_______________________ Finnigan LTQ Hardware Manual ______________________
2-1
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Chapter 2
Functional Description
This chapter describes the principal components of the LTQ system and their
respective functions. The principal components of the LTQ system are as
follows:
•
Autosampler (optional)
•
Liquid chromatograph (optional)
•
Syringe pump
•
Divert/inject valve
•
Mass spectrometer (MS) detector
•
Data system
A functional block diagram of the LTQ system is shown in Figure 2-1. A
sample transfer line connects the LC to the MS detector. The autosampler and
LC are usually installed on the left of the MS detector. The syringe pump and
divert/inject valve are integrated into the MS detector cabinet.
In a typical analysis, a sample can be introduced in any of the following ways:
•
Using the syringe pump (direct infusion)
•
Using the divert/inject valve fitted with a loop and an LC (flow injection
analysis)
•
Using a divert/inject valve and LC fitted with a column (LC/MS)
In analysis by LC/MS, a sample is injected onto an LC column. The sample is
then separated into its various components. The components elute from the
LC column and pass into the MS detector where they are analyzed.
Upon entering the API source, sample molecules are ionized by electrospray
ionization (ESI), atmospheric pressure chemical ionization (APCI),
atmospheric pressure photoionization (APPI), or nanospray ionization (NSI).
The ion optics focus and accelerate the resulting sample ions into the mass
analyzer, where they are analyzed according to their mass-to-charge ratios.
The sample ions are then detected by two ion detection systems that produce a
signal proportional to the number of ions detected. The ion current signal
from the ion detection systems is received and amplified by the system
electronics and is then passed on to the data system for further processing,
storage, and display. The data system provides the primary LTQ user
interface.
