Determination of total fluoride in vegetables and plants by open-flame ashing and microdiffusion: comparison with furnace ashing and oxygen-flask combustion'.

Citation:
W PROFNJENGALYDIAH, W PROFNJENGALYDIAH. "Determination of total fluoride in vegetables and plants by open-flame ashing and microdiffusion: comparison with furnace ashing and oxygen-flask combustion'.". In: Analytical Chemical Acta 212 (1988) 133-143. UoN; 1988.

Abstract:

The sample is ashed in a nickel crucible over an open flame with calcium hydroxide as thefixative; fluoride is separated by micro-diffusion and measured with a fluoride-selective electrode.The calcium hydroxide fixative permits a temperature of 800—850°C during the final ashing, sothat insoluble silicates are decomposed and fluoride is converted to an acid-soluble form. Otheradvantages over furnace ashing at 600°C are less contamination and more rapid ashing (20 mincompared to 6 h). The interference of aluminium and silica on microdiffusion was studied: per-chloric acid was found to be preferable to sulphuric acid as medium. A new way for preparingcalcium hydroxide suspension, low in fluoride, is described. The values found by the proposedmethod generally compare well with those obtained by oxygen flask combustion. Direct diffusion(i.e. without ashing) gave much lower values than the ashing methods, except for tea leaves.

Notes:

n/a

Website

UoN Websites Search