A Modification to Improve the Performance of Small One Stroke Micropipets

Abstract

Flameless atomic absorption techniques have greatly extended the capabilities of analytical chemists to determine metallic elements in a wide variety of sample types. However, regardless of the technical excellence of the particular commercially available or homemade atomizer used, the reliability of the analytical work depends upon how well the tiny volumes of sample and standard solutions can be pipetted. Generally the most accepted method of solution handling has been the use of spring-loaded micropipets used with disposable plastic tips. This author has had experience with three examples of these pipets. Two of these utilized two-stage plungers (i.e., the plunger is depressed to the first level for aspiration of a measured amount of solution and pressed to another stop to express and blow out the pipet) and were satisfactory. The third type, a popular, inexpensive, single stroke system was found to be unsatisfactory as received for use in flameless atomic absorption atomizer applications. The reasons for this and a suggested cure for these problems are discussed in this communication.