A Validated, Stability-Indicating, LC Method for Rabeprazole Sodium

We present a simple and reliable method for simultaneous determination of voriconazole and its main metabolite resulting from N-oxidation (UK-121,265), in human plasma. The work-up procedure used acetonitrile and potassium salts to precipitate plasma proteins. No internal standard was used. The chromatographic system used a LiChroCART^® 250-4 cartridge packed with LiChrospher^® 100 RP-8 (diameter particules, 5 μm). The UV monochromatic detector was set on 260 nm. The mobile phase consisted of a 60/40 (v/v) mixture of acetonitrile and water. The flow rate was 1 mL min^?1. The retention times for voriconazole and its metabolite were 8.98 and 4.02 min respectively, and total run time was 12 min. The linearity of the method was investigated from 0.31 to 10.0 mg L^?1; the lowest limit of quantification was 0.30 mg L^?1. Precision ranged from 2.41% to 6.32% for voriconazole and 0.80% to 11.6% for the N-oxide voriconazole metabolite. Accuracy was between 93.0% and 101% for voriconazole and 90.0% and 101% for the N-oxide voriconazole metabolite. This rapid and accurate method could be interesting to investigate metabolite/voriconazole ratio with respect to CYP2C19 genetic status and CYP3A4 activity changes.     

Preparation of a Novel Amino-Phosphate Zwitterionic Stationary Phase for Hydrophilic Interaction Chromatography

A new stationary phase which contains both negatively charged phosphate groups and positively charged amino groups was successfully synthesized by modification of amino-functionalized silica particles with trichlorophosphine oxide (POCl₃) for hydrophilic interaction chromatography (HILIC). The composition of the surface grafts was determined by Fourier transform infrared spectroscopy and elemental analysis. Various parameters, such as column temperature, water content, pH values and ionic strength of the mobile phase were investigated to study the retention mechanism. The results demonstrated that the stationary phase involved a complex retention process including surface adsorption, partitioning and electrostatic interactions. Under optimized conditions, the separation of nucleobases and nucleosides, water-soluble vitamins, organic acids on the novel stationary phase could be achieved in the HILIC mode.     

Preparation of a Novel Amino-Phosphate Zwitterionic Stationary Phase for Hydrophilic Interaction Chromatography

A new stationary phase which contains both negatively charged phosphate groups and positively charged amino groups was successfully synthesized by modification of amino-functionalized silica particles with trichlorophosphine oxide (POCl₃) for hydrophilic interaction chromatography (HILIC). The composition of the surface grafts was determined by Fourier transform infrared spectroscopy and elemental analysis. Various parameters, such as column temperature, water content, pH values and ionic strength of the mobile phase were investigated to study the retention mechanism. The results demonstrated that the stationary phase involved a complex retention process including surface adsorption, partitioning and electrostatic interactions. Under optimized conditions, the separation of nucleobases and nucleosides, water-soluble vitamins, organic acids on the novel stationary phase could be achieved in the HILIC mode.

     

A New Stationary Phase for Hydrophilic Interaction Chromatography: Polyacrylate-Based Hydrophilic,Monosized-Porous Beads with Zwitterionic Molecular Brushes

Hydrophilic, polyacrylate-based, monosized-porous beads with zwitterionic molecular brushes were synthesized as a new stationary medium for hydrophilic interaction chromatography. Monosized-porous poly(glycerol-1,3-diglycerolate diacrylate-co-glycerol dimethacrylate), poly(GDGDA-co-GDMA), beads 5 μm in size were obtained by a staged-shape template polymerization. As an initiator for surface-initiated atom transfer radical polymerization (SI-ATRP), bromine functionality was obtained on the beads by reacting their hydroxyl groups with 3-(aminopropyl)triethoxysilane and α-bromoisobutyryl bromide, respectively. Zwitterionic molecular brushes on the hydrophilic poly(GDGDA-co-GDMA) beads were generated by SI-ATRP of a sulfobetaine monomer, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (MESH). Poly(MESH)-grafted poly(GDGDA-co-GDMA), poly(MESH)g-poly(GDGDAco-GDMA), beads were slurry packed into the microbore columns with 2 mm i.d. and evaluated as stationary medium for the separation of organic acids, nucleosides and peptides using microbore columns in hydrophilic interaction chromatography with the plate numbers up to 30,000 plates m⁻¹.

     

A New Stationary Phase for Hydrophilic Interaction Chromatography: Polyacrylate-Based Hydrophilic,Monosized-Porous Beads with Zwitterionic Molecular Brushes

Hydrophilic, polyacrylate-based, monosized-porous beads with zwitterionic molecular brushes were synthesized as a new stationary medium for hydrophilic interaction chromatography. Monosized-porous poly(glycerol-1,3-diglycerolate diacrylate-co-glycerol dimethacrylate), poly(GDGDA-co-GDMA), beads 5 μm in size were obtained by a staged-shape template polymerization. As an initiator for surface-initiated atom transfer radical polymerization (SI-ATRP), bromine functionality was obtained on the beads by reacting their hydroxyl groups with 3-(aminopropyl)triethoxysilane and α-bromoisobutyryl bromide, respectively. Zwitterionic molecular brushes on the hydrophilic poly(GDGDA-co-GDMA) beads were generated by SI-ATRP of a sulfobetaine monomer, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (MESH). Poly(MESH)-grafted poly(GDGDA-co-GDMA), poly(MESH)g-poly(GDGDAco-GDMA), beads were slurry packed into the microbore columns with 2 mm i.d. and evaluated as stationary medium for the separation of organic acids, nucleosides and peptides using microbore columns in hydrophilic interaction chromatography with the plate numbers up to 30,000 plates m^?1.     

A Validated Stability-Indicating LC Method for Zonisamide

A simple, isocratic, rapid, and accurate reversed-phase high-performance liquid chromatographic method has been established for quantitative determination of zonisamide. The method is also applicable to determination of related substances in the bulk drug. Chromatographic separation was achieved on a 250 mm × 4.6 mm, 5-μm particle, C₁₈ column; the mobile phase was a 70:30 (v/v) mixture of 0.1% (v/v) aqueous triethylamine, adjusted to pH 2.5 with dilute orthophosphoric acid, and acetonitrile. Chromatographic resolution of zonisamide from its potential impurity, A, was found to be >2. The limits of detection and quantification of zonisamide and impurity A were 0.04 and 0.12 μg mL^?1, respectively, for 20 μL injection volume. Recovery of zonisamide ranged from 98.5 to 101.2% and recovery of impurity A from a sample of zonisamide ranged from 97.4 to 102.7%. The method was validated for linearity, accuracy, precision, and robustness.     

A Validated Stability-Indicating LC Method for Zonisamide

A simple, isocratic, rapid, and accurate reversed-phase high-performance liquid chromatographic method has been established for quantitative determination of zonisamide. The method is also applicable to determination of related substances in the bulk drug. Chromatographic separation was achieved on a 250 mm × 4.6 mm, 5-μm particle, C₁₈ column; the mobile phase was a 70:30 (v/v) mixture of 0.1% (v/v) aqueous triethylamine, adjusted to pH 2.5 with dilute orthophosphoric acid, and acetonitrile. Chromatographic resolution of zonisamide from its potential impurity, A, was found to be >2. The limits of detection and quantification of zonisamide and impurity A were 0.04 and 0.12 μg mL⁻¹, respectively, for 20 μL injection volume. Recovery of zonisamide ranged from 98.5 to 101.2% and recovery of impurity A from a sample of zonisamide ranged from 97.4 to 102.7%. The method was validated for linearity, accuracy, precision, and robustness.

     

A Validated and Stability-Indicating LC Assay Method for Valdecoxib

A gradient reversed-phase liquid chromatographic assay was developed for the quantitative determination of the non-steroidal anti-inflammatory drug valdecoxib. The developed method was also applicable to the determination of related substances in the bulk drug. Forced degradation studies were performed on bulk valdecoxib using acid (2.0 N hydrochloric acid), base (2.0 N sodium hydroxide), oxidation (6.0% v/v hydrogen peroxide), water hydrolysis, heat (60 °C) and photolysis. Mild degradation was observed using alkaline conditions and considerable degradation observed during oxidative stress. Chromatographic separation of process-related impurities and degradation products was achieved using a 5 micron Zorbax SB-CN LC column. The mobile phase consisted of aqueous potassium dihydrogen phosphate (pH 3.0) and acetonitrile. Stressed samples were assayed using the developed LC method and determination of the mass balance accounted for 99.5%, thus indicating the suitability of this stability-indicating method. Linearity, accuracy, precision and robustness have also been evaluated.     

亲水作用色谱/质谱联用方法用于膀胱癌患者血清代谢组学研究

膀胱癌是泌尿系统最常见的恶性肿瘤之一,具有高发病率、高复发率和高进展率的特点.本研究应用69个极性代谢物标样选择合适的分离系统,建立了两性离子亲水作用色谱/质谱联用的代谢组学分析方法.本方法线性范围较宽,检出限低于ng/mL数量级.将本方法用于血清代谢组学分析,85%以上代谢物峰面积的RSD<30%.对64例膀胱癌患者和32例正常人的血清进行代谢组学研究,发现溶血磷脂酰胆碱、游离脂肪酸、氨基酸、胆汁酸、有机酸、核苷等在患病组和正常组中存在显著差异.经筛选和验证,甘磷酸胆碱、胱氨酸、十二碳烯酸、二十碳烯酸和鹅去氧胆酸5种代谢物可以作为区分膀胱癌和正常人的潜在标志物.本研究结果表明,基于亲水作用色谱/质谱联用的代谢组学方法是发现癌症诊断潜在生物标志物的有效手段.     

Electrochemical Determination of Synephrine by Hydrophilic Interaction Liquid Chromatography Using a Zwitterionic Monolith Column

A sensitive method for the electrochemical determination of synephrine (SYN) by hydrophilic interaction liquid chromatography (HILIC) has been developed. Optimal chromatographic separation and high sensitive determination by HILIC with electrochemical detection (HILIC‐ECD) was achieved using a sulfobetaine‐type zwitterionic monolith column (100×1.02 mm, i.d.), a mixture of 10 mM sodium phosphate (pH 4) and acetonitrile (20 : 80, v/v) as mobile phase, and a glassy carbon working electrode which was applied with a potential at +1.0 V vs. Ag/AgCl. The chromatographic peak height of SYN was proportional to the concentration from 5.0 µg/L to 1.0 mg/L (r=0.999). The detection limit of SYN (S/N=3) was 3.7 pg on the column. Moreover, the present HILIC‐ECD could be applied to the accurate and precise determination of SYN in Aurantii nobilis Pericarpium. In conclusion, we have demonstrated that an ECD is one of useful detection methods applicable to HILIC.     

A Validated,Stability-Indicating HPTLC Method for Analysis of Doxofylline

JPC – Journal of Planar Chromatography – Modern TLC - A simple, sensitive, selective, precise, and stability-indicating high-performance thin-layer chromatographic method for analysis...     

Titania-Based Adsorbents for Hydrophilic Interaction Liquid Chromatography

Journal of Analytical Chemistry - Stationary phases based on titania are obtained by the adsorptive attachment of polyethyleneimine followed by crosslinking with 1,4-butanediol diglycidyl ether....     

Determination of N-Glycopeptides by Hydrophilic Interaction Liquid Chromatography and Porous Graphitized Carbon Chromatography with Mass Spectrometry Detection

An offline two-dimensional chromatographic method based on the combination of hydrophilic interaction liquid chromatography (HILIC) and porous graphitized carbon (PGC) chromatography was developed for the separation and purification of glycopeptides. The high selectivity of HILIC and PGC isolated high-purity isomers of N-glycopeptides from ribonuclease B. N-Glycopeptides were first separated from nonglycosylated peptides, and N-glycopeptides were sorted into fractions through the first-dimensional HILIC according to their monosaccharides. Further separation of the glycopeptide isomers in each fraction was achieved using second-dimensional PGC. Structural differences of the glycopeptide isomers were further enzymatically hydrolyzed with peptide-N-glycosidase F. The glycan structure were elucidated by matrix assisted laser desorption ionization tandem quadrupole time-of-flight mass spectrometry. The established procedure allows the isolation of glycopeptide or glycan standards from natural sources.     

Development of a Validated Stability-Indicating LC Method for Nitazoxanide in Pharmaceutical Formulations

A reversed-phase liquid chromatographic (LC) method was developed for the assay of nitazoxanide (NTZ) in solid dosage formulations. An isocratic LC separation was performed on a Phenomenex Synergi Fusion C₁₈ column (250 mm × 4.6 mm, i.d., 4 μm particle size) using a mobile phase of 0.1% o-phosphoric acid solution, pH 6.0: acetonitrile (45:55, v/v) at a flow rate of 1.0 mL min⁻¹. Detection was achieved with a photodiode array detector at 240 nm. The detector response for NTZ was linear over the concentration range from 2 to 100 μg mL⁻¹ (r = 0.9999). The specificity and stability-indicating capability of the method were proved using stress conditions. The RSD values for intra-day precision were less than 1.0% for tablets and powder for oral suspension. The RSD values for inter-day precision were 0.6 and 0.7% for tablets and powder for oral suspension. The accuracy was 100.4% (RSD = 1.8%) for tablets and 100.9% (RSD = 0.3%) for powder for oral suspension. The limits of quantitation and detection were 0.4 and 0.1 μg mL⁻¹. There was no interference of the excipients on the determination of the active pharmaceutical ingredient. The proposed method was precise, accurate, specific, and sensitive. It can be applied to the quantitative determination of drug in tablets and powder for oral suspension.     

Validated Stability-Indicating Chromatographic Method for the Assay of Erlotinib Active Pharmaceutical Ingredient

Abstract

A simple stability-indicating high-performance liquid-chromatographic (HPLC) method for the assay of erlotinib in the presence of its degradation products was developed on a C18 column using a mobile phase of 0.01 M ammonium formate–acetonitrile–containing formic acid with a flow rate of 1.0 mL min^?1. The method was validated. Selectivity was validated by subjecting the stock solution of erlotinib to acidic, basic, photolysis, oxidative, and thermal degradation. The linearity range and values for limits of detection (LOD) and quantification (LOQ) were found to be 1–198, 0.33, and 1.1 µg mL^?1, respectively. The analysis of the tablets containing erlotinib was quite precise (relative standard deviation <1%).     

Analysis of Morpholinium Ionic Liquid Cations by Hydrophilic Interaction Columns Coupled with Indirect UV Detection

A method was developed for the separation and detection of morpholinium ionic liquid cations by hydrophilic interaction column combined with indirect ultraviolet detection using imidazolium ionic liquids as ultraviolet absorbents in high‐performance liquid chromatography. The effects of the ultraviolet absorbents, organic solvents, and the pH value of the aqueous solution in the mobile phase for the determination of morpholinium cations were investigated by using a hydrophilic column with carbamoyl group as the analytical column. The retention and detection behavior of morpholinium cations was discussed. The suitable chromatographic conditions were 0.8 mmol/L 1‐ethyl‐3‐methyl‐imidazolium tetrafluoroborate aqueous solution (pH 3.5 adjusted with acetic acid)/acetonitrile (45/55, v/v) as the mobile phase and a detection wavelength of 210 nm. Under these conditions, the baseline separation of N‐methyl‐N‐ethyl‐morpholinium cation ([MEMo]⁺) and N‐methyl‐N‐propyl‐morpholinium cation ([MPMo]⁺) was successfully achieved in 15 min. The detection limits of [MEMo]⁺ and [MPMo]⁺ were 0.595 and 0.531 mg/L, respectively. Relative standard deviations were less than 0.2%. This method has been successfully applied to the analysis of morpholinium ionic liquid samples synthesized in chemical laboratories, which is simple, reliable, and practical.     

Tetrazole-Functionalized Silica for Hydrophilic Interaction Chromatography of Polar Solutes

In this work, tetrazole-functionalized stationary phase was prepared with nitrile-modified silica by an ammonium-catalyzed (3 + 2) azide-nitrile cycloaddition reaction. The prepared stationary phase was used for separation of nucleobases and nucleosides by hydrophilic interaction chromatography (HILIC) mode. A typical HILIC mechanism was observed at higher content of acetonitrile (>85%, v/v) in the mobile phase. The retention mechanism of the column was investigated by the models used for describing partitioning and surface adsorption through adjustment ratio of water in the mobile phase, and by the influence of salt concentration, buffer pH, and temperature on the retention of solutes. The results illustrated that the surface adsorption through hydrogen bonding dominated the retention behavior of nucleobases/nucleosides under HILIC mode. From the separation ability, the tetrazole-functionalized stationary phase could become a valuable alternative for the separation of the compounds concerned.     

亲水作用色谱填料的研究进展

亲水作用色谱是一种新型的色谱分离模式.此类色谱模式集反相色谱的经济廉价与正相色谱的优点于一体,有效补充了反相色谱的不足.简单介绍实验室中合成的新型亲水色谱固定相.