Abstract
M.Sc.
The 11B/10B stable isotope ratio in wine- and provenance soil samples of four
South African wine regions was determined by means of quadrupole inductively
coupled plasma mass spectrometry (ICP-MS). The data obtained was combined
with multi-element results for the same samples. Discriminant analysis and
ANOVA statistics were utilized to create a footprint of wines compared to their
provenance soil. The results showed that the stable boron isotope ratio was a
distinguishable characteristic in wine and soil samples for the Stellenbosch,
Robertson, Swartland, and Walker Bay wine regions.
The potential improvement of precision and accuracy was investigated
specifically for ICP-QMS (quadrupole mass spectrometry) analysis of boron
isotope ratios. Sample preparation methods for the matrices used in this work
were developed and applied. The influence of the matrix components was
investigated. Ion exchange separation procedures were developed for the
separation of total B from the wine and soil matrices. Results were treated
mathematically to minimize mass bias effects. It was found that combined matrix
effects and TDS (total dissolved solids) deposition did have a pronounced effect
on the 11B/10B isotope ratios of the samples.
The possibility of boron isotope fractionation was investigated in vine plants.
Hydroponic experiments were set up with test plants of two cultivars. A 10B
enriched nutrient solution or growth solution with natural 11B/10B ratio was
supplied to the plants during alternating periods of 5 weeks each. New growth
leaves were harvested once every week during each of these time periods. All
samples were carefully prepared and analyzed to determine the relationship of
the 11B/10B ratio in the leaves compared to that of the supplied nutrient solution. It
was observed that the 11B/10B isotope ratio of the growth solution had an
influence on the 11B/10B stable isotope ratio in new growth leaves of vine plants.