Answers are grounded in this paper and cite their sources.
A spectrophotometric procedure was developed using ashing at 450 °C followed by acid digestion in beakers and reading the diluted digests at 440 nm. Errors were minimized by use of blanks and maintenance of a constant acid concentration in the diluted digests.
No takes yet. Share an insight, caveat, or question.
Fenton et al. (1979) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: