Low-voltage energy-dispersive X-ray microanalysis has a number of
distinct advantages for measuring the concentration of light elements
(Z = 11−20) in a largely organic matrix. Between 10 and 4 kV,
there is a 50-fold decrease in the size of the incident beam-specimen
interaction volume which enables discrete subcel-lular compartments to
be analyzed. Experiments with mineral and organic samples of known chemical
composition show that two of the most widely used analytical algorithms are
capable of providing quantitative data at accelerating voltages as low as 5
kV. This technique is used at 5 kV to analyze frozen hydrated fracture faces
of leaves of the tea plant which are known to contain aluminium. Higher
levels of aluminium are found in the cell walls and are associated with
increased levels of silicon and magnesium. The advantages and
disadvantages of the experimental approach are discussed in relation to
analysis carried out at higher voltages.