Preparative argentation reversed-phase high performance liquid chromatography

In this study, a preparative chromatography method named preparative argentation reversed-phase high performance liquid chromatography (Ag-RP-HPLC) was developed by adding silver ion to the mobile phase of preparative HPLC. Firstly, an analytical Ag-RP-HPLC method was developed, and the effects of silver content and acid content in the mobile phase on the column efficiency were studied. Based on the method of linear amplification, a preparative Ag-RP-HPLC technique with optimized separation conditions was developed. The new technique was applied successfully to the separation of the unsaturated aliphatic acid amide isomers contained in Asarum forbesii Maxim. Compared with the commonly used technique of argentation normal phase chromatography, this method with little solvent consumption is simple, fast, efficient, and flexible for the isolation and purification of the unsaturated compounds.     

Enhancement of selectivity in reversed-phase liquid chromatography

In an effort to gain insight into the relationship between stationary phase solvation and selectivity, the use of short- and medium-chained-length alcohols (methanol, n-propanol, n-butanol, and n-pentanol) as mobile phase modifiers in reversed-phase liquid chromatography (RPLC) was investigated to determine their impact on chromatographic selectivity. A wide range of mobile phase compositions was evaluated because of the large effect exerted by solvent strength on selectivity. Employing a set of six vanillin compounds as retention probes, evidence is presented to support the view that an increase in the hydrophobicity of the organic modifier used in RPLC can increase the selectivity of the C18 alkyl bonded phase while simultaneously decreasing the retention time of the eluting solutes. Thus, we are presented with an interesting paradox: higher selectivity and shorter retention times, which can be attributed to changes in either solvent selectivity and/or stationary phase solvation by the organic modifier.     

拟反相液相色谱法测定阿替洛尔

采用极性色谱柱配以高水量的流动相,建立了测定阿替洛尔的一种新方法—拟反相色谱法,流动相为乙腈-水(甲酸钠溶液0.03 mol/L,pH 2.9,5:95)。在此色谱体系中无需离子对试剂强极性的阿替洛尔即可得到很好的保留,流动相的组成得以简化,在降低测定费用的同时,使方法开发更为迅速;特别是流动相中乙腈的比例只占5%,降低了有机溶剂的消耗和排放。方法已用于阿替洛尔片剂和尿样分析,在线性范围0.5～200μg/mL内(r=0.9995,n=6),加标回收率为95.4%～97.2%。     

反相高效液相色谱手性拆分特布他林

采用新型商品手性柱ShiseidoCD Ph,在反相条件下,对β受体阻滞剂类药物特布他林进行了手性拆分研究。考察了流动相组成、pH、柱温及缓冲盐浓度对特布它林手性拆分的影响。在优化的实验条件下,该药物获得基线分离。该方法可用于该类药物的常规分析。     

高效液相色谱法分析硫双灭多威

研究了用高效液相色谱分析杀虫剂硫双灭多威的方法。在反相ＯＤＳ柱上,用甲醇－水作流动相,紫外检测器检测,以邻苯二甲酸二甲酯作内标定量。方法快速、准确,重现性好,线性范围宽,变异系数为０．１８％,回收率为９９．８９％,色谱分析周期仅为８ｍｉｎ。     

固相萃取RP-HPLC测定小鼠肝脏组织中的多沙唑嗪

研究建立了小鼠肝脏组织中多沙唑嗪的反相高效液相色谱测定方法. 肝组织样品经过匀浆、提取、C18固相萃取小柱富集净化后, 在YMC C18色谱柱(4.6 mm i.d.×250 mm, 5 μm)上, 以V(甲醇)∶V(0.02 mol/L KH2PO4) ＝70∶30, pH 3.0为流动相, 流速0.6 mL/min, 检测波长246 nm对多沙唑嗪进行测定. 结果表明, 肝脏组织中的多沙唑嗪在0.5～10 μg/mL范围内与峰面积呈良好线性关系. 平均回收率为91.0%, RSD为3.3%. 检出限为1 ng. 方法操作简便, 重现性好, 适用于肝脏组织中多沙唑嗪药物的浓度测定及代谢研究.     

反相高效液相色谱法测定盐酸索他洛尔

 建立了用于盐酸索他洛尔的含量测定、有关物质的检查和稳定性考察的 RP-HPL C法。采用 ODS柱、体积分数为 0 .1 %的乙酸水溶液 -乙腈 (体积比为 80∶ 2 0 )为流动相的色谱条件 ,以磺胺二甲基嘧啶为内标物 ,测定的线性范围为 5～ 45 mg/ L(r=0 .9991 ) ,日内精密度为 0 .2 0 % ,日间精密度为 0 .93 %。     

Column selectivity in reversed-phase liquid chromatography III. The physico-chemical basis of selectivity

Reversed-phase liquid chromatography (RP-LC) retention data for 23 additional solutes have been acquired to further test and evaluate a general relationship from part I: log alpha = log (k/kref) = eta'H(i) + sigma'S(ii) beta'S(iii) + alpha'B(iv) +kappa'C(v) The physico-chemical origin of terms i-v above is examined here by comparing values of (a) the solute parameters of Eq. (1) (eta', sigma', etc.) vs. solute molecular structure, and (b) the column parameters (H, S, etc.) vs. column properties (ligand length and concentration, pore diameter, end-capping). We conclude that terms i-v correspond, respectively, to hydrophobic (i), steric (ii), hydrogen bonding (iii, iv) and ionic (v) interactions between solute and stationary phase. While steric interaction (term ii) is superficially similar to what previously has been defined as "shape selectivity", the role of the solute and column in determining steric selectivity (term ii) appears more complex than previously proposed for "shape selectivity". Similarly, what has previously been called hydrogen bonding between donor solutes and an acceptor group in the stationary phase (term iv) is very likely an oversimplification.     

反相高效液相色谱法同时测定化妆品中的9种糖皮质激素

建立了化妆品中9种糖皮质激素的反相高效液相(RP-HPLC)测定方法.采用酸化甲醇振荡提取,HLB固相萃取小柱净化,HPLC分离测定.在定量范围内均呈良好的线性关系(r≥0.999);回收率为85.0%～99.5%,相对标准偏差小于5.8%,检出限(LOD) (S/N≥3)为1.0 ng,定量限(LOQ) (S/N≥10)为2.0 ng.该法可用于化妆品中泼尼松龙、氢化可的松、可的松、甲基强的松龙、地塞米松、氟米松、倍氯米松、曲安奈德和氟轻松的检测.     

反相高效液相色法测定水产品中三聚氰胺

采用反相高效液相色谱法(RP-HPLC) 测定了水产品中的三聚氰胺. 色谱柱为Symmetry C18 (5 μm, 4.6 mm×250 mm), 流动相为含有0.01 mol/L庚烷磺酸钠和0.01 mol/L柠檬酸的乙腈(1+4)水溶液, 检测器为紫外检测器, 检测波长240 nm. 线性范围为1～50 μg/mL, 相关系数为0.9998, 最低检出限为0.24 μg/mL, 样品平均加标回收率为78.8%～96.1%, 相对标准偏差为3.7%～6.4%. 方法可用于水产品中三聚氰胺的测定.     

Analysis of selected ionic liquid cations by ion exchange chromatography and reversed-phase high performance liquid chromatography

The chromatographic behavior of 8 ionic liquids - 7 homologues of 1-alkyl-3-methylimidazolium and 4-methyl-N-butylpyridinium - has been investigated with a strong cation exchange adsorbent. In particular, the dependence of the retention properties of these solutes on mobile phase composition, pH, and buffer concentration was evaluated with the aim of optimizing and improving the selectivity and retention of solute separation. While using the SCX stationary phase, several interactions occurred with varying strengths, depending on the mobile phase composition. Cation exchange, nonspecific hydrophobic interactions, and adsorption chromatography behavior were observed. Reversed phase chromatography occurred at low concentrations of acetonitrile, electrostatic and adsorption interactions at higher organic modifier concentrations. Elevated buffer concentrations lowered the retention factors without affecting the selectivity of ionic liquids. Obtained results were further compared to the chromatographic behaviour of ionic liquids in the reversed phase system. All analyzed ionic liquids follow reversed-phase behavior while being separated. Much lower selectivity in the range of highly hydrophilic compounds is obtained. This suggests preferred use of ion chromatography for separation and analysis of compounds below 4 carbon atoms in the alkyl side chain.     

Temperature selectivity effects in reversed-phase liquid chromatography due to conformation differences between helical and non-helical peptides

In order to characterize the effect of temperature on the retention behaviour and selectivity of separation of polypeptides and proteins in reversed-phase high-performance liquid chromatography (RP-HPLC), the chromatographic properties of four series of peptides, with different peptide conformations, have been studied as a function of temperature (5-80 degrees C). The secondary structure of model peptides was based on either the amphipathic alpha-helical peptide sequence Ac-EAEKAAKEX(D/L)EKAAKEAEK-amide, (position X being in the centre of the hydrophobic face of the alpha-helix), or the random coil peptide sequence Ac-X(D/L)LGAKGAGVG-amide, where position X is substituted by the 19 L- or D-amino acids and glycine. We have shown that the helical peptide analogues exhibited a greater effect of varying temperature on elution behaviour compared to the random coil peptide analogues, due to the unfolding of alpha-helical structure with the increase of temperature during RP-HPLC. In addition, temperature generally produced different effects on the separations of peptides with different L- or D-amino acid substitutions within the groups of helical or non-helical peptides. The results demonstrate that variations in temperature can be used to effect significant changes in selectivity among the peptide analogues despite their very high degree of sequence homology. Our results also suggest that a temperature-based approach to RP-HPLC can be used to distinguish varying amino acid substitutions at the same site of the peptide sequence. We believe that the peptide mixtures presented here provide a good model for studying temperature effects on selectivity due to conformational differences of peptides, both for the rational development of peptide separation optimization protocols and a probe to distinguish between peptide conformations.     

Buffered superheated water as an eluent for reversed-phase high performance liquid chromatography

Summary Inorganic buffers have been used to control the pH of a superheated water eluent for reversed-phase liquid chromatography. Using a temperature gradient from 70–190 °C, the relative order of elution of a series of sulfonamides on a polystyrene-divinyl benzene column was determined at pH 3, 7 and 11. The separations were compared with conventional reversed-phase separations on polymer and ODS-bonded silica columns. The apparent pK _a values of selected sulfonamides at elevated temperatures were determined from their retention factors across in a range of superheated buffers and the values were compared to those reported at room temperature.     

反相高效液相色谱法同时测定食品中14种食品添加剂

采用反相高效液相色谱法研究了一次进样、同时测定食品中苯甲酸、山梨酸、尼泊金甲酯、尼泊金乙酯、尼泊金丙酯、尼泊金丁酯,糖精钠、安赛密,柠檬黄、日落黄、胭脂红、苋菜红、亮蓝及咖啡因等14种食品添加剂的分析方法.实验采用Hypersil ODS柱(4.6×200 mm,5μm,DEAIC)为分离柱,以20 mmol/L乙酸铵(pH 6.8)-甲醇为流动相,用紫外检测器234 nm、254 nm下进行检测,整个分析过程在18 min内完成.被测样品经简单处理后进样,其平均加标回收率为94.5%～99.1%,相对标准偏差小于4.5%.方法适用于食品常规质量检测.     

反相高效液相色谱法同时测定化妆品中7种萘二酚类物质

建立了反相高效液相色谱((RP-HPLC))同时测定化妆品中7种萘二酚类物质的分析方法。膏霜类、乳液类和水类样品用95%(v/v)乙醇提取,粉类样品用95%乙醇-0.1%乙酸(3:2, v/v)溶液提取,经离心、过滤后,用C18柱,以甲醇-0.1%乙酸溶液为流动相梯度洗脱分离,使用二极管阵列检测器检测,以保留时间定性,并以紫外吸收光谱图辅助定性,外标法定量。结果表明,萘二酚类物质在线性范围内线性关系良好,相关系数均不低于0.999 0,方法的定量限(以信噪比为10计)为0.5～1.2 mg/kg,添加水平为5.0～50 mg/kg时回收率为84.0%～102%,相对标准偏差(n=6)为1.3%～5.7%。该法前处理简单、回收率高、精密度好,适用于非蜡基类化妆品中萘二酚类物质的测定。     

反相高效液相色谱法测定可乐、茶叶中的咖啡因

研究了反相高效液相色谱法（RP－HPLC）直接测定茶叶水提取物、可乐饮料中的咖啡因的新方法，采用PE－C18柱，以CH3OH－H2O－HAc(30:69.92:0.08)溶液作流动相，紫外检测波长为260nm。可在8min内将咖啡因与基体分离，咖啡因含量与峰面积在10μg/mL－100μg/mL范围呈线性关系，回归方程为：Y＝33567c(μg/mL)-126421,r=0.9997.该法可用于可乐饮料，茶叶产品质量的监控及产品真伪的辨别。     

反相高效液相色谱法分离测定酪胺

 建立了分离酪胺与酪氨酸及其它杂质的反相键合相高效液相色谱法,讨论了流动相添加剂对色谱分离的影响和离子相互作用的分离机理。在C8烷基键合相分离柱上,以含Tris-高氯酸盐(20mmol/LTris,用HClO4调节pH为7.9,并添加KClO4,使总高氯酸盐浓度为30mmol/L)的甲醇-水溶液(体积比为40∶60)作为流动相,以对甲苯磺酰胺为内标物,测定了p-酪氨酸脱羧工艺产物——酪胺的质量分数。酪胺样品质量分数测定的准确度和重现性数据为(96.40±0.633)(n=11,RSD=0.66),加样回收率为99.33～100.38。方法可用于工艺条件的选择和酪胺产品质量的检测。     

反相键合相高效液相色谱法分离测定萘普生

 建立了分离测定萘普生和溴代萘普生的反相键合相高效液相色谱法。采用ＯＤＳ柱，以添加５０ｍｍｏｌ／Ｌ乳酸并用高氯酸调节ｐＨ为２．５的８０％甲醇－水溶液作为流动相，以苯甲酸为内标物，测定了不对称合成工艺产物中萘普生和溴代萘普生的含量。方法的准确度分别为９９．８３％～１０２．０７％（萘普生）和９９．０％～１００．８３％（溴代萘普生），相对标准偏差分别小于２．５８％（萘普生）和３．６４％（溴代萘普生）。方法可用于工艺条件的选择和质量检测。     

Column selectivity in reversed-phase liquid chromatography. VII. Cyanopropyl columns

Eleven cyanopropyl ("cyano") columns were characterized by means of a relationship developed originally for alkyl-silica columns. Compared to type-B alkyl-silica columns (i.e., made from pure silica), cyano columns are much less hydrophobic (smaller H), less sterically restricted (smaller S*), and have lower hydrogen-bond acidity (smaller A). Because sample retention is generally much weaker on cyano versus other columns (e.g., C8, C18), a change to a cyano column usually requires a significantly weaker mobile phase in order to maintain comparable values of k for both columns. For this reason, practical comparisons of selectivity between cyano and other columns (i.e., involving different mobile phases for each column) must take into account possible changes in separation due to the change in mobile phase, as well as change in the column.