Calibration / Qualification of GC

Calibration / Qualification of GC:

Flow: Flow Rate Accuracy (Carrier gas, Detector gasses)
Injector: Repeatability and Carry Over
Column Oven: Temperature Accuracy and Gradient
Detector: Linearity
Detector: Noise and Drift (just for Qualification)

• Oven Temperature Accuracy, Stability Test and Temperature Ramp Accuracy
In gas chromatography, the relationship between peak retention and column temperature is fundamental. Changes in temperature cause significant exponential retention shifts. In addition to changes in the average oven temperature from one run to the next, other important temperature variabilities, include spatial fluctuations along the column because of temperature gradients in the GC oven, dynamic short-term oven temperature fluctuations because of electronic, and software temperature-control processes. If large, enough, such spatial and short-term changes will affect peak shapes and resolution

• Flow rate Accuracy and Stability

Stability of carrier gas flow is important to achieve repeatable injection and retention time. Also the carrier gas flow affect the resolution and separation process.

• Detector Gas flow rate accuracy
The detector gas flows affect the peak area, baseline noise and drift, detection resolution, peak tailing and shape.

• Injector Module

Injection precision is critical for quantitative analysis. It depend on septum, liner type and volume, Split or split less injection and ….
• Injection Carry Over

Small amounts of analyte may be carried over from the previous injection and contaminate the next sample to be injected. The carryover will affect the accurate quantitation of the subsequent sample. This test challenges the injector system (manual injection and Headspace) in the GC system.

• Detector Response Linearity
The linearity of a detector is a critical parameter to establish for reliable and accurate quantitative results.

• Detector Noise and Drift
The amplitude expressed in amperes of the baseline envelope that includes all random variations of the detector signal of a frequency about one or more cycles per minute. Short-term noise corresponds to the observed noise only. The actual noise of the system may be larger or smaller than the observed value, depending upon the method of data collection or signal monitoring from the detector, since observed noise is a function of the frequency, speed of response, and the bandwidth of the electronic circuit measuring the detector signal.
The average slope of the baseline envelope expressed in amperes per hour as measured over 1⁄۲ h.