Tungstophosphoric acid as a new reagent for the spectrophotometric determination of phenothiazines

A simple and rapid spectrophotometric method for the determination of phenothiazines based on the formation of a colored compound between tungstophosphoric acid and phenothiazines is described. The proposed method is successfully employed for the determination of phenothiazine drugs in various pharmaceutical products.     

Rapid spectrophotometric determination of ruthenium(III) with prochlorperazine maleate

A rapid, simple spectrophotometric method for the determination of μg amounts of ruthenium, based on the formation of a pink complex between the metal and prochlorperazine maleate (PCPM) in sulphuric or hydrochloric acid solution, is described. The complex has an absorption maximum at 530 nm and its molar absorptivity is 6.733·10³ l mol^?1 cm^?1. The sensitivity is 0.0151 μg Ru cm^?2 for log I_o/I = 0.001. Beer's law is valid over the range 0.2–10 μg Ru ml^?1 ; the optimal range for spectrophotometric determination is 0.8–8.0 μg Ru ml^?1. Job's method of continuous variation, the mole ratio method and the slope ratio method indicate a 1:1 composition for the complex. The effects of acidity, time, temperature, order of addition of reagents, reagent concentration, and the interferences from various ions are reported.     

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.     

Spectrophotometric determination of microgram amounts of penicillins by solvent extraction with azure b

Penicillins are determined by means of ion-pair formation with azure B and extraction into chloroform: the absorbance of the extract is stable for several days. The apparent molar absorptivities for sodium penicillin G and potassium penicillin V at 634 nm are 3.91 × 10³ and 1.25 × 10⁴ l mol^-1 cm^-1, respectively. Calibration graphs are linear over the range 60–950 μg of sodium penicillin G and 40–600 μg of potassium penicillin V in 10 ml. The method is successfully applied to pharmaceutical preparations.     

Bioimaging of Peroxynitrite in MCF-7 Cells by a New Fluorescent Probe Rhodamine B Phenyl Hydrazide

Peroxynitrite is a potent oxidizing and nitrating agent which has detrimental effects on cells by altering the structure and function of biomolecules present within. A fluorescent probe rhodamine B phenyl hydrazide (RBPH) has been proposed for peroxynitrite (ONOO^?) imaging in MCF-7 cells based on its oxidation property, which converts RBPH to pink colored and highly fluorescent rhodamine B. The fluorescence emission intensity of the rhodamine B produced in the above process is linearly related to the concentration of peroxynitrite. The method obeys Beer’s law in the concentration range 2–20 nM and the detection limit has been found to be 1.4 nM. The possible reaction mechanism of peroxynitrite with RBPH to produce rhodamine B has been discussed with spectroscopic evidence. The Probe is selective to the peroxynitrite in the pH range 6–8 which is near physiological pH. Fluorescence microscopic studies suggest that the probe is cell permeable and hence peroxynitrite was imaged in MCF-7 cells.