Adsorptive stripping voltammetry of antibiotics of rifamycin SV (RSV) and rifampicin (RIF) was investigated by cyclic
voltammetry and differential pulse voltammetry using a renewable pencil graphite electrode (PGE). The nature of the
oxidation process of RSV and RIF taking place at the PGE was characterized. The results show that the determination
of highly sensitive oxidation peak current is the basis of a simple, accurate and rapid method for quantification of RSV
and RIF in bulk forms, pharmaceutical formulations and biological fluids by differential pulse adsorptive stripping
voltammetry (DPASV). Factors influencing the trace measurement of RSV and RIF at PGE are assessed. The limits of
detection for the determination of RSV and RIF in bulk forms are 6.0 × 10–8 mol/L and 1.3 × 10–8 mol/L, respectively.
Moreover, the proposed procedure was successfully applied to assay both RSV and RIF in pharmaceutical formulations
and in biological fluids. The capability of the proposed procedure for simultaneous assay of antibiotics RSV-isoniazid
and RIF-isoniazid was achieved. The statistical analysis and calibration curve data for trace determination of RSV and
RIF are reported.

The present work describes the synthesis of a novel series of heterocyclic moieties derived from 5-acetylpyrazolo[3,4-b]pyridine (1). The formation of chalcones (2a-d) was utilized to synthesize pyrazoline, isoxazoline and pyrimidine derivatives (3-10). Thiosemicarbazone and semicarbazone (11, 17) were utilized to synthesize other new triazolethiones, thiadiazole and selenadiazole derivatives (11-19). Some new spiro derivatives (22-25) were synthesized by the reaction of chalcone (21) of 1 and isatine with hydrazines, hydroxyl amines and thiourea. Also, The reaction of 1 with cyanoacetyl hydrazine gave the hydrazide-hydrazone derivative 26, which was allowed to react with aromatic aldehydes and α-cyanocinnamonitrile to afford coumarine and substituted pyridine derivatives (28, 29). The structures of all the new compounds have been established on the basis of their analytical and spectral data. Twenty two of the synthesized compounds were also evaluated for their antibacterial and antifungal activity against various strains of bacteria and fungi and most are found to possess promising antimicrobial activity when compared with Chloramphenicol and Clotrimazole