The atmospheric pressure ionization (API) source forms gas-phase sample ions from sample molecules that are contained in solution. The API source also serves as the interface between the LC and the MS.

The OptaMax Plus ion source, which is provided with the Stellar MS, is APCI-ready; that is, it has both a built-in corona discharge needle mount inside the housing and an APCI On/Off control knob on the exterior of the housing. You can configure the API source for the following ionization modes:

For more details on the ionization modes, see Ionization Modes.

 

IMPORTANT

Hot surface

The API source housing and its components can be very hot and cause severe burns if touched. Allow the ion source housing and its components to cool to room temperature (approximately 20 minutes) before you touch them.

Figure OptaMax Plus ion source (front view)
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No.DescriptionNo.Description

1

Grounding union holder

6

Front-to-back adjustment knob

2

API spray insert depth adjustment lever

7

APCI needle mount

3

Retainer knob to secure the API spray insert (on right and left side)

8

APCI On/Off switch

4

Locking lever (on right and left side, in lock position)

9

Drain insert

5

Left-to-right adjustment knob

10

Clear window

 

The OptaMax Plus ion source includes the following features:

Feature

Description

Heater assembly

Mounts on top of the API source housing, and is used for H-ESI, APCI, and APPI modes. In H-ESI mode, the heater heats the auxiliary gas, which aids desolvation. In APCI and APPI modes, the heater vaporizes the sample before it reaches the APCI corona discharge needle (APCI mode) or the PhotoMate™ light source (APPI mode).

Adjustable API spray insert mount

Lets you move the API spray insert and heater assembly front-to-back or rotate them slightly to increase sensitivity or robustness. You can also adjust the spray insert depth.

Mounting angle of the API spray insert

By default, the spray insert is fixed at an optimum angle for signal intensity and API source robustness. You can view the spray insert through the API source window while positioning it.

Interchangeable ionization modes

Lets you change the ionization mode by installing a different spray insert and reconfiguring the housing.

Safety interlock system

The API source housing has a safety interlock system that prevents contact with high voltages. Safety interlock switches turn off the following voltages:

  • Electrospray needle voltage or APCI corona discharge voltage
  • All API source and lens voltages, including the ion transfer tube offset voltage
  • The voltages on the MS ion guides


The following actions turns off these voltages:

  • Removing the API spray insert from the API source
  • Removing the API source from the MS

Internal wiring and gas plumbing

Lets you remove the API source or change the ionization mode without needing to remove the LC or the gas plumbing.

Internal drain tube

Lets you remove the API source without needing to remove an external drain tube. The API source contains an internal drain insert that connects to the drain tube located inside the MS.

Cooling vents

During operation, the external surface of the API source can become hot. The ventilation holes in the housing aid cooling.