Comparison of two column characterisation systems based on pharmaceutical applications

A useful column characterisation system should help chromatographers to select the most appropriate column to use, e.g. when a particular chromatographic column is not available or when facing the dilemma of selecting a suitable column for analysis according to an official monograph. Official monographs of the European Pharmacopoeia and the United States Pharmacopeia are not allowed to mention the brand name of the stationary phase used for the method development. Also given the overwhelming offer of several hundreds of commercially available reversed-phase liquid chromatographic columns, the choice of a suitable column could be difficult sometimes. To support rational column selection, a column characterisation study was started in our laboratory in 2000. In the same period, Euerby et al. also developed a column characterisation system, which is now released as Column Selector by ACD/Labs. The aim of this project was to compare the two existing column characterisation systems, i.e. the KUL system and the Euerby system. Other research groups active in this field will not be discussed here. Euerby et al. developed a column characterisation system based on 6 test parameters, while the KUL system is based on 4 chromatographic parameters. Comparison was done using a set of 63 columns. For 7 different pharmaceutical separations (fluoxetine, gemcitabine, erythromycin, tetracycline, tetracaine, amlodipine and bisacodyl), a ranking was built based on an F-value (KUL method) or Column Difference Factor value (Euerby method) versus a (virtual) reference column. Both methods showed a similar ranking. The KUL and Euerby methods do not perfectly match, but they yield very similar results, allowing with a relatively high certainty, the selection of similar or dissimilar columns as compared to a reference column. An analyst that uses either of the two methods, will end up with a similar ranking. From a practical point of view, it must be noted that the KUL method only includes 4 parameters and 3 chromatographic methods compared to 6 parameters and 4 methods for the Euerby method. Hence, the time needed to determine the chromatographic properties of a column is shorter for the KUL approach. Access to the KUL method also requires no download procedures.     

Evaluation of two approaches to characterise liquid chromatographic columns using pharmaceutical separations

In this paper a comparison of two column characterisation systems is reported: the method based on the hydrophobic-subtraction model of Dolan and Snyder (HS method) versus the method developed at the Katholieke Universiteit Leuven (KUL method). Comparison was done for seven different pharmaceutical separations (fluoxetine, gemcitabine, erythromycin, tetracycline, tetracaine, amlodipine and bisacodyl), using a set of 59 columns. A ranking was built based on an F value (KUL) or F_s value (HS) versus a (virtual) reference column. Both methods showed similar probabilities of ranking patterns. Correlation of the respective test parameters of both approaches was poor. Both methods are not perfect and do not match well, but anyhow yield results which allow, with a relatively high certainty, the selection of similar or dissimilar columns as compared to a reference column. An analyst that uses either of the two methods will end up with a similar probability to choose an adequate column. From a practical point of view, it must be noted that the KUL method is easier to use.     

Separation of alicyclic and aromatic hydrocarbons on a PLOT column coated with 3-benzylketoiminepropyl group

An interpretation of specific electron-donor-acceptor interactions between the adsorbent coating the walls of a capillary column and adsorbates from the groups of alicyclic and aromatic hydrocarbons is proposed. The adsorbent was based on silica the surface of which was modified with silane containing 3-benzylketoimine groups to improve its adsorption properties. The columns studied had walls coated with 3-benzylketoimine groups, and Cu(II) chloride complexes or with Ni(II) chloride complexes. The adsorbate-adsorbent interactions were interpreted on the basis of the Kovats retention index, specific retention volume, molecular retention index, and ??M _e values. The influence of particular elements of spatial structure and the positions of double bonds in the adsorbate molecule was evaluated on the modelling calculations based on the quantitative structure-retention relationships. The introduction of transition metal ions in the form of complexes into the adsorbents studied increased the strength of the interactions between the adsorption layer of the capillary column and the adsorbate molecules. The increased strength of the interactions was accompanied by increased selectivity of the columns with regard to a group of alicyclic and aromatic hydrocarbons. The analytical performance of the columns thus obtained was compared with that of a commercial column coated with the 100 % dimethyl polysiloxane phase.     

色谱柱选择对六味安消胶囊中大黄素和大黄酚含量测定的影响

以中国药典收载的六味安消胶囊中大黄素与大黄酚的含量测定方法为典型案例,揭示了色谱柱是影响HPLC质量控制方法测定结果准确性的关键风险因素。参加能力验证的155家实验室均采用方法规定的C₁₈柱,但由于不同品牌C₁₈柱间的选择性差异,有20家实验室的分析结果中大黄素峰与样品水解产物的色谱峰共流出,导致测定结果明显偏离正常值。统计结果表明,A型（早期开发、硅羟基残留较多）和E型（内嵌极性基团或以极性基团封尾）C₁₈柱更适于六味安消胶囊中大黄素与大黄酚的含量测定,这可能是因为大黄素和大黄酚结构中含有多个酚羟基,能与A型柱的残留硅羟基或E型柱内嵌/封尾的极性基团相互作用,从而增强其保留行为有关。建议相关实验室在制订HPLC质量控制方法时应特别注重色谱柱的耐用性考察,并尝试采用国外色谱柱分类数据库科学地指导色谱柱的选择,尽量采用难分离物质对作为系统适用性指标,完善质量标准,减少由于色谱柱选择不适宜导致测定结果不准确的风险。     

启发式方法研究有机化合物在全二维气相色谱中的定量结构-保留关系

采用半经验量子化学PM3的方法计算出130个有机化合物的描述符,用启发式方法分别对化合物在全二维气相色谱的3支色谱柱上的保留值建立了相应的定量结构-保留相关模型,并对模型进行了检验。所建模型呈现较好的线性,相关系数的平方(R2)均大于0.88,标准偏差（S）均小于0.105,留一法交互检验的相关系数的平方(R2cv)与所建模型的R2相当,说明模型具有良好的稳定性。化合物的预测结果显示所建模型有较准确的预测能力。     

芯片液相色谱技术进展

微型化是现代分析仪器发展的重要趋势.微型化液相色谱仪器在提供与常规尺度液相色谱相同甚至更高分离效率的同时,可以有效减少溶剂和样品的消耗;在液相色谱-质谱联用中,低流速进样可以有效提高质谱离子源的离子化效率,提高质谱检测效率;对于极微量样品的分离,微型化的液相色谱可以有效减少样品稀释;液相色谱的微型化还有利于液相色谱仪器...     

Quantitative Relationships Between the Structure of Benzenes,Phenolic Compounds and Their Retention Data in Reversed Phase PRP-1 Column

The reversed phase chromatographic behaviors of benzenes and phenolic compounds in PRP-1 column were investigated using quantitative structure-retention relationships(QSRRs).     

开管毛细管色谱柱的制备及其在蛋白质组学研究中的应用进展

近年来随着生命科学等领域的深入发展,人们对微量样本分离分析的需求越来越高,液相色谱系统的微量化受到了更多的关注。由于开管毛细管色谱柱具有较低的反向压力,可通过采用更长的色谱柱提高柱效,从而实现对复杂生物样本的高效分离,因而成为液相色谱柱新的发展方向。本文对开管毛细管色谱柱的制备方法及应用进展进行了综述。     

色谱柱选择对23种防腐剂测定结果的影响

以化妆品中23种防腐剂检测方法为例,探讨色谱柱选择对液相色谱方法测定结果的影响。参照《化妆品安全技术规范》甲基异噻唑啉酮等23个组分的检验方法,在2台不同的高效液相色谱仪上用15款不同品牌、型号的C₁₈色谱柱检测23种防腐剂,计算色谱峰的理论塔板数和分离度,对23种组分的分离效果进行分析,并应用USP (United States Pharmacopeia)数据库和PQRI (Product Quality Research Institute)数据库等2种等效色谱柱选择方法,对不同色谱柱的分离效果及等效性进行评价和预测。实验结果表明,15款色谱柱对23种防腐剂的分离效果差异显著,仅有2款色谱柱可以实现23种组分的完全分离。USP和PQRI数据库中2种等效色谱柱选择方法均无法预测出合适的等效色谱柱,对23种防腐剂的液相色谱分析参考价值均较小。色谱柱是影响23种防腐剂液相色谱法测定结果准确性的关键因素,有关实验室在应用该方法时,应考虑色谱柱选择性差异。化妆品基质复杂,如何在现有研究成果的基础上,开发色谱柱的筛选和预测评价体系,进而指导实际样品的分离是下一步研究的重点、难点。建议有关部门在制修订检测方法时,注重色谱柱的耐用性考察,完善系统适应性指标,细化色谱柱分类和增加描述信息,指导色谱柱的合理选择,从而规避由于色谱柱使用过程中选择依据缺失而导致测定结果不准确的风险。     

Development of a Dual Capillary Column GC Method for the Trace Determination of C2–C9 Hydrocarbons in Ambient Air

An analytical method based on a dual capillary gas chromatographic technique combining the advantages of GasPro PLOT and a non polar narrow bore WCOT column was developed for the analysis of air samples containing C2–C9 NMHCs. A refocusing step was not required due to the fast heating rate of the sample preconcentration trap and the resolving power of the PLOT column for C2 and C3 NMHCs. Water had to be removed from the air samples to avoid plugging of the columns if the initial GC oven temperature was below ambient temperature. To dry air samples, a scrubber and a cryogenic technique were employed. The interferences caused by carbon dioxide were reduced by purging the loaded sample preconcentration trap with helium. The dual column system was compared to a method employing a refocusing device and a single narrow bore WCOT column. Both systems provided a high degree of precision. However, the dual column approach was superior to the single column system due to better resolution of low molecular weight components.     

化合物色谱保留参数与其三维结构关系的研究

利用比较分子场分析(CoMFA)方法,建立了烷基取代苯、氯代苯、多环芳烃和二硝基取代芳烃等4类结构相近的化合物在甲醇／水体系中反相C18柱上的保留参数a,c值与其三维结构之间关系的定量模型。前3类化合物所得到的3个模型的交叉验证相关系数q2均大于0.5,其中针对烷基取代苯、氯代苯所建立的两个模型的非交叉验证相关系数r2大于0.995,表明模型具有较好的预测能力。该研究结果对进一步开展化合物液相色谱保留参数与其三维结构关系的研究提供了思路和方法。     

基于微机电系统的微型气相色谱柱研究进展

气相色谱柱是气相色谱仪的关键部件,主要用于混合气体组分的分离。与传统气相色谱柱相比,基于微机电系统（MEMS）技术设计制作的微型气相色谱柱具有重量轻、体积小、功耗低、分离快速等优点,便于集成到便携式气相色谱仪中,适应了目前气相色谱仪微型化的发展趋势。该文综述了MEMS微型气相色谱柱的研究进展,首先阐述了MEMS微型气相色谱柱理论基础,随后对MEMS微型气相色谱柱沟道布局及柱内结构、固定相支撑层及固定相制备等方面进行了综述,最后对其发展趋势进行了展望。     

适用于质谱分析的在线固相萃取除盐方法

建立了一个简单、快速、有效的适用于质谱或液相色谱-质谱联用的在线固相萃取(SPE)高通量除盐方法。方法分为单柱和双柱模式,借助于包含双梯度泵(上样泵/分析泵)、自动进样器和配有十通切换阀的柱温箱的高效液相色谱系统,完成样品的自动化在线除盐。单柱模式通过上样泵实现在SPE柱上进样和除盐,被分析物则保留在SPE柱上;除盐完成后,通过阀切换利用分析泵洗脱富集在SPE柱上的被分析物。双柱模式则在单柱模式基础上增加了1根SPE柱,在色谱管理软件控制下2根SPE柱轮流工作,高效率完成样品的在线除盐。该方法在结合质谱分析蛋白质、多肽等领域具有较好的应用前景。