A chemical assay method for the determination of aflatoxin residues in animal tissues

The present paper describes stability indicating high-performance thin-layer chromatography (HPTLC) assay method for Ozagrel in bulk drugs. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of toluene: methanol: triethylamine (6.5: 4.0: 0.1 v/v/v). The system was found to give compact spot for Ozagrel (Rf value of 0.40 ± 0.010). Densitometric analysis of Ozagrel was carried out in the absorbance mode at 280 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.999 with respect to peak area in the concentration range 30 - 120 ng/spot. The developed HPTLC method was validated with respect to accuracy, precision, recovery and robustness. Also to determine related substance and assay determination of Ozagrel that can be used to evaluate the quality of regular production samples. The developed method can also be conveniently used for the assay determination of Ozagrel in pharmaceutical formulations. The limits of detection and quantitation were 4.069 and 12.332 ng/spot, respectively by height. Ozagrel was subjected to acid and alkali hydrolysis, oxidation, photochemical and thermal degradation. The drug undergoes degradation under acidic, basic, oxidation and heat conditions. This indicates that the drug is susceptible to acid, base hydrolysis, oxidation and heat. Statistical analysis proves that the method is repeatable, selective and accurate for the estimation of said drug. The proposed developed HPTLC method can be applied for identification and quantitative determination of Ozagrel in bulk drug and tablet formulation.

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COMPARISON OF VARIOUS METHODS FOR THE CHEMICAL ASSAY OF CORTICOIDS IN URINE

Acta Endocrinologica ◽

10.1530/acta.0.0180374 ◽

1955 ◽

Vol 18 (4) ◽

pp. 374-378

Author(s):

Mogens Sprechler

Keyword(s):

Calibration Curve ◽

Periodic Acid ◽

Reducing Power ◽

Standard Technique ◽

Phosphomolybdic Acid ◽

Florisil Column ◽

Chemical Assay ◽

Chromatographic Procedure ◽

Acid Reagent

SUMMARY Since 1949 about 10,000 urinary corticoid analyses have been performed routinely in our laboratory. The method used for this purpose was described in 1950 (Sprechler). We determine the corticoids which can be extracted from the urine with chloroform immediately after acidification to pH 1. The extract is washed with sodium hydroxide and water, a Girard separation is performed, and finally the reducing power of the ketonic fraction is measured by means of the phosphomolybdic acid reagent reaction. During the last few years two other chemical reactions have been used for comparison: The formaldehyde and the Porter-Silber method. After a thorough examination of the above methods a standard technique was followed. In the formaldehyde method a microdiffusion in a Conway unit was used instead of distillation of the formaldehyde following the oxidation with periodic acid. The calibration curve was corrected for loss of material by taking the standard doses of DOC through all the procedures of the method. A micromodification of the Porter-Silber method was chosen. Furthermore attempts were made to determine how specific the chromatographic procedure is in the determination of steroids in urinary extracts. For this purpose the Florisil column was used, and the technique described by Nelson & Samuels was followed. Finally we have investigated the glucuronide-bound corticoids in urine in a smaller series of objects.

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Stability Indicating Liquid Chromatographic Method for the Determination of Fenofibrate and its Application to Kinetic Studies

International Journal of Pharmaceutical Sciences and Nanotechnology ◽

10.37285/ijpsn.2012.5.4.6 ◽

2013 ◽

Vol 5 (4) ◽

pp. 1866-1874

Author(s):

K. Srinivasa Rao ◽

Keshar N K ◽

N Jena ◽

M.E.B Rao ◽

A K Patnaik

Keyword(s):

Degradation Products ◽

Kinetic Studies ◽

Pharmaceutical Formulations ◽

Assay Method ◽

Pharmaceutical Dosage Form ◽

Stability Indicating ◽

Zero Order Kinetics ◽

Relative Standard ◽

Liquid Chromatographic

A stability-indicating LC assay method was developed for the quantitative determination of fenofibrate (FFB) in pharmaceutical dosage form in the presence of its degradation products and kinetic determinations were evaluated in acidic, alkaline and peroxide degradation conditions. Chromatographic separation was achieved by use of Zorbax C18 column (250 × 4.0 mm, 5 μm). The mobile phase was established by mixing phosphate buffer (pH adjusted 3 with phosphoric acid) and acetonitrile (30:70 v/v). FFB degraded in acidic, alkaline and hydrogen peroxide conditions, while it was more stable in thermal and photolytic conditions. The described method was linear over a range of 1.0-500 μg/ml for determination of FFB (r= 0.9999). The precision was demonstrated by relative standard deviation (RSD) of intra-day (RSD= 0.56– 0.91) and inter-day studies (RSD= 1.47). The mean recovery was found to be 100.01%. The acid and alkaline degradations of FFB in 1M HCl and 1M NaOH solutions showed an apparent zero-order kinetics with rate constants 0.0736 and 0.0698 min−1 respectively and the peroxide degradation with 5% H2O2 demonstrated an apparent first-order kinetics with rate constant k = 0.0202 per min. The t1/2, t90 values are also determined for all the kinetic studies. The developed method was found to be simple, specific, robust, linear, precise, and accurate for the determination of FFB in pharmaceutical formulations.

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Development and Validation of a New Method for the Determination of Anti-hepatitis C Agent Simeprevir in Human Plasma using HPLC with Fluorescence Detection

Current Analytical Chemistry ◽

10.2174/1573411015666181217121619 ◽

2020 ◽

Vol 16 (4) ◽

pp. 428-435

Author(s):

Ahmed F.A. Youssef ◽

Yousry M. Issa ◽

Kareem M. Nabil

Keyword(s):

Hepatitis C ◽

Human Plasma ◽

Fluorescence Detection ◽

Internal Standard ◽

Protein Precipitation ◽

Assay Method ◽

Fluorescence Detector ◽

Limit Of Quantification ◽

Relative Standard

Background: Simeprevir is one of the recently discovered drugs for treating hepatitis C which is one of the major diseases across the globe. Objective: The present study involves the development of a new and unique High-Performance Liquid Chromatography (HPLC) method using fluorescence detection for the determination of simeprevir (SIM) in human plasma. Methods: Two methods of extractions were tested, protein precipitation using acetonitrile and liquidliquid extraction. A 25 mM dipotassium hydrogen orthophosphate (pH 7.0)/ACN (50/50; v/v), was used as mobile phase and C18 reversed phase column as the stationary phase. The chromatographic conditions were optimized and the concentration of simeprevir was determined by using the fluorescence detector. Cyclobenzaprine was used as an internal standard. Results: Recovery of the assay method based on protein precipitation was up to 100%. Intra-day and inter-day accuracies range from 92.30 to 107.80%, with Relative Standard Deviation (RSD) range 1.65-8.02%. The present method was successfully applied to a pharmacokinetic study where SIM was administered as a single dose of 150 mg SIM/capsule (Olysio®) to healthy individuals. Conclusion: This method exhibits high sensitivity with a low limit of quantification 10 ng mL-1, good selectivity using fluorescence detection, wide linear application range 10-3000 ng mL-1, good recovery and highly precise and validation results. The developed method can be applied in routine analysis for real samples.

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