33.1: Overview of Automated Methods of Analysis

An automated method of analysis is one in which the one or more steps in an analysis are completed without the direct action of the analyst. Instead, the instrument itself completes these actions. Some of these actions are carried out discretely, such as an autosampler that can complete all facets of sample preparation, from collecting discrete samples, adding reagents, and diluting the mixture to a desired volume, prior to the analysts analyzing the samples. Another example of a discrete instrument is an automated titrator (see Figure \(\PageIndex{1}\)) that relieves the analyst from manually operating a buret. Instead, the analyst introduces the sample into the automated titrator and lets the instrument complete the titration.

Figure 33.1.1 . Typical instrumentation for an automated acid–base titration showing the titrant, the pump, and the titrand. The pH electrode in the titrand’s solution is used to monitor the titration’s progress. You can see the titration curve in the lower-left quadrant of the computer’s display. Modified from: Datamax (commons. Wikipedia.org).

Other automated instruments are continuous in nature, in which samples are injected, either manually or with an autosampler, into a flowing stream of reagents that can serve to transport the samples to a detector and can serve as a source of reagents that convert the analyte into a form suitable for analysis.

Both discrete and continuous automated methods of analysis have the advantage of allowing for a high throughput of samples and providing for greater reproducibility in results by relieving the analyst of the tedium associated with completing repetitive tasks. In general, continuous automated methods can handle more samples per unit time than can a discrete method.