ABSTRACT
By using a double loop technique based on a set of mechanical transmission components and a flow path system,a double function of injection and fraction collection was realized. On the basis of double loop technique,a novel type of online/offline interface for two-dimensional liquid chromatography was designed to construct an efficient separation system coupling two different separation modes with a higher peak capacity, and the functions of the interface were evaluated. By means of connecting the interface to an HPLC system, the multiple functions of injection, fraction collection and injection again were fulfilled for preparation and purity analysis of 4 kinds of aromatic compounds. As for combination of 2 sets of HPLC system,5 kinds of protein samples were separated preliminarily by strong cation exchange chromatography, and the components difficult to separate were collected and injected into reversed phase chromatographic system for further separation. Furthermore, the interface was applied to coupling two chromatographic systems in both strong cation exchange mode and microcolumn reversed-phase mode for the two-dimensional separation of bovine serum albumin enzymatic digest. When 1 mAU was set as the integral threshold,a total number of 292 peaks were identified. With the help of the online/offline interface, the preparation of microscale samples, fine separation of hardly separated samples and two-dimensional separation of complex samples were achieved flexibly. The result indicated that the system was a potent tool for the construction of two-dimensional chromatographic system and separation research.
ABSTRACT
We carried out parallel design and development of two differently structured auto sampler based on a multi-axis and multi-mode high-precision closed-loop servo control system. An integrated embedded control drive module was developed based on the idea of compatibility and inter-changeability, so that DC motor and encoder were standardized into uniform models. Meanwhile, electric and mechanical interfaces were uniformed to a same standard. This allows the direct exchange of above-mentioned components between the two models. A 1-μL manual sample injection syringe was installed on both standard 110-sample and platform 40-sample liquid auto sample injectors connected with gas chromatographer. Approximately 0. 5μL of cetane-isooctyl was sampled for 6 consecutive times at six different positions in the sample bottle. The repeatability RSDs of the injection peak areas of the two systems were 1. 1% and 1. 5%, respectively. A linear correlation coefficient (0. 9947) of peak area with injection volume was achieved based on the gradient sampling volume of 0. 1, 0. 3, 0. 5, 0. 7 and 0. 9 μL.