Figure 4.

Evaluation of carryover and its elimination. (A) Top: duplicate injections of one sample containing 16 mM thiourea, acetophenone, and propiophenone, followed by five blank droplets. Only the first blank has carryover signals. Bottom: zoomed-in view of intensity between 0 and 0.1 V. (B) Top: duplicate injections of one sample and one blank droplet with a 10 nL uninjected wash droplet (100% acetonitrile) in between. The carryover of thiourea, acetophenone, and propiophenone was reduced to 0, 2.3, and 7.8%, respectively, calculated from the peak heights. Bottom: zoomed-in view of intensity between 0 and 0.1 V.