Spectrophotometric Determination of Sodium Mercaptoundecahydrododecaborate with 5, 5′-Dithiobis(2-nitrobenzoic acid)

Abstract

A simple, sensitive and accurate method for the determination of sodium mercaptoundecahydrododecaborate, Na₂¹⁰B₁₂H₁₁SH, which is one of the most useful agents for boron neutron-capture therapy of brain tumors, was developed by spectrophotometry with 5, 5′-dithiobis(2-nitrobenzoic acid) [DTNB]. The color development based on 2-nitro-5-mercaptobenzoic acid liberated from DTNB by an exchange reaction of the sulfhydryl group showed maximal absorbance at 398nm with 1.65×10⁴dm³ mol^-1 cm^-1. Beer′s law was obeyed up to 6×10^-4mol dm^-3. The detection limit was 2×10^-5mol dm^-3.