	A typical APCI usually consists of three main parts: a nebulizer probe which can be heated to 350-500C, an ionization region with a corona discharge needle, and an ion-transfer region under intermediate pressure. The analyte in solution is introduced from a direct inlet probe or a liquid chromatography (LC) eluate into a pneumatic nebulizer with a flow rate 0.2–2.0mL/min. In the heated nebulizer, the analyte coaxially flows with nebulizer N gas to produce a mist of fine droplets. By the combination effects of heat and gas flow, the emerged mist is converted into a gas stream. Once the gas stream arrives in the ionization region under atmospheric pressure, molecules are ionized at corona discharge which is 2 to 3 kV potential different to the exit counter-electrode. Sample ions then pass through a small orifice skimmer into the ion-transfer region. Ions may be transported through additional skimmer or ion-focusing lenses into a mass analyzer for subsequent mass analysis.