Firma:              Perkin Elmer

Modell:            API III

Kommentar:   Dokumente engl.

The API III system consists of the API III LC/MS/MS and an Apple Macintosh Computer with associated peripherals. A powerful and versatile system, the API III provides the capability of analyzing liquid streams for polar compounds. The term LC/MS/MS is used as a generic description of the separation and analysis processes which are provided by the system, including separation by Liquid Chromatography, CZE, IC and potentially ITP, and analysis by either MS or MS/MS.

In general, the amount of separation (chromatography) required is determined by the type of sample and the complexity of the matrix. In some cases, samples can be introduced directly with no separation, either by flow injection through an injection loop or by pumping the sample continuously through either an LC pump or the syringe drive provided with the system. In other cases, chromatography is required in order to separate the analyte from the matrix, thereby providing both added information (retention time) and reduced matrix effects. Similarly, some analyses may require the specificity of MS/MS for identification or confirmation, while others require only molecular weight information (provided by MS).

All of these combinations are available with the API III. It is up to the analyst to determine which mode of operation best satisfies the requirements of the analysis: chromatography or direct injection; MS or MS/MS; full scan, selected ion monitoring (SIM), or multiple reaction monitoring (MRM); or other MS/MS scan modes such as parent scan or constant neutral loss scan.

Positioning the Sample Inlets

Important: The ground plug for the IonSpray and Heated Nebulizer Inlets must be plugged in to activate an interlock which turns on the high voltage power supplies. When shutting down the system, remove the ground plug before closing the Ion Gate Valve.

The Ions created by both sample inlets are drawn into the mass analyzer by the electrical potential difference between the orifice and the tip of the IonSpray or, in the case of the Heated Nebulizer, the tip of the Corona Discharge Needle — not between the orifice and the nebulized spray itself. Therefore, the spray should be directed away from the orifice for maximum sensitivity, to reduce chemical noise, and to prevent the orifice from possible plugging.

Consider the Interface Plate to be a clock face with the orifice representing the center of the clock:

IonSpray

The spray should be aimed at about 3 o'clock, 0.5" (1.2 cm) to the right of the orifice. The tip of the IonSpray should be about 1" (2.5 cm) back from the Ion Gate Valve (or set at the 2.5" mark on the z-axis scale). The IonSpray nebulizer tube should be at an angle of about 45 to 600 with respect to the Interface.

Heated Nebulizer

Turn the two positioning knobs on the Multi-purpose Front End counterclockwise to the end of their travel, then turn the adjusting knobs clockwise one turn. The spray should be aimed at about 1 o'clock, 1" (2.5 cm) to the right of the orifice. The tip of the probe should be about 1 to 3" (2 to 7.5 cm) back from the Ion Gate Valve.

The Corona Discharge Needle tip should be located slightly off-axis, about half-way between the tip of the probe and the Interface.

Operating the Heated Nebulizer

Turn on the Sample Pump and make sure that it is venting the plenum chamber. By adjusting the valve at the bottom of the plenum chamber, obtain a Source Delta P value of 0.8" H ₂ O. With the Auxiliary and Nebulizer Gases flowing, increase the Heated Nebulizer's temperature to 400°C. After 5 minutes of warming, start the LC solvent flowing at 1 mL/min and increase the temperature to 480°C. This indicated temperature produces vapour temperatures of approximately 100°C. To prevent damage to the Heated Nebulizer, do not start the LC solvent flowing if the temperature is above 400°C.

Note: The values given are intended as a general guide and may not be optimum for all systems.

Dl         Discharge Needle Current

ISV       IonSpray Voltage

IN          Interface Plate Voltage

OR       Orifice Plate Voltage

RO       Q0 Rod Offset Voltage

M1        Q1 Park Mass

RE1      Q1 Resolution

DM1     Q1 Delta Mass

R1        Q1 Rod Offset Voltage

L7         Lens Element 7 Voltage

R2        Q2 Rod Offset Voltage

M3        Q3 Park Mass

RE3      Q3 Resolution

DM3     Q3 Delta Mass

R3        Q3 Rod Offset Voltage

L9         Lens Element 9 Voltage

FP        Faraday Plate Voltage

MU        Channel Electron Multiplier (CEM) Voltage

CC       Count Control

CGT     Collision (CAD) Gas Thickness

Note: The values given are intended as a general guide and may not be optimum for all systems. If a parameter value is not given, it is assumed to be the PPG state file value.