Spectrophotometric methods for the determination of some thiols with aminophenols and iron(III)

Abstract

Two spectrophotometric methods have been developed for the determination of thiols by use of two pairs of reagents, p-aminophenol (PAP) -Fe(lll) for cysteine, cystarnine hydrochloride, glutathione, P-mercaptopropionic acid, P-mercaptoethanol, thioglycolic acid, thiomalic acid and thiosalicylic acid and Metol [p-(methy1amino)phenol sulphate] -Fe(l1l) for the above plus p-aminothiophenol, o-aminothiophenol and thiobarbituric acid. The methods are simple, sensitive, reproducible and accurate to within ?1.5% and have been applied to the assay of cystine after reduction and cystine in groundnut protein.

Determination of thiourea in fruit juice by a kinetic spectrophotometric method

“…These are based on direct reflectance spectrometric measurements [23][24][25], Raman spectroscopy [26], mass spectrometry [27], FTIR [28,29], voltammetry [16], potentiometry [30], amperometry [31], titrimetry with iodine [32], potassium dichromate [33] and Masson and Race reagent [34], gas chromatography after benzoylation [35], highperformance liquid chromatography [36], flow injections methods [37][38][39] and kinetic methods [40,41]. Catalytic kinetic spectrophotometric method is a suitable technique for determination of trace levels of thiourea because of its high sensitivity and selectivity and ease of instrumentation.…”

Electroanalytical exploitation of quinone–thiol interactions: application to the selective determination of cysteine

“…The aim of this paper was to report on the application of electrochemical techniques, principally square wave voltammetry, to the reaction of quinones with thiols as a method of quantifying the latter. The addition of thiols to quinone moieties is well established, forming the basis of numerous spectroscopic [39][40][41][42] and pre-column chromatographic derivatisation protocols. 43,44 The basic reaction pathway exploited in the proposed protocol is shown in Scheme 1 with the foundations of the approach relying on the ability of the electrochemical technique primarily to differentiate between the unreacted quinone (I) and the consequent quinone-thiol adduct (II and III).…”

Spectrophotometric and Kinetic Determination of Some Sulphur Containing Drugs in Bulk and Drug Formulations

“…The proposed method was successfully applied for determination of the studied sulphur drugs in their different dosage forms, as shown in Table 6, compared with the results obtained by the reference methods. 4,6,10,25 Mechanism of the Reaction. The stoichiometry of the reaction was studied adopting the limiting logarithmic method [30].…”

“…The rate of the reaction may be estimated by the variable time method measurement 25 as ∆A/∆t, where A is the absorbance and t is the time in seconds. Taking logarithms of rates and concentrations (Table 1), Eq.…”