we developed two analytical procedures for boron isotope determinations based on single collector SF-ICPMS combined with a sample preparation procedure consisting of dry-ashing and a three step ion chromatographic boron-matrix separation. The developed procedures consist of one low resolution (LR) and one medium resolution (MR) procedure. The repeatability for the delta(11)B determination in three independently measured aliquots lies between 0.2 and 0.8 parts per thousand for the LR procedure and between 0.3 and 1.5 parts per thousand for the MR procedure. The expanded uncertainties with a coverage factor of k=2 range between 1.4 and 1.6 parts per thousand for the LR procedure and between 2.9 and 3.2 parts per thousand for the MR procedure. The accuracy, expressed as average deviation from the reference values, is 0.43 parts per thousand for the LR procedure and 0.33 parts per thousand for the MR procedure. To test the practicability of the procedures the matrix tolerance has been investigated as well and was found to be up to 2 mg kg(-1) of alkaline and alkaline earth elements in the final measurement solution containing 100 mg kg(-1) boron. Thus a highly efficient matrix separation for SF-ICPMS boron isotope determinations is required, similar to TIMS.