An approximate experimental model for predicting solute retention times in RPHPLC with quaternary solvent systems

✍ Scribed by Chunfeng, Zhou ;Nina, Mo ;Xianfeng, Shu ;Hong, Wu ;Peihong, Zhang ;Minggao, Xie

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 547 KB
• Volume: 15
• Category: Article
• ISSN: 0935-6304
• DOI: 10.1002/jhrc.1240150815

✦ Synopsis

procedures were compared there was no significant difference regardless of whether or not the high results for the four above-mentioned compounds were included.

The great advantage of magnetic stirring is that it is not labor intensive. The technique was, in addition, reproducible and consistent, whereas the performance of manual shaking depended on the individual performing the extraction: the rate of shaking is different from one operator to another, and for the same operator varies during the course of a day or from one day to another [4]. Magnetic stirring can be too vigorous and could cause errors as a result of evaporation and variations in the rate of stirring. More work needs to be performed to determine the extent of such effects.

The centrifugal concentrator can be set up faster than the conventional Kuderna-Danish apparatus and the glassware is simpler and easier to clean. Sample handling is, therefore, greatly reduced by use of the latter technique: sample preparation time is reduced more than a third. The trapping system of the centrifugal evaporator eliminates emission of solvent vapors into the atmosphere, thus minimizing the expense of hooded ventilation and reducing air contamination. The solvent can also be recycled.

Centrifugal concentration has one disadvantage in common with Kuderna-Danish evaporation. the samples must not be evaporated to dryness, or volatile material will be lost. The method must be used with care and skill and with the proper controls.

The emulsions which form in some environmental water samples can cause problems during extraction by both magnetic stirring and manual shaking.