A single 10 port valve permits alternate injections from two loops, which may be identical or of different sizes. This technique replaces a 4 port switching valve (used as the sample selector) and a 6 port sample injector.
In Position A, Loop 2 is loaded with sample 2 while the mobile phase flows through Loop 1 and onto the column. In Position B, the Loop 2 sample is injected onto the column and Loop 1 is loaded with sample 1. When the valve is returned to Position A, the Loop 1 sample is injected onto the column and Loop 2 is reloaded with sample 2.