We define a tandem method as having two columns in linear sequence with no detection between them so the eluate from column 1 flows directly onto column 2 (Figure 1A). A Multi-D method involves two or more columns where the eluate from one column flows through a detector, is shuttled into secondary storage (for example, a static loop), and then applied to the next column (Figure 1B). This process of elution, detection, shuttling, and application onto a new column can be repeated several times to create an automated multistep chromatography workflow. The theory behind Multi-D chromatography is based on the concept of orthogonality in which complimentary but different purification types are used to gain specific information about a substance.
An automated workflow provides one-push functionality that enables the user to start a method and walk away. Thus, the user is able to focus on other work concurrently, maximizing productivity. The automated nature of the workflow also ensures that the purification methods are highly consistent and reproducible, providing confidence that the end product will meet purity and yield requirements run after run.
In this chapter, we focus on some important parameters to consider before setting up an automated tandem or Multi-D chromatography workflow and pinpoint the various system components or modules needed.