Recording an ion IR spectrum involves stepping the laser frequency through the range of interest and takes longer than the width of an LC peak. Therefore, fractions of LC eluent containing ions of interest were collected using a two-position six-port switching valve and an 80 µl sample loop. Here, the LC eluent is diverted to waste by the switching valve until the peak of interest arrives at the end of the column. At that point, the valve is switched such that the peak of interest is stored in the sample loop. After the elution of the peak, the valve is switched back and the contents of the sample loop are infused into the ion trap instrument by a syringe pump at reduced flow rate (120-180 µL h - 1 ). In separate experiments, solutions of reference standards (~1 µM in MeOH/H2O 50:50 [v/v]) were directly infused by the syringe pump for IRIS analysis.