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1

Determination of di-n-butyl Phthalate in Environmental Samples

Ziembowicz Sabina, Kida Małgorzata

Rocznik Ochrona Środowiska

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2023

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Tom 25

242--249

EN

A devised methodology presented here allows the determination of di-n-butyl phthalate in environmental samples (water and landfill leachate) using solid-phase extraction (SPE) and gas chromatography. It is developed based on the use of a gas chromatograph with an FID detector. Preliminary testing has also provided extraction parameters and conditions for chromatographic determination, with calibration applied by reference to an internal standard. The linearity of the calibration curve has been tested in DBP concentrations ranging from 0 to 7.5 mg/L, with the data obtained showing that, throughout this range, the detector readings as a function of the DBP concentrations remain linear (R2 coefficient >0.99). The average levels of recovery of DBP from aqueous solutions of phthalates are in the range of 97-109%, while the corresponding figures for leachates are 85-101%. The values of the coefficients of variation associated with the results obtained do not exceed 5%. The results, therefore, indicate that the applied extraction method is effective as regards DBP extraction from both water and landfill leachate, while numerous other substances present in the leachate from landfill sites apparently do not affect the correct determination of di-n-butyl phthalate by the method developed.

2

Simultaneous densitometric determination of β-sitosterol and lupeol through validated HPTLC method in different plant parts of Uraria picta (Jacq.) Desv. ex DC. – A dashmool species

Saxena Hari Om, Parihar Samiksha, Pawar Ganesh, Rao G. Rajeshwar

Acta Chromatographica

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2023

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Vol. 35, no. 1

99--105

EN

β-sitosterol (BS) and lupeol (LU) exhibit a number of biological activities and are the important bioactive marker compounds in pharmaceutical science. In the present study, a simple, precise, accurate and validated high performance thin layer chromatographic (HPTLC) method was developed for simultaneous quantification of these two compounds in leaves, stem and roots of Uraria picta, a critically endangered medicinal plant and one of the important constituents of ten plants ayurvedic formulation called Dashmoola. Standards and test samples were applied on TLC aluminum plate precoated with 0.2 mm layer of silica gel 60F254. The plate was run in a twin glass chamber comprising toluene: methanol: chloroform (8:1:1, v/v/v) as a mobile phase. The plates were immersed in anisaldehyde-sulfuric reagent and then heated at 105 °C for 5 min in CAMAG TLC plate heater for appearance of bands. Densitometric scanning was performed at λmax = 525 nm using tungsten light source in CAMAG TLC Scanner4 armed with WinCATS software. RF values of BS and LU standards and those of test samples were found to be 0.53 ± 0.01 and 0.63 ± 0.01 respectively. The method was further validated by following the International Conference of Harmonization (ICH) guidelines. For BS and LU, the linear regression data for the calibration plots revealed a satisfactory linear association with r2 = 0.995 and 0.998, respectively. Linear range for both BS and LU was 200–600 ng/band. Accuracy of the method was evaluated by performing recovery study at three different levels by standard addition methods with an average recovery of 99.86% and 101.07%. The results revealed that the leaf samples of U. picta contained highest concentration of BS (0.150 ± 0.02%) while its root samples confined the highest concentration of LU (0.149 ± 0.01%). The developed method can be applied for routine and quality control analysis in different herbal formulations containing U. picta species.

3

The RP-HPLC method development and validation for simultaneous determination of oryzalin and ethofumesate pesticides in soil and water

Tandon Shishir, Pal Suman Lata

Acta Chromatographica

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2022

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Vol. 34, no. 4

469--474

EN

A sensitive and reliable method for simultaneous determination of oryzalin and ethofumesate residues in pantnagar soil and water was validated. The compounds were extracted by LLE with dichloromethane from water, and acetone:methanol mixture from soil followed by SPE cleanup. Detection and quantification was done by RP-HPLC using mobile phase methanol:water (70:30, v/v) at 280 nm. The developed method showed satisfactory validation results with linearity (0.99), relative standard deviations (1.55 and 1.73%), and limit of quantification (0.002 μg g⁻¹ and 0.005 μg g⁻¹) for ethofumesate and oryzalin, respectively. Recoveries ranged for oryzalin and ethofumesate from 79.80–90.52, 75.58–86.04% (soil) and 83.50–95.92, 82.28–94.60% (water), respectively. The method could be used for routine high-throughput detection and determination of these compounds.

4

Extraction process and method validation for bioactive compounds from Citrus reticulata cv. Chachiensis : application of response surface methodology and HPLC–DAD

Mei Zhenying, Zhang Rongfei, Zhao Zhimin, Zheng Guodong, Xu Xinjun, Yang Depo

Acta Chromatographica

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2021

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Vol. 33, no. 3

270--280

EN

Citrus reticulata cv. Chachiensis, a traditional Chinese herb, has extensive medicinal and edible effects. 3′,4′,5,6,7,8-Hexamethoxyflavone (HM) and 5,6,7,8,4′-pentamethoxyflavone (PM) are main bioactive compounds in Chachiensis, which have been reported to possess various biological properties. In this study, supercritical CO2 extraction (SCE) and high-speed countercurrent chromatography (HSCCC) were utilized to prepare HM and PM from Chachiensis. The contents of target compounds were determined by a high-performance liquid chromatography method with diode-array detection (HPLC-DAD), which was validated using the following parameters: linearity, sensitivity, repeatability, stability, precision and accuracy. The SCE conditions were optimized using response surface methodology with central composite design. Obtained optimum conditions were temperature of 37.9 °C, pressure of 26.3 MPa, and modifier volume of 81.0 mL. Under above conditions, the recoveries of target compounds were 92.52 ± 0.83 and 96.36 ± 0.43%, respectively. The most appropriate solvent system for HSCCC was selected as n-hexane/ethyl acetate/methanol/water (1:0.8:1:1.2, v/v). The HSCCC fractions were detected by HPLC-DAD, liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR). The results indicated that this method was successfully applied to obtain HM and PM with high purities and high recoveries from Chachiensis.

5

Method validation for the determination of fraction of modern (F14C) in wood samples using conventional method

Baydoun R., El Samad O., Nsouli B., Younes G.

Geochronometria

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2018

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Vol. 45, no. 1

68--73

EN

The radiocarbon laboratory at the Lebanese Atomic Energy Commission is undertaking environmental studies, in order to determine the anthropogenic impact of technologies on the ecosystem through the determination of radiocarbon content in tree leaves and plants. Thus, it was important to validate the method used to demonstrate that the applied procedure gives reliable results. Method validation is universally applied in analytical laboratories as an essential part of quality assurance system and as a basic technical requirement of the ISO 17025 standard. The conventional method used for determination of Fraction Modern (F14C) is a standard method issued by the American Society for Testing and Materials in 2011 with a code ASTM-D 6866-11 Method C. According to Eurachem guide, internal validation was expressed in terms of accuracy that was evaluated by trueness and precision. Trueness was expressed in terms of relative bias, while for precision ten consecutive replicates were carried out to under repeatability conditions and five duplicates were analyzed under reproducibility conditions. The limit of detection and the minimum detectable activity (MDA) were calculated. Uncertainty sources were defined and their relative standard uncertainties were calculated in order to determine the combined standard uncertainty. Five reference samples of different matrices were analyzed; calculated z score values were acceptable as being between –2 and +2. The calculation and results are presented in this work.

6

Simultaneous quantification of related substances of ezetimibe and simvastatin in combined dosage form using a novel stability-indicating liquid chromatographic method

Desai P. R., Mehta P. J., Ojha S. K., Chokshi A. B.

Acta Chromatographica

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2018

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Vol. 30, no. 2

85--94

EN

A novel, simple, robust, and rapid reversed-phased high-performance liquid chromatographic method has been developed for the separation and quantitative determination of the related substances of ezetimibe and simvastatin in combined dosage forms. Successful separation of the drug from the process-related impurities and degradation products formed under stress conditions was achieved on Inertsil ODS-3V (150 × 4.6 mm, 5.0 μm) column. The gradient liquid chromatography (LC) method employs solution A and solution B as mobile phase. The solution A contains 0.1% orthophosphoric acid solution in water, and solution B contains 0.1% orthophosphoric acid solution in acetonitrile. Flow rate was monitored at 2.0 mL/min, and the ultraviolet (UV) detection, at 238 nm. In forced degradation studies, the effect of acid, base, oxidation, UV light, and temperature was investigated, showing that good resolution between the peaks corresponds to process-related impurities and degradation products from both analyte. The performance of the method was validated according to the present International Conference on Harmonization (ICH) guidelines for specificity, limit of detection, limit of quantification, linearity, accuracy, precision, ruggedness, and robustness. To the best of our knowledge, a rapid LC method, which separates all the impurities of ezetimibe and simvastatin in combined dosage forms, disclosed in this investigation was not published elsewhere.

7

Development and validation of a reversed-phase HPLC method for simultaneous determination of doxazosin mesylate and finasteride

Krotz D., Mengesha A. E.

Acta Chromatographica

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2017

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Vol. 29, no. 3

309--324

EN

A reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the simultaneous determination of doxazosin mesylate (DOX) and finasteride (FIN) in bulk powders and pharmaceutical formulations. The compounds were separated on a Pinnacle II C18 column (250 × 4.6 mm i.d.; particle size, 5 μm) with an isocratic mobile phase at a flow rate of 1.0 mL min−1. The mobile phase was a mixture of 25 mM ammonium acetate and acetonitrile in the ratio of 50:50 %v/v. The pH of the buffer was adjusted to 4.0 ± 0.05 with glacial acetic acid. The detection was performed at 230 nm. The total chromatographic analysis time per sample was 15 min with DOX and FIN eluting at 3.9 and 7.2 min, respectively. The accuracy, precision, specificity, linearity, and sensitivity of the method were validated according to the International Conference on Harmonization (ICH) guidelines. The calibration plots were linear (r2 > 0.999) over the concentration range 24.25–291.0 μg mL−1 and 122.5–1470.0 μg mL−1 for DOX and FIN, respectively. The method was used for the simultaneous determination of DOX and FIN in capsules.

8

Rozterki laboranta czyli jak spełnić wymagania i przeżyć

Uporek J.

Analityka : nauka i praktyka

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2015

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nr 1

78--80

9

Optimizing SIC assay method for acetyl salicylic acid and rosuvastatin and adapting to HPLC with performance comparison

Idris A. M., Alnajjar A. O.

Acta Chromatographica

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2015

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Vol. 27, no. 1

111--125

EN

Acetyl salicylic acid (ASA), as the major drug consumed in the world, has been combined with other various drugs. In this regard, ASA-rosuvastatin is the most recent combination. The current article reported the first two separation methods for the assay of that combination utilizing sequential injection chromatography (SIC) and high-performance liquid chromatography (HPLC). The optimization process was conducted for SIC, and the optimum conditions were then adapted to HPLC. Both methods, SIC and HPLC, were validated and successfully applied to tablet formulation. In both methods, the analytes were chromatographed onto a short C18 monolithic column (4.6 × 25 mm) by a mobile phase composition of 10 mmol L -1 phosphate:acetonitrile: methanol (50:30:20, v/v/v at pH 3.0). The performances of both methods were compared. The remarkable advantages of the SIC method over HPLC method were the reduction in reagent consumption and instrumentation simplicity and cost-effectiveness. The total volume of mobile phase consumed is three orders of magnitude larger in HPLC than that in SIC. Other analytical features of the SIC and HPLC methods were comparable and acceptable for pharmaceutical analysis. Accordingly, the SIC method could be more suitable for routine analysis of simple matrices after examining the capability of the technique to work under industrial conditions.

10

Fingerprint of ethyl acetate extraction combined with qualitative and quantitative analysis on Patrinia scabra Bunge: Distinguish P. scabra Bunge from its confusable species

Liu W., Wei M. L, Wu Ch. Y, Zhu H. Y, Feng F, Xie N

Acta Chromatographica

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2015

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Vol. 27, no. 1

177--187

EN

Patrinia scabra Bunge has long been used in clinic as a traditional Chinese medicine for treating leukemia and cancer and regulating host immune response. Despite their wide use in China, no report on system analysis on their chemical constituents is available so far. The current study was designed to profile the fingerprint of ethyl acetate extract of it, and in addition, to characterize the major fingerprint peaks and determine their quantity. Therefore, a detailed gradient high-performance liquid chromatography was described to separate more than 30 compounds with satisfactory resolution in P. scabra Bunge. Based on the chromatograms of 10 batches samples, a typical high-performance liquid chromatographic (HPLC) fingerprint was established with 23 chromatographic peaks being assigned as common fingerprint peaks. Furthermore, a quadrupole time of flight mass spectrometry (Q-TOF/MS) was coupled for the characterization of major compound. As (+)-nortrachelogenin was the most predominant compound in P. scabra Bunge, the quantification on it was also carried out with the method being validated. As a result, (+)-nortrachelogenin was found to be from 1.33 to 2.21 mg g−1 in this plant material. This rapid and effective analytical method could be employed for quality assessment of P. scabra Bunge, as well as pharmaceutical products containing this herbal material.

11

Validation of an HPLC method for determination of aripiprazole and its impurities in pharmaceuticals

Djordjević Filijović N., Pavlović A., Nikolić K., Agbaba D.

Acta Chromatographica

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2014

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Vol. 26, no. 1

13--28

EN

Aripiprazole is a novel atypical antipsychotic drug used in the treatment of schizophrenia. The sensitive and reproducible ion pair RPLC method was developed and validated for determination of aripiprazole and its nine impurities, which are significantly different in polarity. The separation was performed on Phenomenex Luna® C18 column (5.0 μm particle size, 250 × 4.6 mm id) using a gradient mobile phase A (phosphate buffer pH 3.0) and mobile phase B (acetonitrile) at the working temperature of 25°C. The buffer was 1.11 g KH2PO4 with 1.2 g sodium pentanesulfonate/L of the solution, adjusted to pH 3.0 with orthophosphoric acid. The flow rate was 1.0 mL/min. The detection was carried out at 215 nm using a diode array detector. The developed method was validated according to the International Conference on Harmonization (ICH) guidelines for specificity, limit of detection, limit of quantification, linearity, precision and robustness. The proposed method is convenient and reliable for the purity control in both raw materials and dosage forms.

12

Simultaneous identification and quantitative determination of azithromycin, clarithromycin, roxithromycin, spiramycin and troleandomycin by thin-layer chromatography and densitometry

Kwiecień A., Krzek J., Gądek M.

Acta Chromatographica

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2014

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Vol. 26, no. 4

657--670

EN

The purpose of this work was to develop a TLC-densitometric method for simultaneous identification and quantitative determination of azithromycin, clarithromycin, roxithromycin, spiramycin, and troleandomycin. The method was developed on TLC aluminium plates precoated with silica gel F254 using solvent system izopropanol:n-hexane:ammonia 25% (8:12:3, v/v/v), which gives compact spots for azithromycin (RF = 0.65), clarithromycin (RF = 0.54), roxithromycin (RF = 0.49), spiramycin (RF = 0.22), and troleandomycin (RF = 0.36). Densitometric analysis was carried out at 478 nm after spraying with (1:4, v/v) sulphuric acid:ethanol and heating at 100°C for 5 min. The linear regression analysis data for the calibration plots showed good linear relationship with correlation coefficient higher than 0.99. The method is distinguished by high sensitivity, with limit of detection (LOD) from 0.34 μg/spot for troleandomycin to 0.67 μg/spot for clarithromycin and limit of quantification (LOQ) from 1.02 μg/spot for troleandomycin to 2.04 μg/spot for clarithromycin and a wide linearity range from 2 to 12 μg/spot for spiramycin and 2–15 μg/spot for other antibiotics. The precision of the determination was good; relative standard deviation (RSD) varied in the range from 1.49% to 4.14%.

13

Facile assay method for norfloxacin and ciprofloxacin by sequential injection chromatography

Elgorashe R. E. E., Idris A. M., Abdelrahman M. A., Saeed A. E. M.

Acta Chromatographica

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2014

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Vol. 26, no. 2

321--334

EN

Sequential injection chromatography (SIC) is a simple, inexpensive, portable, reagent-saving, and environmentally benign separation technique. This paper reports the development of a facile assay method for norfloxacin (NF) and ciprofloxacin (CF) in their formulations (tablets and eye drops) using SIC. The analytes were rapidly chromatographed on a short C18 monolithic column (4.6 × 50 mm) at a flow rate of 30 μL s -1. An isocratic mode was adopted. The optimum mobile phase composition was 90% water, 10% acetonitrile, and 0.3% triethylamine at pH 3.0. Miniaturized fiber optic spectrometric devices were coupled to the SIC system for UV detection at 280 nm. Sufficient separation with a resolution of 1.6 and numbers of theoretical plates of more than 1500 was achieved. Additionally, acceptable peak shapes with peak symmetries of 0.89 and 0.92 for NF and CF, respectively, were obtained. The method was validated and found to be reliable (the recovery was 98.0–100.6%) and precise (the RSDs of intra-/inter-day precision were less than 2.0%). The method is also sensitive. The limits of detection were less than 0.27 μg mL -1. The provided method could be considered an industrial scale since the sample frequency was seven samples h -1 and the total volume of consumed reagents was 11.5 mL.

14

Ion-pair RP-HPLC method for the estimation of eberconazole nitrate in bulk form and in pharmaceutical dosage forms

Vamsi Krishna M., Dash R. N., Jalachandra Reddy B., Venugopal P., Sandeep P., Madhavi G.

Acta Chromatographica

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2013

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Vol. 25, no. 3

503--518

EN

An isocratic ion-pair reversed phase high-performance liquid chromatography-ultraviolet (RP-HPLC-UV) method for analysis of eberconazole nitrate in bulk and in pharmaceutical dosage forms has been developed and validated. Best separation was achieved on Lichrospher C18 column (250 mm × 4.6 mm, 5 μm) using a mobile phase of 10 mM potassium dihydrogen phosphate containing 10 mM tetra-butyl ammonium hydroxide (pH adjusted to 2.8 with ortho phosphoric acid) and methanol (75:25, v/v) at a flow rate of 1.0 mL min-1. UV detection was performed at 220 nm. The method was validated for specificity, linearity, precision, accuracy, limit of detection, limit of quantification, robustness, and solution stability. The calibration plot was linear over the concentration range of 10–80 μg mL-1 (r2 = 0.999) and the limits of detection and quantification were 0.3 and 0.9 μg mL-1, respectively. Intra-day and inter-day precisions were 1.13% and 1.67%, respectively. Experimental design was employed to optimize the method. The method was successfully used for analysis of eberconazole nitrate in commercially available cream (Ebernet).

15

HPLC determination of enantiomeric thiazolidine-2-carboxylic acid on chiral stationary phase with pre-column derivatization

Zhang Y., Peng Q., Zeng H., Yao S, Zhang Y., Song H.

Acta Chromatographica

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2013

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Vol. 25, no. 2

287--296

EN

A new high-performance liquid chromatography (HPLC) method has been developed and validated for determination of enantiomeric purity of thiazolidine-2-carboxylic acid within a short run time of less than 10 min. The method was based on pre-column derivatization of thiazolidine-2-carboxylic acid with aniline, and complete separation of enantiomers has been achieved on a Chiralcel OD-H analytical column (250 × 4.6 mm) using n-hexane-isopropanol (85:15 v/v) as mobile phase at a flow rate of 1.0 mL min-1 under UV and optical rotation (OR) detection. Detection wavelength was set at 254 nm. Then the effects of mobile phase and temperature on enantioselectivity were further evaluated. The method was validated with respect to precision, accuracy, linearity, limit of detection (LOD), limit of quantification (LOQ), and robustness. The recoveries were between 98.5 and 101.3% with percentage relative standard deviation less than 1.16%. The LOD and LOQ for the aniline derivatives of (+)-thiazolidine-2-carboxylic acid were 4.9 and 16.4 μg mL-1 and for the aniline derivatives (−)-thiazolidine-2-carboxylic acid were 5.1 and 17.2 μg mL-1, respectively.

16

Validated stability-indicating RP-HPLC UV method for simultaneous determination of metformin and repaglinide

Joshi S. S, Nahire R. R, Shastri N. R, Surendranath K. V, Satish J

Acta Chromatographica

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2012

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Vol. 24, no. 3

419--432

EN

A simple, rapid, precise, and accurate, stability-indicating reversed phase high performance liquid chromatographic method was developed and validated for simultaneous determination of metformin HCl and repaglinide. The chromatographic separation was achieved on YMC Pack AM ODS (5 μm, 250 mm length × 4.6 mm i.d.) column at a detector wavelength of 210 nm, using an isocratic mobile phase consisting of methanol and 10 mM potassium dihydrogen phosphate buffer (pH 2.5) in a ratio of 70:30 v/v at a flow rate of 1 mL min-1. The retention times for metformin and repaglinide were found to be 2.6 and 11.3 min, respectively. The drugs were exposed to thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analyzed by the proposed method. Validation of the method was carried out as per International Conference on Harmonization (ICH) guidelines. Linearity was established for metformin and repaglinide in the range of 5–200 μg mL-1 and 1–200 μg m-1. L, respectively. The limits of detection were 0.3 μg mL-1 and 0.13 μg mL-1 for metformin and repaglinide, respectively. The method was found to be specific and stability-indicating as no interfering peaks of degradants and excipients were observed. The proposed method is hence suitable for application in quality-control laboratories for quantitative analysis of both the drugs individually and in combination, since it is simple and rapid with good accuracy and precision.

17

Development and validation of a stability-indicating LC-UV method for the determination of doripenem and biapenem in pharmaceutical dosage forms

Cielecka-Piontek J., Krause A, Zalewski P., Lunzer A, Jelińska A.

Acta Chromatographica

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2012

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Vol. 24, no. 2

207--219

EN

A stability-indicating LC assay method was developed and validated for the quantitative determination of doripenem and biapenem in pharmaceutical dosage forms in the presence of degradation products formed during forced degradation studies. An isocratic RP-HPLC method was developed with a C-18 (250 mm × 4.6 mm, 5 μm) column and 12 mM ammonium acetate-acetonitrile (96:4 υ/υ) as mobile phase. The flow rate of the mobile phase was 1.0 mL min-1 for doripenem and biapenem. The determination was carried out at the wavelength of 295 nm. The carbapenems were subjected to stress conditions of degradation in aqueous solutions including hydrolysis, oxidation, photolysis, and thermal degradation. The developed method was validated with respect to linearity, accuracy, precision, selectivity, and robustness.

18

Stability-indicating liquid chromatographic method for analysis of pitavastatin calcium in tablet dosage forms

Panchal H. J, Suhagia B. N

Acta Chromatographica

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2011

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Vol. 23, no. 1

81--94

EN

A simple, specific, sensitive, precise, accurate, and robust stability-indicating reversed-phase liquid chromatographic (LC) method has been established for analysis of pitavastatin calcium in tablet dosage forms. LC separation was achieved on a 250 mm × 4.6 mm i.d., 5-μm particle, C18 column with acetonitrile-water-triethylamine 80:19.8:0.2 (υ/υ), adjusted to pH 3.5 ± 0.05 with orthophosphoric acid as isocratic mobile phase at a flow rate of 1.5 mL min-1. Detection, with a photodiode-array detector, was at 238 nm, the wavelength of maximum absorbance in a spectrum obtained from its solution in methanol. The retention time was approximately 5.70 min. The method was validated for linearity, accuracy, precision, limits of detection and quantification, and robustness. Quantification was performed over the concentration range 0.1–2.5 μg mL-1. Mean recovery was 100.26 ± 0.75%. The limit of detection (LOD) was 0.0055 µg mL-1. The method was successfully used for analysis of pitavastatin calcium in tablets and for stability studies, because the method separates pitavastatin calcium from its degradation products and from excipients.

19

Simultaneous analysis of six bioactive lignans in Phyllanthus species by reversed phase hyphenated high performance liquid chromatographic technique

Shanker K., Singh M., Srivastava V., Verma R. K., Gupta A. K., Gupta M. M.

Acta Chromatographica

|

2011

|

Vol. 23, no. 2

321--337

EN

An online-hyphenated high-performance liquid chromatography-photodiode array-mass spectrometry (HPLC-PDA-MS) analytical method was developed for the simultaneous determination of six lignans of therapeutic importance in four Phyllanthus spp. (P. amarus, P. maderaspatensis, P. urinaria, and P. virgatus). HPLC with monolithic reverse phase silica column (4.6 × 100 mm) and simple isocratic elution of methanol-water mixed with dioxane facilitated the separation of lignans of diverse nature such as diarylbutyrolactone, tetrahydrofuran, isomeric aryltetralin, and diarylbutane type for quantitative analysis. Targeted lignans viz. heliobuphthalmin lactone (1), virgatusin (2), hypophyllanthin (3), phyllanthin (4), nirtetralin (5), and niranthin (6) were confirmed unambiguously in four Phyllanthus species by their abundant molecular adduct ions, retention time, UV, and mass spectra as compared with those of reference compounds. Advantages and limitations of both detection techniques for qualitative (fingerprinting) and quantitative analysis of the above mentioned lignans in four Phyllanthus spp. are discussed. The method was validated following international guidelines. The described method can be utilized for assays and stability tests of P. amarus extracts as well as traditional Indian medicine based on Phyllanthus herb.

20

Development and validation of an RP-HPLC-UV method for the determination of ondansetron in rabbit plasma: Application to a pharmacokinetic study

Ravi S., Khan N., Darwis Y

Acta Chromatographica

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2011

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Vol. 23, no. 4

579--593

EN

A new sensitive and specific isocratic RP-HPLC-UV method was developed and validated for the determination of ondansetron in rabbit plasma using risperidone as an internal standard (IS). The sample preparation involved a simple deprotenization procedure with a mixture of 1 mL of acetonitrile and 50 μL of 10% w/υ zinc sulfate. Analysis was performed on a Phenomenex CN column (250 mm × 4.6 mm, 5 μm) with 50 mM ammonium acetate (pH 3.5) and acetonitrile (35:65, υ/υ) as mobile phase at a flow rate of 1.0 mL min-1. Column eluent was monitored at 310 nm. The calibration curve was linear over the concentration range of 25–1000 ng mL-1. (r2 = 0.9999) with a limit of quantification (LOQ) 25 ng mL. -1.The intraday and interday precision and accuracy were between 0.93% and 3.41% and −3.63% and 1.01%, respectively. The mean recoveries of ondansetron and risperidone were 85.87% and 99.80%, respectively. Ondansetroncontaining plasma samples were stable at −20°C for 14 days. The validated method was successfully applied for a pharmacokinetic study after a single oral administration of ondansetron (8 mg) to rabbits.