LimsPulse
GC · Calibration procedure

Oven temperature accuracy

Checks that the column oven reaches and holds the set temperature, using a calibrated temperature probe placed near the column.

Photo of a GC
Photo: Sarka Na kopci, CC BY-SA 4.0 (cropped), via Wikimedia Commons
PURPOSE

Why this is checked

Retention times in GC depend strongly on oven temperature. An oven that reads high or low shifts retention, changes resolution between close peaks and makes methods non-transferable.

Frequency

Typically every 6 or 12 months, and after major repair or relocation, as defined in your calibration SOP.

Learn how the GC works
YOU WILL NEED

Standards & tools

  • Calibrated digital thermometer with a thermocouple or Pt100 probe covering at least 40–300 °C, traceable to national standards
BEFORE YOU START

Prerequisites

  • Fix the probe in the centre of the oven near the column hanger, not touching the walls or the column
  • Close the oven door with the probe lead routed through the door seal or a port
  • Switch off the detector flame if the probe lead passes near it
PROCEDURE

Step by step

  1. 1Set the oven to the first set point (e.g. 40 °C) and wait at least 10–15 minutes after the instrument shows it is ready.
  2. 2Record the probe reading (take the mean of a few readings over 1–2 minutes).
  3. 3Repeat at set points covering the range your methods use, for example 100, 200 and 300 °C.
  4. 4Optionally record readings every 30 s for 10 minutes at one set point to check stability.
RECORD

Example observation table

Set (°C)Observed (°C)Difference (°C)
4040.3+0.3
100100.6+0.6
200199.2−0.8
300298.9−1.1
CALCULATION

How to calculate the result

Difference = Observed − Set
  1. Set 300 °C, observed 298.9 °C
  2. Difference = 298.9 − 300 = −1.1 °C
  3. Within a typical ±2 °C limit, so it passes
ACCEPTANCE CRITERIA

Pass if

  • Typically within ±2 °C of the set value at each point (some SOPs use ±1 °C or ±1% of the set value). Use the limit in your SOP.
  • Stability, if tested: typically within ±0.5 °C over 10 minutes.
IF IT FAILS

What to do

  • Label the instrument 'Out of calibration' and stop using it.
  • Check probe position and repeat once to rule out a measurement error.
  • Get the oven sensor or controller serviced and adjusted by an engineer.
  • Assess the impact on results generated since the last passing calibration.
MORE

Other GC calibrations

In LimsPulse · Calibration Management

LimsPulse schedules this calibration, records the result against limits, and blocks the instrument everywhere if it fails or goes overdue.

See how