GC-MS ( Gas chromatography–mass spectrometry ) Calibration Procedure

Gas chromatography–mass spectrometry Calibration Procedure

Check parameters	Acceptance criteria
Mass Sensitivity	S/N Ratio > 60:1
Repeatability-RT GC-MS/MS FID & ECD	% RSD MAX 0.5 % 2.0 %
Repeatability-Area GC-MS/MS                                                FID & ECD	% RSD MAX 5 % 3 %
Detector linearity	R² ≥ 0.99
Split Ratio	R² ≥ 0.99
Carry-over	Height should be less than 0.4%

Sensitivity (GC-MS)

• Check the Autotune, Self-calibration and save the calibration details.
• Prepare the standard octafluoronaphthalene (OFN) in the concentration of 1 pg/ul in iso octane in suitable sample vial.
• Inject octafluoronaphthalene and run the GCMS.
• Check the signal noise ratio and mass spectrum of the OFN.

Acceptance

EI Sim Or MRM: S/N> 60 octafluoronaphthalene for 10 ppb molecular ion at m/z 272.

Repeatability 

Instrument	Details	Acceptance criteria
GC-MS	Lindane is taken for calibration of Gc-Ms. Other Gc compounds of known purity can also be selected as reference material. Prepare 100 μg /ml from the stock solution. Inject 5 replicates and calculates the % RSD for the Retention time and Area.	% RSD for Retention time should be ≤ 0.5 %         % RSD for Area Should be ≤ 0.5 %
GC-FID	Prepare 10% ethanol in water. Stock volume and final volume can be changed depending on the availability of micro pipette and volumetric flask.  Inject 5 replicates and calculates the % RSD for the Retention time and Area.	% RSD for Retention time should be ≤ 2 %     % RSD for Area Should be ≤ 3 %
GC-ECD	Prepare 100 μg/ml of lindane in ethyl acetate and Inject 5 replicates and calculates the % RSD for the Retention time and Area.	% RSD for Retention time should be ≤ 2 %   % RSD for Area Should be ≤ 3 %

 

Detector Linearity

Instrument	Linearity
GC-MS	Prepare 20, 40, 60, 80, 100 ng/ml lindane Calibration Solution and inject. Plot linearity graph between concentration on the X axis and Area on the Y axis.
GC-FID	Prepare 0.5, 1, 5, 10, 25, 50 % ethanol in water and inject in GC-FID. Plot linearity graph between concentration on the X axis and Area on the Y axis.
GC-ECD	Prepare 20, 40, 60, 80, 100 ng/ml lindane in ethyl acetate and inject in GC-ECD. Plot a linearity graph between concentration on the X axis and Area on the Y axis.

 Acceptance criteria

The correlation coefficient r² obtained from the linearity graph for different levels should not be less than 0.99
 

Split Ratio (Gc-Ms)

Inject same concentration of standard solⁿ at different split ratio as 1:10, 1:50, 1:100 and record the chromatogram for each split ratio. Plot a linearity graph between ratio on the X-axis and area on the Y-axis.

 Acceptance criteria

The correlation coefficient r² obtained from the linearity graph for split ratio should not be less than 0.99
 

Carry Over (GC-MSMS, GC-MS, GC-FID, GC-ECD and Head Space)

Keep the vials Containing solvent and analyte in solvent in the following order.

Vial No.	Position given for reference,	Sample Details
1.	10	Solvent
2.	11	Std. in Solvent
3.	12	Solvent

 

Calculate the percentage of carry over as following

Carry Over (%) = H_Co *100 / H_i

Where

       H_Co  - peak height of analyte from vial 12.

       H_i -  peak height of analyte from vial 11.

 

Acceptance criteria

Height should be less than 0.4%

 

 

Head Space

Inject 1 mg/l hexane in oil in 5 replicates and calculate the % RSD for the Retention time and Area.

Acceptance criteria

% RSD for Retention time should be ≤ 0.5 %

% RSD for Area Should be ≤ 0.5 %

 

 

RSD Formula

RSD = STDED * 100 / Avg

Frequency- Every Six Month

Maintenance

• Check the gas connection, moisture trap condition column connections, any leak in the helium cylinder and change the septa if damaged.
• Run the column conditioning at the end of the sequence.
• After every 50-60 injections the septas are needs to be changed.
• Do bake out the system whenever the vacuum is put down and the moisture is high.
• Clean the liner in every hundred injections depending on the sample matrix analysed.
• Change the wash solvent in the vial daily. Before start of analysis.
• Do a frequent test of gas leakage to avoid any hazard.

 

 

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