苯并芘DNA加合物anti-BPDE-N^2-dG四种立体异构体的合成及色谱分离

体外合成了苯并芘DNA加合物-邻二醇环氧苯并芘-脱氧鸟苷加合物(anti-BPDE-N2-dG)四种立体异构体(两对手性异构体)。通过优化体外反应条件,anti-BPDE-N2-dG四种异构体的合成产量较现有合成方法提高了2倍多,为定量检测生物体中anti-BPDE-N2-dG提供了标准品。并首次将五氟苯基色谱柱应用于该立体异构体的色谱分离提纯,通过优化色谱条件,采用常规的五氟苯基色谱柱(250 mm×4.6 mm,5μm),以乙腈-0.1%甲酸水(22.5∶77.5)为流动相,流速1.2 mL/min条件下,45 min内即可分离提纯四种立体异构体。该方法与常规C18柱(250 mm×4.6 mm,5μm)需要160 min,苯基柱(250 mm×4.6 mm,5μm)需要85~100 min才能将四种立体异构体实现色谱分离相比,缩短了分离时间,提高了提纯效率。通过紫外吸收光谱、质谱、圆二色谱对四种立体异构体进行表征,确定出峰顺序为trans(-)、trans(+)、cis(+)、cis(-)-anti-BPDE-N2-dG。此外,利用高效液相色谱-串联质谱(HPLC-MS/MS)检测anti-BPDE-N2-dG四种立体异构体标准品时,使用常规的五氟苯基色谱柱可在30 min内完成分离检测,与相同规格的苯基柱需要60 min相比提高了检测效率。     

Simultaneous Determination of Major Flavonoids in Rat Plasma by a Rapid Resolution LC-ESI–MS Method After Oral Administration of the Flavonoid Fraction of Flos Lonicerae japonicae

A rapid resolution liquid chromatography-tandem mass spectrometric method was developed for the simultaneous analysis of four flavonoids in rat plasma. Key features of this method include a 6.5 min separation by a rapid resolution liquid chromatography system with a 4.6 × 50 mm, 1.8 μm particle size reverse phase column and detection by electrospray ionization tandem mass spectrometric performed in MS–MS mode for multiple reaction monitoring. The developed method was validated with respect to linearity, accuracy, precision and stability and applied for a pharmacokinetic study successfully after oral administration of the flavonoid fraction of Flos Lonicerae japonicae.     

Automated signature peptide approach for proteomics

This paper addresses the issue of automating the multidimensional chromatographic, signature peptide approach to proteomics. Peptides were automatically reduced and alkylated in the autosampler of the instrument. Trypsin digestion of all proteins in the sample was then executed on an immobilized enzyme column and the digest directly transferred to an affinity chromatography column. Although a wide variety of affinity columns may be used, the specific column used in this case was a Ga(III) loaded immobilized metal affinity chromatography (IMAC) column. Ga(III)-IMAC is known to select phosphorylated peptides. Phosphorylated peptides selected by the affinity column from tryptic digests of milk were automatically transferred to a reversed-phase liquid chromatography (RPLC) column. Further fractionation of tryptic peptides on the RPLC column was achieved with linear solvent gradient elution. Effluent from the RPLC column was electrosprayed into a time-of-flight mass spectrometer. The entire process was controlled by software in the liquid chromatograph. With slight modification, it is possible to add multiple columns in parallel at any of the single column positions to further increase throughput. Total analysis time in the tandem column mode of operation was under 2 h.     

Simultaneous Determination of Major Flavonoids in Rat Plasma by a Rapid Resolution LC-ESI–MS Method After Oral Administration of the Flavonoid Fraction of Flos Lonicerae japonicae

A rapid resolution liquid chromatography-tandem mass spectrometric method was developed for the simultaneous analysis of four flavonoids in rat plasma. Key features of this method include a 6.5 min separation by a rapid resolution liquid chromatography system with a 4.6 × 50 mm, 1.8 μm particle size reverse phase column and detection by electrospray ionization tandem mass spectrometric performed in MS–MS mode for multiple reaction monitoring. The developed method was validated with respect to linearity, accuracy, precision and stability and applied for a pharmacokinetic study successfully after oral administration of the flavonoid fraction of Flos Lonicerae japonicae.

     

High-sensitivity phenylthiohydantoin amino acid analysis using conventional and microbore chromatography

Reversed-phase microbore high-performance liquid chromatography was investigated for high-sensitivity analysis of phenylthiohydantoin (PTH) amino acids. A mixed nitrile alkylsilane bonded phase was developed and ternary gradient elution conditions were devised for resolution of the common PTH amino acids. Elution conditions were developed with a conventional 150 X 4.6 mm I.D. column and transferred to a 150 X 1 mm I.D. microbore column. The performance of these columns was evaluated in terms of PTH amino acid resolution, enhanced sample detectability, and retention time precision. For this work a general purpose high-performance liquid chromatograph was modified to reduce extra column band broadening and a preformed gradient elution technique was developed to achieve rapid analysis times at microbore flow-rates. The microbore high-performance liquid chromatographic system is useful for high-sensitivity analysis of PTH amino acids in micro-sequencing applications.     

Two-dimensional reversed-phase liquid chromatography using two monolithic silica C18 columns and different mobile phase modifiers in the two dimensions

Comprehensive two-dimensional (2D) HPLC in the reversed-phase liquid chromatography (RPLC) mode using C18 silica monolith columns at first dimension (1st-D) (10 cm x 4.6mm I.D.) and second dimension (2nd-D) (5 cm x 4.6mm I.D.) was carried out successfully. A mixture of water and tetrahydrofuran (THF) was used as a mobile phase in the 1st-D separation, and a mixture of water and methanol (CH3OH) in the 2nd-D separation. Sample fractions from 1st-D column were directly loaded into an injection loop of the 2nd-D HPLC equipped with two injector valves for one column. The fractionation time at the 1st-D that was equal to the separation time at the 2nd-D was 45 or 60s. Total peak capacity up to 900 was obtained in about 60 min for the isocratic mode separation of aromatic compounds in this system. Gradient elution mode applied to both 1st-D and 2nd-D separations resulted in shorter separation time and better separation efficiencies than the isocratic mode. It was demonstrated that 2D-HPLC systems employing popular C18 stationary phases with different organic modifiers in mobile phases for each dimension could produce large peak capacity. The different selectivities were provided by the difference in polar interactions between a solute and the organic modifier existing in the stationary phase.     

Preparative purification of Plasmodium falciparum circumsporozoite protein synthetic polypeptides by displacement chromatography

Displacement chromatography was used for the preparative purification of a synthetic polypeptide that is a promising malaria vaccine. It was prepared by solid-phase synthesis and contains two important epitopes of circumsporozoite (CS) protein of Plasmodium falciparum sporozoite. With apparatus typically employed in analytical high-performance liquid chromatography (HPLC) and on a 250 x 4.6 mm I.D. reversed-phase column, up to 50 mg of crude polypeptide were purified in a single run and with a yield higher than 95%. The results demonstrate that displacement chromatography is suitable for the isolation of several milligrams of a pure polypeptide from a complex mixture that is difficult to separate even by analytical HPLC. In such a preparative application, displacement appears to be superior to elution chromatography as used traditionally.     

Determination of ospemifene in human plasma by LC–MS/MS and its application to a human pharmacokinetic study

A highly sensitive, specific and rapid liquid chromatography–tandem mass spectrometry (LC–MS/MS) analytical method has been developed and validated for the determination of ospemifene in human plasma using ospemifene‐d₄ as an internal standard. Solid‐phase extraction technique with Phenomenex Strata X‐33 μm polymeric sorbent cartridges (30 mg/1 mL) was used to extract the analytes from the plasma. The chromatographic separation was achieved on Agilent Eclipse XDB‐Phenyl, 4.6 × 75 mm, 3.5 μm column using the mobile phase composition of methanol and 20 mm ammonium formate buffer (90:10, v/v) at a flow rate of 0.9 mL/min. A detailed method validation was performed as per the US Food and Drug Administration guidelines and the calibration curve obtained was linear (r² = 99) over the concentration range 5.02–3025 ng/mL. The API‐4500 MS/MS was operated under multiple reaction monitoring mode during the analysis. The proposed method was successfully applied to a pharmacokinetic study in healthy human volunteers after oral administration of an ospemifene 60 mg tablet under fed conditions.     

Rapid displacement chromatography of melittin on micropellicular octadecyl-silica.

Rapid high-performance liquid chromatographic analysis and displacement purification of melittin and its variants were carried out by reversed-phase chromatography. High speed of separation was achieved by the use of columns packed with a micropellicular stationary phase consisting of a thin C18 hydrocarbonaceous layer on the surface of 2-microns fluid-impervious silica microspheres at elevated temperature. In the case of melittin from bee venom or its synthetic variants the plots of the logarithmic retention factor against acetonitrile concentration in the eluent were straight lines whereas the van't Hoff plots in the temperature range from 20 to 80 degrees C were non-linear. Purification of melittins by displacement was carried out with benzyldimethylhexadecyl ammonium chloride as the displacer. In a 20-min displacement run at 40 degrees C about 5 mg of highly pure melittin were isolated from 10 mg of synthetic mixture by using a 105 x 4.6 mm column. The results demonstrate that columns packed with micropellicular sorbents not only facilitate rapid high-performance liquid chromatographic analysis but are also suitable for fast peptide purification with high recovery.     

Enzymes immobilized on montmorillonite: comparison of performance in batch and packed-bed reactors

Summary The enzymes a-amylase, invertase and glucoamylase were immobilized on acid activated montmorillonite using two techniques, viz. adsorption and covalent binding, and their activities were tested in a batch and packed-bed reactor and were compared. The packed-bed reactor showed an improved performance for all immobilized enzymes, which was attributed to lowering of diffusional restrictions to mass transfer. Lower activity in case of batch reactor for immobilized invertase was due to a combined effect of loss of native conformation of enzyme on account of immobilization and mass transfer resistances due to improper diffusion of substrate to the active site of enzyme. For immobilized glucoamylase, the packed-bed reactor demonstrated exceptionally high activity that was very close to the free enzyme. Covalently bound glucoamylase showed higher activity than the free enzyme.     

Displacement chromatography of isomers and therapeutic compounds

Displacement chromatography was successfully used to separate a binary isomer mixture, epirubicin and doxorubicin, on Kromasil KR100-10 C18 250x4.6 mm I.D. (10 microm) column. Displacement parameters such as the types and the concentrations of displacer, the composition and the flow rate of the mobile phase were critically examined in this study. The displacer employed was 30 mg/ml benzethonium chloride. Loading of feed at lower initial organic level of mobile phase coupled with displacement at higher organic level was found to give efficient separation. A 30-mg amount of binary isomer mixture was separated on an analytical column. The purification of epirubicin from the closely related impurities present in raw product solution by displacement chromatography was also investigated. The purity of epirubicin required was greater than 99% with a recovery of 60%. The results have indicated that this process made good use of the high feed load, low solvent costs, and high resolution characteristics of displacement chromatography and offered the chromatographic engineer a powerful tool for the preparative purification of therapeutic compounds.     

反相高效液相色谱法测定肉松制品中姜黄素的含量

建立了肉松制品中姜黄素含量的反相高效液相色谱测定方法。35℃下,以Ultimate XB-C18（4.6mm×150 mm,5μm）为分析柱,乙腈和0.1%磷酸水溶液（pH2.2）作流动相（体积比为50∶50）等度洗脱,流速1.0 mL/min,425 nm波长下检测。结果表明姜黄素在1.69~169μg/mL浓度范围内呈良好的线性关系,线性回归系数r=0.999 9,方法检出限为1.0 mg/kg,实际样品加标回收率范围为86.9%~94.5%,相对标准偏差为4.6%~7.8%（n=6）。该方法准确可靠、重复性好,可用于肉松制品中姜黄素含量测定。     

二维反相液相色谱制备五味子中的木脂素

应用自主研发的具有分离-富集模式的制备色谱工厂,建立了分离制备五味子木脂素有效部位及其单体化合物的方法。该方法首先以C₁₈（250 mm×4.6 mm,5 μm）为色谱柱,水和甲醇为流动相,分离度和保留时间为考察指标,采集4个不同梯度的色谱信息,通过XTool色谱专家系统软件模拟,确定五味子木脂素第一、二维色谱条件;然后采用线性放大的方法,以C₁₈（250 mm×30 mm,10 μm）为第一、二维分离柱,C₁₈（80 mm×30 mm,10 μm）为富集柱,水为富集稀释液,对五味子木脂素进行二维色谱分离纯化;最后第一维分离得到9个可重复组分,第二维分离得到20个高纯度化合物,其中有6个单体化合物。结果表明该法重现性良好,可以实现五味子木脂素的系统性分离,对五味子化学成分的研究具有重要意义。     

A sensitive liquid chromatography–tandem mass spectrometry method for quantitative bioanalysis of fingolimod in human blood: Application to pharmacokinetic study

A simple and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed and validated for the determination of fingolimod in human blood. The analyte and internal standard fingolimod-d4 were extracted from 300 μl of human blood using protein precipitation coupled with solid-phase extraction method. The chromatographic separation was achieved with a Kinetex biphenyl column (100 × 4.6 mm, 2.6 μm) under isocratic conditions at the flow rate of 0.8 ml/min and column temperature was maintained at 45°C. The detection of analyte and internal standard was carried out by tandem mass spectrometry, operated in positive ion and multiple reaction monitoring acquisition mode. The method was fully validated for its selectivity, precision, accuracy, linearity, stability, detection and quantification limit. The extraction recovery of fingolimod in human blood ranged from 98.39 to 99.54%. The developed method was linear over the concentration range of 5–2500 pg/ml with a detection limit of 1 pg/ml. The developed method was validated and successfully applied for pharmacokinetic study after oral administration of fingolimod capsules.     

Determination of M+4 stable isotope labeled cortisone and cortisol in human plasma by microElution solid-phase extraction and liquid chromatography/tandem mass spectrometry

A sensitive microElution solid-phase extraction (SPE) liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for the determination of M+4 stable isotope labeled cortisone and cortisol in human plasma. In this method, M+4 cortisone and M+4 cortisol were extracted from 0.3 mL of human plasma samples using a Waters Oasis HLB 96-well microElution SPE plate using 70 microL methanol as the elution solvent, and chromatographed on a Waters Symmetry C18 column (4.6 x 50 mm, 3.5 microm). M+9 cortisone and M+9 cortisol were used as the internal standards. A PE Sciex API 4000 tandem mass spectrometer interfaced with the liquid chromatograph via a turboionspray source was used for mass analysis and detection. The selected reaction monitoring (SRM) of precursor --> product ion transitions were monitored at m/z 365.2 [M+H](+) --> 167.0 and at m/z 367.3 [M+H](+) --> 125.1 for M+4 cortisone and M+4 cortisol, respectively. The lower limit of quantitation was 0.1 ng mL(-1) and the linear calibration range was from 0.1 to 100 ng mL(-1) for both analytes. This method demonstrated to be very reproducible and reliable.     

Residue measurement of pendimethalin in tobacco by using heart‐cutting two dimensional liquid chromatography coupled with tandem mass spectrometry

A novel heart‐cutting two‐dimensional liquid chromatography coupled with tandem mass spectrometry method was developed for quantitative analysis of pendimethalin residue in tobacco. The strategy of reversed phase liquid chromatography coupled with another reversed‐phase liquid chromatography was employed for high column efficiency and excellent compatibility of mobile phase. In the first dimensional chromatography, a cyano column with methanol/water as the eluent was applied to separate pendimethalin from thousands of interference components in tobacco. By heart‐cutting technique, which effectively removed interference components, the target compound was cut to the second dimensional C18 column for further separation. The pendimethalin residue was finally determined by the tandem mass spectrometry under multiple reaction monitoring reversed‐phase liquid chromatography mode. Sample pretreatment of the new method was simplified, involving only extraction and filtration. Compared with traditional methodologies, the new method showed fairly high selectivity and sensitivity with almost no matrix interference. The limit of quantitation for pendimethalin was 1.21 ng/mL, whereas the overall recoveries ranged from 95.7 to 103.3%. The new method has been successfully applied to non‐stop measure of 200 real samples, without contamination of ion source. Detection results of the samples agreed well with standard method.     

A high‐performance liquid chromatography–tandem mass spectrometry method coupled with protein precipitation for determination of granisetron in human plasma and its application to a comparative pharmacokinetic study

A rapid, simple and validated method based on liquid chromatography coupled with tandem mass spectrometry (LC‐MS/MS) has been developed for the determination of granisetron in human plasma. Plasma samples were pre‐purified by protein precipitation procedure. The chromatographic separation was achieved with Synergi Polar‐RP (75 × 2 mm, 4 µm) column using a mixture of 5 mm pH4.0 ammonium formate and methanol (300:316, v/v) under isocratic conditions at a flow rate of 0.3 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer in multiple reaction monitoring mode using positive electrospray ionization. The analysis time was about 2.5 min. The method was fully validated over the concentration range 0.1–10 ng/mL. The lower limit of quantification was 0.1 ng/mL. Inter‐ and intra‐batch precision was <6.1% and the accuracy was within 95.6–100.0%. The mean extraction recovery was 96.3%. Selectivity, matrix effect and stability were also validated. The method was applied to the comparative pharmacokinetic study of granisetron in Chinese healthy subjects. Copyright © 2014 John Wiley & Sons, Ltd.     

超高效液相色谱-串联质谱法测定食用植物油中胆固醇含量

提出了食用植物油中胆固醇的超高效液相色谱-串联质谱测定方法。食用植物油经皂化后用石油醚-乙醚(1+1)溶液提取,以Waters ACQUITY UPLC BEH C18色谱柱(50mm×2.1mm,5μm)为分离柱,以甲酸-甲醇(0.1+99.9)溶液为流动相,以2,2,3,4,4,6-d6胆固醇为内标,采用大气压化学电离源在多反应监测负离子模式下进行测定,胆固醇和内标的定量离子对分别为m/z369.2/146.9,369.2/160.9和375.2/166.5。胆固醇在0.1～5mg·L-1范围内呈线性,测定下限(10S/N)为0.02ng。在3个浓度水平上对方法做回收试验,测得回收率在102%～110%之间。     

Development of an immobilized brain glutamine synthetase liquid chromatographic stationary phase for on-line biochemical studies

Glutamine synthetase (GS) plays a key role in the regulation of glutamate availability to neurons. In the present study glutamine synthetase was immobilized on a silica-based immobilized artificial membrane liquid chromatographic stationary phase (IAM-SP) to create the GS-IAM. The stability of GS was improved by immobilization, but the enzyme's affinity for the substrates L-glutamate and D-glutamate was significantly decreased. In contrast, immobilization significantly increased GS sensitivity to inhibition by methionine sulfoximine. The GS-IAM was packed into a chromatography column to create an immobilized enzyme reactor (GS-IMER). On-line experiments with the GS-IMER demonstrated that the immobilized enzyme was comparable to the non-immobilized enzyme with regards to retention of activity and selectivity toward substrates and inhibitors and was reusable for several weeks.     

On-line immunoaffinity column-liquid chromatography-tandem mass spectrometry method for trace analysis of diuron in wastewater treatment plant effluent sample

An on-line immunoaffinity column with liquid chromatography/tandem mass spectrometry (IAC-LC-MS/MS) method for the determination of diuron in water matrices was described. This method used a sol-gel immunoaffinity column (20 mm x 4 mm I.D.) for on-line sample cleanup and enrichment, a monolithic analytical column (100 mm x 4.6 mm I.D.) for separation, and a triple quadrupole mass spectrometer for quantitation. The major challenges for the on-line set-up were discussed. The optimized on-line protocol was emphasized by the fact that low limit of quantitation (LOQ) of 1.0 ng/L was achieved with only 2.5-mL sample. In addition, a satisfactory accuracy ( approximately 90% of recovery) and precision (<6% of relative standard deviation) at 50 ng/L concentration were also obtained. Due to the ability of the sol-gel immunoaffinity column to eliminate matrix effect, the on-line IAC-LC-MS/MS analysis method can reliably determine diuron in wastewater treatment plant effluent sample.