阀切换-离子色谱法测定分析纯硫酸钠中痕量氯离子

建立了阀切换-离子色谱法测定分析纯硫酸钠固体中痕量氯离子含量的方法。ICS-2100离子色谱系统,配置十通阀,用IonPac AS18色谱柱将硫酸钠固体样品中的氯离子和硫酸根离子预分离后,以IonPac TAC-ULP1为富集柱,将氯离子富集后在相同的IonPac AS18色谱柱上进行定量分析。同时以淋洗液发生器产生的不同浓度的KOH作为淋洗液,以抑制型电导检测器测定氯离子的含量。结果表明,阀切换-离子色谱法测定分析纯硫酸钠固体中的痕量氯离子,检出限为10 μg/L,线性相关系数(r2)大于0.999,实际样品的加标回收率为98.0%～103.0%,具有分离度和灵敏度高,选择性好,操作简单等特点。该方法能够准确测定硫酸钠固体中痕量氯离子的含量,适用于高纯化学试剂中痕量氯离子的分离测定。     

Analysis of streptokinase by validated liquid chromatography methods and correlation with an in vitro bioassay

Reversed‐phase and size‐exclusion liquid chromatography methods were validated for the assessment of streptokinase. The reversed‐phase method was carried out on a Jupiter C₄ column (250 mm × 4.6 mm id) maintained at 25°C. The mobile phase consisted of 50 mM sodium sulfate solution pH 7.0 and methanol (90:10, v/v), run isocratically at a flow rate of 0.8 mL/min. The size‐exclusion method was carried out on a Protein KW 802.5 column (300 mm × 8.0 mm id), at 25°C. The mobile phase consisted of 40 mM sodium acetate solution pH 7.0, run isocratically at a flow rate of 1.0 mL/min. Retention times were 19.3 min, and 14.1 min, and calibration curves were linear over the concentration range of 0.25–250 μg/mL (25.75–25 750 IU/mL) (r ² = 0.9997) and 5–80 μg/mL (515–8240 IU/mL) (r ² = 0.9996), respectively, for reversed‐phase and size exclusion, with detection at 220 and 204 nm. Chromatographic methods were employed in conjunction with the in vitro bioassay for the content/potency assessment of Streptokinase, contributing to improve the quality control and ensure the efficacy of the biotherapeutic.     

Binding of low molecular mass compounds to proteins studied by liquid chromatographic techniques

The newest achievements in the application of miscellaneous liquid chromatographic techniques such as size-exclusion, ion-exchange and reversed-phase high-performance liquid chromatography, and thin-layer chromatography for the elucidation of the various aspects of the binding of ligands to proteins are compiled and briefly discussed. Examples of employment in pharmaceutical and clinical chemistry, drug design, enzyme kinetic studies and environmental protection are presented.     

Flow-injection in-line complexation for ion-pair reversed phase high performance liquid chromatography of some metal-4-(2-pyridylazo) resorcinol chelates

Flow injection (FI) was coupled to ion-pair reversed phase high performance liquid chromatography (IP-RPHPLC) for the simultaneous analysis of some metal-4-(2-pyridylazo) resorcinol (PAR) chelates. A simple reverse flow injection (rFI) set-up was used for in-line complexation of metal-PAR chelates prior to their separation by IP-RPHPLC. The rFI conditions were: injection volume of PAR 85 μL, flow rate of metal stream 4.5 mL min⁻¹, concentration of PAR 1.8 × 10⁻⁴ mol L⁻¹ and the mixing coil length of 150 cm. IP-RPHPLC was carried out using a C₁₈ μBondapak column with the mobile phase containing 37% acetonitrile, 3.0 mmol L⁻¹ acetate buffer pH 6.0 and 6.2 mmol L⁻¹ tetrabutylammonium bromide (TBABr) at a flow rate of 1.0 mL min⁻¹ and visible detection at 530 and 440 nm. The analysis cycle including in-line complexation and separation by IP-RPHPLC was 16 min, which able to separate Cr(VI) and the PAR chelates of Co(II), Ni(II) and Cu(II).     

High performance liquid chromatography for the determination of glucosamine sulfate in human plasma after derivatization with 9-fluorenylmethyl chloroformate

In this study, we developed a simple, rapid, sensitive, and reliable method for the determination of glucosamine sulfate in human plasma, which was based on derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) followed by reverse-phase HPLC-FLD. For the first time, FMOC-Cl was introduced into derivatization of glucosamine sulfate in human plasma. The amino groups of glucosamine sulfate and vertilmicin sulfate (the internal standard) were trapped with FMOC-Cl to form glucosamine-FMOC-Cl and vertilmicin-FMOC-Cl adducts, which can be very suitable for HPLC-FLD. Precipitation of plasma proteins by acetonitrile was followed by vortex mixing and centrifugation. Chromatographic separation was performed on a C18 column (DIAMONSIL 150 x 4 mm id, 5 microm) with a mobile phase gradient consisting of acetonitrile and water at a flow-rate of 1 mL/min. The retention times of glucosamine-FMOC-Cl and vertilmicin-FMOC-Cl adducts were 8.9 and 21.2 min, respectively. This method was shown to be selective and sensitive for glucosamine sulfate. The limit of detection was 15 ng/mL for glucosamine sulfate in plasma and the linear range was 0.1-10 mg/mL in plasma with a correlation coefficient (r) of 0.9999. The relative standard deviations (RSDs) of intra-day and inter-day assays were 5.2-8.1% and 6.1- 8.5%, respectively. Extraction recoveries of glucosamine sulfate in plasma were greater than 90%. The validated method was successfully applied to the determination of glucosamine sulfate in human plasma samples.     

Quantitative determination of p-aminosalicylic acid and its degradation product m-aminophenol in pellets by ion-pair high-performance liquid chromatography applying the monolithic Chromolith Speedrod RP-18e column

An ion-pair high performance liquid chromatographic method was developed for the simultaneous determination of p-aminosalicylic acid (PAS) and its degradation product m-aminophenol (MAP) in a newly developed multiparticular drug delivery system. Owing to the concentration differences of PAS and MAP, acetanilide and sulfanilic acid were used as internal standards, respectively. The separation was performed on a Chromolith SpeedROD RP-18e column, a new packing material consisting of monolithic rods of highly porous silica. The mobile phase composition was of 20 mm phosphate buffer, 20 mm tetrabutylammonium hydrogen sulphate and 16% (v/v) methanol adjusted to pH 6.8, at a flow-rate of 1.0 mL/min, resulting in a run-time of about 6 min. Detection was by UV at 233 nm. The method was validated and proved to be useful for stability testing of the new dosage form. Separation efficiency was compared between the new packing material Chromolith SpeedROD RP-18e and the conventional reversed-phase cartridge LiChroCART 125-4 (5 microm). A robustness test was carried out on both columns and different separation parameters (retention, resolution, run time, temperature) were determined.     

Isolation and purification of recombinant human plasminogen Kringle 5 by liquid chromatography and ammonium sulfate salting‐out

In this work, a novel method was established to isolate and purify Human plasminogen Kringle 5 (HPK5) as a histidine‐tagged fusion protein expressed in Escherichia coli BL21 (DE3). This method consisted of sample extraction using a Ni‐chelated Sepharose Fast‐Flow affinity column, ammonium sulfate salting‐out and Sephadex G‐75 size‐exclusion column in turn. The purity analysis by SDS–PAGE, high‐performance size‐exclusion and reversed‐phase chromatographies showed that the obtained recombinant fusion HPK5 was homogeneous and its purity was higher than 96%; the activity analysis by chorioallantoic membrane model of chicken embryos revealed that the purified recombinant HPK5 exhibited an obvious anti‐angiogenic activity under the effective range of 5.0–25.0 µg/mL. Through this procedure, about 19 mg purified recombinant fusion HPK5 can be obtained from 1 L of original fermentation solution. Approximate 32% of the total recombinant fusion HPK5 can be captured and the total yield was approximately 11%. Copyright © 2013 John Wiley & Sons, Ltd.     

Adsorption of the anionic surfactant sodium dodecyl sulfate on a C18 column under micellar and high submicellar conditions in reversed‐phase liquid chromatography

Micellar liquid chromatography makes use of aqueous solutions or aqueous‐organic solutions containing a surfactant, at a concentration above its critical micelle concentration. In the mobile phase, the surfactant monomers aggregate to form micelles, whereas on the surface of the nonpolar alkyl‐bonded stationary phases they are significantly adsorbed. If the mobile phase contains a high concentration of organic solvent, micelles break down, and the amount of surfactant adsorbed on the stationary phase is reduced, giving rise to another chromatographic mode named high submicellar liquid chromatography. The presence of a thinner coating of surfactant enhances the selectivity and peak shape, especially for basic compounds. However, the risk of full desorption of surfactant is the main limitation in the high submicellar mode. This study examines the adsorption of the anionic surfactant sodium dodecyl sulfate under micellar and high submicellar conditions on a C₁₈ column, applying two methods. One of them uses a refractive index detector to obtain direct measurements of the adsorbed amount of sodium dodecyl sulfate, whereas the second method is based on the retention and peak shape for a set of cationic basic compounds that indirectly reveal the presence of adsorbed monomers of surfactant on the stationary phase.     

Characterization and quantification of triacylglycerols in peanut oil by off‐line comprehensive two‐dimensional liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry

The complexity of natural triacylglycerols (TAGs) in various edible oils is prodigious due to the hundreds of set is of TAG compositions, which makes the identification of TAGs quite difficult. In this investigation, the off‐line 2D system coupling of nonaqueous RP and silver‐ion HPLC with atmospheric pressure chemical ionization MS detection has been applied to the identification and quantification of TAGs in peanut oil. The method was successful in the separation of a high number of TAG solutes, and the TAG structures were evaluated by analyzing their atmospheric pressure chemical ionization mass spectra information. HPLC and MS conditions have been optimized and the fragmentation mechanisms of isomers have been validated. In addition, an internal standard approach has been developed for TAG quantification. Then this system was applied in peanut oil samples and there was a total of 48 TAGs including regioisomers that have been determined and quantified.     

Optimization of ion-pair based hollow fiber liquid phase microextraction combined with HPLC-UV for the determination of methimazole in biological samples and animal feed

Ion-pair based hollow fiber liquid phase microextraction (IP-HFLPME) coupled with high performance liquid chromatography-ultraviolet detection was applied for the preconcentration and determination of methimazole in biological samples and animal feed. Optimization of the conditions for the high extraction efficiency was studied simultaneously using the experimental design. For the first step, the Plackett-Burman design was applied to screen the significant factors on the extraction efficiency. Central composite design (CCD) was then used for the optimization of important factors and the response surface equations were obtained. The optimum experimental conditions were donor phase pH, 12.2; extraction temperature, 45°C; extraction time, 50 min; sodium perchlorate concentration, 1.5 M; cetyltrimethylammonium bromide concentration, 0.65 mM, and without salt addition in donor phase. The limit of detection and the dynamic linear range were in the range of 0.1-0.7 μg L(-1) and 0.5-1000 μg L(-1) , respectively. Preconcentration factors were obtained in the range of 93-155 in different matrices. Finally, the performance of the proposed method was tested for the determination of trace amounts of methimazole in plasma, urine, bovine milk, and animal feed samples, and satisfactory results were obtained (RSDs < 7.1%).     

An environmentally friendly sodium dodecyl sulfate‐synergistic microwave‐assisted extraction followed by ultra‐high‐performance liquid chromatography with photodiode array method for the simultaneous extraction and determination of iridoids,phenylpropanoids, and lignans from Eucommiae Cortex

A simple and green sodium dodecyl sulfate‐synergistic microwave‐assisted extraction method was developed to extract and determine the iridoids, phenylpropanoids, and lignans in Eucommiae Cortex followed by ultra‐high‐performance liquid chromatography with photodiode array detection. The biodegradable solution (sodium dodecyl sulfate) was used as a promising alternative to organic solvents. The response surface methodology provided the optimum extraction conditions (2 mg/mL sodium dodecyl sulfate, 1100 W microwave power, and 6 min extraction time). The recoveries of three types of components ranged from 95.0 to 105% (RSDs < 5%). The intra‐ and inter‐day precision and accuracy were less than 3.40% and within the range of 97.1‐105%, respectively. Compared with other extraction methods, this newly established method was more efficient and environmental friendly. The results demonstrated that sodium dodecyl sulfate‐synergistic microwave‐assisted extraction followed by ultra‐high‐performance liquid chromatography with photodiode array method was applicable for the simultaneous extraction and determination of these three types of compounds for quality evaluation of Eucommiae Cortex.     

缓冲盐类型和离子对试剂非对离子对强离解酸性化合物离子对反相液相色谱保留行为的影响

在离子对反相液相色谱(IP-RPLC)分析中,溶质保留受对离子(counter ion)的影响比较受人关注,但鲜有研究流动相中缓冲盐类型和离子对试剂中非对离子(non-counter ion)对溶质保留行为的影响.鉴于此,该文以14种磺酸化合物为研究对象,甲醇为有机调节剂,分别考察了3种缓冲盐体系(磷酸二氢铵、氯化铵和...     

Use of 2-mercaptopyridine for the determination of alkylating agents in complex matrices: application to dimethyl sulfate

A rapid and sensitive method for the determination of alkylating agents in complex reaction mixtures was developed and characterized. Analyses are based on the alkylation of 2-mercaptopyridine by the analyte; the derivative is separated by RP-HPLC and measured by fluorescence detection. When applied to the determination of dimethyl sulfate, the method is linear over four orders of magnitude: 0.01-10 μg mL⁻¹. By using recrystallized 2-mercaptopyridine, quantitation limits of 10 ng mL⁻¹ can be achieved. Precision of the assay is 2% R.S.D. in the 1-10 μg mL⁻¹ range and about 15% R.S.D. at 10 ng mL⁻¹. Studies on the pH dependence of the derivatization reaction were key to minimizing interference from the dimethyl sulfate degradation product, monomethyl sulfate, in quenched reaction samples.     

Sheath liquid interface for the coupling of normal-phase liquid chromatography with electrospray mass spectrometry and its application to the analysis of neoflavonoids

A novel interface that allows normal-phase liquid chromatography to be coupled with electrospray ionization (ESI) is reported. A make-up solution of 60 mM ammonium acetate in methanol, infused at a 5 microl min(-1) flow-rate at the tip of the electrospray probe, provides a sheath liquid which is poorly miscible with the chromatographic effluent, but promotes efficient ionization of the targeted analytes. Protonated molecules generated in the ESI source were subjected to tandem mass spectrometric experiments in a triple-quadrupole mass spectrometer. The main fragmentation reactions were characterized for each analyte and specific mass spectral transitions were used to acquire chromatographic data in the multiple reaction monitoring detection mode. Results obtained during optimization of the sheath liquid composition and flow-rate suggest that the electrospray process was mainly under the control of the make-up solution, and that it forms an external charged layer around a neutral chromatographic mobile phase core. This sheath liquid interface was implemented for the analysis of some neoflavonoid compounds and its performance was evaluated. Limits of detection were established for calophillolide, inophyllum B, inophyllum P and inophyllum C at 100, 25, 15 and 100 ng ml(-1), respectively.     

Determination of the novel antiarrhythmic drug sulcardine sulfate in human plasma by liquid chromatography tandem mass spectrometry and its application in a clinical pharmacokinetic study

Sulcardine sulfate (Sul), a novel antiarrhythmic agent, is currently in phase I and phase II clinical trials. To elucidate its clinical pharmacokinetic characteristics, a rapid and accurate liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed and validated for the quantification of Sul in human plasma. Plasma samples were precipitated by acetonitrile and isotope‐labeled sulcardine was added as internal standard. The analysis was carried out on a Capcell Pak C₁₈ MG III column (100 × 2.0 mm, 5 μm) with 0.1% formic acid in acetonitrile solution and water (17:83, v/v) as mobile phase. The linear range was 5.0–1000 ng/mL for Sul, with a lower limit of quantification of 5.0 ng/mL. The intra‐ and inter‐batch CVs were within ±11.0% and the accuracies were 4.9–107.3%. Our method, for the first time, allows the rapid (only 3.0 min) and accurate quantification of Sul in human plasma. The method has been successfully applied in the pharmacokinetic study of Sul in a clinical trial following oral administration of Sul to healthy volunteers. Copyright © 2016 John Wiley & Sons, Ltd.     

Rapid column-switching liquid chromatography/mass spectrometric assay for DHEA-sulfate in the plasma of patients with Alzheimer's disease

A simple and highly sensitive method for the quantification of dehydroepiandrosterone-3-sulfate (DHEAS) in human plasma was developed. DHEAS was directly determined in plasma using column-switching liquid chromatography/mass spectrometry (LC-MS). The plasma was filtered with a membrane filter. The filtrate was injected onto a pre-column without further sample preparation such as extraction or derivatization. The pre-column was washed with an aqueous solution to remove interference and the analyte was eluted into a reversed-phase C(18) analytical column for separation and detection using a column-switching valve. The calibration range of DHEAS was 0.01-10 micromol/L, and the linearity of the method was 0.999. The limit of detection (LOD) at a signal-to-noise (S/N) ratio of 3 was 5 nmol/L. The accuracy and precision (%CV) were less than 10% in within-day and day-to-day variations. To explore the relationship between Alzheimer's disease and the DHEAS level in human plasma, the concentrations of DHEAS in female patients with Alzheimer's disease (n = 20) and in normal female subjects (n = 20) were measured. The level of DHEAS was significantly decreased in the plasma of patients with Alzheimer's disease (p < 0.0002) compared with that in normal subjects. From the results, we concluded that our method is sufficiently sensitivity and reliability for the quantification of DHEAS in clinical samples. Plasma DHEAS concentration could be an important marker to understand the pathogenesis of Alzheimer's disease.     

Effect of sodium dodecyl sulfate on the reactivity of 2-dimethylaminomethylphenol with 4-nitrophenylbis(chloromethyl)phosphinate

The reactivity of 2-dimethylaminomethylphenol (1) toward 4-nitrophenylbis(chloromethyl)phosphinate (2) was studied in micellar solutions and in the lyotropic liquid-crystalline mesophase of the sodium dodecyl sulfate (SDS)-water system. The reaction between1 and2 is inhibited in the presence of SDS, which is explained by the shift of the acid-base equilibrium of1 toward the formation of a nonreactive protonated form.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1959–1962, October, 1995.     

Dispersive admicelle solid‐phase extraction based on sodium dodecyl sulfate coated Fe3O4 nanoparticles for the selective adsorption of three alkaloids in Gegen‐Qinlian oral liquid before high‐performance liquid chromatography

A novel dispersive admicelle solid‐phase extraction method based on sodium dodecyl sulfate‐coated Fe₃O₄ nanoparticles was developed for the selective adsorption of berberine, coptisine, and palmatine in Gegen‐Qinlian oral liquid before high‐performance liquid chromatography. Fe₃O₄ nanoparticles were synthesized by a chemical coprecipitation method and characterized by using transmission electron microscopy. Under acidic conditions, the surface of Fe₃O₄ nanoparticles was coated with sodium dodecyl sulfate to form a nano‐sized admicelle magnetic sorbent. Owing to electrostatic interaction, the alkaloids were adsorbed onto the oppositely charged admicelle magnetic nanoparticles. The quick separation of the analyte‐adsorbed nanoparticles from the sample solution was performed by using Nd‐Fe‐B magnet. Best extraction efficiency was achieved under the following conditions: 800 μL Fe₃O₄ nanoparticles suspension (20 mg/mL), 150 μL sodium dodecyl sulfate solution (10 mg/mL), pH 2, and vortexing time 2 min for the extraction of alkaloids from 10 mL of diluted sample. Four hundred microliters of methanol was used to desorb the alkaloids by vortexing for 1 min. Satisfactory extraction recoveries were obtained in the range of 85.9–120.3%, relative standard deviations for intra‐ and interday precisions were less than 6.3 and 10.0%, respectively. Finally, the established method was successfully applied to analyze the alkaloids in two batches of Gegen‐Qinlian oral liquids.     

Sensitive determination of aliphatic amines by high-performance liquid chromatography with a new fluorogenic probe 3-(4-fluorinebenzoyl)-2-quinoline carboxaldehyde

A new fluorogenic reagent 3-(4-fluorinebenzoyl)-2-quinoline carboxaldehyde (FBQCA) has been synthesized and used as a derivatizing reagent for the determination of aliphatic amines with HPLC. The reagent is nonfluorescent, but forms highly fluorescent isoindole upon the reaction with primary amines in alkaline medium. Eleven amine derivatives were baseline separated in 8 min using a gradient elution on a C(8) column and detected with fluorescence detection at lambda(ex)/lambda(em) = 480/546 nm. The detection limits were in the range of 0.5-2 nM (S/N = 3). The proposed method has been successfully applied to the analysis of aliphatic amines in food and environmental samples, including white wine, soybean oil, soil, and tap water with satisfactory recoveries in the range of 94-106%.     

Evaluation and application of a mixed‐mode chromatographic stationary phase in two‐dimensional liquid chromatography for the separation of traditional Chinese medicine

In this study, two mixed‐mode chromatography stationary phases (C8SAX and C8SCX) were evaluated and used to establish a two‐dimensional liquid chromatography system for the separation of traditional Chinese medicine. The chromatographic properties of the mixed‐mode columns were systematically evaluated by comparing with other three columns of C8, strong anion exchanger, and strong cation exchanger. The result showed that C8SAX and C8SCX had a mixed‐mode retention mechanism including electrostatic interaction and hydrophobic interaction. Especially, they were suitable for separating acidic and/or basic compounds and their separation selectivities could be easily adjusted by changing pH value. Then, several off‐line 2D‐LC systems based on the C8SAX in the first dimension and C8SAX, C8SCX, or C8 columns in the second dimension were developed to analyze a traditional Chinese medicine—Uncaria rhynchophylla. The two‐dimensional liquid chromatography system of C8SAX (pH 3.0) × C8SAX (pH 6.0) exhibited the most effective peak distribution. Finally, fractions of U. rhynchophylla prepared from the first dimension were successfully separated on the C8SAX column with a gradient pH. Thus, the mixed‐mode stationary phase could provide a platform to separate the traditional Chinese medicine in practical applications.