A polar-copolymerized method to prepare silica-based anion exchanger for ion chromatography

A novel silica-based strong anion exchanger was developed for ion chromatography by copolymerizing methyltrichlorosilane and 3-chloropropyltrichlorosilane. The method allows the column capacity to be easy control simply by adjusting the ratio of silanes. The unwanted residual silanol groups onto the surface of silica gel could also be greatly reduced by this strategy. The effective column capacity of the column used was measured to be 50.8 μequiv/column (2.03 μequiv/cm). The exchanger was characterized by solid state CP/MAS ¹³C NMR and elemental analysis and its separation performance was evaluated for the separation of common inorganic anions. The results showed that the column had good separation efficiency (e.g. the plate number of nitrite is 80,000/m) and the separation mechanism was observed to be dominantly governed by ion exchange mechanism. The utility of the column was demonstrated for the determination of nitrite and nitrate in saliva sample.     

基于QuEChERS前处理技术和弱阳离子交换色谱的牛奶和奶粉中三聚氰胺的快速检测方法

应用QuEChERS前处理技术,并结合弱阳离子交换色谱,建立了牛奶和奶粉中三聚氰胺的快速检测方法。样品使用医用酒精(乙醇含量75%)和一种新型脂肪吸附(LAS)材料超声振荡处理,在沉淀(吸附)蛋白质和脂肪的同时提取三聚氰胺,然后经8000 r/min离心,上清液过膜直接分析。色谱分析在弱阳离子交换色谱柱(WCX)上进行,采用2 mmol/L pH为3.8的磷酸二氢钾水溶液为流动相,在5 min内实现分离分析。结果表明,该方法在0.02～20 mg/L内线性相关系数大于0.9999。在1～50 mg/kg添加浓度范围内,牛奶的平均回收率为98.9%～105.2%,相对标准偏差(RSD)为0.9%～3.4%;奶粉的平均回收率为86.4%～102.9%, RSD为1.5%～6.7%。本方法的检出限为0.05 mg/kg(牛奶)和0.1 mg/kg(奶粉)。整个分析检测过程没有使用有毒有害有机溶剂,是一种绿色的分析方法。     

Selective separation of structure-related alkaloids in Rhizoma coptidis with "click" binaphthyl stationary phase and their structural elucidation with liquid chromatography-mass spectrometry

It is a new task to separate structure-related compounds into a fraction according to their structural characteristics in a complex traditional Chinese medicine (TCM). This method makes separation of the components of the sample simple and structural elucidation easy. In this study, selective separation of alkaloids in Rhizoma coptidis was realized on a "click" binaphthyl column possessing a planar conjugate structure. Three kinds of alkaloids, aporphine, tetrahydroprotoberberine and protoberberine in Rhizoma coptidis showed better retention than other compounds by virtue of π-π interactions with the stationary phase. Moreover, the "click" binaphthyl column could distinguish the aporphine and tetrahydroprotoberberine alkaloids possessing two benzene rings from the protoberberine alkaloids possessing three benzene rings. After separating on the "click" binaphthyl column, the fractions containing the alkaloids were collected and then analyzed with liquid chromatography-mass spectrometry (LC-MS). Totally, 23 alkaloids were identified, and among these alkaloids, three tetrahydroprotoberberine, two aporphine and seven protoberberine alkaloids were first found in Rhizoma coptidis. These newly found alkaloids are minor compounds, and they are always neglected without eliminating the interference of compounds in large amounts by pre-separation on the "click" binaphthyl column. The typical fragmentation pathways of each class of alkaloids were summarized to illustrate their structures. In the MS(2) spectrum, the loss of a molecule of dimethylamine ((CH(3))(2)NH) was observed as the characteristic loss of aporphine alkaloids. All the tetrahydroprotoberberine alkaloids would undergo the Retro-Diels-Alder (RDA) fragmentation reaction in the MS(2) fragmentation. For protoberberine alkaloids, different characteristic fragmentations were observed with different skeleton structures.     

反相液相制备色谱法结合超临界流体制备色谱法分离纯化海风藤中的化合物

建立了基于反相液相制备色谱和超临界流体制备色谱的组合方法,用于分离纯化醇提水沉后石油醚层中的海风藤。首先以甲醇作为改性剂,采用醇提水沉法去除海风藤甲醇提取物中的叶绿素,加入硅藻土后用石油醚回流富集目标成分。选用反相C18制备色谱柱将其分为18个组分,然后将组分在SFC模式下进行制备。选用酰胺色谱柱,以甲醇为改性剂,在柱温30℃、背压15.0 MPa的条件下进行分离。基于反相色谱和超临界流体色谱不同的分离选择性,最后分离得到6个高纯度化合物。该法展示了反相制备色谱和超临界流体制备色谱在海风藤分离纯化方面的优势,特别是超临界流体色谱在天然产物的分析和制备方面的巨大潜力。     

Blending Technology Based on HPLC Fingerprint and Nonlinear Programming to Control the Quality of Ginkgo Leaves

The breadth and depth of traditional Chinese medicine (TCM) applications have been expanding in recent years, yet the problem of quality control has arisen in the application process. It is essential to design an algorithm to provide blending ratios that ensure a high overall product similarity to the target with controlled deviations in individual ingredient content. We developed a new blending algorithm and scheme by comparing different samples of ginkgo leaves. High-consistency samples were used to establish the blending target, and qualified samples were used for blending. Principal component analysis (PCA) was used as the sample screening method. A nonlinear programming algorithm was applied to calculate the blending ratio under different blending constraints. In one set of calculation experiments, the result was blended by the same samples under different conditions. Its relative deviation coefficients (RDCs) were controlled within ±10%. In another set of calculations, the RDCs of more component blending by different samples were controlled within ±20%. Finally, the near-critical calculation ratio was used for the actual experiments. The experimental results met the initial setting requirements. The results show that our algorithm can flexibly control the content of TCMs. The quality control of the production process of TCMs was achieved by improving the content stability of raw materials using blending. The algorithm provides a groundbreaking idea for quality control of TCMs.