Chemical profiling of Ziziphi spinosae semen using on-line comprehensive two-dimensional liquid chromatography-mass spectrometry based on a novel phthalic anhydride bonded stationary phase

Ziziphi spinosae semen has been widely used to treat insomnia and anxiety. To profile its chemical components, an online comprehensive two-dimensional liquid chromatography-mass spectrometry was developed. In this two-dimensional liquid chromatography system, a novel phthalic anhydride-bonded stationary phase column was combined with a C18 column. As a result, this new stationary phase exhibited remarkable differences in separation selectivity from C18, achieving a good orthogonality of 83.3%. Moreover, this new stationary phase with weaker hydrophobicity than C18 realized solvent compatibility in the online configuration. Coupled with tandem MS, 154 compounds were identified, including 51 unreported compounds. Compared with one-dimensional liquid chromatography-mass spectrometry, this online two-dimensional liquid chromatography-mass spectrometry system exhibited a much higher resolving power in isomer separation. This work provided an effective separation and characterization method for the material basis of Ziziphi spinosae semen. This strategy provides ideas for the material basis research of other traditional Chinese medicines.     

Synthesis and evaluation of a maltose‐bonded silica gel stationary phase for hydrophilic interaction chromatography and its application in Ginkgo Biloba extract separation in two‐dimensional systems

Maltose covalently bonded to silica was prepared by using carbonyl diimidazole as a cross‐linker and employed as a stationary phase for hydrophilic interaction liquid chromatography. The column efficiency and the effect of water content, buffer concentration, and pH value influenced on retention were investigated. The separation or enrichment selectivity was also studied with nucleosides, saccharides, amino acids, peptides, and glycopeptides. The results indicated that the stationary phase processed good separation efficiency and separation selectivity in hydrophilic interaction liquid chromatography mode. Moreover, a two‐dimensional hydrophilic interaction liquid chromatography× reversed‐phase liquid chromatography method with high orthogonality was developed to analyze the Ginkgo Biloba extract fractions. The development of this two‐dimensional chromatographic system would be an effective tool for the separation of complex samples of different polarities and contents.     

High performance liquid chromatography-mass spectrometry analysis of protoberberine alkaloids in medicine herbs

RP-HPLC is the main method for the analysis of alkaloids. However, peak tailing is a problem that commonly occurs in the separation of alkaloids. In order to overcome this, three kinds of RP columns were compared for the analysis of protoberberine alkaloids in Coptidis Rhizoma and Phellodendri Cortex in this work. XTerra MS C18 column was the best one which gave the best symmetry factor under the same conditions. With this column, a good separation of the crude extracts of C. Rhizoma and P. Cortex was achieved using 0.1% v/v formic acid buffer and methanol as mobile phase. At the same time, the crude extracts of C. Rhizoma and P. Cortex were analyzed by the LC-ESI-MSn and LC-atmospheric pressure chemical ionization (APCI)-MSn methods. In the analysis of HPLC-ESI/MSn, structures of five protoberberine alkaloids were elucidated, compared to authentic standards, and data from the literature. At the same time, the structure of a novel compound was elucidated. In the HPLC-APCI/ MSn analysis, there was an interesting phenomenon that the relative abundance of the ions M+ and [M + 2]+ was different for different alkaloids. The possible fragmentation pathways of protoberberine alkaloids in APCI/MS analysis were studied for the first time in the present work.     

Studies of iridoid glycosides using liquid chromatography/electrospray ionization tandem mass spectrometry

Fragmentation pathways of five iridoid glycosides have been studied by using electrospray ionization multi-stage tandem mass spectrometry (ESI-MS(n)). The first-stage MS data of the five iridoid glycosides were compared. The MS spectra showed that the adduct ions of iridoid glycosides and the formate anion were diagnostic ions to distinguish iridoid glycosides with a carboxyl group at the C-4 position or an ester group at the C-4 position. The MS fragmentation pathways of the five iridoid glycosides were also studied. Analyzing the product ion spectra of iridoid glycosides, some neutral losses were observed, such as H(2)O, CO(2) and glucose residues, which were very useful for the identification of the functional groups in the structures of iridoid glycosides. Furthermore, specific loss of one molecule of methyl 3-oxopropanoate or 3-oxopropanic acid was firstly discussed, which corresponded to the isomerization of the hemiacetal group in the structure of iridoid aglycone. According to the fragmentation mechanisms and HPLC/MS(n) data, the structures of five iridoid glycosides in a crude extract of Gardenia jasminoisdes fruit have been identified. Three compounds were compared with standards and the other two were identified as shanzhiside and genipin gentibioside by their MS(n) data without standard compounds. In order to further validate the veracity of the deduction, genipin gentiobioside was isolated from the extract of Gardenia jasminoisdes fruit using Purification Factory and was further identified by C- and H-NMR.     

Synergy of Single‐ion Conductive and Thermo‐responsive Copolymer Hydrogels Achieving Anti‐Arrhenius Ionic Conductivity

Artificial intelligence sensations have aroused scientific interest from electronic conductors to bio‐inspired ionic conductors. The conductivity of electrons decreases with increasing temperature, while the ionic conductivity agrees with an Arrhenius equation or a modified Vogel–Tammann–Fulcher (VTF) equation. Herein, thermo‐responsive poly(N‐isopropyl amide) (PNIPAm) and single‐ion‐conducting poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic lithium salt) (PAMPSLi) were copolymerized via a facile radical polymerization to demonstrate a very intriguing anti‐Arrhenius ionic conductivity behaviour during thermally induced volume‐phase transition. These smart hydrogels presented very promising scaffolds for architecting flexible, wearable or advanced functional ionic devices.     

螺旋霉素分子印迹磁性纳米吸附剂的合成及应用

制备了一种以螺旋霉素为模板分子的分子印迹磁性纳米吸附剂。以磁性纳米Fe₃O₄为内核,经丙烯酸表面修饰后再以螺旋霉素为模板分子、甲基丙烯酸为功能单体、乙二醇二甲基丙烯酸酯为交联剂,通过表面自由基聚合反应制备得到。该吸附剂对螺旋霉素、交沙霉素、替米考星和酒石酸泰乐菌素4种大环内酯类抗生素表现出良好的富集效果（富集倍数分别为310、118、758和72）,其选择性明显优于常规C₁₈吸附剂。该吸附剂可重复使用至少6次。结合高效液相色谱-紫外检测器建立了上述4种抗生素的分析方法。方法检出限为0.53~2.75 μg/L,定量限为1.78~9.16 μg/L;在50、100和150 μg/L低中高3个添加水平下,方法回收率在80.78%~123.02%之间,相对标准偏差<15.8%（n=5）。该方法被应用于分析蜂蜜中的上述4种抗生素。     

糖类化合物在两性离子亲水作用色谱柱上的保留行为评价

糖类化合物因其极性强,在反相色谱模式下保留较弱,因此常用亲水作用色谱(HILIC)对其进行分离分析。本文以9种糖类化合物的混合物为研究对象,系统评价了其在Click TE-Cys亲水色谱柱上的保留行为,分别考察了流动相中有机相比例和盐浓度对其保留行为的影响。实验证明:9种糖类化合物按极性由小到大的顺序依次从Click TE-Cys色谱柱上被洗脱下来。随着有机相比例的增加,糖类化合物的保留增强;随着盐浓度的增加,除唾液酸外的糖类化合物的保留增强。用顶替-吸附液相相互作用模型模拟了糖类化合物在HILIC上的保留行为,采用保留方程ln k=a+blnC_B+cC_B描述HILIC的保留规律,对HILIC的保留值进行多元线性回归。结果表明糖类化合物在Click TE-Cys色谱柱上的保留行为符合HILIC的保留规律。     

碳青霉烯类抗生素亲水作用色谱方法研究及其应用

建立了测定人尿液和自来水中4种碳青霉烯类抗生素(比阿培南、美罗培南、多利培南和厄他培南)的亲水作用色谱方法,所用流动相具有较好的质谱兼容性,可用于色谱-质谱联用。以XAmide为色谱柱,考察了乙腈比例、缓冲盐浓度和pH值对4种抗生素保留的影响,提出了可能的保留机理;所发展的方法对目标样品具有良好的线性响应:比阿培南、多利培南和厄他培南的线性范围为0.1~250 mg/L, R²=0.9999;美罗培南的线性范围为0.5~250 mg/L, R²=0.9998; 4种抗生素的定量限(LOQ)为0.1~0.5 mg/L。尿液样品和自来水样品在5 mg/L和25 mg/L两个水平的加标回收率分别为100.4%~111.9%和79.6%~107.4%,相对标准偏差(RSD)分别不大于1%和5%。该方法准确、灵敏、简便,可用于人尿液和自来水中多种碳青霉烯类抗生素的检测。     

高效液相色谱-大气压化学电离质谱联用分析天然(口山)酮甙类化合物

利用高效液相色谱大气压化学电离质谱联用技术,探讨了酮单糖甙和酮双糖甙在负离子模式下的质谱断裂特点,比较相同条件下不同酮甙的质谱图,借助[Y0-1]-.和Y0-离子的相对丰度关系探讨了糖基的性质对断裂规律的影响。同时借助[Y0-1]-.、Y1-及Z1-离子的丰度实现对双糖基为1→2与1→6连接的酮双糖甙的区分。     

Retention properties of novel β-CD bonded stationary phases in reversed-phase HPLC mode

With the given special structures, the CD bonded stationary phases are expected to have complementary retention properties with conventional C18 stationary phase, which will be helpful to enhance the polar selectivity in RP mode separation. In this work, two β-cyclodextrin (β-CD) bonded stationary phases for reversed-phase HPLC, including 1, 12-dodecyldiol linked β-CD stationary phase (CD1) and olio (ethylene glycol) (OEG) linked β-CD stationary phase (CD2), have been synthesized via click chemistry. The resulting materials were characterized with FT-IR and elemental analysis, which proved the successful immobilization of ligands. The similarities and differences in retention characteristics between the CD and C18 stationary phases have been elucidated by using comparative linear solvation energy relationships (LSERs). The force related to solute McGowan volume has no significant difference, while the hydrogen bonding and dipolar interactions between solutes and CD stationary phases are stronger than between solutes and C18, which is attributed to the special structures (CD and triazole groups) of CD stationary phases. Chemical origins are interpreted by comparison between CD1 and CD2. Similar dispersive interactions of CD1 and CD2 are attributed to their similar length of spacer arms. CD2 which contains OEG spacer arm has relative weaker HBD acidity but stronger HBA basicity. CD stationary phases display no serious different methylene selectivity and higher polar selectivity than in the case of C18. Higher acid selectivity and lower basic selectivity are observed on CD2 than on CD1. Distinctive retention properties and good complementary separation selectivity to C18 make the novel CD bonded stationary phases available for more application in RPLC.