Efficient separation of oxidized cello-oligosaccharides generated by cellulose degrading lytic polysaccharide monooxygenases

We present an evaluation of HPLC-based analytical tools for the simultaneous analysis of native and oxidized cello-oligosaccharides, which are products of enzymatic cellulose degradation. Whereas cello-oligosaccharides arise from cellulose depolymerization by glycoside hydrolases, oxidized cello-oligosaccharides are produced by cellobiose dehydrogenase and the recently identified copper dependent lytic polysaccharide monooxygenases (LPMOs) currently classified as CBM33 and GH61. The latter enzymes are wide-spread and expected to play crucial roles in further development of efficient enzyme technology for biomass conversion. Three HPLC approaches with well documented performance in the field of oligosaccharide analysis have been investigated: high-performance anion-exchange chromatography (HPAEC), hydrophilic interaction chromatography (HILIC) and porous graphitized carbon liquid chromatography (PGC-LC). HPAEC with pulsed amperometric detection (PAD) was superior for analysis of oxidized oligosaccharides, combining the best separation with superior sensitivity for oligosaccharide species with a degree of polymerization (DP) ranging from 1 to 10. Furthermore, the HPAEC method can be optimized for operation in a high-throughput manner (run time 10 min). Both PGC-LC and HILIC allow reasonable run times (41 and 25 min, respectively), with acceptable separation, but suffer from poor sensitivity compared to HPAEC-PAD. On the other hand, PGC-LC and HILIC benefit from being fully compatible with online mass spectrometry. Using an LC–MS setup, these methods will deliver much better sensitivity than what can be obtained with conventional detectors such as ultraviolet-, charged aerosol-, or evaporative light scattering and may reach sensitivities similar to or even better than what is obtained in HPAEC-PAD. Pure oxidized cello-oligosaccharide standards, ranging from DP2 to DP5, were obtained by semi-preparative PGC and characterized by MS and NMR analysis.     

Characterizing plant cell wall derived oligosaccharides using hydrophilic interaction chromatography with mass spectrometry detection

Analysis of complex mixtures of plant cell wall derived oligosaccharides is still challenging and multiple analytical techniques are often required for separation and characterization of these mixtures. In this work it is demonstrated that hydrophilic interaction chromatography coupled with evaporative light scattering and mass spectrometry detection (HILIC-ELSD-MS(n)) is a valuable tool for identification of a wide range of neutral and acidic cell wall derived oligosaccharides. The separation potential for acidic oligosaccharides observed with HILIC is much better compared to other existing techniques, like capillary electrophoresis, reversed phase and porous-graphitized carbon chromatography. Important structural information, such as presence of methyl esters and acetyl groups, is retained during analysis. Separation of acidic oligosaccharides with equal charge yet with different degrees of polymerization can be obtained. The efficient coupling of HILIC with ELSD and MS(n)-detection enables characterization and quantification of many different oligosaccharide structures present in complex mixtures. This makes HILIC-ELSD-MS(n) a versatile and powerful additional technique in plant cell wall analysis.     

亲水作用色谱法测定胡芦巴中的胡芦巴碱

建立了亲水作用色谱法(HILIC)测定胡芦巴药材中胡芦巴碱含量的方法。采用Waters Atlantis HILIC Silica色谱柱(150 mm×2.1 mm, 3 μm),以乙腈-乙酸铵溶液(pH 4.4)(体积比为70:30)为流动相,流速0.4 mL/min,检测波长265 nm。胡芦巴碱的线性范围为2.50～100 mg/L (r=0.9996);两个加标水平的平均加样回收率为102%,相对标准偏差(RSD)分别为4.17%和2.28%(n=3)。结果表明所建方法分离效果好、快速简易,可以弥补中国药典中离子对色谱法(IPLC)平衡时间过长的缺陷,适用于胡芦巴药材中强极性胡芦巴碱的测定,为胡芦巴的质量控制提供了有效的方法。     

亲水作用色谱柱与阳离子交换树脂柱结合分离无机离子（英文）

A combination of hydrophilic interaction chromatographic(HILIC) column and a weakly acidic cation-exchange resin(WCX) column was used for simultaneous separation of inorganic anions and cations by ion chromatography(IC).Firstly,the capability of HILIC column for the separation of analyte ions was evaluated under acidic eluent conditions.The columns used were SeQuant ZIC-HILIC(ZIC-HILIC) with a sulfobetaine-zwitterion stationary phase(ZIC-HILIC) and Acclaim HILIC-10 with a diol stationary phase(HILIC-10).When using tartaric acid as the eluent,the HILIC columns indicated strong retentions for anions,based on ion-pair interaction.Especially,HILIC-10 could strongly retain anions compared with ZIC-HILIC.The selectivity for analyte anions of HILIC-10 with 5 mmol/L tartaric acid eluent was in the order of I-> NO-3 > Br-> Cl-> H2PO-4.However,since HILIC-10 could not separate analyte cations,a WCX column(TSKgel Super IC-A/C) was connected after the HILIC column in series.The combination column system of HILIC and WCX columns could successfully separate ten ions(Na+,NH+4,K+,Mg2+,Ca2+,H2PO-4,Cl-,Br-,NO-3 and I-) with elution of 4 mmol/L tartaric acid plus 8 mmol/L 18-crown-6.The relative standard deviations(RSDs) of analyte ions by the system were in the ranges of 0.02%-0.05% in retention times and 0.18%-5.3% in peak areas through three-time successive injections.The limits of detection at signal-to-noise ratio of 3 were 0.24-0.30 μmol/L for the cations and 0.31-1.2 μmol/L for the anions.This system was applied for the simultaneous determination of the cations and the anions in a vegetable juice sample with satisfactory results.     

亲水作用色谱-电雾式检测用于5种抗病毒药物的定量分析

抗病毒药物具有广泛的应用,对人类和动物的健康有着重要的作用。但抗病毒药物紫外吸收差异大、极性分布广,要实现该类药物的同时分析较为困难。本实验以Click TE-Cys为固定相,结合电雾式检测(CAD),建立了多种抗病毒药物同时分离分析的方法。考察了不同的检测器、色谱模式、色谱柱和流动相对抗病毒药物峰形、分离选择性及检测信号响应的影响。在优化的条件下定量分析了5种抗病毒药物,结果证明该方法具有较好的日内重复性(RSD≤3.06%)和日间重复性(RSD≤5.38%)。同时,该方法还具有较宽的线性范围(0.07~2.28 mg/mL)和较高的灵敏度(LOQ≤0.04 mg/mL),可用于相关药物的定量、定性分析。     

Quantitative determination of trigonelline in mouse serum by means of hydrophilic interaction liquid chromatography–MS/MS analysis: Application to a pharmacokinetic study

Trigonelline is a pyridine alkaloid found in fenugreek seeds and coffee beans. Most of the previous studies are concerned with the quantification of trigonelline along with other constituents in coffee herbs or beverages. Only a few have focused on its determination in animal or human tissues by applying different modes of HPLC with UV or MS detection. The aim of the study was to develop and validate a fast and simple method for trigonelline determination in serum by the use of hydrophilic interaction liquid chromatography (HILIC) with ESI‐MS/MS detection. Separation of trigonelline was achieved on a Kinetex HILIC column operated at 35°C with acetonitrile–ammonium formate (10 mm , pH = 3) buffer mixture (55:45, v/v) as the mobile phase. The developed method was successfully applied to determine trigonelline concentration in mouse serum after intravenous administration of 10 mg/kg. The developed assay is sensitive (limit of detection = 1.5 ng/mL, limit of quantification = 5.0 ng/mL) and linear in a concentration range from 5.0 to 250.0 ng/mL. Sample preparation is limited to deproteinization, centrifugation and filtration. The application of the HILIC mode of chromatography with MS detection and selection of deuterated trigonelline as internal standard allowed a rapid and precise method of trigonelline quantification to be to developed.     

Simultaneous analysis of twenty-one glucocorticoids in equine plasma by liquid chromatography/tandem mass spectrometry

A method for the simultaneous separation, identification, quantification and confirmation of the presence of 21 glucocorticoids (GCC) in equine plasma by liquid chromatography coupled with triple stage quadrupole tandem mass spectrometry (LC/TSQ-MS/MS) is described. Plasma sample augmented with the 21 GCC was extracted with methyl tert-butyl ether (MTBE) and analyzed by positive electrospray ionization. Desoxymetasone or dichlorisone acetate was used as the internal standard (IS). Quantification was performed by IS calibration. For each drug, one major product ion was chosen and used for screening for that drug. Analyte confirmation was performed by using the three most intense product ions formed from the precursor ion and the corresponding mass ratios. The recovery of the 21 GCC when spiked into blank plasma at 5 ng/mL was 45-200% with coefficient of variation (CV) from 0.3-18%. The limit of detection (LOD) and that of quantification (LOQ) for most of the analytes were 50-100 pg/mL and 1 ng/mL, respectively, whereas that of confirmation (LOC) was 100-300 pg/mL depending on the analyte. Intra- and inter-day precisions expressed as CV for quantification of 1 and 10 ng/mL was 1.0-17%, and 0.51-19%, respectively, and the accuracy was from 84-110%. The linear concentration range for quantification was 0.1-100 ng/mL (r(2) > 0.997). Estimated measurement uncertainty was from 11-37%. This study was undertaken to develop a method for simultaneous screening, identification, quantification and confirmation of these agents in post-race equine plasma samples. The method has been successfully applied to screening of a large number of plasma samples obtained from racehorses in competition and in pharmacokinetic studies of dexamethasone in the horse and concurrent changes in endogenous GCC, hydrocortisone and cortisone. The method is simple, sensitive, selective and reliably reproducible.     

液相色谱-串联质谱法测定百日咳和百白破疫苗中百日咳杆菌气管细胞毒素

百日咳杆菌气管细胞毒素（TCT）是一种引起百日咳及百日咳相关疫苗不良反应的毒性糖肽。尽管各国药典均规定了百日咳疫苗产品中TCT的含量限度，但均没有推荐TCT的含量测定方法。该研究发展了一种液相色谱-串联质谱法用于TCT的含量测定。实验优化了包括色谱柱类型和流动相组成在内的TCT色谱条件。虽然TCT在反相色谱模式和亲水作用色谱（HILIC）模式下均具有较好的保留，但HILIC模式与蛋白质沉淀的前处理方法兼容性更好，因此采用HILIC模式分离TCT。优化所得的方法具有较宽的线性范围（5.76~369 ng/L），良好的重复性（峰面积的相对标准偏差不大于3.9%），各种基质中均有较好的回收率（96.4%~102.5%），且定量限是药典要求的TCT最高限量的1/1279。将本方法用于共纯化百日咳疫苗、组分百日咳疫苗、共纯化无细胞百白破疫苗和组分无细胞百白破疫苗中TCT的检测，所有产品均未检出TCT，表明被检样品具有较好的工艺条件可避免TCT在产品中的残留。     

Detection of organophosphate pesticides in human body fluids by headspace solid-phase microextraction (SPME) and capillary gas chromatography with nitrogen-phosphorus detection

Summary Organosphosphate pesticides have been found extractable by headspace solid-phase microextraction (SPME), and the best conditions of their extraction from human whole blood and urine samples have been investigated. The body fluid samples containing nine pesticides (IBP, methyl parathion, fenitrothion, malathion, fenthion, isoxathion, ethion, EPN and phosalone) were heated at 100°C in a septum-capped vial in the presence of various combinations of acid and salts, and SPME fiber was exposed to the headspace of the vial to allow adsorption of the pesticides before capillary gas chromatography (GC) with nitrogen-phosphorus detection. The heating with distilled water/HCl/(NH₄)₂SO₄/NaCl and with distilled water/HCl gave the best results for urine and whole blood, respectively. Recoveries of the nine pesticides were 0.8–10.6% except for phosalone (0.03%) for whole blood, and 3.8–40.2% for urine. The calibration curves for the pesticides showed linearity in the range of 50–400 ng/0.5 mL for whole blood except for malathion (100–400 ng/0.5 mL whole blood) and 7.5–120 ng/0.5 mL for urine except for phosalone (15–120 ng/0.5 mL urine) with detection limits of 2.2–40 ng/0.5 mL for whole blood and 0.8–12 ng/0.5 mL for urine.     

High-performance liquid chromatography of lactose with evaporative light scattering detection, applied to determine fine particle dose of carrier in dry powder inhalation products

A method for quantification of the fine particle dose of lactose is described, using a hydrophilic interaction chromatography (HILIC) method and evaporative light scattering detection. The HILIC method used an aminopropyl column and a mobile phase consisting of acetonitril/water (80/20, v/v) for isocratic elution. Sensitive chromatography was obtained using a low concentration of water in the extraction solvent. The detection limit (RSD<10%) at an injection volume of 10 microL is 10 microg/mL. Linearity was obtained in the range of 10-80 microg/mL (R(2)>0.99). A relative standard deviation (RSD) of 0.5% (N=6) demonstrated good precision of the optimized method.     

聚[2-(丙烯酰氧基)乙基]三甲基氯化铵-乙二醇二甲基丙烯酸酯整体柱固相萃取结合高效液相色谱法测定尿液中3种苯二氮（卄卓）类药物

以[2-（丙烯酰氧基）乙基]三甲基氯化铵（DAC）为单体,乙二醇二甲基丙烯酸酯（EDMA）为交联剂在注射器中制备聚合物整体柱,用其固相萃取尿液中溴西泮（BRZ）、劳拉西泮（LRZ）和地西泮（DZP）3种苯二氮（卄卓）类药物（BZDs）,并采用高效液相色谱法（HPLC）分析。实验考察了整体柱聚合时间及固相萃取条件（淋洗溶液、洗脱溶剂种类和体积）对BZDs萃取效率的影响。结果表明,仅聚合4 h得到的整体柱对BZDs吸附效率为100%。取尿液样品4 mL上样,用4 mL H₂O冲洗,1 mL乙酸乙酯洗脱,采用高效液相色谱分析。在最优条件下,3种BZDs在4.0~1000 ng/mL范围内线性关系良好（r=0.999）,检出限（S/N=3）和定量限（S/N=10）分别为1.0~1.2 ng/mL和3.3~4.0 ng/mL;在10、25和50 ng/mL加标水平下回收率为81.4%~102%,日内（n=3）和日间（n=3）相对标准偏差分别为1.2%~4.5%和2.5%~8.3%。该整体柱可对尿液中3种BZDs有效净化,且富集达12~15倍。方法构筑的聚合物整体柱制备简单,萃取高效,可成功用于尿液中3种BZDs的分析。     

Determination of gabapentin in human plasma using hydrophilic interaction liquid chromatography with tandem mass spectrometry

A rapid, sensitive and selective method for the determination of gabapentin in human plasma was developed using hydrophilic interaction liquid chromatography/tandem mass spectrometry (HILIC/MS/MS). The devised method involved protein precipitation with acetonitrile followed by separation on an Atlantis HILIC silica column using an acetonitrile/ammonium formate mobile phase (100 mM, pH 3.0) (85:15, v/v). Analytes were detected using an electrospray ionization mass spectrometer in the multiple-reaction monitoring mode. The standard curve was linear (r = 1.000) over the concentration range of 50.0-10000 ng/mL. The lower limit of quantification for gabapentin was 50.0 ng/mL (ca. 20 pg gabapentin) using a 10-microL plasma sample. The coefficients of variation and relative errors for intra- and inter-assay at four QC levels (i.e., 50.0, 125, 750, and 7500 ng/mL) were 4.7 to 9.4% and -4.1 to 1.6%, respectively. Absolute and relative matrix effects for gabapentin and metformin were practically absent. Gabapentin and metformin recoveries were 98.5% and 99.0%, respectively. This method was successfully applied to a bioequivalence study of gabapentin in humans.     

高效液相色谱-柱后衍生法检测养殖水体及沉积物中11种磺胺药物残留

建立了养殖水体及沉积物中11种磺胺化合物的高效液相色谱-柱后衍生分析方法。养殖水体过滤后采用HLB固相萃取柱进行净化、富集;沉积物采用甲醇/EDTA-Mcllvaine缓冲液(1:1, v/v)提取,HLB固相萃取柱净化富集。经高效液相色谱分离,用荧光胺衍生试剂进行柱后衍生,荧光检测器检测。对柱后衍生系统参数进行了优化,确定了荧光胺溶液的浓度、流速和反应温度分别为0.2 g/L、0.15 mL/min和50 ℃,磺胺化合物在0.01~1.0 mg/L范围内线性显著,其相关系数r²值大于0.99995。11种磺胺类药物在养殖水体和沉积物中的加标回收率分别为79.3%~100.7%和74.6%~95.3%,相对标准偏差为2.2%~11.0%和2.6%~10.3%,检出限(LOD, S/N=3)为0.9~5.5 ng/L和0.3~1.3 μg/kg,定量限(LOQ, S/N=10)为3.0~18.1 ng/L和1.0~4.4 μg/kg。该法可应用于养殖环境中磺胺类药物的定性定量检测,具有较好的实用性。     

Separation of monosaccharides by hydrophilic interaction chromatography with evaporative light scattering detection

Hydrophilic interaction liquid chromatography (HILIC) was used to separate monosaccharides that are common in N-linked oligosaccharides in glycoproteins and other compounds. A TSKgel Amide-80 column was eluted with 82% acetonitrile, in 5 mM ammonium formate (pH 5.5). Column temperature was 60 degrees C and evaporative light scattering was used for detection (ELSD). With this method, L-fucose, D-galactose, D-mannose, N-acetyl-D-glucosamine, N-acetylneuraminic acid, and D-glucuronic acid were separated, with detection limits of 0.3-0.5 microg for each monosaccharide, and intermediate precisions were 3-6% RSD (n=6).     

基于整体柱的固相萃取-高效液相色谱法测定尿液中4种羟基多环芳烃

建立了基于聚合物整体柱的固相萃取-高效液相色谱测定尿液中4种羟基多环芳烃（OH-PAHs）的分析方法。在注射器管中合成聚（甲基丙烯酸丁酯-乙二醇二甲基丙烯酸酯）整体柱（poly （BMA-co-EDMA））,并将其用于尿液中4种羟基多环芳烃的前处理,同时考察了上样浓度、淋洗液、洗脱液和洗脱体积对萃取效率的影响。结合高效液相色谱-荧光分析,4种羟基多环芳烃在各自的范围内线性关系良好（r≥0.9991）;方法的检出限和定量限分别为0.06~0.09 ng/mL和0.20~0.30 ng/mL;日内（n=5）和日间（n=3）精密度分别为1.4%~5.3%和2.6%~7.3%。对焦炉工人尿液样品进行加标（3 ng/mL）回收试验,回收率为78.2%~117.0%。该固相萃取柱能够有效萃取和净化尿液中4种羟基多环芳烃,并且可以重复使用。该法简单、准确,可应用于尿液中羟基多环芳烃的分析。     

Identification and quantification of nucleosides and nucleobases in Geosaurus and Leech by hydrophilic-interaction chromatography

A simple hydrophilic-interaction chromatography (HILIC) method was developed for the identification and quantification of 14 nucleosides and nucleobases, namely cytosine, uracil, cytidine, guanine, hypoxanthine, xanthine, uridine, thymine, inosine, guanosine, thymidine, 2′-deoxyadenosine, 2′-deoxyinosine and 2′-deoxyuridine in two traditional Chinese medicines, Geosaurus and Leech. The separation was achieved on a TSKgel Amide-80 column (150 mm × 2.0 mm, 3.0 μm) with a mixture of acetonitrile and 10 mM aqueous ammonium acetate as the mobile phase at a flow rate of 0.2 mL/min. The temperature was set at 30 °C and UV detection wavelength was set at 260 nm. All calibration curves showed good linearity (R² > 0.9957) within the test ranges. The overall intra- and inter-day RSD ranged from 0.4 to 3.4% and from 0.7 to 3.3%, respectively. The LOD and LOQ were in the range of 0.07-30.49 ng/mL and 0.26-60.98 ng/mL, respectively. The repeatability of the method was in the range of 2.2-5.8% for Geosaurus and 1.4-5.5% for Leech. The recoveries of the samples were in the range of 91.4-100.9% for Geosaurus, and 91.9-99.3% for Leech. The established method was applied successfully for the analysis of nucleosides and nucleobases in 22 commercially available samples collected from different regions in China and Japan. Our data showed that HILIC had advantages as a useful tool for the study of the bioactive components in Geosaurus and Leech as well as their quality control, and could therefore be used for the determination of the analytes in pharmaceutical products and biological fluids.     

Separation of phospholipid classes by hydrophilic interaction chromatography detected by electrospray ionization mass spectrometry

A new isocratic separation method was developed for separation of phospholipid (PL) classes based on a silica hydrophilic interaction liquid chromatography (HILIC) column with electrospray ionization (ESI) mass spectrometric detection. Although HILIC is typically used for polar compounds, also amphiphilic molecules like phospholipids can be separated very well. Compared to normal-phase (NP) chromatography, which is usually used for PL class separation, HILIC has the advantage to use on-line ESI-MS detection because its eluents are ESI compatible. Furthermore, this HILIC method is isocratic and hence less time consuming than most (gradient) NP HPLC methods. A chromatographic baseline separation of a standard mixture containing phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), sphingomyelin (SM) and lysophosphatidylcholine (LPC) was achieved within a total run time of 17 min using a mobile phase consisting of acetonitrile, methanol and ammonium acetate 10 mM. The new method was subsequently tested on phospholipid fractions of a body fluid (human blood plasma) and a tissue extract (swine brain) whereby it achieved nearly the same baseline separation of the PL classes. The detected classes in both cases were PE, PC, SM and LPC.     

Synthesis of heparin oligosaccharides and their interaction with eosinophil-derived neurotoxin

A convenient route for the synthesis of heparin oligosaccharides involving regioselective protection of D-glucosamine and a concise preparation of rare L-ido sugars from diacetone α-D-glucose is described. Stereoselective coupling of a D-glucosamine-derived trichloroacetimidate with a 1,6-anhydro-β-L-idopyranosyl 4-alcohol gave the desired α-linked disaccharide, which was used as repeating unit for dual chain elongation and termination. Stepwise assembly from the reducing to the non-reducing end with a D-glucosamine-derived monosaccharide as starting unit furnished the oligosaccharide skeletons having different chain lengths. A series of functional group transformations afforded the expected heparin oligosaccharides with 3, 5 and 7 sugar units. Interaction of these oligosaccharides with eosinophil-derived neurotoxin (EDN), a cationic ribonuclease and a mediator produced by human eosinophils, was further investigated. The results revealed that at 5 μg mL(-1), the heptasaccharide has sufficiently strong interference to block EDN binding to Beas-2B cells. The tri- and pentasaccharides have moderate inhibitory properties at 50 μg mL(-1) concentration, but no inhibition has been observed at 10 μg mL(-1). The IC(50) values of the tri-, penta- and heptasaccharides are 69.4, 47.2 and 0.225 μg mL(-1), respectively.     

以亲水作用色谱为核心的液相色谱联用技术及其应用研究

亲水作用色谱(HILIC)是近年来色谱领域研究的热点之一。本文围绕复杂体系样品中亲水性组分的分离分析,综述了国际上近年 来发展的以HILIC为核心的多种液相色谱联用技术及其应用。简要介绍了HILIC的起源、定义、分离特点及其常用固定相;比较了HILIC和反相色谱(RPLC)的选择特性;针对不同层次的分离对象和分离要求,讨论了多种基于HILIC的液相色谱以及液相色谱-质谱联用技术的分离特点和适用范围。     

Retention behavior of peptides in hydrophilic-interaction chromatography

Selected hydrophilic interaction chromatography (HILIC) columns packed with bare silica, bridge-ethyl hybrid silica, or an amide sorbent chemistry were utilized for an investigation of chromatographic behavior and separation selectivity of tryptic peptides. Retention model was proposed allowing for retention prediction of peptides with correlation coefficient R(2)~0.92-0.97 for various columns. The values of optimized amino acid retention coefficients were compared to those obtained for reversed-phase liquid chromatography (Gilar et al., Anal. Chem. 2010, 82, 265-275) and used to elucidate the impact of different amino acid on peptide HILIC retention. In contrast to reversed-phase chromatography, where presence of Phe, Trp, Ile, and Leu amino acid residues in sequence strongly promoted, and presence of hydrophilic His, Lys and Arg residues strongly reduced peptide retention, the effects of these amino acid residues in HILIC were opposite (His, Lys and Arg promote, Phe, Trp, Ile and Leu demote peptide retention in HILIC). Retention coefficient optimized for pH experiments illustrated the impact of silanols on HILIC retention.