Optimization of RP-HPLC analysis of low molecular weight organic acids in soil

RP-HPLC analysis for low molecular weight organic acids in soil solution has been optimized. An Atlantis (TM) C-18 column was used for the analyses. An optimal determination for eleven organic acids in soil solution was found at room temperature (25 degrees C) and 220 nm detection wavelength, with a mobile phase of 10 mM KH2PO4 -CH3OH (955, pH 2.7), a flow rate of 0.8 mL/min and 10 mu L sample size. The detection limits ranged 3.2-619 ng/mL, the coefficients of variation ranged 1.3-4.6%, and the recoveries ranged 95.6-106.3% for soil solution with standard addition on the optimal conditions proposed.

Retention modeling and simultaneous optimization of pH value and gradient steepness in RP-HPLC using feed-forward neural networks

A novel approach is proposed for the simultaneous optimization of mobile phase pH and gradient steepness in RP-HPLC using artificial neural networks. By presetting the initial and final concentration of the organic solvent, a limited number of experiments with different gradient time and pH value of mobile phase are arranged in the two-dimensional space of mobile phase parameters. The retention behavior of each solute is modeled using an individual artificial neural network. An "early stopping" strategy is adopted to ensure the predicting capability of neural networks. The trained neural networks can be used to predict the retention time of solutes under arbitrary mobile phase conditions in the optimization region. Finally, the optimal separation conditions can be found according to a global resolution function. The effectiveness of this method is validated by optimization of separation conditions for amino acids derivatised by a new fluorescent reagent.

Study of normal and modified nucleosides in serum by RP-HPLC

Modified nucleosides derived predominantly from transfer ribonucleic acid (tRNA) have been studied as possible tumor markers. In this paper a reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been applied to study 15 normal and modified nucleosides in serum. The nucleoside levels in normal human serum were established, and the concentrations of 15 nucleosides in serum from 19 cancer patients were determined, it was found that the concentrations of modified nucleosides were significantly higher in patient sera. Based on 15 nucleoside concentrations in serum, factor analysis could classify correctly 90% of cancer patients from the normal humans Further work showed that urine was slightly better than serum when determining nucleosides as biological marker candidates. More work is ongoing to determine the clinical usefulness of modified nucleosides as tumor markers.

Excretion pattern investigation of urinary normal and modified nucleosides of breast cancer patients by RP-HPLC and factor analysis method

Modified nucleosides, formed post-transcriptionally in RNA by a number of modification enzymes, are excreted in abnormal levels in the urine of patients with malignant tumors. To test their usefulness as tumor markers, and to compare them with the conventional tumor markers, a reversed-phase high-performance liquid chromatographic (RP-HPLC) method and a factor analysis method have been used to study the excretion pattern of nucleosides of breast cancer patients. A clear cut differentiation of the breast cancer group and the healthy individuals in two clusters without overlapping was obtained. Copyright (C) 2000 John Wiley & Sons, Ltd.

RP-HPLC测定几种花类药材黄酮含量

目的：为充分利用花类药材，建立马蔺花、桃花、月季等15种花类药材中黄酮含量测定的RP—HPLC方法，并比较它们的含量。方法：花类药材用甲醇提取，反相高效液相色谱法分析药材中槲皮素、山柰酚、异鼠李素3种黄酮苷元。结果：采用KromasilC_18柱（4．6mm×250／mm，5μm），以甲醇-0．1％磷酸（50：50）为流动相，可使3种黄酮苷元达到基线分离，其中马蔺花含槲皮素1．536％，桃花含山柰酚0．572％，茶花含异鼠李素0．029％，皆为听测样品中最高。结论：本实验首次采用RP—HPLC法测定这15种花类药材的总黄酮含量，本方法操作简便，快速，准确，可作为黄酮的定量分析方法。

藏药短管兔耳草中松果菊苷和麦角甾苷的RP-HPLC分析

建立了藏药短管兔耳草中松果菊苷和麦角甾苷含量的高效液相色谱分析法.采用Waters XTerra RP18色谱柱(150mm×4.6 mm,5μm),以甲醇-1%冰醋酸溶液(28:72,V:V)为流动相,流速1.0 mL/min,检测波长330 nm,柱温30℃,在20 min内分离检测了该两种化合物.松果菊苷和麦角甾苷进样量分别在0.077～4.950μg(r=0.999 9)和0.085～5.450μg(r=0.999 9)内呈良好线性,平均加样回收率分别为98.35%和92.50%,RSD分别为2.35%和2.86%.所建立的方法简便、快捷、结果准确可靠,重现性好,可用于藏药短管兔耳草的质量控制,并为兔耳草属植物中苯丙素苷类化合物的分离分析提供一定的参考.

藏药独一味RP-HPLC色谱指纹图谱的建立及其质量评价

[目的]建立独一味药材HPLC指纹图谱，研究不同地区独一味药材的质量，为其质量控制提供有效的方法。[方法]采用RP-HPLC方法梯度洗脱，测定10批不同地区的独一味样品。[色谱备件]Kromasil C18柱（250mm×4．60mm，5μm），流动相为甲醇-0．4％的磷酸水溶液（55：45），梯度洗脱程序为0～70min，甲醇的体积分数由1％线性增加至15％；70～100min内，甲醇由15％线性增加至17％；100～130min内，甲醇由17％线性增加至20％；130～150min，甲醇由20％线性增加至100％；流速为1ml/min，检测波长为254n／n，柱温为30℃。[结果]确定了独一味药材中的7个共有峰。根据聚类分析结果，将独一味药材分为3类。[结论]该研究建立的方法重复性好，可用于不同地区独一味药材的质量评价，结合含量测定可用于独一味药材的质量的全面控制。

RP-HPLC测定藏木香中土木香内酯和异土木香内酯含量

目的 建立了反相高效液相色谱法同时测定藏木香中土木香内酯和异土木香内酯的方法.方法 采用Phenomenex Kromasil C18色谱柱(4.6mm×250mm,5.0μm);流动相为乙腈-0.04%磷酸溶液(50:50);检测波长:194 nm;流速:1.0 mL•min~(-1).结果 异构体土木香内酯和异土木香内酯达到基线分离,含量测定的线性良好,线性范围和相关系数分别为0.07～4.80μg•L~(-1) (r=0.999 8),0.07～4.85μg•L~(-1) (r=0.999 8);回收率分别为97.5%和102.1%;方法精密度良好,RSD分别为1.56%和1.87%(n=5);方法重现性良好,RSD分别为1.67%和0.92%(n=5).结论 所建立的方法简便、快捷、准确,重现性好,可用于藏木香药材及其制剂的质量控制.

Effects of sample solvent composition and injection volume on chromatographic peak profiles of methyl w- benzimidazolecarbamate and 3-butyl1-2,4-dioxo[1,2-a]-s- triazinobenzimidazole in RP-HPLC

The effects of sample solvent composition and the injection volume, on the chromatographic peak profiles of two carbamate derivatives, methyl 2-benzimidazolecarbamate (MBC) and 3-butyl-2,4-dioxo[1,2-a]-s-triazinobenzimidazole (STB), were studied using reverse phase high performance liquid chromatograph. The study examined the effects of acetonitrile percentage in the sample solvent from 5 to 50%, effects of methanol percentage from 5 to 50%, effects of pH increase from 4.42 to 9.10, and effect of increasing buffer concentration from ° to 0.12M. The effects were studied at constant and increasing injection mass and at four injection volumes of 10, 50, 100 and 200 uL. The study demonstrated that the amount and the type of the organic solvents, the pH, and the buffer strength of the sample solution can have a pronounced effect on the peak heights, peak widths, and retention times of compounds analysed. MBC, which is capable of intramolecular hydrogen bonding and has no tendency to ionize, showed a predictable increase .in band broadening and a decrease in retention times at higher eluting strengths of the sample solvent. STB, which has a tendency to ionize or to strongly interact with the sample solvent, was influenced in various ways by the changes in ths sample solvent composition. The sample solvent effects became more pronounced as the injection volume increased and as the percentage of organic solvent in the sample solution became greater. The peak height increases for STB at increasing buffer concentrations became much more pronounced at higher analyte concentrations. It was shown that the widely accepted procedure of dissolving samples in the mobile phase does not yield the most efficient chromatograms. For that reason samples should be dissolved in the solutions with higher aqueous content than that of the mobile phase whenever possible. The results strongly recommend that all the samples and standards, regardless whether the standards are external or internal, be analysed at a constant sample composition and a constant injection volume.

Synthesis and comparative physical-chemical characterisation of neutral and cationic amphiphiles using RP-HPLC

A series of norbornane containing amphiphiles was synthesized, their lipophilicity corresponding to neutral and cationic forms was then investigated using reverse phase HPLC (High Performance Liquid Chromatography). This series of amphiphiles incorporated varied lipophilic chain length and also varied distances between the polar/cationic head group from the norbornane scaffold. Our investigation included studying the impact of the stationary phase as a replication of a membrane for both cationic and neutral amphiphiles. The choice of stationary phase was shown to be a very important consideration for this type of measurement. In this connection, C18, Cyano and Polar columns were all investigated, the cyano column was observed to be the optimal stationary phase for the comparison of both charged and neutral amphiphiles.

Multivariate optimization and validation of an analytical methodology by RP-HPLC for the determination of losartan potassium in capsules

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Development and validation of an analytical method by RP-HPLC for quantification of sibutramine hydrochloride in pharmaceutical capsules

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Application of on-line C30 RP-HPLC-NMR for the analysis of flavonoids from leaf extract of Maytenus aquifolium

The application of on-line C30-reversed-phase high-pressure liquid chromatography-nuclear magnetic resonance spectroscopy is described for the analysis of tetraglycosylated flavonoids in aqueous and hydroalcoholic extracts of the leaves of Maytenus aquifolium (Celastraceae). Triacontyl stationary phases showed adequate separation for on-line 1H-NMR measurements at 600 MHz and allowed the characterisation of these flavonoids by detection of both aromatic and anomeric proton signals. Copyright (C) 2000 John Wiley and Sons, Ltd.

Evaluation of a propolis water extract using a reliable RP-HPLC methodology and in vitro and in vivo efficacy and safety characterisation

Since the beginning of propolis research, several groups have studied its antibacterial, antifungal, and antiviral properties. However, most of these studies have only employed propolis ethanolic extract (PEE) leading to little knowledge about the biological activities of propolis water extract (PWE). Based on this, in a previous study, we demonstrated the anti-inflammatory and immunomodulatory activities of PWE. In order to better understand the equilibrium between effectiveness and toxicity, which is essential for a new medicine, the characteristics of PWE were analyzed. We developed and validated an RP-HPLC method to chemically characterize PWE and PEE and evaluated the in vitro antioxidant/antimicrobial activity for both extracts and the safety of PWE via determining genotoxic potential using in vitro and in vivo mammalian micronucleus assays. We have concluded that the proposed analytical methodology was reliable, and both extracts showed similar chemical composition. The extracts presented antioxidant and antimicrobial effects, while PWE demonstrated higher antioxidant activity and more efficacious for the most of the microorganisms tested than PEE. Finally, PWE was shown to be safe using micronucleus assays. © 2013 Bruno Alves Rocha et al.