Application of Azure C for the extractive spectrophotometric determination of microgram amounts of penicillin.

A simple, accurate, and rapid method for the quantitative determination of penicillin is proposed. The method is based on the formation of a blue penicillin-Azure-C ion-pair that can be extracted into chloroform in phosphate-citric acid buffer. The molar absorptivities for sodium penicillin G and potassium penicillin V at 635 nm were 5.46 X 10(3) and 2.19 X 10(4) l/mol/cm, respectively. Beer's law was valid over the concentration range of 4-80 micrograms/ml for sodium penicillin G and 3-55 micrograms/ml for potassium penicillin v. Maximum absorbance was obtained almost instantaneously and was stable for several days. The method was successfully applied to pharmaceutical preparations.

Potentiometric and visual titrations with bromamine-B.

Bromamine-B is proposed as an oxidimetric titrant for potentiometric and visual end-point titrations of arsenic(II), hexacyanoferrate(II), antimony(III), hydroquinone, semicarbazide hydrochloride, isonicotinic acid hydrazide, hydrazine sulphate, ascorbic acid, phenylhydrazine hydrochloride and metol. Quinoline Yellow, naphthidine, dimethylnaphthidinedisulphonic acid, o-dianisidine, diphenylbenzidine, Variamine Blue, alpha-naphthoflavone, Amaranth, Methyl Orange and Methyl Red are proposed as indicators in macro and micro titrations of the reductants with bromamine-B. The transition potentials of Quinoline Yellow, naphthidine, dimethylnaphthidinedisulphonic acid, and o-dianisidine in the titration of ascorbic acid are reported. Arsenic(III) and hexacyanoferrate(II) are suggested for the standardization of bromamine-B solutions.

Redox indicators in titrations with dichloramine-B.

Naphthidine, dimethylnaphthidine, dimethylnaphthidinedisulphonic acid, o-dianisidine, Quinoline Yellow, diphenylbenzidine and Amaranth are proposed as indicators in titrations of arsenic(III), iron(II), antimony(III), hydroquinone, hydrazinium sulphate, phenylhydrazine hydrochloride, semicarbazide hydrochloride and ascorbic acid with dichloramine-B. They give a very sharp colour change at the equivalence point. Arsenic(III) and iron(II) are suggested for standardization of dichloramine-B solutions. A potentiometric method for the determination of arsenic(III) and semicarbazide hydrochloride is described.

N-substituted phenothiazines as redox indicators in titrations with chloramine-T and chloramine-B.

Profenamine hydrochloride, fluphenazine dihydrochloride, trifluopromazine hydrochloride, cyamepromazine maleate, perphenazine dihydrochloride and mepazine hydrochloride are proposed as redox indicators in the titration of hydroquinone, metol and ascorbic acid with chloramine-T and chloramine-B in sulphuric, hydrochloric and acetic acid media. They give a sharp reversible colour change at the equivalence point. A simple but accurate method for the determination of hydroquinone, metol and ascorbic acid is described. The conditional potentials and molar absorptivities of the indicators and redox potential of chloramine-B are reported.

N-substituted phenothiazines as redox indicators in bromatometry.

Diethazine hydrochloride, butaperazine dimaleate, trifluoperazine hydrochloride, promethazine hydrochloride, prochlorperazine maleate and chlorpromazine hydrochloride have been studied as indicators in bromate titration of quinol, metol and ascorbic acid. They give a very sharp reversible colour change at the equivalence point. Their formal potentials have been determined. A simple but accurate method for the estimation of quinol and metol is reported.

Rapid spectrophotometric determination of platinum with trifluoperazine dihydrochloride.

Trifluoperazine dihydrochloride reacts with platinum(IV) in sodium acetate-hydrochloric acid buffer containing copper(II) catalyst to form a bluish-green 1:1 complex with absorbance maximum at 504 nm. A 50-fold ratio of reagent to metal ion is necessary for complete complexation. Beer's law is valid over the concentration range 0.5-8 ppm of platinum(IV) with optimum concentration range 1-7 ppm. The molar absorptivity is 6.50 x 10(3) l.mole(-1).cm(-1). The effects of pH, time, temperature, concentration of reagent and copper, order of addition of reagents, and the interferences from various ions are reported.

Rapid spectrophotometric determination of ruthenium with diethazine hydrochloride.

Diethazine hydrochloride reacts with ruthenium(III) instantaneously at high acidity (sulphuric or hydrochloric acid) to form a red 1:1 complex with absorbance maximum at 515nm. A tenfold molar excess of reagent is necessary for complete complexation. Beer's law is obeyed for 1.0-10.4 ppm of ruthenium(III), with optimum concentration range 2-9 ppm. The molar absorptivity is 5.35 x 10(3) 1.mol(-1) .cm(-1).

Substituted phenothiaziiies as indicators in the ferrocyanide titration of zinc.

Chlorpromazine, promethazine and diethazine hydrochlorides and prochlorperazine maleate have been tested as indicators in the ferrocyanide titration of zinc. Only the first and last are useful, giving a sharp reversible colour change in both the direct and reverse titrations, but the results are negatively biased by 0.2-1.3%.

Promethazine hydrochloride as a new redox indicator in vanadametry.

Promethazine hydrochloride is proposed as a new redox indicator in vanadametry. It has been tested rigorously in the titration of iron(II), hydroquinone, uranium(IV) and antimony(III) with sodium vanadate. The indicator gives a very sharp reversible colour change from green to violet at the equivalence point. It has advantages over all the proposed redox indicators in vanadametry. Its redox and transition potentials are reported.

Chlorpromazine hydrochloride as a new redox indicator in vanadametry.

Chlorpromazine hydrochloride is proposed as an indicator in the vanadametric titration of iron(II) and molybdenum(V). It gives a sharp, reversible colour change from green to violet at the equivalence point. It has advantages over the diphenylamine class of indicators. Its redox and transition potentials are reported.