http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Thu, 16 May 2013 09:08:19 +0000 http://www.hindawi.com/isrn/chromatography/2013/460787/ A homologous series of chiral imidazolinone herbicide was previously resolved on Chiralcel OJ column in high performance liquid chromatography. However, the mechanism of the chiral separation remains unclear. In this study, chromatographic behaviors of five chiral imidazolinone herbicides were characterized by thermodynamic and extrathermodynamic methods in order to enhance the understanding of the chiral separation. Thermodynamic parameters of this study were derived from equilibrium constant () that was estimated from the moment analysis of the chromatographic peak. Van't Hoff plots of ( versus ) were linear at a range of 15–50°C, only nonlinear at a range of 5–15 °C with n-hexane (0.1%, trifluoroacetic acid)-2-propanol 60/40 (v/v) mobile phase. The enantiomer retention on the chiral column was entropy-driven at a lower temperature (5°C) and enthalpy-driven at a higher temperature (10 to 50°C). Enantioseparations of four of the five imidazolinone herbicides were enthalpy-driven, only entropy-driven for imazaquin. Enantioseparation mechanisms were different in between 5–10°C and 15–50°C probably due to the conformational change of the OJ phase. Enthalpy-entropy compensation showed similar mechanisms in retention and chiral separation for the five or enantiomers. Several extrathermodynamic relationships were able to be extracted to address additivity of group contribution. Wenjian Lao Copyright © 2013 Wenjian Lao. All rights reserved. Tue, 14 May 2013 19:17:38 +0000 http://www.hindawi.com/isrn/chromatography/2013/401629/ N,N-Dimethylformamide (DMF) is a toxic organic solvent commonly found in the textile and pharmaceutical industrial effluents. The DMF degradation was successfully archived by bacterial strain Paracoccus denitrificans SD1. The study demonstrates the high performance liquid chromatographic (HPLC) approach for the estimation of residual DMF in liquid medium. The investigation mainly focuses on the method development for the detection and quantification of DMF. The bacterium is capable of utilizing DMF (1% v/v) as the sole source of carbon and nitrogen. Utilization of DMF by the bacterium was investigated at regular intervals of time to check the complete degradation at a particular period. The method was validated based on the precision, accuracy, limit of detection, and limit of quantification. Herein, the method was executed in liquid chromatographic condition which enables direct analysis of aqueous samples from the spent medium avoiding the extraction and prederivatization. This improved method allows estimation of residual DMF from the aqueous medium in adequate ranges of precision and accuracy with 99.17% and 99.43% recovery, respectively. The method was validated by investigating the limit of detection (LOD) and limit of quantification (LOQ) of 0.2 and 0.40 mg/l, respectively. The method was found to be precise for detection of DMF by using liquid chromatography. Sanjeevkumar Sanganal, Guruprasad B. Kulkarni, and Timmanagouda B. Karegoudar Copyright © 2013 Sanjeevkumar Sanganal et al. All rights reserved. Thu, 18 Apr 2013 15:32:14 +0000 http://www.hindawi.com/isrn/chromatography/2013/183654/ A simple, reliable, and sensitive method was based on high-performance liquid chromatography (HPLC) was developed and validated for the estimation of abamectin residues present in tea. The abamectin residues extracted with acetone-water mixture (70 : 30, v/v) and derivatised with 1-methylimidazole (1-MIM) and trifluoroacetic anhydride (TFAA) were estimated by HPLC using fluorescence detector (FLD). The technique was validated in terms of linearity, precision, recovery, specificity, limit of detection (LOD), and limit of quantification (LOQ). A good linear relationship () was absorbed in the abamectin concentration range from 0.01 to 1.0 μg mL−1. The limit of detection and limit of quantification of the method were 0.01 and 0.02 μg g−1, respectively. The average recoveries of the pesticide from black tea and dried green leaves ranged from 83.3 to 103.8% and 83.8 to 98.0%, respectively. Madasamy Kottiappan, Shanmugaselvan Veilumuthu Anandhan, and Selvaganapathi Chandran Copyright © 2013 Madasamy Kottiappan et al. All rights reserved. Wed, 27 Feb 2013 10:55:12 +0000 http://www.hindawi.com/isrn/chromatography/2013/738397/ Quality by design (QbD) refers to the achievement of certain predictable quality with desired and predetermined specifications. The objective of this study was to develop and demonstrate an integrated multivariate approach to develop and quantify the constituent concentrations of glipizide (GPZ) drug in its pure and tablet forms. The method was developed using Zorbax Extend C-18 (50 mm × 4.6 mm × 1.8 μm) column with mobile phase consisting of a mixture of phosphate buffer of pH 3.5 and acetonitrile (60 : 40 v/v). The method fulfilled validation criteria and was shown to be sensitive, with limits of detection (LOD) and quantitation (LOQ) of 0.001 and 0.005 μg mL−1, respectively. The percentage relative standard deviations for robustness and ruggedness were observed within the range of 0.1 and 0.99. The calibration graph was linear in the range of 0.005–300 μg mL−1. The applicability of the method was shown by the analysis of formulated drug and spiked urine samples. The proposed method can be used for routine analysis in quality control laboratories for its bulk and formulated product, and this is the first UPLC method reported for the assay of GPZ in bulk, formulated form and urine. Cijo M. Xavier, Kanakapura Basavaiah, K. B. Vinay, and N. Swamy Copyright © 2013 Cijo M. Xavier et al. All rights reserved. Mon, 04 Feb 2013 16:16:20 +0000 http://www.hindawi.com/isrn/chromatography/2013/484592/ A method for determining ranitidine in human plasma by ESI-LC-MS/MS was validated, using propranolol as internal standard. The extraction method used was solid phase extraction (SPE). Chromatographic separation was performed in a Chromolith C18 (50 mm × 4.6 mm i.d.) analytical column, which provided good separation of ranitidine and propranolol peaks with an analysis time of 2.5 minutes. Extraction yields of 94.4% for ranitidine and 89.4% for the internal standard were obtained. The lower limit of quantification (LLOQ) was 3.00 ng/mL, and limit of detection (LOD) was 0.05 ng/mL, with linearity ranging from 3.00 to 500 ng/mL. The results, thus, showed that this method is suitable for application in bioequivalence studies of ranitidine in human plasma. Karini B. Bellorio, Maria Isabel R. Alves, and Nelson R. Antoniosi Filho Copyright © 2013 Karini B. Bellorio et al. All rights reserved. Mon, 28 Jan 2013 10:25:23 +0000 http://www.hindawi.com/isrn/chromatography/2013/878295/ A simple, rapid, and stability-indicating RP-HPLC method for a combination of tenofovir disoproxil fumarate (TDF), emtricitabine (FTC), and efavirenz (EFV) was developed and validated with the help of a suitable statistical software as an application tool for the quality by design. The drugs individually, and in combination, were subjected to forced degradation (thermal, photolytic, hydrolytic, and oxidative stress conditions) and accelerated stability studies (40 ± 1°C/75 ± 3% RH for three months). Successful separation of combined drugs from degradation products was achieved by gradient elution on a reverse-phase C18 column, using a mobile phase containing phosphate buffer (pH 3.5): acetonitrile at 1.5 mL min−1 flow rate, detection wavelength 256 nm, column oven temperature 25°C, and injection volume 10 μL. Linearity was established in the range of 20–300 μg mL−1, 24.5–367.5 μg mL−1 and 60–900 μg mL−1 for FTC, TDF, and EFV, respectively. The method was successfully applied for quantifying the drugs in marketed dosage forms and on stability samples. Prashant S. Devrukhakar, Roshan Borkar, Nalini Shastri, and K. V. Surendranath Copyright © 2013 Prashant S. Devrukhakar et al. All rights reserved. Tue, 22 Jan 2013 15:15:46 +0000 http://www.hindawi.com/isrn/chromatography/2013/134586/ Seeds of Ipomoea muricata, well known in Ayurveda for its purgative action, contains mainly indole alkaloids. Lysergol (major alkaloid) exhibits hypotensive, psychotropic, and uterus and intestine-stimulating properties. TLC fingerprint profile of I. muricata seeds was developed using chloroform : methanol (95 : 5 v/v) as the mobile phase. Plate was visualized under UV 254 nm and UV 366 nm and after derivatization with Van Urk reagent. Lysergol resolved at . Further, TLC-densitometric method was developed and validated for quantification of Lysergol avoiding derivatization step. Ethyl acetate :  methanol (7 : 3 v/v) was used as the mobile phase. Linear regression analysis data for the calibration curve showed a good linear relationship () in the concentration range from 20 ng to 140 ng, with respect to the peak area. The developed method was precise with RSD for intraday (range from 1.20 to 1.89) and interday (range from 1.39 to 1.92) for 60, 80, and 100 ng/spot of Lysergol. The instrumental precision was 0.67 (% RSD). The limit of detection and limit of quantification for Lysergol were 12 ng and 40 ng, respectively. The average percentage recovery was 99.68. The amount of Lysergol was found to be 0.23% w/w. To the best of our knowledge, this is the first report for the quantification of Lysergol from I. muricata seeds without derivatization. Shrikant Patil, Manish Nivsarkar, and Sheetal Anandajiwala Copyright © 2013 Shrikant Patil et al. All rights reserved. Tue, 15 Jan 2013 11:53:30 +0000 http://www.hindawi.com/isrn/chromatography/2013/859024/ An efficient separation and quantification of the individual neutral and polar lipid classes and their constituent fatty acids was achieved by the combination of two different detection techniques: Iatroscan TLC-FID and GC-FID. The solvent composition and ratio of development system, the sample size, the fidelity, and precision were tested in order to estimate the effectiveness of separation of individual neutral and polar lipid classes and the quantitative reproducibility of the Iatroscan TLC-FID technique. GC-FID method, with a high-quality capillary column, allowed sensitive and reproducible fatty acid qualitative and quantitative analyses, separation of fatty acid structural isomers (e.g., n-C16:0, iso-C16:0 and anteiso-C16:0), positional isomers (e.g., C18:1ω-9 and C18:1ω-7), geometrical isomers (cis-trans), and homologues (e.g., C16:0, C17:0, C18:0, etc.) in standards and complex lipid samples. Seventeen (17) lipid classes and fifty-two (52) saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids were identified and quantified, respectively, in samples of standard lipid and fatty acid mixtures, simulating the composition of natural lipids and their fatty acid methyl esters in common foods. The wide number of applications establishes this combination of Iatroscan TLC-FID and GC-FID methods as a powerful tool for lipid class and fatty acid analysis of any fat origin. Vassilia J. Sinanoglou, Irini F. Strati, Sotirios M. Bratakos, Charalampos Proestos, Panagiotis Zoumpoulakis, and Sofia Miniadis-Meimaroglou Copyright © 2013 Vassilia J. Sinanoglou et al. All rights reserved. Wed, 19 Dec 2012 13:02:45 +0000 http://www.hindawi.com/isrn/chromatography/2012/592849/ Quality by Design (QbD) is a philosophy that refines the level of knowledge associated with a product that uses process understanding to deliver a product with the desired critical quality attributes. The objective of this study was to develop an integrated multivariate QbD approach to develop and quantify the constituent concentrations of pioglitazone hydrochloride (PGZ) drug in its pure and formulated forms. To facilitate studies investigating the determination of PGZ in bulk drug and its pharmaceutical formulations, a rapid UPLC method was developed and validated for the determination of PGZ accompanied by its degradation studies in different stress conditions. The method fulfilled validation criteria and was shown to be sensitive, with limits of detection (LOD) and quantitation (LOQ) of 0.01 and 0.05 μg mL−1, respectively. The percent relative standard deviations for robustness and ruggedness were observed within the range of 0.1–1.74. The calibration graph was linear in the range of 0.05–300 μg mL−1. The applicability of the method was shown by analysis of formulated drug samples and spiked human urine. The proposed method can be used for routine analysis in quality controlled laboratories for its bulk and formulated product and this is the first reported UPLC method for the assay of PGZ. Cijo M. Xavier and Kanakapura Basavaiah Copyright © 2012 Cijo M. Xavier and Kanakapura Basavaiah. All rights reserved. Mon, 17 Dec 2012 13:18:49 +0000 http://www.hindawi.com/isrn/chromatography/2012/836132/ A selective ultraperformance liquid chromatographic (UPLC) method for the quantification of valproic acid and its known related impurities using ion pair reagent has been developed. The method includes reversed-phase Acquity HSS T3 column with 100 mm × 2.1 mm i.d. and 1.7 μ particle size. The mobile phase consists of acetonitrile, 5 mM 1-hexanesulphonic acid sodium salt, flow rate is 0.6 mL/min, and UV detection is performed at 215 nm. A system suitability test (SST) was developed to govern the quality of the separation. The developed method has been validated further with respect to linearity, accuracy, precision, selectivity, LOD, LOQ, and Robustness. Rakshit Thakkar, Hitesh Saravaia, Mrunal Ambasana, Madhavi Patel, and Anamik Shah Copyright © 2012 Rakshit Thakkar et al. All rights reserved. Sun, 16 Dec 2012 09:24:55 +0000 http://www.hindawi.com/isrn/chromatography/2012/639514/ Extensive investigation has been carried out to elucidate the mechanisms involved in pseudoligand affinity chromatography using textile dyes, and, empirically, it has been attributed to the chemical and steric structures of dye and protein. Possibly, a variety of interactions especially ionic and/or hydrophobic influence with a varying share in the binding and differ from protein to protein and from dye to dye. In this study, we have attempted to understand the effect of various biophysical parameters like the nature of the eluant, pH, and ionic strength on the binding of crude luteinizing hormone (LH) with various triazine-based dyes and thus predict their nature. Based on the elution patterns, cibacron and reactive brown suggested a dual electrostatic and hydrophobic nature. Reactive blue and reactive yellow reflected a major electrostatic/ionic nature with yellow offering 50-fold purification in a single step, while reactive red and reactive green had a predominant hydrophobic nature. Appreciably, reactive red was binding LH very tightly unlike other dyes, and addition of the arginine in the elution buffer substantially weakened the protein-dye interactions. pH was observed to be a principal factor assisting the protein-dye binding as well as hydrophobicity of the dye and the proteins. Taruna Arora, Pankaj Patel, and K. Muralidhar Copyright © 2012 Taruna Arora et al. All rights reserved. Thu, 13 Dec 2012 15:17:38 +0000 http://www.hindawi.com/isrn/chromatography/2012/970685/ Size-exclusion chromatography (SEC) was used to evaluate gold nanoparticles (Au NPs) for variations in their sizes after microwave (MW) irradiation, with the eluted NPs monitored through diode array detection to reveal their surface plasmon absorptions. The sizes of citrate-capped Au NPs decreased upon increasing the MW irradiation temperature, consistent with digestive ripening of these NPs under the operating conditions. In contrast, Au NPs capped with sodium dodecyl sulfate increased in size upon increasing the MW irradiation temperature, consistent with Ostwald ripening. When the Au NPs were capped with 3A-amino-3A-deoxy-(2AS,3AS)--cyclodextrin (H2N--CD), however, their dimensions were barely affected by the MW irradiation temperature, confirming that H2N--CD is a good stabilizer against MW irradiation. Therefore, SEC—with its short analysis times, low operating costs, automated operation, and in situ analysis—has great potential for use in the rapid monitoring of NPs subjected to treatment under various MW irradiation conditions. Fu-Ken Liu Copyright © 2012 Fu-Ken Liu. All rights reserved. Tue, 11 Dec 2012 14:48:19 +0000 http://www.hindawi.com/isrn/chromatography/2012/252895/ A simple, precise, and accurate reversed-phase liquid chromatographic method has been developed for the simultaneous determination of paracetamol (PCM), chlorzoxazone (CHZ), and nimesulide (NIM) in pharmaceutical dosage form. The chromatographic separation was achieved on a Thermo Hypersil GOLD C18 column (250 × 4.6 mm i.d., 5 μm particle size). The mobile phase consisted of water : acetonitrile (55 : 45 v/v). The flow rate was set to 1.2 mL min−1 and UV detection was carried out at 275 nm. The retention time () for PCM, CHZ, and NIM was found to be 2.69 ± 0.02, 4.61 ± 0.01, and 9.55 ± 0.02 min, respectively. The validation of the proposed method was carried out for linearity, precision, robustness, limit of detection, limit of quantitation, specificity, and accuracy. The linear dynamic ranges were 32.5–65.0 μg mL−1 for PCM, 37.5–75.0 μg mL−1 for CHZ, and 10.0–20.0 μg mL−1 for NIM. The developed method can be used for routine quality control analysis of titled drugs in pharmaceutical dosage form. Snehal J. More, Suparna S. Tandulwadkar, Ajinkya R. Nikam, Atul S. Rathore, L. Sathiyanarayanan, and Kakasaheb R. Mahadik Copyright © 2012 Snehal J. More et al. All rights reserved. Mon, 10 Dec 2012 16:09:50 +0000 http://www.hindawi.com/isrn/chromatography/2012/761679/ A reliable, rapid, and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay has been proposed for the determination of rizatriptan in human plasma using sumatriptan as internal standard (IS). The analyte and IS were extracted from 300 μL human plasma via liquid-liquid extraction and the chromatography was achieved on Hypurity C18 (50 mm × 4.6 mm, 5 μm) column under isocratic conditions. Detection of rizatriptan and IS was done by tandem mass spectrometry, operating in positive ionization and multiple-reaction monitoring mode. The limit of detection and lower limit of quantitation of the method were 0.04 and 0.20 ng/mL, respectively, with a linear dynamic range of 0.20–60.0 ng/mL. The intrabatch and interbatch precision (% CV) was ≤8.4% while the mean extraction recovery was >78% across quality control levels. Bench top stability, freeze and thaw stability, processed sample stability, and long-term stability in plasma were evaluated at two quality control levels. It was successfully applied to a bioequivalence study of 10 mg rizatriptan orally disintegrating tablet formulation in 40 and 32 healthy Indian male subjects under fasting and fed conditions, respectively. The reproducibility in the measurement of study data was demonstrated by reanalysis of 254 incurred samples. Dinesh S. Patel, Naveen Sharma, Mukesh C. Patel, Bhavin N. Patel, Pranav S. Shrivastav, and Mallika Sanyal Copyright © 2012 Dinesh S. Patel et al. All rights reserved. Tue, 20 Nov 2012 10:07:25 +0000 http://www.hindawi.com/isrn/chromatography/2012/828719/ A liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for the determination of therapeutic levels of caffeine in dried blood spot (DBS) samples. Caffeine is used in the treatment of Apnoea of Prematurity (AoP) in newborn children. Calibration DBS samples were prepared by spotting 15 μL of whole blood spiked with the analyte onto specimen collection cards. 3 mm disks cut from the centre of the DBS were extracted in methanol containing the internal standard. The extract was separated using a Zorbax Eclipse Plus C18 column and the MS, operated in electrospray positive ion mode, used single ion monitoring at m/z 195 for caffeine and m/z 198 for the IS. The overall extraction recovery of caffeine from spiked blood spots was demonstrated to be 44–47%. Validation of the microanalytical method showed good precision (coefficient of variation) and accuracy (relative error) and specificity and was linear within the tested calibration range 500–25000 ng/mL for caffeine. Investigation of different specimen collection papers revealed different matrix effects with significant ion suppression from the FTA Elute paper itself. Requiring only a microvolume (15 μL) blood sample for analysis, the developed DBS based microanalytical method has the potential to facilitate the routine monitoring of caffeine in neonates. Graham Lawson, Parul Patel, Hussain Mulla, and Sangeeta Tanna Copyright © 2012 Graham Lawson et al. All rights reserved. Wed, 14 Nov 2012 10:13:29 +0000 http://www.hindawi.com/isrn/chromatography/2012/609095/ In this work three chromatographic methods were developed to reduce the total time of the analysis of main compounds in Aloe vera extracts. The first method was developed in a regular reverse phase chromatographic system using a particulate reverse phase C-18 column. Methods already published were used as a starting point for the development of the new method. All the compounds were separated in 32 minutes. The second method was developed in a regular reverse phase chromatographic system employing a monolithic type column. Using a 4.5 mL min−1 flow, the total time of analysis was reduced to 6 minutes with very similar resolution values. The third method was developed in an ultraperformance liquid chromatographic system, and the final time for the analysis of the phenolic compounds was reduced to 4 minutes. The analytical properties of the three chromatographic methods were compared for the main compounds in the chromatograms. Robustness of the three new methods was also checked with regard to the injection volume and the amount of methanol in the sample. A fast method (4 min) is then available for bioactive compounds from Aloe vera determination. L. Azaroual, A. Liazid, G. F. Barbero, J. Brigui, M. Palma, and C. G. Barroso Copyright © 2012 L. Azaroual et al. All rights reserved. Thu, 01 Nov 2012 12:04:38 +0000 http://www.hindawi.com/isrn/chromatography/2012/916932/ A simple, precise, and accurate, and stability-indicating isocratic Ultraperformance Liquid Chromatography (UPLC) method was developed for the determination of methdilazine hydrochloride (MDH) in bulk drug and in its tablets. The use of UPLC, with a rapid 5-minute-reversed-phase isocratic separation on a 1.7 μm reversed-phase packing material to provide rapid ‘‘high throughput’’ support for MDH, is demonstrated. The method was developed using Waters Acquity BEH C18 column (100 mm × 2.1 mm, 1.7 μm) with mobile phase consisting of a mixture of potassium dihydrogenorthophosphate and 1-pentane sulphonic acid buffer of pH 4.0 and acetonitrile (60 : 40 v/v). The eluted compound was detected at 254 nm with a UV detector. The standard curve of mean peak area versus concentration showed an excellent linearity over a concentration range 0.5–80 μg mL−1 MDH with regression coefficient () value of 0.9999. The limit of detection () was 0.2 μg mL−1 and the limit of quantification () was 0.5 μg mL−1. Forced degradation of the bulk sample was conducted in accordance with the ICH guidelines. Acidic, basic, hydrolytic, oxidative, thermal, and photolytic degradations were used to assess the stability indicating power of the method. The drug was found to be stable in acidic, basic, thermal, hydrolytic, and photolytic stress conditions and showed slight degradation in oxidative stress condition. Madihalli S. Raghu, Kanakapura Basavaiah, Cijo M. Xavier, and Kudige N. Prashanth Copyright © 2012 Madihalli S. Raghu et al. All rights reserved. Sun, 08 Jul 2012 08:18:30 +0000 http://www.hindawi.com/isrn/chromatography/2012/894965/ A simple, rapid, accurate, and precise gradient reversed-phase HPLC (RP-HPLC) method has been developed for the determination of ganciclovir (GNC) in pharmaceuticals. Chromatographic separation was carried out on inertsil ODS C18 (4.6 mm i.d×250 mm, 5.0 μm) LC column using ammonium acetate buffer, sodium salt of hexane sulfonic acid as ion-pairing reagent in 1000 mL water, and acetonitrile (90 : 10) (v/v) as mobile phase at a flow rate of 1.0 mL min−1 and with UV detection at 245 nm at column temperature (30°C). The runtime under these chromatographic conditions was 10 min. The method was linear over the range of 0.02–75 μg mL−1. The limits of detection (LOD) and quantification (LOQ) values were 4.1 and 20 ng mL−1, respectively. The method was successfully extended to study the effect on GNC upon treatment with 2 N NaOH, 2N HCl, and 5% H2O2 for 2 hrs at 80°C and upon exposure to UV (1200 K lux hrs) for 72 hrs and thermal (105°C) for 5 hrs. The proposed method was further applied to the determination of GNC in pharmaceuticals, with good percent recovery. The accuracy and the precision of the method were validated on intraday and interday basis in accordance with ICH guidelines. P. J. Ramesh, K. Basavaiah, K. B. Vinay, and Cijo M. Xavier Copyright © 2012 P. J. Ramesh et al. All rights reserved. Thu, 05 Jul 2012 10:17:45 +0000 http://www.hindawi.com/isrn/chromatography/2012/649746/ Gram-negative bacteria are widely used for the production of gene-based products such as DNA vaccines and bio-drugs, where endotoxin contamination can occur at any point within the process and its removal is of great concern. In this article, we review the structures of endotoxin and the effects that it causes in vivo. The endotoxin removal strategies are also discussed in the light of the different interaction mechanisms involved between endotoxins and bioproducts particularly plasmid DNA and proteins. For most cases, endotoxin removal is favoured at a highly ionic or acidic condition. Various removal methods particularly chromatography-based techniques are covered in this article according to the relevant applications. Clarence M. Ongkudon, Jia Han Chew, Boyin Liu, and Michael K. Danquah Copyright © 2012 Clarence M. Ongkudon et al. All rights reserved. Mon, 18 Jun 2012 10:12:20 +0000 http://www.hindawi.com/isrn/chromatography/2012/680929/ Chromatographic techniques are among the most useful analytical methods. Gas and liquid chromatography were used in the analysis of some organic compounds: phenol, hydroquinone, benzoquinone, and maleic and fumaric acids. The analytical way for the determination of these compounds in water samples was investigated. Solid-phase extraction (SPE) technique was used on the sample preparation step, different divinylbenzene-based sorbents were applied. Calibration curves of given compounds were linear over the ranges: 50–500 μg/mL for phenol and its acetic derivatives, 50–1500 μg/mL for benzoquinone in GC analysis, and 50–250 μg/mL for phenol, 40–1000 μg/mL for hydroquinone, and 4–4500 μg/mL for carboxylic acids in HPLC analysis. The LOD and LOQ of proposed analytical procedure were in the ranges of LOD: 0.042–23.83 μg/mL; LOQ: 0.138–78.64 μg/mL. Katarzyna Bielicka-Daszkiewicz, Monika Hadzicka, and Adam Voelkel Copyright © 2012 Katarzyna Bielicka-Daszkiewicz et al. All rights reserved. Thu, 14 Jun 2012 15:01:22 +0000 http://www.hindawi.com/isrn/chromatography/2012/693249/ Natural peat was tested for extraction of pyrimethanil, flumetralin, and krexosim-methyl from water, with analysis using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode (SIM). Experiments were carried out at one fortification level (0.1 μg L−1) and resulted in recoveries in the range 41–96%, with RSD values between 6.8 and 12.6% for natural peat as sorbent. Detection and quantification limits ranged from 0.02 to 0.05 μg L−1 and from 0.07 to 0.1 μg L−1, respectively, for the different pesticides studied. The method developed was linear over the range tested (0.07–4.0 μg L−1), with correlation coefficients ranging from 0.9919 to 0.9989. Comparison between peat and commercial sorbents (C18-bonded silica, ENVI-Carb, Florisil, silica gel, ENVI-Carb/LC-NH2) showed better performance of peat sorbent for flumetralin and kresoxim-methyl. Alex S. M. S. J. Santos, Adriano Aquino, Luciane P. C. Romão, and Sandro Navickiene Copyright © 2012 Alex S. M. S. J. Santos et al. All rights reserved. Wed, 30 May 2012 15:32:24 +0000 http://www.hindawi.com/isrn/chromatography/2012/838432/ The hazardous psychoactive designer drugs are compounds in which part of the molecular structure of a stimulant or narcotic has been modified. A quantitative structure-retention relationship (QSRR) study based on a Levenberg-Marquardt artificial neural network (L-M ANN) was carried out for the prediction of the capacity factor (k′) of hazardous psychoactive designer drugs that contain Tryptamine, Phenylethylamine and Piperazine. The genetic algorithm-partial least squares (GA-PLS) method was used as a variable selection tool. A PLS method was used to select the best descriptors and the selected descriptors were used as input neurons in neural network model. For choosing the best predictive model from among comparable models, square correlation coefficient (R2) for the whole set is suggested to be a good criterion. Finally, to improve the results, structure-retention relationships were followed by nonlinear approach using artificial neural networks and consequently better results were obtained. Also this demonstrates the advantages of L-M ANN. This is the first research on the QSRR of the designer drugs using the GA-PLS and L-M ANN. Hamzeh Karimi, Hadi Noorizadeh, and Abbas Farmany Copyright © 2012 Hamzeh Karimi et al. All rights reserved. Tue, 29 May 2012 09:35:44 +0000 http://www.hindawi.com/isrn/chromatography/2012/278583/ A simple, sensitive, precise, specific and stability indicating high-performance thin-layer chromatographic (HPTLC) method for the determination of emtricitabine both in bulk drug and pharmaceutical dosage form was developed and validated. The method employed aluminium plates precoated with silica gel G60 F254 as the stationary phase. The solvent system consisted of toluene : ethyl acetate : methanol (2 : 8 : 1, v/v/v). This solvent system was found to give compact spots for emtricitabine with 𝑅𝑓 value 0.26±0.01. Densitometric analysis of emtricitabine was carried out in the absorbance mode at 284 nm. Linear regression analysis showed good linearity (𝑟2=0.9997) with respect to peak area in the concentration range of 30–110 ng spot−1. The method was validated for precision, limit of detection (LOD), limit of quantitation (LOQ), robustness, accuracy and specificity. Emtricitabine was subjected to acid and alkali hydrolysis, oxidation, neutral hydrolysis, photodegradation and dry heat treatment. Also the degraded products peaks were well resolved from the pure drug with significantly different 𝑅𝑓 values. Statistical analysis proved that the method is repeatable and specific for the estimation of the said drug. As the method could effectively separate the drugs from their degradation products, it can be employed as a stability indicating method. Atul S. Rathore, Lohidasan Sathiyanarayanan, and Kakasaheb R. Mahadik Copyright © 2012 Atul S. Rathore et al. All rights reserved. Sun, 11 Mar 2012 17:55:16 +0000 http://www.hindawi.com/isrn/chromatography/2012/783752/ Incarvillea emodi (Bignoniaceae) is a rich source of bioactive iridoid glucosides. This plant contains two major iridoid glucosides: plantarenaloside, a neurotropic compound, and boschnaloside, a strong antibacterial compound. Here, in this study we have developed a simple and fast HPLC-DAD method for the total comparative estimation of these two major iridoids from different parts of Incarvillea emodi. A linear calibration curve (𝑟2=0.999) for both iridoid glucosides in varying range (15.6–500 μg/ml) is obtained. The limit of detection (LOD) and limit of quantification (LOQ) for plantarenaloside were 11.4 ng and 38 ng and for boschnaloside were 22.8 ng and 76 ng, respectively. The shoots, roots, and flowers of Incarvillea emodi have a combined presence of 7.66, 1.22, and 6.99 percent of these iridoid glucosides on dry weight basis. In shoots, plantarenaloside shows complete dominance (6.78%) over boschnaloside (0.88%), and a reversal of this trend was observed in case of flowers where boschnaloside shows complete dominance (6.12%) over plantarenaloside (0.87%). The roots contain 1.19% and 0.03% of both iridoids, respectively. Ajay Rana, Harsh Pratap Singh, and Devendra Dhyani Copyright © 2012 Ajay Rana et al. All rights reserved. Sun, 04 Mar 2012 19:12:29 +0000 http://www.hindawi.com/isrn/chromatography/2012/945198/ A method was established to monitor organic reactions by micellar capillary electrokinetic chromatography (MEKC). After optimizing conditions such as the composition of the solvents, the surfactant, and the apparent pH (pH*) of the system, the method was utilized to analyze the reaction of glycidyl methacrylate (GMA) and allyl amine. The main products were identified in the electropherograms. The reaction procedure was monitored in real time. This method was found to have common applicability, being able to separate and detect nonaqueous soluble, nonionic, and low-UV-Vis absorbance compounds. It provides a rapid and low-cost way to understand organic reactions and to direct synthesis works. Chun Yang, Chunyang Chang, Jun Wang, Qishu Qu, Xiaoya Hu, and Yang Wang Copyright © 2012 Chun Yang et al. All rights reserved. Sun, 04 Mar 2012 19:10:55 +0000 http://www.hindawi.com/isrn/chromatography/2012/582375/ A stability-indicating liquid chromatographic (LC) method was studied for the determination of paliperidone in osmotic-controlled release oral delivery system (OROS) tablets. A tablet extraction procedure was developed by testing the efficiency of solvents (water, HCl, NaOH, acetonitrile, methanol) and techniques (ultrasonic bath, magnetic stirrer), and evaluating the release of the drug with respect to time. A forced degradation study was conducted to demonstrate the stability-indicating power of the method. Chromatographic separation was achieved using an isocratic elution in a reversed-phase system with a mobile phase prepared from a mixture of phosphate buffer and acetonitrile. The use of an ultrasonic bath demonstrated paliperidone release from OROS tablets in a total time of 60 min. Verifying the efficiency of the chromatographic procedure, the theoretical plates (𝑁=12634.21) and tailing factor (tf=1.31) were constant during repeated injections. The retention time of paliperidone was 4.8 min, and the method was validated within the concentration range of 10–50 μg mL−1 (𝑟=0.9999). Adequate reproducibility (RSD% = 0.30–0.59), interday precision (RSD%=1.81), and accuracy were obtained. The proposed method was successfully applied to paliperidone determination in the presence of degradation products, and an efficient extraction procedure from the OROS tablets was developed. Fábio Barbosa, Luciano Mantovani, Cássia V. Garcia, and Andreas S. L. Mendez Copyright © 2012 Fábio Barbosa et al. All rights reserved. Wed, 29 Feb 2012 16:28:42 +0000 http://www.hindawi.com/isrn/chromatography/2012/120780/ The multivariate calibration methods—principal component regression (PCR) and partial least squares (PLSs)—were employed for the prediction of total phenol contents of four Prunella species. High performance liquid chromatography (HPLC) and spectrophotometric approaches were used to determine the total phenol content of the Prunella samples. Several preprocessing techniques such as smoothing, normalization, and column centering were employed to extract the chemically relevant information from the data after alignment with correlation optimized warping (COW). The importance of the preprocessing was investigated by calculating the root mean square error (RMSE) for the calibration set of the total phenol content of Prunella samples. The models developed based on the preprocessed data were able to predict the total phenol content with a precision comparable to that of the reference of the Folin-Ciocalteu method. PLS model seems preferable, because of its predictive and describing abilities and good interpretability of the contribution of compounds to the total phenol content. Multivariate calibration methods were constructed to model the total phenol content of the Prunella samples from the HPLC profiles and indicate peaks responsible for the total phenol content successfully. Saliha Şahin, Esra Işık, and Cevdet Demir Copyright © 2012 Saliha Şahin et al. All rights reserved. Sun, 19 Feb 2012 16:11:49 +0000 http://www.hindawi.com/isrn/chromatography/2012/487138/ Two concentration methods for fast and routine determination of caffeine (using HPLC-UV detection) in surface, and wastewater are evaluated. Both methods are based on solid-phase extraction (SPE) concentration with octadecyl silica sorbents. A common “offline” SPE procedure shows that quantitative recovery of caffeine is obtained with 2 mL of an elution mixture solvent methanol-water containing at least 60% methanol. The method detection limit is 0.1 μg L−1 when percolating 1 L samples through the cartridge. The development of an “online” SPE method based on a mini-SPE column, containing 100 mg of the same sorbent, directly connected to the HPLC system allows the method detection limit to be decreased to 10 ng L−1 with a sample volume of 100 mL. The “offline” SPE method is applied to the analysis of caffeine in wastewater samples, whereas the “on-line” method is used for analysis in natural waters from streams receiving significant water intakes from local wastewater treatment plants. Sònia Moret, Manuela Hidalgo, and Juan M. Sanchez Copyright © 2012 Sònia Moret et al. All rights reserved. Tue, 07 Feb 2012 16:49:40 +0000 http://www.hindawi.com/isrn/chromatography/2012/293830/ The high-performance liquid chromatography—mass spectrometry (HPLC-MS) qualitative analysis method in negative mode of detection was used to record the presence of orellanine in the stomach contents of rats after ingestion of Cortinarius orellanus. Intoxication with orellanine causes acute renal failure (ARF), which is characterized by sudden loss of the ability of the kidneys to excrete wastes. The detection method presented here can be used as a platform for future development of analytical procedures for detecting orellanine in cases of human intoxication by toadstools. The presence of orellanine in animal stomach contents was analytically recorded and compared with standard orellanine, which was donated by the R&D Department of Jupiter Ltd, Norway. The MS fragmentation described in the literature and the MS fragmentation of standard samples of isolated orellanine verified the presence of orellanine in the stomach contents of laboratory animals. The presence of a diglucoside of orellanine, which was described as part of the toxic orellanine complex by Spiteller et al., in the stomach contents of animals, was also verified using HPLC-MS. Ilia Brondz and Anton Brondz Copyright © 2012 Ilia Brondz and Anton Brondz. All rights reserved. Mon, 06 Feb 2012 14:43:19 +0000 http://www.hindawi.com/isrn/chromatography/2012/892806/ This paper investigates Raman spectroscopy as a quick and reliable method to quantify the alpha (α) and gamma (γ) polymorphic forms of indomethacin compared to differential scanning calorimetry (DSC). Binary mixtures with different ratios of α and γ indomethacin were prepared and analyzed by Raman and DSC. The Raman method was found to be more reliable and superior compared to DSC. The partial conversion of the alpha to gamma polymorphic form during the DSC measurement was the major limitation for the use of full DSC as a quantitative method and resulted in difference between the calculated and measured enthalpy of both polymorphic forms. Eman Atef, Harsh Chauhan, Dev Prasad, Dunesh Kumari, and Charles Pidgeon Copyright © 2012 Eman Atef et al. All rights reserved.