Gas and Residual Gas Analysis with a Quadrupole Mass Spectrometer

Mass spectrometry is a widely used analytical method that looks at the chemical composition of substances. Our devices for (residual) gas analysis all have the same core: a quadrupole mass spectrometer (QMS).

Suitable for every application

There are various configurations and different peripheral devices for quadrupole mass spectrometers (QMS), which can be selected specifically to suit the area of application depending on the requirements.

Basically, partial pressures are determined with a mass spectrometer, also known as RGA for short, while vacuum measuring tubes are used to measure total pressure. Only the measurement of gases is possible - which includes the analysis of solid or liquid substances if they have previously been evaporated.

Important decision criteria for device selection are:

  • The pressure range and the associated design

  • Analytical performance (this includes masses to be detected, resolution, detection limit, measurement speed)

Setup of a Pfeiffer Vacuum mass spectrometer

Video for a quick start after receiving the device. You can find this, as well as other interesting videos, on our YouTube channel.

Influence of the pressure range on the construction

The gases in a chamber that has been pumped down to low pressure, are prepared for analysis by ionizing the electrons. The ions generated in this way are separated in a mass filter according to their mass to charge ratio. High vacuum is a mandatory requirement for these processes. Accordingly, the pressure range in which the gas is to be analyzed usually also dictates the design.

In practice, different components are chosen to fulfill different types of measurement tasks. From ready-made complete solutions such as the OmniStar to the actual individual device, the compact quadrupole mass spectrometer, called PrismaPro, there is a suitable solution for every application.

Need help with your selection?
We will be happy to advise you on which equipment can be used for your individual analysis task.


Complete solution

ThermoStar / OmniStar

Single device


Analytical performance

There is no one universal mass spectrometer that covers all possible applications. Regardless of the pressure, the initial conditions and the goal of the analysis vary. Therefore, before selecting the equipment, it makes sense to be clear about which analysis task is to be solved and to define what goal you want to achieve with the equipment. The requirements to be taken into account primarily include the following criteria.

  • Measuring speed

  • Resolution

  • Masses to be detected

  • Limit of detection

Let's look at the influence of the individual components on analytical performance. The general rule also applies to mass spectrometry: precision is proportional to price. In some use cases, there are critical factors to consider that require specific actions or special attention.

Measuring speed

The measurement speed can also be adjusted depending on the analysis task, for example with the PrismaPro from a minimum of 1 ms up to 16s. The measurement speed influences the amount of noise (both the signal and the background).


The resolution can be adjusted depending on the area of application, mainly via the software. It affects separation and signal height. A so-called standard resolution is common.

Masses to be detected

Which masses must be found for the area of application? The smallest suitable mass range should be chosen. Smaller mass range ensures better sensitivity (signal).

Detection limit

The detection limit is influenced by the sensitivity and peak overlap. Sensitivity also varies depending on the detector used (Faraday vs. Faraday/SEM).

The criteria in detail

Our user-friendly PV Mass-Spec software can be used for individual data acquisition and evaluation

Software and interfaces (Ethernet)

PV Mass Spec software is easy to use and is provided when you purchase the device, and updates are also available online.

Our mass spectrometers also offer certain interfaces to communicate directly with a PLC.


Depending on the operating pressure, different detectors are used:

For the Faraday detector (F), the operating pressure does not need to be as low as for the combined Farady /C-SEM detector (M). However, this has a direct impact on the detection limits. The exact numbers depend, among other things, on the residence time and the ion source used, which can be found in our brochures.

Faraday Cup

Configurable RGA systems

Every test task is different. In addition to the standard OmniStar / ThermoStar solutions, our team of experts accesses the full range of Pfeiffer Vacuum products and uses them to configure the system that best suits your requirements. One example is our RGA cleanliness verification system called OmniGrade.

RGA system Omnigrade

Not only are the individual components such as quadrupole mass spectrometers, vacuum pumps, chambers and other individual components selected, but the total operating costs and delivery times of the tailor-made, turnkey solution are also taken into account.

Hardware connection

The following hardware connections are available for integrating our devices: The Prisma Pro is equipped with a DN 40 CF flange, the HiQuad Neo with DN 63 CF, and OmniStar and ThermoStar each with capillary hose or a suitable adapter 1/4" / DN 16 ISO-KF to meet the requirements of various applications.

Capillary hose adapter

Support & Service

We have experts working for different areas of application. They are available to advise you on choosing the right equipment, to help you with any questions you may have about the measuring recipe, or to help you with other questions. In addition to support, we also offer services for the devices.If you have any questions, we are happy to help.

Service man working with a mass spectrometer