RP–HPLC Method Validation for Simultaneous Estimation of Paracetamol and Caffeine in Formulating Pharmaceutical Form

A novel, simple and accurate, Reversed Phase High Performance Liquid Chromatography (RP-HPLC) method for simultaneous estimation of Paracetamol (PCM) and Caffeine (CAF) in mixture of standard and formulation tablets was validated in this research. The absorbance maximum of drugs using UV- spectroscopy was found at (244.8 and 272.6nm) for PCM and CAF respectively in deionized water: methanol mixture (60:40 V/V) as solvent. This method involves the separation of PCM and CAF on RP - HPLC Shimadzu type LC–20 - A, Japan, and Phenomenex column, C18 (250mm, 4.6mm and 5μm). The elution was done using an eluent phase composed of methanol and water in the ratio of (40:60 V/V with a pH adjusted at 4.0 using acetic acid). A separation was fixed for 10 min at 270nm, using a UV-Vis - detector and 1.0mL/min, flow rate and the drugs were eluted in (3.468 and 5.376 min) for PCM and CAF respectively. The suitable conditions such as the elution phase composition, rate of flow, pH and wavelength were studied. The linearity of the method was in the range of concentration within (0.5 – 25 and 0.1 - 30μg/mL), while, R2 values within (0.9995 and 0.9997), and the means of recovery were found within (99.57 and 100.36) for PCM and CAF respectively. The method was applied for the estimation of gradient active of drugs in different formulating form samples. The method accuracy was validated by the mean of recovery percentages which, were found in acceptable limit.

Structure-Assembly-Property Relationships of Simple Ditopic Hydrogen Bonding Capable π-Conjugated Oligomers

A series of simple ditopic hydrogen bonding capable molecules functionalized with 2,4-diamino-1,3,5-triazine (DAT), barbiturate (B), and phthalhydrazide (PH) on both termini of a 2,2′-bithiophene linker were designed and synthesized. The intrinsic electronic structures of the ditopic DAT, PH, and B molecules were investigated with ground-state DFT calculations. Their solution absorbance was investigated with UV-vis, where it was found that increasing size of R group substituent on the bithiophene linker resulted in a general blue-shift in solution absorbance maximum. The solid-state optical properties of ditopic DAT and B thin films were evaluated by UV-vis, and it was found that the solid-state absorbance was red-shifted with respect to solution absorbance in all cases. The three DAT molecules were vacuum thermal deposited onto Au(111) substrates and the morphologies were examined using STM. (DAT-T)2 was observed to organize into six-membered rosettes on the surface, whereas (DAT-TMe)2 formed linear assemblies before and after thermal annealing. For (DAT-Toct)2 , an irregular arrangement was observed, while (B-TMe)2 showed several co-existent assembly patterns. The work presented here provides fundamental molecular-supramolecular relationships useful for semiconductive materials design based on ditopic hydrogen bonding capable building blocks.

Properties of a fungicidal product formed from a reaction between L-cystine and pyridoxal

Previously we found that three components of a commonly used mammalian cell culture medium incorporated into agar killed cryptococci (Granger and Call 2019). The components were L-cystine, iron [Fe(III)], and pyridoxal (CIP). We now report on a buffered solution at neutral pH of the three components, which was highly fungicidal without agar. We showed that CIP fungicidal activity, identical to the findings with cell culture medium, was inactivated by visible light and was unstable with storage in the dark. Congeners replacing either pyridoxal or L-cystine in CIP revealed structural requirements for fungicidal activity. Replacing pyridoxal in CIP with 2-hydroxy-5-nitrobenzaldehyde produced a solution that was equally fungicidal and maintained fungicidal activity upon storage in the dark for up to 50 days. We employed methods for excluding iron from CIP and found that fungicidal activity was not affected. Upon mixing L-cystine and pyridoxal in buffer at pH 7.0, diode array spectroscopy revealed a red-shift of absorbance maximum from 391 nm to 398 nm. Our findings point to Schiff base reaction between the pyridoxal aldehyde group of C1 with the alpha amino group(s) of cystine to yield a fungicidal compound. Light at wave length approximately 400 nm inactivates this complex accompanied by bleaching of the pyridine ring of pyridoxal. Our findings may be useful for design of a class of fungicidal compounds formed through Schiff base reaction of disulfide compounds with aromatic ring-bearing aldehydes.

Determination of Satranidazole through Ion-Associative Complex Reaction

A simple, selective, accurate and low-cost spectrophotometric method has been described for determination of satranidazole in bulk and pharmaceutical formulations. The developed method involves the formation of chloroform extractable colored ion-association complex of satranidazole with Tropaeolin OOO (TPooo). The extracted colored complex showed absorbance maximum at wavelength 484 nm and obeying Beer′s law in the concentration 4-20 μg mL-1 with the correlation coeffiecent of 0.9998. The results of statistical analysis of the proposed method reveals high accuracy and good precession. Thus, the proposed method can be used commercially for the determination of satranidazole in bulk and pharmaceutical formulations.

SPECTROPHOTOMETRIC DETERMINATION OF COPPER COMPLEXES OF CHLOROPHYLLINS (E141ii)

In this study, the water-soluble green food colorant copper complexes of chlorophyllins, E141ii, as one of the most popular within the food industry was investigated. First, the spectroscopic parameters, absorbance maximum, λmax-vis, and molar absorptivities, ε, of E141ii dye were determined. The impact of the presence of aspartame, citric acid and vitamin C on the change in the positions of the absorbance maximum and change of its intensity in the visible range of the E141ii spectra also was investigated. Recorded absorption spectra was show that this dye had two absorbance maxima. The average molar absorptivities were calculated. These values of molar absorptivities were later used to quantify the unknown dye concentration in the analyzed food samples. It was found that the use of additives (vitamin C, citric acid and aspartame) does not cause a change in the positions of the absorbance maximum and change of its intensity in the visible range of the E141ii spectra. Therefore, it can be concluded that it is possible to quantify the E141ii by UV-Vis spectrophotometric method in the presence of these additives. Based on determined spectroscopic parameters, the dye concentration was calculated in green rubber candy colored with E141ii.

Development of New Analytical Method for Estimation of Lansoprazole in Bulk and Tablet dosage forms

The present paper reports a simple, accurate and precise spectroscopic technique for estimation of Lansoprazole by first order derivative technique in tablet dosage form. The spectroscopic method for estimation of Lansoprazole by first order derivative technique was carried out using methyl alcohol as solvent. The absorbance maximum was 275nm. Beers law observed in the range of 30 - 150μg/ml concentration. The recovery studies demonstrated the accuracy of the proposed procedure and the results were established as per ICH guidelines. The technique was used successfully for the estimation of Lansoprazole in bulk and tablet and pure dosage form.

Interaction of Cetylpyridinium Chloride and Methylene Blue in Methanol-Water Solvent Media

The interaction of Methylene blue with Cetylpyridinium chloride (CPC) in a series of solvents containing 0.1, 0.2 and 0.3 volume fractions of methanol in water were studied at room temp (300±2 K) by UV-Vis spectrophotometer. The CPC concentrations were varied from 0.2 x 10-3 to 2 x 10-3 mol dm-3. A fixed dye concentration of 2.5 x 10-5 mol dm-3 was used for this purpose. The spectrum analysis was performed for both the dye solution and mixtures containing dye and surfactant of different concentrations. The dye solution showed the absorbance maximum at 664 nm and a shoulder at 610 nm. In 0.3 volume fraction of methanol as solvent, the dye and surfactant mixed solution showed a shift in peak values towards shorter wavelength (blue shift) from peak of the dye solution. The shift in peak increased with increase in surfactant concentration up to 0.6 x10-3 mol dm-3, beyond which no further shift increment occurred. In the case of 0.1 and 0.2 volume fractions of methanol in water, no shift in peak was found at all concentrations of dye and surfactant. The absorbance of dye and surfactant mixed solution decreased gradually in 0.2 volume fraction of methanol with increase in surfactant concentration, whereas no significant change in absorbance was seen in 0.1 volume fraction of methanol. The shift decreased gradually with decrease in methanol concentration in the solvent.

Estimation of Glycopyrrolate by Analytical Quality by Design Supported Difference UV Spectrophotometric Method

A novel difference UV spectrophotometric method was developed and validated for estimation of glycopyrrolate (GLP) in injection formulations using analytical quality by design approach. GLP shows two different absorbance maxima in 0.1M HCl and 0.1M NaOH. Principle of difference spectroscopy was utilized to avoid the variation in absorbance maximum and amplitude of analyte solutions were measured keeping analyte in 0.1M HCl in reference cell and analyte in 0.1M NaOH in sample cell. The amplitude was measured considering maxima at 219nm and minima at 233nm. Further, analytical quality by design approach proved worthy by ensuring method robustness prior to method development. Scanning speed and sampling interval were the two variables which were studied for the robustness purpose using an experimental design. The method validation studies were carried out to evaluate linearity, accuracy, precision, sensitivity etc. The method was applied successfully for estimation of GLP in bulk and present in injections.

A SIMPLE SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF TETRACYCLINE AND DOXYCYCLINE IN PHARMACEUTICAL FORMULATIONS USING CHLORAMINE-T

A simple, rapid, accurate and inexpensive spectrophotometric method for the determination of tetracycline and doxycycline has been developed. The method is based on the reaction between these drugs and chloramine-T in alkaline medium producing red color products with absorbance maximum at the ë = 535 and 525 nm for the tetracycline and doxycycline, respectively. The best conditions for the reactions have been found using multivariate method. Beer´s law is obeyed in a concentration ranges 1.03 x 10-5 to 3.61 x 10–4 mol L-1 and 1.75 x 10-5 to 3.48 x 10–4 mol L-1 for the tetracycline and doxycycline, respectively. The quantification limits were 5.63 x 10-6 mol L-1 and 7.12 x 10-7 mol L-1 for the tetracycline and doxycycline, respectively. The proposed method was successfully applied to the determination of these drugs in pharmaceutical formulations and the results obtained were in good agreement with those obtained by the comparative method at the 95% confidence level.

DEVELOPMENT AND VALIDATION OF UV SIMULTANEOUS EQUATION METHOD FOR DETERMINATION OF AZITHROMYCIN AND LEVOFLOXACIN IN BULK DRUGS AND MARKETED FORMULATION

Azithromycin and levofloxacin used for the treatment of bacterial infections. Simple, specific, accurate and precise UV spectroscopy method has been developed and validated for simultaneous determination of azithromycin and levofloxacin in bulk drugs and marketed formulation. The developed method involves solving of simultaneous equations using methanol as solvent where an absorbance maximum for azithromycin and levofloxacin was found to be at 291.92nm and 294.08nm, respectively. The drugs obeyed Beer’s law in the concentration range of 50- 250 μg/ mL & 2 – 10 μg/ mL. The method was validated as per ICH guidelines .The method showed good correlation coefficients (r2) 0.999, indicated good linearity of calibration curve for both the drugs. The recovery of azithromycin and levofloxacin was 98.82% and 97 .74% respectively. The robustness and ruggedness of azithromycin (0.368, 0.285), and levofloxacin (0.556, 0.442). The developed method was found to be accurate, reliable, robust showing LOD 0.012μg/mL and 0.016μg/mL LOQ 0.053μg/mL and 0.058μg/mL for azithromycin and levofloxacin.