Masoom Raza Siddiqui

Rapid and sensitive method for analysis of nitrate in meat samples using ultra performance liquid chromatography-mass spectrometry.

A sensitive and selective ultra performance liquid chromatography-mass spectrometric method has been developed for the quantitative analysis of nitrate in meat samples. Selected ion reaction (SIR) mode was adopted to identify and quantify the nitrate. Chromatographic analyses were performed on a BEH C-18 column with a mobile phase consisting of a surfactant (Cetylpyridinium chloride) and acetonitrile in equal ratio (50/50, v/v) at a flow rate of 0.4 mL min(-1). The limit of detection and limit of quantitation of the developed method was found to be 0.0599 and 0.1817 mg kg(-1), respectively. The linearity of the proposed method was checked in the concentration range of 0.5-10 mg kg(-1) with an excellent correlation coefficient (r) of 0.997. The recovery of the nitrate in the meat samples were in the range of 98.02-98.99%.

High-Throughput UPLC–MS Method for the Determination of N-Acetyl-l-Cysteine: Application in Tissue Distribution Study in Wistar Rats

N-Acetylcysteine (NAC) is the N-acetyl derivative of the amino acid l-cysteine and is extensively used as a medicine to treat a variety of diseases. High-throughput ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) method has been developed for the quantitative assessment of N-acetyl-l-cysteine. The method was further applied to study the distribution of the intraperitoneal injected drug into different tissues and plasma of Wistar rats, including liver, kidney, heart, lungs and spleen. The drug was having highest concentration in plasma and liver followed by kidney, lungs, heart and spleen. Method validation studies suggested being linear in the range of 1-15 µg mL(-1) for liver, kidney, heart, lungs and spleen and 1-120 µg mL(-1) for the plasma. The limit of detection and limit of quantitation were found to be 0.20 and 0.66 µg mL(-1), respectively. The recovery studies suggested that in all the cases, the obtained recovery was in the range of 98.51-101.88%. Our analyses provide a validated UPLC-MS method for the determination of NAC and its successful application for the analysis in plasma and tissues obtained from Wistar rats.

HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC METHOD FOR THE QUANTITATIVE ANALYSIS OF CEFUROXIME IN PHARMACEUTICAL PREPARATIONS

ABSTRACT New Analytical method has been developed for the determination of Cefuroxime in pharmaceutical formulations. The method involves the application of high performance Liquid chromatography (HPLC) for the quantitative analysis of cefuroxime. HPLC method has a shorter analysis time of 10 min. The developed method obeyed the Beer’s law in the range of 5- 300 µg mL -1 . Limit of detection (LOD) and limit of quantitation (LOQ) of the developed method was found to be 0.538 and 1.63, µg mL -1 respectively. Keywords: Cefuroxime, High Performance liquid chromatography, Method validation, Pharmaceutical preparations INTRODUCTION Cefuroxime sodium is chemically known as [6R - [6α,7β(Z)]] - 3 - [[(2 - Aminocarbonyl)oxy]methyl] - 7 - [2 - furanyl(methoxyimino)acetyl]amino] - 8 - oxo - 5 - thia - 1 - azabicyclo[4.2.0]oct - 2 - ene - 2 - carboxylic acid monosodium salt. It is a broad spectrum, semi synthetic cephalosporin antibiotics which is administered for treating variety of bacterial infections such as case of pharyngitis, chronic bronchitis and infection of urinary tract as well as uncomplicated gonorrhea, bone and joint infections, meningitis and septicaemia [1,2]. It is a second generation cephalosporin and can be administered orally as well as in the parenteral dosage form [3]. The mode of action of cefuroxime against the bacteria is upon inhibiting the bacterial wall synthesis by binding to one or many penicillin binding proteins. Due to such type of binding, development of osmotically unstable defective cell wall occurs which shows bactericidal properties [3, 4]. Assay of the pharmaceuticals is one of the important aspects of the pharmaceutical industry, as it determines the drug product having same quantity as label claim; however, advanced analytical instruments are also capable of detecting the impurities. Some of the analytical methods are reported for the assay of cefuroxime in marketed form includes spectrophotometry [5-8], High performance liquid chromatography (HPLC) [9-11], Capillary electrophoresis [12-14], HPTLC [15] and LC-MS/MS [16]. The current communication proposes simple analytical procedure to quantify cefuroxime in pure and marketed products using HPLC. The proposed HPLC analytical procedure is based on the separation of cefuroxime using ion pair reagent, octane-1-sulfonic acid sodium salt.

Spectrophotometric investigation on the kinetics of oxidation of adrenaline by dioxygen of μ-dioxytetrakis(histidinato)-dicobalt(II) complex

The cobalt(II)histidine complex binds molecular oxygen reversibly to form an oxygen adduct complex, μ-dioxytetrakis-(histidinato)dicobalt(II). The molecular oxygen can be released from the oxygenated complex by heating it or by passing N2, He or Ar gas through its solution. μ-Dioxytetrakis-(histidinato)dicobalt(II) complex oxidizes adrenaline into leucoadrenochrome at 25°C while at higher temperature (>40°C) adrenochrome with λmax at 490nm is formed. The rate of formation of leucoadrenochrome was found to be independent of [bis(histidinato)cobalt(II)]. The rate of reaction for the formation of leucoadrenochrome and adrenochrome increased with the increase in [adrenaline] at its lower concentration but become independent at higher concentration. Similarly, the rate of formation of both leucoadrenochrome and adrenochrome was linearly dependent upon [NaOH]. The values of activation parameters i.e. ΔEa, ΔH(‡) and ΔS(‡) for the formation of leucoadrenochrome are reported.

Ultraperformance Liquid Chromatography -Mass Spectrometric Method for Determination of Ampicillin and Characterization of Its Forced Degradation Products

In the current study, a rapid and sensitive UPLC-MS method has been developed for the quantitative analysis of ampicillin in pure and pharmaceutical formulations. Forced degradation analysis was performed and the stress degradation product thus obtained was characterized by mass spectrometry. The chromatographic separation was carried out using BEH C18 column (100 × 2.1 mm, 1.7 µm particle size) using a binary mobile phase mixture of 0.001% acetic acid in water and methanol (30:70). The flow rate was set at 0.3 mL min(-1). The total chromatographic analysis time for ampicillin was as short as 1.5 min. The detection and quantitation of the studied drug was carried out using positive electrospray ionization and selected ion reaction modes. The developed method was found to be linear over the concentration range of 0.25-3.0 µg mL(-1). The recovery studies suggest an excellent recovery of the procedure which was found in the range of 99.45-100.90%. The relative standard deviation range of the developed analytical procedure ranged from 1.98 to 2.67% in intraday studies and 2.38-2.98% in case of interday study. The limit of detection and limit of quantitation of the method were found to be 0.016 and 0.049 µg mL(-1), respectively.

Second derivative synchronous fluorimetric method for simultaneous determination of harman and norharman in coffee samples.

The simultaneous determination of harman and norharman using second derivative synchronous fluorescence method has been developed based on their natural fluorescence. Due to their similar molecular structures, it is difficult to determine them simultaneously in the mixture using conventional fluorimetry. Overlapping of fluorescence spectra was resolved by using a constant second derivative synchronous fluorimetry. The derivative synchronous spectrum, maintaining a constant difference of Δλ=150 nm between emission and excitation for both the compounds, has been selected for the analysis. The range of application is between 0.182 and 18.2 μg/mL (correlation coefficient, R=0.9982) for harman and between 0.504 and 16.8 μg/mL (correlation coefficient, R=0.9962) for norharman. The recovery ranges of 98.5-101.1% for harman and 97.5-99.1% for norharman from their synthetic mixture was reported. The detection limits are 0.016 μg/mL and 0.038 μg/mL for harman and norharman, respectively. Similarly, the quantitation limit of the two compounds was found to be 0.049 and 0.109 μg/mL, respectively. The method was applied to the simultaneous determination of both compounds in coffee samples with satisfactory results.

Mercerized mesoporous date pit activated carbon—A novel adsorbent to sequester potentially toxic divalent heavy metals from water

A substantive approach converting waste date pits to mercerized mesoporous date pit activated carbon (DPAC) and utilizing it in the removal of Cd(II), Cu(II), Pb(II), and Zn(II) was reported. In general, rapid heavy metals adsorption kinetics for Co range: 25–100 mg/L was observed, accomplishing 77–97% adsorption within 15 min, finally, attaining equilibrium in 360 min. Linear and non-linear isotherm studies revealed Langmuir model applicability for Cd(II) and Pb(II) adsorption, while Freundlich model was fitted to Zn(II) and Cu(II) adsorption. Maximum monolayer adsorption capacities (qm) for Cd(II), Pb(II), Cu(II), and Zn(II) obtained by non-linear isotherm model at 298 K were 212.1, 133.5, 194.4, and 111 mg/g, respectively. Kinetics modeling parameters showed the applicability of pseudo-second-order model. The activation energy (Ea) magnitude revealed physical nature of adsorption. Maximum elution of Cu(II) (81.6%), Zn(II) (70.1%), Pb(II) (96%), and Cd(II) (78.2%) were observed with 0.1 M HCl. Thermogravimetric analysis of DPAC showed a total weight loss (in two-stages) of 28.3%. Infra-red spectral analysis showed the presence of carboxyl and hydroxyl groups over DPAC surface. The peaks at 820, 825, 845 and 885 cm-1 attributed to Zn–O, Pb–O, Cd–O, and Cu–O appeared on heavy metals saturated DPAC, confirmed their binding on DPAC during the adsorption.

IODATE OXIDATION OF N-ACETYL L-CYSTEINE: APPLICATION IN DRUG DETERMINATION AND CHARACTERIZATION OF ITS OXIDATION AND DEGRADATION PRODUCT BY MASS SPECTROMETRY

A kinetic spectrophotometric method based on the initial rate measurement has been developed for the determination of N-acetyl L-cysteine. The developed method is based on the oxidation of N-acetyl L-cysteine with iodate. The reaction product was studied and characterized using the mass spectrometry and the structure of the product was proposed. From the mass spectrometric studies it was concluded that the oxidation of the drug resulted in the formation of a disulfide. The developed method was validated as per the guidelines of international conference on harmonization. The developed initial rate method was found to be linear in the concentration range of 1.25 - 30 µg ml-1. The detection and quantitation limits were found to be 0.018 and 0.056 µg ml-1. In the current study, the degradation For the assessment of accuracy and precision, the quality control samples were prepared at three concentration levels of 1.25 µg ml -1 , 15 µg ml -1 and 30 µg ml -1 . The pharmaceutical dosage form Mucinac-600 was obtained from the lo- cal market. A 0.038 M KI and 0.007 M KIO 3 (BDH Chemicals limited Poole, England) solutions were freshly prepared. Proposed procedure for the determination of N-acetyl L-cysteine N-acetyl L-cysteine standard solution equivalent to 1.25 µg ml -1 - 30 µg ml -1 were pipetted into a series of 10 ml standard flask. To each standard flask 1.5 ml of 0.0072 M KIO 3 was added followed by addition of 1.8 ml of 0.026 M KI and made up to the mark with milli Q water. The content of the each standard flasks were thoroughly mixed and was subjected to spectrophoto - metric studies and increase in the absorbance was recorded at 352 nm. The absorbance-time plot was prepared and initial rate of the reaction (ν) at various concentrations was obtained by measuring the slope of the tangent of the previ- ously plotted absorbance-time curve. The analyses were performed at 30±1oC. Determination of N-acetyl L-cysteine in commercial dosage form Two tablets equivalent to 1200 mg of N-acetyl L-cysteine was weighed crushed and the amount of the crushed tablet equivalent to 250 mg of N-acetyl L-cysteine was dissolved in 1000 ml of milli Q water in a volumetric flask. The content of the flask was sonicated for 5 minutes and filtered. N-acetyl L- cysteine equivalent to 1.25 -30 µg ml -1 were pipetted and analyzed by the above mentioned procedure. The amount of the drug was calculated either from the calibration graph or from the linear regression equation. Optimization of variables During the experiments the optimum condition responsible for the forma- tion of the yellow colored products was studied and the same was maintained throughout the determination process. Effect of the concentration of KIO 3 The effect of potassium iodate on the initial rate of reaction was studied in the concentration range of 1.43 × 10 -4 M - 1.22 × 10

Cetyltrimethylammonium bromide intercalated and branched polyhydroxystyrene functionalized montmorillonite clay to sequester cationic dyes

Herein, Cetyltrimethyl ammonium bromide (CTAB) intercalated and branched polyhydroxystyrene (BPS) functionalized montmorillonite (MMT) nano-composite (BPS-CTAB-MMT) was developed, characterized, and its potential as an adsorbent was tested in sequestering cationic dyes viz. rhodamine B (RB), crystal violet (CV), and methylene blue (MB) from aqueous environment. N2 adsorption/desorption isotherm showed mesoporous BPS-CTAB-MMT surface with a BET surface area of 273.8 m2/g. The appearance of sharp spikes at 2855 and 2925 cm-1 (associated with symmetric and asymmetric tensions of C - H bonds) in infra-red spectrum of BPS-CTAB-MMT indicates successful intercalation of MMT with CTAB and functionalization with BPS. The observed crystallite size of BPS-CTAB-MMT was 66 nm. Comparatively greater weight loss for BPS-CTAB-MMT (11%) than MMT (9%) was observed during thermogravimetric analysis. The adsorption of dyes on BPS-CTAB-MMT was pH dependent with maximum uptake was observed in the pH range: 5-6. For initial dyes concentration (Co) range: 50-150 mg/L, the observed equilibration time for CV was 300 min, whereas for RB and MB the equilibration time varied between 300 and 360 min. Modeling investigations revealed the applicability of Sips isotherm and pseudo-second-order (PSO) kinetic models to dyes adsorption data. Sips maximum adsorption capacity (qs) values for RB, CV, and MB at 55 °C were 476.5, 438.7, and 432.7 mg/g, respectively. The adsorption of dyes on BPS-CTAB-MMT was thermodynamically favorable. Desorption studies showed 42.1% RB and 41.9% CV recovery with 0.1 M NaOH and CH3COCH3, respectively, while only traces of MB were recovered with tested eluents.

SOLID PHASE EXTRACTION AND LC-MS/MS METHOD FOR QUANTIFICATION OF VENLAFAXINE AND ITS ACTIVE METABOLITE O-DESMETHYL VENLAFAXINE IN RAT PLASMA

A rapid, simple, sensitive LC-MS/MS method involving a least pretreatment process has been proposed for the quantitative assessment of venlafaxine (VEN) and O-desmethyl venlafaxine (ODV) using cetirizine as an internal standard. The method was validated over the range of 1.03 ng/mL to 453.50 ng/mL (venlafaxine) and 1.32 ng/mL to 585.21 ng/mL (O-desmethyl venlafaxine). The lowest limit of quantification for venlafaxine and O-desmethyl venlafaxine was found to be 1.03 ng/mL and 1.32 ng/mL, respectively. The solid phase extraction procedure provided reliable and reproducible recoveries of the drug as well as its active metabolite with no interference at their retention time. The recovery for all analyzed drugs was found to be in the range of 72.55% to 74.75%. The result indicates that the developed procedure could be considered suitable for carry out simultaneous preclinical pharmacokinetics studies for VEN and ODV.