An automated titration for the Winkler method is presented for measuring primary productivity in the ocean. The system is based on a microcomputercontrolled titration with potentiometric endpoint detection. By the use of 0.005-N sodium thiosulfate as a titrant and a program designed to shorten the time for measuring, the method achieves a precision of 0.04% coefficient of variation with a range...

carbon paste electrode was modified by disodium 2,4-diamino-7-methylbenzo[g] pteridine-5,10-dioxide to fabricate a sensor for potentiometric determination of vanadyl ion (vo2+) in aqueous medium. the new ligand was synthesized in three steps with high yield. the optimal composition of the carbon paste was made of graphite powder (64.5%), ionophore (16.6%), paraffin oil (17.8%), and sodium tetra...

Three simple methods using visual titrimetric, potentiometric and spectrophotometric techniques are described for the determination of acyclovir in pure form and in pharmaceutical formulations. The methods are based on the neutralisation reaction involving the primary amino group of the drug and acetous perchloric acid in acetic acid medium. In titrimetric methods, the titration is completed wi...

The acid dissociation constants of the hydroxyl groups in 25, 26, 27, 28-tetrahydroxy-5, 11, 17, 23-tetrasulphonic-calix[4]arene (SC4) were determined at 25οC by a combination of potentiometric and spectrophotometric titration method. The first and second acid dissociation constants (pKa1, pKa2) were found to be 3.19 and 12.1, which demonstrated pKa shift due to intramolecular hydrogen bonding ...

A review of the works reflecting authors' research on synthesis and study physico-chemical properties polymer biologically active substances (BAS) is presented. The results are analyzed in relation to specific biological activity polymers order establish possibility predicting their prolonged bioactive effect based values constants formation, stability, dissociation other characteristics comple...