Fig. 3.
Injection techniques for amino acid analysis. (A) The standard process involves a 10-s cross-injection from sample to waste at –2.5 kV followed by the run stage. (B) A 2-s direct injection is performed by first executing a cross-injection followed by a 2-s injection from sample, waste, and anode to the cathode at –15 kV. (C) Extension of the direct injection for 10 s increases the signal strength 100-fold with reduced resolution.