scholarly journals Purine quantification in digesta from ruminants by spectrophotometric and HPLC methods

1999 ◽  
Vol 81 (2) ◽  
pp. 107-112 ◽  
Author(s):  
H. P. S. Makkar ◽  
K. Becker
Keyword(s):  
Nucleic Acids ◽  
Accurate Determination ◽  
Internal Standard ◽  
Hplc Method ◽  
E Coli ◽  
Purine Bases ◽  
Microbial Preparation ◽  
Hydrolysis Conditions ◽  
Hydrolysis Of

The method of Zinn & Owens (1986;Canadian Journal of Animal Science66, 157–166), based on release of purine bases by HClO4followed by their precipitation with AgNO3, was used to study recovery of purines from lyophilized rumen microbial orEscherichia colipreparations added to matrices such as cellulose, starch and neutral-detergent fibre. The recovery of purines was poor (approximately 50 %). Under the hydrolysis conditions (12 M-HClO4, 90–95° for 1 h) used in the method of Zinn & Owens (1986), the recovery of purines from the rumen microbial preparations added to matrices measured using an HPLC method was 95–102 %, suggesting that the lower recovery of purines in the method of Zinn & Owens (1986) was not due to incomplete hydrolysis of nucleic acids. Using the HPLC method, adenine and allopurinol (an internal standard) were found to be heat-labile as substantial destruction was observed on heating at 121°. On the other hand, another commonly used internal standard, caffeine, was stable at 121°. A complete hydrolysis of nucleic acids from the rumen microbial preparation was observed with 2·5 ml 0·6 M-HClO4in a total volume of 3 ml (0·5 M-HClO4during hydrolysis) at 90–95° for 1 h, and under these conditions adenine, guanine, allopurinol and caffeine were stable. Moreover, under these milder hydrolysis conditions, the recovery of purine bases from the rumen microbial orE. colipreparations added to matrices ranged from 92 to 108 % using the method of Zinn & Owens (1986). Based on the results, changes in hydrolysis conditions have been proposed for accurate determination of purine bases using spectrophotometric or HPLC methods.

Simultaneous Determination of Chloroquine and Pyrimethamine with Cetirizine in an Active Form and Human Serum by RP-HPLC

2021 ◽  
Author(s):  
Hina Shamshad ◽  
Ali Sayqal ◽  
Jahan Zeb ◽  
Agha Zeeshan Mirza
Keyword(s):  
Human Serum ◽  
Simultaneous Determination ◽  
Active Form ◽  
Internal Standard ◽  
Hplc Method ◽  
Serum Samples ◽  
Rp Hplc ◽  
Cetirizine Hydrochloride ◽  
Bulk Drug

Abstract A simple, accurate and precise RP-HPLC method was developed for the simultaneous determination of chloroquine, pyrimethamine and cetirizine hydrochloride concentrations in bulk drug and human serum. The assay was performed using a mobile phase of methanol: water (70:30) at pH of 2.8 ± 0.05 on the Purospher C-18 column with UV detection at 230 nm and rosuvastatin used as an internal standard. The retention times observed for chloroquine, pyrimethamine and cetirizine hydrochloride were 3.5, 2.5 and 5.5 minutes, respectively. The method was found to be specific for the assayed drugs showing a linear response in the concentration range of 1–100 μg mL−1 with coefficients of determination values of (r = 0.999). The method was developed and validated according to ICH guidelines. The method was used to monitor the serum samples and was found to be sensitive for therapeutic purposes, showing the potential to be a useful tool for routine analysis in laboratories.

scholarly journals A new selective, and sensitive method for the determination of lixivaptan, a vasopressin 2 (V2)-receptor antagonist, in mouse plasma and its application in a pharmacokinetic study

2018 ◽  
Vol 16 (1) ◽  
pp. 614-620
Author(s):  
Haitham Alrabiah ◽  
Mohammed Abunassif ◽  
Sabry Attia ◽  
Gamal Abdel-Hafiz Mostafa
Keyword(s):  
Receptor Antagonist ◽  
Pharmacokinetic Study ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Hplc Method ◽  
Maximum Plasma ◽  
Mouse Plasma ◽  
V2 Receptor ◽  
V2 Receptor Antagonist

AbstractA new, selective and sensitive HPLC method for the determination of lixivaptan, an oral selective vasopressin 2 (V2)-receptor antagonist, was investigated and validated. A Waters symmetry C18 column was used as a stationary phase in isocratic elution mode using a mobile phase composed of KH2PO4 (100 mM)-acetonitrile (40: 60, v/v) at a flow rate of 1.5 mL min-1. Diclofenac was used as the internal standard (IS). Lixivaptan and the IS were extracted from plasma by protein precipitation and were detected at 260 nm. Lixivaptan and diclofenac were eluted at 3.6 and 6.2 min, respectively. The developed method showed good linearity over the calibration range of 50 -1000 ng mL-1 with a lower limit of detection of 16.5 ng mL-1. The extraction percentage of lixivaptan in the mouse plasma was in the range of 88.88 - 114.43%, which indicates acceptable extraction. The aforementioned method was validated according to guidelines of the International Council on Harmonization (ICH). The intra- and inter-day coefficients of variation did not exceed 5.5%. This method was presented to be simple, sensitive, and accurate and was successfully adapted in a pharmacokinetic study of the profile of lixivaptan in mouse plasma. A mean maximum plasma concentration of lixivaptan of 113.82 ng mL-1 was achieved in 0.5 h after oral administration of a 10 mg kg-1 dose in mouse as determined using the developed method.

Simultaneous determination of Sulphadoxine and Pyrimethamine by taking Tolterodine as an internal standard in Pharmaceutical dosage form by RP-HPLC

2021 ◽  
pp. 145-150
Author(s):  
Sushil D. Patil ◽  
Pravin B. Shelke ◽  
Priti Aher ◽  
Maswood Ahmed Hafizur Rahman
Keyword(s):  
Simultaneous Determination ◽  
Dosage Form ◽  
Internal Standard ◽  
Hplc Method ◽  
Control Analysis ◽  
Pharmaceutical Dosage Form ◽  
Quality Control Analysis ◽  
Rp Hplc ◽  
Sulphadoxine Pyrimethamine

A simple, rapid, economic, sensitive and precise HPLC method has been developed for the simultaneous determination of Sulphadoxine and Pyrimethamine in pharmaceutical dosage form by taking Tolterodine as an internal standard. The method was carried out using Phenomenex C18 (4.6ID × 250mm; 5µm) column and mobile phase comprised of methanol and Phosphate Buffer in proportion of ratio 60:40 v/v. The flow rate was 1.0mL/min and detection was carried out at 276nm. The retention time of Sulphadoxine, Pyrimethamine and Tolterodine were found to be 2.967, 4.058 and 6.908 respectively. Linearity of Sulphadoxine and Pyrimethamine in the range of 2 to 12μg/mL and 4 to 24μg/mL respectively. The % recoveries of Sulphadoxine and Pyrimethamine were found to be in between 99.93% to 99. 96 % respectively. The proposed method is suitable for the routine quality control analysis for simultaneous determination of Sulphadoxine and Pyrimethamine was in bulk and pharmaceutical dosage form.

scholarly journals Simultaneous determination of mycophenolic acid and its glucuronide in human plasma using a simple high-performance liquid chromatography procedure

1998 ◽  
Vol 44 (7) ◽  
pp. 1481-1488 ◽  
Author(s):  
Maria Shipkova ◽  
Paul Dieter Niedmann ◽  
Victor William Armstrong ◽  
Ekkehard Schütz ◽  
Eberhard Wieland ◽  
...  
Keyword(s):  
Mycophenolic Acid ◽  
High Performance ◽  
Internal Standard ◽  
Gradient Elution ◽  
Reversed Phase ◽  
Hplc Method ◽  
Free Concentration ◽  
Elution Chromatography ◽  
Glucuronide Metabolite

Abstract We describe a reversed-phase HPLC method for determination of total mycophenolic acid (MPA), its free concentration (MPAf), and the glucuronide metabolite (MPAG), based on simple sample preparation and gradient elution chromatography. The compounds were quantified in parallel by absorbance at 254 nm and 215 nm in the internal standard mode. Linearity was verified up to 50 mg/L for MPA and up to 500 mg/L for MPAG (r >0.999). Detection limits at 215 and 254 nm were, respectively, 0.01 and 0.03 mg/L for MPA, and 0.03 and 0.1 mg/L for MPAG. The recovery of MPA was 95–106%;recovery of MPAG was 96–106%. The imprecision (CV) for MPA (0.2–25 mg/L) was <8.4% (254 nm) and <4.4% (215 nm) within day (n = 12) and <9.2% (254 nm) and <6.2% (215 nm) between days (n = 12). The imprecision for MPAG (10–250 mg/L) was <4.9% (254 nm) and <3.4% (215 nm) within day, and <6.1% (254 nm) and <5.9% (215 nm) between days. For quantification of MPAf, 100 μL of ultrafiltrate was applied directly to the column. The detection limit was 0.005 mg/L at 215 nm and 0.015 mg/L at 254 nm. In the range between 18–210 μg/L, the within-day CVs were <11.8% (n = 12) and the between-day CVs were <15.8% (n = 12).

scholarly journals Reversed-Phase HPLC Analysis of Levetiracetam in Tablets Using Monolithic and Conventional C18 Silica Columns

2010 ◽  
Vol 93 (4) ◽  
pp. 1077-1085 ◽  
Author(s):  
Nafiz O Can ◽  
Goksel Arli
Keyword(s):  
Monolithic Column ◽  
Stationary Phases ◽  
Internal Standard ◽  
Reversed Phase ◽  
Hplc Method ◽  
Array Detector ◽  
Pharmaceutical Tablets ◽  
System Suitability ◽  
Development And Validation

Abstract Development and validation of an RP-HPLC method for determination of levetiracetam in pharmaceutical tablets is described. The separation and quantification of levetiracetam and caffeine (internal standard) were performed using a single analytical procedure with two different types of stationary phases, conventional Phenomenex Gemini C18 (100 4.6 mm, 5 m) and Merck Chromolith Performance RP18e (100 4.6 mm, macropore size 2 mm, micropore size 13 nm) monolithic silica. Five-microliter aliquots of samples were injected into the system and eluted using wateracetonitrile (90 + 10, v/v) mobile phase pumped at the rate of 1 mL/min. The analyte peaks were detected at 200 nm using a diode array detector with adequate resolution. Validation studies were performed using the method recommended by the International Conference on Harmonization, the U.S. Pharmacopeia, and AOAC INTERNATIONAL, which includes accuracy, precision, range, limits, robustness, and system suitability parameters. Levetiracetam and caffeine were detected in about 7 min using the conventional column, whereas less than 5 min was required when the monolithic column was used. Calibration plots had r values close to unity in the range of 0.88.0 g/mL. Assay of levetiracetam in a tablet formulation was demonstrated as an application to real samples.

scholarly journals A Liquid Chromatographic Method for Routine Analysis of 5-Mononucleotides in Pediatric Formulas

2010 ◽  
Vol 93 (3) ◽  
pp. 966-973 ◽  
Author(s):  
Brendon D Gill ◽  
Harvey E Indyk ◽  
Maureen C Kumar ◽  
Nathan K Sievwright ◽  
Merilyn Manley-Harris
Keyword(s):  
Bovine Milk ◽  
Internal Standard ◽  
Standard Technique ◽  
Gradient Elution ◽  
Hplc Method ◽  
Routine Analysis ◽  
Liquid Chromatographic Method ◽  
Sample Dissolution ◽  
Liquid Chromatographic

Abstract An RP-HPLC method for the routine determination of supplemented 5-mononucleotides (uridine 5-monophosphate, inosine 5-monophosphate, adenosine 5-monophosphate, guanosine 5-monophosphate, and cytidine 5-monophosphate) in pediatric formulas and milk products is described. Following sample dissolution, potential interferences were removed by anion-exchange SPE. Chromatographic analyses were performed using a C18 stationary phase with gradient elution, UV detection, and quantitation by an internal standard technique. A single-laboratory validation was performed, with recoveries of 92101 and repeatability RSDs of 1.02.3. The method was optimized for the rapid, routine analysis of nucleotide-supplemented bovine milk-based infant and follow-on formulas.

scholarly journals Development and Validation of Stability Indicating RP-HPLC Method for the Determination of Metaxalone in Bulk and its Pharmaceutical Formulations

2011 ◽  
Vol 8 (s1) ◽  
pp. S439-S447 ◽  
Author(s):  
Prafulla Kumar Sahu ◽  
M. Mathrusri Annapurna ◽  
Sahoo Dillip Kumar
Keyword(s):  
Dynamic Range ◽  
Internal Standard ◽  
Pharmaceutical Formulations ◽  
Hplc Method ◽  
Pharmaceutical Dosage Form ◽  
Stability Indicating ◽  
Standard Curve ◽  
Oxidation Reduction ◽  
Development And Validation

A stability indicating reverse phase HPLC method was developed for the determination of metaxalone, a skeletal muscle relaxant, present in bulk and its pharmaceutical formulations using gliclazide as the internal standard (I.S). A hypersil ODS C18 column (250 × 4.6 mm, packed with 5 micron) in an isocratic mode with mobile phase Acetonitrile: phosphate buffer 3.6 (50:50%v/v) was used at a flow rate of 0.8 mL/ min and effluent was monitored at 225 nm. The assay exhibited a linear dynamic range of 0.6-100 µg/mL. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The retention times were 5.13 min and 9.08 min for metaxalone and IS respectively. The extraction recovery of metaxalone from pharmaceutical dosage form (tablets) was >97% and the calibration curve was linear (r2= 0.999) over the entire linear range. The method had an accuracy of >98% and LOD and LOQ of 0.2 µg/mL and 0.6 µg/mL respectively. The specificity of the proposed method was performed whereby metaxalone undergoes different stress conditions like oxidation, reduction, photolysis, acid and alkaline hydrolysis.

scholarly journals Validation of an HPLC method for the simultaneous determination of eletriptan and UK 120.413

2006 ◽  
Vol 71 (11) ◽  
pp. 1195-1205 ◽  
Author(s):  
Mira Zecevic ◽  
Biljana Jocic ◽  
Snezana Agatonovic-Kustrin ◽  
Ljiljana Zivanovic
Keyword(s):  
Mobile Phase ◽  
Analytical Procedure ◽  
Internal Standard ◽  
Correlation Coefficients ◽  
Hplc Method ◽  
Control Analysis ◽  
Internal Standard Method ◽  
Rp Hplc ◽  
Good Repeatability

Arapid and sensitive RPHPLCmethod was developed for the routine control analysis of eletriptan hydrobromide and its organic impurity UK 120.413 in Relpax? tablets. The chromatography was performed at 20?C using a C18 XTerra ? (5 ?m, 150 x 4,6 mm) column at a flow rate 1.0 ml/min. The drug and its impurity were detected at 225 nm. The mobile phase consisted of TEA (1 %) - methanol (67.2:32.8 v/v), the pH of which was adjusted to 6.8 with 85 % orthophosphoric acid. Quantification was accomplished by the internal standard method. The developed RP HPLC method was validated by testing: accuracy, precision, repeatability, specificity, detection limit, quantification limit, linearity, robustness and sensitivity. High linearity of the analytical procedure was confirmed over the concentration range of 0.05 - 1.00 mg/ml for eletriptan hydrobromide and from 0.10 - 1.50 ?g/ml for UK 120.413, with correlation coefficients greater than r = 0.995. The low value of the RSD expressed the good repeatability and precision of the method. Experimental design and a response surface method were used to test robustness of the analytical procedure and to evaluate the effect of variation of the method parameters, namely the mobile phase composition, pH and temperature. They showed small deviations from the method setting. The good recovery and low RSD confirm the suitability of the proposed RP HPLC method for the routine determination of eletriptan hydrobromide and its impurity UK 120.413 in Relpax? tables.

Phenylboronic Acid Solid Phase Extraction Cleanup and Isotope Dilution Liquid Chromatography-Tandem Mass Spectrometry for the Determination of Florfenicol Amine in Fish Muscles

2015 ◽  
Vol 98 (3) ◽  
pp. 566-574 ◽  
Author(s):  
Della Wai-Mei Sin ◽  
Clare Ho ◽  
Yiu-Tung Wong
Keyword(s):  
Isotope Dilution ◽  
Solid Phase ◽  
Phenylboronic Acid ◽  
Accurate Determination ◽  
Internal Standard ◽  
Fish Muscles ◽  
Liquid Chromatography Tandem Mass ◽  
Cleanup Procedure ◽  
Acid Catalyzed

Abstract Florfenicol (FFC) residues in foods are regulated as the sum of florfenicol and its metabolites measured as florfenicol amine (FFA). An isotope dilution LC-MS/MS method utilizing phenylboronic acid (PBA) SPE cleanup is established for the accurate determination of FFA in fish muscles (i.e., salmon and tilapia) after acid catalyzed hydrolysis. Comparisons of the PBA SPE cleanup procedure with other cleanup procedures such as mixed-mode cationic (MCX) SPE and solid supported liquid–liquid extraction were performed. Quantification of FFA in fish muscles was accomplished by using matrix-matched calibration with FFA-D3 as the internal standard. The method was validated with FFA fortified fish muscles at three different levels (50, 100, and 200 μg/kg). Conversion of FFC to FFA by acid catalyzed hydrolysis was evaluated and found to be ≥88%. The recoveries of FFA in fish muscles at the three fortification levels ranged from 89 to 106%, and RSDs were ≤9% in all cases. The LOD values in salmon and tilapia muscles were 0.13 and 1.64 μg/kg, respectively. The LOQ values in salmon and tilapia muscles were 0.29 and 4.13 μg/kg, respectively. This method is suitable for the application in routine control of FFC in fishes according to its residue definition.

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