A Sensitive Reversed-Phase High-Performance Liquid Chromatography Method for the Quantitative Determination of Milk Xanthine Oxidase Activity

A new reversed-phase high performance liquid chromatography method was developed to quantitate the activity of xanthine oxidase involved in milk fat globule membrane with xanthine as the substrate and the separation of product (uric acid). The increment of uric acid in the reaction system was used to calculate the total activity of XO. The optimized assay conditions, linearity of detection, recovery of uric acid and chromatogram were developed in text, indicating this method is simple, rapid and efficient. It is an alternative potential method for the determination of the activity of XO in milk.

A highly sensitive SPE-liquid/liquid extraction-RPLC analytical method for the determination of 6β-hydroxycortisol and cortisol in cancer patients' urine

A highly sensitive SPE-liquid/liquid extraction RPLC method has been developed for the analysis of 6β-hydroxycortisol and cortisol in the urine of cancer patients. Methods： After SPE column purification and liquid-liquid extraction, the sample test solutions were analyzed with RPLC using a C18 analytical column. This improved analytical method has been validated for linearity, accuracy （recovery from urine）, repeatability （within-day and between-day precision）, specificity, sensitivity, and stability. This SPE-liquid/liquid extraction-RPLC is rapid, simple, accurate and reproducible. The technique is particularly useful for monitoring the CYP3A activity of cancer patients in clinical settings. The results are expressed as the ratio of 6β-hydroxycortisol to cortisol. Results： The CYP3A activity from a total of 153 samples was measured using this improved method. Considerable variation in the CYP3A activity of different cancer patients has been documented. Thus, personalized medical treatment based on the individual metabolic enzyme activity level is necessary. Conclusion： This new analytical method facilitates such individualized medical treatments.

反相高效液相色谱法测定绿茶中绿原酸

采用反相高效液相色谱法对绿茶中的有效成分绿原酸进行分离,并对其含量进行测定,建立反相高效液相色谱法测定绿茶中绿原酸含量的方法。绿茶中绿原酸最佳提取条件为50%乙醇提取液,100℃提取温度,60min提取时间。色谱柱为symmetryC18柱(150mm×4.6mmi.d,5μm),流动相为甲醇-水-冰醋酸(20∶80∶0.5);流速为1.0mL/min,检测波长为328nm,柱温为30℃。绿原酸在0.25μg/mL^80.0μg/mL的范围内呈良好的线性关系;相关系数为0.9996,加标回收率为96.8%,RSD为0.98%。本方法快速、简单、准确、分离度好,可用于绿茶中绿原酸的测定。

变异胰岛素症

变异胰岛素症是在糖尿病患者中发现的分子病。对变异胰岛素的研究是近年在胰岛素结构与功能,临床医学和分子遗传学方面的新课题。本文就变异胰岛素的发现及其特点、变异胰岛素的鉴定技术以及变异胰岛素与糖尿病的关系作一综述。

Isolation and purification of uremic middle molecules by multi-step liquid chromatography

Isolation and comparison of uremic sera and urine and normal sera and urine were performed by gel permeation chromatography, anion exchange chromatography and reversed-phase high performance liquid chromatography. Two uremic middle molecular fractions (A and B) were obtained from uremic sera and urine and normal urine by gel permeation chromatography, but not from normal sera. The anion exchange chromatographic results of fraction A from different origins demonstrate that subfraction A-3 could be excreted in urine by healthy subject, but accumulated in uremic serum for renal failure of patient with uremia. After desalinization subfraction A-3 was analyzed by MALDI-TOF-MS. The results show that subfraction A-3 consists of six compounds with molecular weight 839, 873, 1007.94, 1106, 1680 and 2015 respectively. Finally, by reversed-phase high performance liquid chromatography, subfraction A-3 was further resolved into six independent fractions. Thus, the isolation and purification of six middle molecular compounds in subfraction A-3 came true by our method.

Separation and Measurement of Three Kinds of Endogenous Hormones in Rhizome of Alhagi sparsifolia

[ Objective] The aim was to establish effective method for endogenous hormone extraction and explore conditions of chromatographic analysis for three endogenous hormones in rhizome of Alhagi sparsifolia. [ Methed ] Activol （GA3 ）, zeatin （ZR） and indole-3-acetic acid （IAA） in rhizome were separated and measured as per RP-HPLC. [Result] The average recovery rates of GA3, ZR and IAA were 98.3%, 90.3% and 101.3%, respectively, indicating that the method is suitable for quantitative analysis with little errors. The chromatographic conditions were as follows： methanol/0. 75% of acetic acid at 45：55 （mobile phase） ; flow speed at 0.7 ml/min; wavelength at 254 nm; column temperature at 25 ℃. [Conclusion] The research preliminarily established HPLC conditions for separation of endogenous hormones in rhizome of Alhagi sparsifolia.

指示稳定性的高效液相色谱方法和强制降解研究片剂型马西替坦中的杂质（英文）

Macitentan (MAC) is a pulmonary arterial hypertension (PAH) drug marketed as a tablet and often has stability issues in the final dosage form. Quantitative determination of MAC and its associated impurities in tablet dosage form has not been previously reported. This study quantified impurities present in Macitentan tablets using a binary solvent-based gradient elution method using reversed phase-high performance liquid chromatography.The developed method w as validated per International Conference on Harmonization (ICH) guidelines and the drug product w as subjected to forced degradation studies to evaluate stability. The developed method efficiently separated the drug and impurities (48 min) w ithout interference from solvents,excipients,or other impurities. The developed method met all guidelines in all characteristics w ith recoveries ranging from 85%-115%,linearity w ith r 2≥0. 996 6,and substantial robustness. The stability-indicating nature of the method w as evaluated using stressed conditions (hydrolysis:1 N HCl at 80℃/15 min; 1 N NaOH at 25℃/45 min; humidity stress (90%relative humidity) at 25℃for 24 h,oxidation:at 6%(v/v) H2O2,80℃/15 min,thermolysis:at105℃/16 h and photolysis:UV light at 200 Wh/m2; Fluorescent light at 1. 2 million luxh). Forced degradation experiments show ed that the developed method w as effective for impurity profiling. All stressed samples w ere assayed and mass balance w as> 96%. Forced degradation results indicated that MAC tablets w ere sensitive to hydrolysis (acid and alkali) and thermal conditions. The developed method is suitable for both assay and impurity determination,w hich is applicable to the pharmaceutical industry.

Effects of Different Drying Methods on Content of Paederosidic Acid in Paederia scandens

[Objectives]To establish a method to simultaneously determine the content of paederosidic acid in Paederia scandens dried by four different methods.[Methods]Reversed-phase high performance liquid chromatography(RP-HPLC)was adopted.The chromatographic column:Thermo SCIENTIFIC Hypersil GOLD Dim.(mm);mobile phase:acetonitrile-0.1%phosphoric acid aqueous solution;gradient elution;column temperature:30℃;flow rate:1 mL/min;detection wavelength:236 nm;injection volume:10μL.[Results]The linear range of the detection injection volume of paederosidic acid was 0.64-9.60μg(R=0.9992);the limit of quantity(LOQ)was 5.10 ng,and the limit of detection(LOD)was 1.36 ng;the RSD of the precision,stability and reproducibility test was all less than 3%;the sample recovery rate was 98.87%,RSD<3.00,n=6.The results show that the content of paederosidic acid in the shade-dried P.scandens is the highest,and the order of the content is P.scandens(dry in shade)>P.scandens(dried at 50℃)>P.scandens(dried at 60℃)>P.scandens(dried at 70℃).[Conclusions]This method is sensitive,reliable and reproducible,and can be used to simultaneously determine the content of paederosidic acid in P.scandens dried by four different methods.