Utilization of bromination reactions for the determination of carbamazepine using bromate-bromide mixture as a green brominating agent

One titrimetric and two spectrophotometric procedures have been developed for the assay of carbamazepine (CBZ) in bulk drug, formulations and spiked human urine. The methods are based on the bromination of CBZ by the bromine generated in situ by the action of the acid on the bromate-bromide mixture. The twin advantages of avoiding liquid bromine and analysis in a cost-effective manner are realized. In titrimetry, the drug was treated with a known excess of bromate-bromide mixture in hydrochloric acid medium followed by the determination of unreacted bromine iodometrically. Spectrophotometry involves the addition of a measured excess of bromate-bromide reagent in acid medium to CBZ, and after the reaction is ensured to be complete, the residual bromine was determined by reacting with a fixed amount of either methyl orange and measuring the absorbance at 510nm (method A) or indigo carmine and measuring the absorbance at 610nm (method B). Titrimetric procedure is applicable over the range of 1.00-7.50mg CBZ, and the calculations are based on a 1:1 reaction stoichiometry (CBZ:KBrO3). In spectrophotometric methods, Beer's law is valid within concentration ranges of 0.25-1.50 and 0.50-6.00μgml-1 CBZ for methods A and B, respectively. The proposed methods were successfully applied to the determination of CBZ in tablets and syrup, in addition to spiked human urine by the spectrophotometric methods, with mean recoveries of 95.50-104.0% and the results were statistically compared with those of an official method by applying Student's t-test and F-test

NON-AQUEOUS TITRIMETRIC ASSAY OF GABAPENTIN IN CAPSULES USING PERCHLORIC ACID AS TITRANT Non-aqueous titrimetric assay of gabapentin in capsules using perchloric acid as titrant

Two simple, rapid, accurate and inexpensive methods using visual and potentiometric titrimetric techniques are described for the determination of gabapentin (GBP) in bulk drug as well as in capsules. The methods are based on the neutralization reaction of the primary amino group of GBP with acetous perchloric acid as titrant in anhydrous acetic acid medium. The end point was detected either visually using crystal violet as indicator or potentiometrically using a modified glass electrode SCE electrode system. Both methods are applicable over the range 1.0-16.0 mg of GBP and the titration reaction follows a 1:1 stoichiometry. The methods were successfully applied to the determination of GBP in capsules. The validity of the proposed methods was further ascertained by parallel determination by a reference method and by recovery studies via standard-addition technique

Changes in the source and transport mechanism of terrigenous input to the Indian sector of southern ocean during the late quaternary and its palaeoceanographic implications

Changes in the terrigenous sediment source and transport mechanisms during the late Quaternary have been investigated using four sediment cores within the Indian sector of Southern Ocean, using the magnetic susceptibility (MS) and sedimentological records. Sediments deposited during the Holocene and other interglacial periods were characterised by low MS, low sand content, reduced ice-rafted detritus (IRD) input and increased illite possibly transported via hydrographic advection from the south. The glacial intervals are characterised by high MS, high sand content, increased IRD input and reduced illite clays, derived from both local as well as Antarctic sources. Significant reduction in clay fraction and illite content during glacials suggests that the erosive and transporting capabilities of the deep and bottom waters could have reduced compared to the interglacial times. The changes in terrigenous influx to this region were significantly influenced by the rhythmic glacial–interglacial fluctuations in bottom circulation and the position of the Polar Front

Iodometric determination of milligram and microgram amounts of levocetirizine in pharmaceuticals

Four simple, selective and sensitive methods are described for the determination of levocetirizine dihydrochloride (LCT) in bulk drug and in tablets. The methods exploit the well-known analytical reaction between iodide and iodate in the presence of acid solution. Iodide present is oxidized by iodate in an amount equivalent to the HCl present in LCT to iodine and the liberated iodine is determined by four different procedures which inturn quantify LCT at varying detection range and sensitiveness. Two direct titrimetric procedures involve titration of iodine by thiosulphate either towards starch end point (method A) or potentiometrically (method B). Both the methods have a reaction stiochiometry of 1: 1 (LCT: liberated iodine) and have quantification ranges of 2–20 mg LCT for method A and method B. The liberated iodine is also measured spectrophotometrically at 350 nm (method C) or the iodine-starch complex measured at 570 nm (method D). In both the methods, the absorbance is found to be linearly dependent on the concentration of iodine which in turn is related to LCT concentration. The calibration curves are linear over 5–40 and 1.25–12.5 mg mL−1 LCT for method C and method D, respectively. The calculated molar absorptivity and Sandel sensitivity values are 1.0 × 104 L mol−1 cm−1 and 0.0435 mg cm−2, respectively for method C, and their respective values for method D are 2.9 × 104 L mol−1 cm−1 and 0.0156 mg cm−2. The intra-day and inter-day accuracy and precision studies were carried according to the ICH guidelines. The method was successfully applied to the analysis of two brands of tablets LCT. The accuracy was also checked by placebo blank and synthetic mixture analyses besides recovery study via standard addition procedure

Antimikrobno djelovanje derivata 3-hidroksi-2-metilen-3-fenilpropionske kiseline

Twenty Baylis-Hillman adducts were synthesized from different aromatic aldehydes and activated vinyl derivatives. The adducts, which are differently substituted 3-hydroxy-2-methylene-3-phenylpropionic acid derivatives, were screened for their antimicrobial activity in vitro by the serial dilution method. Many of these molecules displayed potent antibacterial and antifungal activities. The ease of synthesis from low-cost starting materials along with potent antimicrobial activity of these molecules provide the lead for further improvement of activity and reflect the possibility of therapeutic use.Iz različitih aromatskih aldehida i aktiviranih vinil derivata sintetizirano je dvadeset Baylis-Hillmanovih adukata, različito supstituiranih derivata 3-hidroksi-2-metilen-3-fenilpropionske kiseline. Ispitano je njihovo antimikrobno djelovanje in vitro metodom serijskih razrjeđenja. Većina ispitivanih spojeva pokazala je snažno antibakterijsko i antifungalno djelovanje. Jednostavni sintetski postupak iz jeftinih sirovina i snažno antimikrobno djelovanje pružaju vodeće spojeve za daljnju modifikaciju, koji mogu dovesti do ljekovitih tvari pogodnih za terapijsku primjenu

Titrimetric and spectrophotometric assay of diethylcarbamazine citrate in formulations using iodate and iodide mixture as reagents

One titrimetric and two spectrophotometric methods are proposed for the determination of diethylcarbamazine citrate (DEC) in bulk drug and in formulations using potassium iodate and potassium iodide as reagent. The methods employ the well-known analytical reaction between iodate and iodide in the presence of acid. In titrimetry (method A), the drug was treated with a measured excess of thiosulfate in the presence of unmeasured excess of iodate-iodide mixture and after a standing time of 10 min, the surplus thiosulfate was determined by back titration with iodine towards starch end point. Titrimetric assay is based on a 1:3 reaction stoichiometry between DEC and iodine and the method is applicable over 2.0-10.0 mg range. The liberated iodine is measured spectrophotometrically at 370 nm (method B) or the iodine-starch complex measured at 570 nm (method C). In both methods, the absorbance is found to be linearly dependent on the concentration of iodine, which in turn is related to DEC concentration. The calibration curves are linear over 2.5-50 and 2.5-30 µg mL-1 DEC for method B and method C, respectively. The calculated molar absorptivity and Sandell sensitivity values were 6.48×103 L mol-1 cm-1 and 0.0604 µg cm-2, respectively, for method B, and their respective values for method C are 9.96×103 L mol-1 cm-1 and 0.0393 µg cm-2. The intra-day and inter-day accuracy and precision studies were carried out according to the ICH guidelines. The methods were successfully applied to the analysis of DEC formulations