Bonded Silica Gel Column Research Articles

Rapid Analysis of Eight Kinds of Catechins in Green Tea Beverage Using an Isocratic Elution Method by HPLC-UV on a Triacontyl Bonded Silica Gel Column

Rapid Analysis of Eight Kinds of Catechins in Green Tea Beverage Using an Isocratic Elution Method by HPLC-UV on a Triacontyl Bonded Silica Gel Column

Synthesis of polyethylene glycol functional bonded silica gel for selective recognition and separation of α-cyclodextrin

In this work, we for the first time synthesized the polyethylene glycol (PEG) bonded silica gel via KH-560 as a silane coupling reagent for column chromatography by a solid/liquid surface continuous reaction method. The molecular interaction, structure, morphology, and thermostability was characterized by fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), scanning electronic microscope (SEM) and thermogravimetric analysis (TGA). Given that PEG is capable to self-assemble with α-CD, the PEG bonded silica gel was used as packing of column chromatography to achieve the selective separation of α-cyclodextrin (α-CD) at room temperature and atmospheric pressure. The bonded silica gel column could realize the effective separation of α-CD in the enzymatic hydrolysis mixture, which provides support for industrial separation of α-CD.

Simultaneous determination of febrifugine and isofebrifugine in Dichroa febrifuga root by HPLC method

To develop the HPLC method for simultaneous determination of febrifugine and isofebrifugine in Dichroa febrifuga root, and on the basis of this, the feasibility of quantitative analysis of multi-component by a single-marker (QAMS) model for the determination of the two alkaloids was investigated. The chromatographic separation was performed on an octadecyl bonded silica gel column with mixed solvent consisting of acetonitrile-water-glacial acetic acid-triethylamine (9∶91∶0.36∶0.745) as mobile phase at a flow rate of 1.0 mL•min⁻¹. The detection wavelength was set at 225 nm, and the column temperature was set at 30 ℃. The linear range of febrifugine and isofebrifugine were 10.7-426 ng and 10.6-424 ng, respectively. Their average recovery were 98.33% (RSD 2.7%) and 100.4% (RSD 1.8%), respectively. On the basis of this established method, febrifugine was used as the internal reference substance to calculate the relative correction factors (RCF) and the relative retention values (RRV) of isofebrifugine to febrifugine. Through a series of methodology evaluations, the two alkaloids were simultaneously assayed only by quantitative determination of febrifugine. This result played the part of demonstration role for the application of QAMS model in the determination of isomers.

Regioisomeric separation of ring-substituted cathinones by liquid chromatography–mass spectrometry with a naphthylethyl column

Recently, various new psychoactive substances (NPSs) have been detected as components of “legal high” products. Synthetic cathinones are one of the most popular classes of NPSs, and are structurally related to the stimulants amphetamine and methamphetamine. In this study, we investigated the differentiation of 2-, 3-, and 4-ring-substituted regioisomers for ethylmethcathinones, fluoromethcathinones, ethylethcathinones and fluoroethcathinones by liquid chromatography–mass spectrometry (/mass spectrometry). At the first step, it was difficult to differentiate the regioisomers by product ion spectra for each cathinone group. Therefore, we had to differentiate them by retention times. Under all tested conditions, the 3- and 4-ring-substituted cathinones were not separated by a conventional octadecylsilyl bonded silica gel column, but complete chromatographic separation of all regioisomers was achieved under optimized conditions using a column with a naphthylethyl-bonded stationary phase. Using these conditions, an authentic “legal high” product containing a fluoromethcathinone was analyzed, and the active ingredient was 4-fluoromethcathinone clearly differentiated from 2- and 3-fluoromethcathinone. The proposed method enables the separation of regioisomeric ring-substituted cathinones without the need for pretreatment steps, such as derivatization or purification. To our knowledge, this is the first trial to use the naphthylethyl-bonded column to separate ring-substituted cathinone regioisomers completely. This column seems to have potential to be successfully used for separation of other types of compounds with ring-substituted regioisomer structures.

アミノプロピルカラムを用いるHPLCによる緑茶飲料中のL-テアニンの定量

アミノプロピルカラムを用いるHPLCによる緑茶飲料中のL-テアニンの定量

Selective speciation of inorganic antimony on tetraethylenepentamine bonded silica gel column and its determination by graphite furnace atomic absorption spectrometry

A speciation system for antimony (III) and antimony (V) ions that based on solid phase extraction on tetraethylenepentamine bonded silica gel has been established. Antimony was determined by graphite furnace atomic absorption spectrometry (GF-AAS). Analytical conditions including pH, sample volume, etc., were studied for the quantitative recoveries of Sb (III) and Sb (V). Matrix effects on the recovery were also investigated. The recovery values and detection limit for antimony (III) at optimal conditions were found as >95% and 0.020μgL−1, respectively. Preconcentration factor was calculated as 50. The capacity of adsorption for the tetraethylenepentamine bonded silica gel was 7.9mgg−1. The validation was checked by analysis of NIST SRM 1573a Tomato laves and GBW 07605 Tea certified reference materials. The procedure was successfully applied to speciation of antimony in tap water, mineral water and spring water samples. Total antimony was determined in refined salt, unrefined salt, black tea, rice, tuna fish and soil samples after microwave digestion and presented enrichment method combination.

Development and validation of a chromatographic method for determining Clematichinenoside AR and related impurities

BackgroundClematichinenoside AR is a promising lead compound for the treatment of rheumatoid arthritis. A systematic research for the related impurities in AR bulk samples is still lacking. For the safe use of this natural product in future clinical practice, the structure and content of each constituent, including the main ingredient as well as the impurities in AR bulk sample must be characterized in detail.ResultsA simple and stability indicating RP-HPLC method was developed and validated for determining the purity of clematichinenoside AR (AR), a natural product from the roots of Clematis manshurica Rupr. (Ranunculaceae) with the potential of treating rheumatoid arthritis. Five impurities were characterized, and impurity 2 (Clematomandshurica saponin F) is a new triterpenoid saponin isolated from this product. Optimum separation for clematichinenoside AR and five related impurities was carried out on an Agilent octadecylsilane bonded silica gel column (TC-C18, 4.6 mm ×150 mm, 5 μm) using a gradient HPLC method. The validation results showed good sensitivity, specificity, linearity(r2>0.9992) precision(RSD<1.63%), accuracy(recoveries in the range of 95.60%-104.76%) and robustness. Three AR bulk samples containing all the impurities were examined by two methods, and the stability of correction factors for the determination of related impurities was discussed. The proposed stability-indicating method was suitable for the quality control of this natural product.ConclusionFive related impurities of clematichinenoside AR were characterized, including a new triterpenoid saponins firstly found in clematichinenoside AR bulk samples. In the simple chromatographic method for determining clematichinenoside AR and its related impurities in bulk samples, the correction factor was better for the quality control in the relative stable concentrations.

Characterization of sodium laureth sulfate by reversed-phase liquid chromatography with evaporative light scattering detection and 1H nuclear magnetic resonance spectroscopy

A direct and effective method utilizing reversed-phase liquid chromatography combined with evaporative light scattering detection was developed to determine the relative ratio of different alkyl chain lengths, to quantify the average ethylene oxide (EO) level and to identify EO distribution in the presence of sodium laureth sulfates. A C8 bonded silica gel column and an acetonitrile–water gradient mobile phase containing ammonium acetate were used as the best stationary and mobile phase, respectively. The results were confirmed by nuclear magnetic resonance spectroscopy. The detection limit was 80 μg/mL and the calibration curve, i.e., the log–log plots (peak area vs. concentration), was linear in the working range of 80–4200 μg/mL with R 2 values of above 0.999 (in the case of 3 mol sodium laureth sulfates). Furthermore, the application of the chromatographic method to a commercial product without pretreatment was presented. The raw material was identified by fast atom bombardment mass spectrometry.

Ionic strength, pH and temperature effects upon selectivity for transition and heavy metal ions when using chelation ion chromatography with an iminodiacetic acid bonded silica gel column and simple inorganic eluents

An investigation into the selectivity of an iminodiacetic acid (IDA) modified silica gel column for transition and heavy metal ions using non-chelating inorganic eluents has been carried out. A number of eluent parameters were investigated to determine the exact retention mechanism taking place and to control selectivity. The parameters studied were eluent ionic strength and the nature of the inorganic salt used, eluent pH and eluent temperature. The results obtained showed how despite certain metal ions exhibiting similar stability constants with the bonded IDA groups, careful control of each of the above parameters, in particular eluent chloride ion concentration and eluent temperature, could result in large changes in selectivity. Optimal conditions for the isocratic and gradient separation of Mg(II), Ca(II), Mn(II), Cd(II), Co(II), Zn(II) and Pb(II) were determined. An isocratic method using a 0.035 M KCl, 0.065 M KNO 3 (pH 2.5) eluent was successfully applied to the determination of Mn(II), Cd(II), Co(II) and Zn(II) at concentrations between 20 and 121 μg/l in a freshwater certified reference material (NIST 1640).

Reversed-phase HPLC separation of proteins on chemically bonded silica gel columns.

Reversed-phase high-performance liquid chromatographic (RP-HPLC) separation of proteins on chemically bonded silica gel columns is described. Efficiency of nonporous alkylsilyl bonded silica gel is compared with that of a macroporous gel that has been widely used for the purpose. A comparative study of the separation under conventional and fast separation conditions is also given. The fast separation technique on the nonporous reversed-phase column has the advantage of improving the recovery of late-eluting hydrophobic and large proteins, such as ovalbumin and apoferritin.

Functional Monomers and Polymers CLXXVIII. Specific Interaction of Nucleic Acid Analogs in HPLC System

Selective separation of oligoethyleneimine derivatives having pendant adenine or thymine bases was found in high performance liquid chromatography (HPLC) using nucleic acid base, such as thymine or adenine, bonded silica gel columns. The separation behavior of the oligomers was concluded to be caused by the specific interaction between the oligomers and the nucleic acid base on silica gel.

High-performance liquid chromatography separations of nitrosamines : III. Conformers of N-nitrosamino acids

The separation of a selected group of N-nitrosamino acids and their syn and anti conformers by high-performance liquid chromatography using an α-cyclodextrin bonded silica gel column and a mobile phase of acetonitrile—triethylammonium acetate was achieved. The effects of mobile phase pH and concentration of acetonitrile on resolution and elution times are also reported.

Automatic Determination of Clomipramine, Imipramine and Their Demethylated Metabolites in Plasma by High Performance Liquid Chromatography

Abstract Determination of tricyclic antidepressant drugs (clomipramine, imipramine and their demethylated metabolites) in plasma can be carried out by extraction on a precolumn (n-octyl bonded silica gel) and washing with phosphate buffer (0.005 M, pH = 11.5). The elution is carried out on-line (with back-flush) on an alkylnitrile bonded silica gel column with the mobile phase: acetonitrile-methanolphosphate buffer 0.005 M, pH = 7.2, 50: 25: 30 (v/v). The AASP (Advanced Automated Sample Processor) allows full automatization for this determination. The total analysis time is only 10 minutes. The obtained reproducibility is 5.6% for clomipramine and 4% for demethylclomipramine while the detection limit (10 μL−1) is lower than the therapeutic concentrations of these antidepressants (and metabolites) in plasma. The correlation with the classical (but tedious) method involving liquid-liquid extraction is excellent.

The Determination of Aspartame in Diet Soft Drinks by High Performance Liquid Chromatography

Abstract A simple procedure for the qualitative and quantitative determination of aspartame (Nutrasweet) in diet soft drinks is described. A high performance liquid chromatography method is used which requires a 250 × 4.6 mm β-cyclodextrin bonded silica gel column and a mobile phase of methanol/1% triethyl ammonium acetate (pH 4.5). The effluent was monitored at 214 nm. The method was applied for the analysis of aspartame in diet Coke, diet Pepsi, diet 7-Up and the sweetner Equal. Determination of sodium benzoate caramel coloring and caffeine is also possible by this procedure.

Quantitative analysis of tertiary and quaternary alkaloids in Corydalis Tuber by ion-pair high-performance liquid chromatography and its application to an oriental pharmaceutical preparation.

A new, simple and precise method using ion-pair high-performance liquid chromatography was developed for the determination of alkaloids in Corydalis Tuber and Anchusan-to dry extract, i.e., tetrahydrocolumbamine, glaucine, tetrahydropalmatine, corydaline, columbamine, coptisine, palmatine, berberine and dehydrocorydaline. Reversed-phase systems with an octadecylsilane chemically bonded silica gel column using a mixture of sodium dodecyl sulfate, 0.05M tartaric acid and acetonitrile (0.5 : 62 : 38) and a mixture of sodium dodecyl sulfate, Britton-Robinson buffer (pH 3.0) and acetonitrile (0.5 : 56 : 34) as the mobile phases were suitable for the separation of tertiary alkaloids and quaternary alkaloids, respectively, in Corydalis Tuber.

Determination of Gentamicin Sulf ate C1a, C2, and C1 Components by Ion Pair Liquid Chromatography with Electrochemical Detection

Abstract The 3 major components of gentamicin sulfate (C1a, C2, and C1) were separated by a liquid chromatographic method using a reverse phase C18 bonded silica gel column and an aqueous ion pair solvent system consisting of 0.015M pentanesulfonic acid sodium salt, 0.2M sodium sulfate, and 0.1% acetic acid. Individual C components as well as several unknown minor constituents were detected by an electrochemical flow cell with a glassy carbon working electrode set at a potential of +1.3 ± 0.1 V vs Ag/Agd. The analytical response was linear over a concentration range of 16-30 μg. A plot of peak areas vs concentration of C fractions yielded a correlation coefficient of 0.999 or better for the Cla, C2, and C1 components of gentamicin sulfate.

A simultaneous determination of norephedrine, pseudoephedrine, ephedrine and methylephedrine in Ephedrae Herba and oriental pharmaceutical preparations by ion-pair high-performance liquid chromatography.

A new, simple and rapid analytical method using ion-pair high-performance liquid chromatography was developed for simultaneous determination of norephedrine, pseudoephedrine, ephedrine and methylephedrine in Ephedrae Herba and oriental pharmaceutical preparations. A reversed-phase system consisting of an ODS chemically bonded silica gel column and a mixture of water, acetonitrile, sodium dodecyl sulfate and phosphoric acid (65 : 35 : 0.5 : 0.1) as the mobile phase was used. The four components extracted with the mobile phase could be completely separated within 15 min. The detection limits for the four components were 20 ng at a signal-to-noise ratio of 3 : 1.

Reversed-phase liquid chromatographic resolution of underivatized d,l-amino acids using chiral eluents

Resolution of underivatized amino acid enantiomers by reversed-phase liquid chromatography is described using chiral eluents containing the copper(II) complexes of the chiral chelates N-( p-toluenesulfonyl)- l-phenylalanine and N-( p-toluenesulfonyl)- d-phenylglycine. Resolution of the enantiomers of neutral, basic and acidic amino acids and their amides was accomplished on a octadecylsilyl bonded silica gel column. A chromatographic model is proposed that is based on dynamic ligand-exchange mechanism of d,l-amino acid with tosylated amino acid-copper(II) complex on the chemically bonded phase.

Quantitation of Daunorubicin, Doxorubicin, and Their Aglycones by Ion-pair Reversed-Phase Chromatography

A fast and sensitive high-pressure liquid chromatographic method was developed for the quantitation of doxorubicin, daunorubicin, and their aglycones in pharmaceutical preparations. Because its higher pH extends column life while permitting determination of impurities, this system represents an improvement over previously published methods. It utilizes a C18 bonded silica gel column and a solvent system consisting of methanol-0.01 M monobasic ammonium phosphate aqueous solution (65:35) at pH 4.0 and 1600 psi of pressure. The accuracy of the doxorubicin and daunorubicin determinations, expressed as the coefficient of variation, is 1.65 and 1.27%, respectively. The aglycones can be determined with a precision of <1.3%.

Separation of urushiol by high-performance liquid chromatography on an 8% octadecylsilane chemically bonded silica gel column with electrochemical detection : Analysis of urushiol in the sap of lac trees ( Rhus vernicifera) and that in the japanese lac-making process

Urushiol, a major component of a sap of lac trees ( Rhus vernicifera), is resolved into four components due to differences in the degree of unsaturation by high-performance liquid chromatography on Hitachi 3053 gel (an 8% octadecylsilane chemically bonded silica gel), using 1% lithium perchlorate in acetonitrile-water (7:3) as eluent and electrochemical detection. This method was applied to the analysis of the urushiol components of two samples of sap and in the lac-making process.