IQ and OQ – What Does This Mean for Thermal Analysis Users?

– In particular for users of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) –

Installation qualification (IQ) and operational qualification (OQ) are part of the so-called analytical instrument qualification (AIQ) process at the user´s lab to confirm that an instrument is properly installed, works correctly and yields the expected results. A key term in this context is “demonstration of fitness for purpose”. In the following, we would like to explain in more detail what’s behind that, mainly on the basis of USP <1058>, the corresponding chapter in the US pharmacopeia.

Risk-Based Approach

Depending on the complexity of the instrument or how critical the measurement is, the instruments are classified in 3 groups: A, B and C. However, depending on the purpose for which the device is used, the same instrument type can belong to more than one group.
  • Group A includes standard equipment without measurement capability or user requirement for calibration. If they are obviously working well, no further qualification will be necessary.
  • Group B includes instruments providing measured values or experimental conditions which can affect a measurement and therefore need routine calibration, maintenance or performance checks. Such instruments may have firmware but no software which is updated by the user.
  • Group C includes instruments with a significant degree of computerization and complexity. For such instruments, all elements of qualification (see below) plus software validation is required. However, software validation and instrument qualification can be combined into a single activity because the software is generally essential to run the instrument.
In USP 41, only a limited number of instrument examples are given: pH meters and ovens for group B as well as mass spectrometers and HPLC instruments for group C. In older USP versions, both DSC and TGA are explicitly classified as group C.

The Four Qualification Phases

These are DQ (Design Qualification), IQ (Installation Qualification), OQ (Operational Qualification) and PQ (Performance Qualification). PQ is also sometimes called “user acceptance test (UAT)”. For complex systems, this framework can be extended by function specifications (FS) and/or factory acceptance tests (FAT), if necessary. Most important is that all required activities are performed in a logical order. In addition, all qualification activities should be predefined and contemporaneously documented. Design Qualification DQ takes place prior to the purchase decision and defines the requirement profile of the DSC or TGA device. This includes the functional and operational specifications as well as the intended purpose of the instrument and, finally, shows that the selected instrument is appropriate. DQ can be performed by the instrument manufacturer or by the user. Some laboratories additionally issue a separate user requirement specification (URS) list which prepends the DQ. In the URS, future users specify what they want the instrument to be able to do. Installation Qualification IQ stands for the documented evidence that the particular DSC or TGA instrument, including software, accessories, etc., is delivered as designed and as specified, that the planned environment is suitable and that the instrument is properly installed. It applies to new or pre-owned DSC or TGA instruments and takes place after installation and commissioning of the instrument at the owner´s site. Operational Qualification OQ follows the installation qualification. It is a documented collection of activities with the objective to verify that the DSC or TGA instrument works correctly in the selected environment and fulfills the operational specifications given in the Design Qualification (DQ) and/or the user requirement specifications (URS). Performance Qualification PQ is the last of the four qualification phases and documents continuous suitability of the DSC or TGA instrument for its intended use under real operating conditions. This usually also implies using typical on-site applications and laboratory´s own testing substances. The test frequency depends, amongst others, on the ruggedness of the DSC or TGA device, the experience and how critical the analytical method is. Another part of performance qualification is preventive maintenance and documentation of repairs and changes on the equipment. Preventive maintenance also comprises periodic calibration of the DSC or TGA instrument.


The final responsibility for qualification of the DSC or TGA instrument lies with the user, whereas the term user covers not only the operator but also his supervisors, the associated instrument specialists and the organization management. Instrument manufacturers and suppliers can just advice and assist.

What NETZSCH Offers

Nevertheless, NETZSCH Analyzing & Testing offers various services to support users during the qualification process of NETZSCH DSC or TG units. These are
  • IQ-OQ documents (in standard version and – optional – customized), including a template for recurring PQ tests
  • Installations with subsequent processing of the IQ-OQ-(PQ) documents
  • Maintenance contracts which comprise calibration of the instruments on a regular basis
carried out by well-trained, experienced service personnel. For more information, please contact your local NETZSCH representative.  
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