Calibration of Gas Liquid Chromatgraphy [GLC] used in Aroma chemical industry

                                                                                         

Calibration of Gas Liquid Chromatgraphy [GLC] used in Aroma chemical industry

By Prashantkumar Kudli Shrinivas and Prabhakar Rao Mallavarappu

Monitoring the analytical parameters of Aroma chemicals is very crucial and critical as certain impurities even at trace level affect the odor profile .

To get correct and reliable results, the analytical instruments should be checked periodically for their performance.

That means instruments should be calibrated.Emploing the uncalibrated instruments for measuring purpose may jeopardize the assurance of the quality.

Calibration is a method of checking the instrument performance by using standard samples of known analytical values. If instrument produces those known results then the instrument is said to be performing well, otherwise it cannot be used for the testing the samples till the problem is rectified.

Calibration methods of Gas chromatography used in aroma industry are described below.

For Gas liquid chromatography, FID temperature, OVEN temperature, INJECTION temperature, Carrier gas flow, Column performance should be monitored.

The calibrations are carried out as follows;

1] FID/TCD Temperature: By using platinum resistance thermometer(PRT)

Frequency: every six months


2] OVEN temperature : By using platinum resistance thermometer(PRT)

Frequency: every six months


3] Injection temperature: By using platinum resistance thermometer(PRT)

Frequency: every six months


4] Carrier gas flow: By using Electronic flow meter

Frequency: Every month


5] Column performance: To be monitored for Retention time consistency and sample composition consistency


As Per FCC ,the GC system suitability test sample consists of an equal weight
mixture of the following;


Acetophenone,


Benzyl alcohol,


Benzyl acetate,


Linalool, and


Hydroxycitronellal.


Using this test sample, daily test the performance and resolution provided by the gas chromatograph employed.

The test sample must display results comparable in quantitative composition, peak shape, and peak elution order to those specified herein.

The quantitative composition should not deviate from the results listed below by more than _10%.

Analyze the GC test sample using the
GC Conditions as described below;

GC CONDITIONS FOR ANALYSIS

Column: Open tubular capillary column of fused silica

Dimensions: 30 m × 0.25 to 0.53 mm (id), or equivalent
.
Stationary phase:

NON-POLAR column (or equivalent): methyl silicone
gum, or equivalent (preferably a bonded and cross-linked
dimethyl polysiloxane)

POLAR column (or equivalent): polyethylene glycol,
or equivalent (preferably a bonded and cross-linked polyethylene
glycol)

The stationary phase coating should have a thickness of 0.25 um.

Carrier gas: Helium or nitrogen flowing at a linear velocity of 20 to 40 cm/s.

Sample size: 0.1 to 1.0 misrelate

Split ratio: 50:1 to 200:1

Inlet temperature: 225° to 275°.

Detector temperature: 250° to 300°.

Detector: FID

Oven program: 50° to 240°, increasing the temperature by
5°/min; and holding at 240° for 5 min.


Order of Elution in Non-polar column

Component in Test sample & Area %

Benzyl Alcohol -22.0%

Acetophenone- 21.1%

Linalool -20.8%

Benzyl Acetate -18.6%

Hydroxycitronellal-16.7%


Order of Elution in Polar column

Component in Test sample & Area %

Linalool -21.3 %

Acetophenone -21.4 %

Benzyl Acetate- 21.0 %

Benzyl Alcohol-19.1 %

Hydroxycitronellal -16.7

Determine the retention time and area % of different components in the test sample , and daily monitor the performance .

When ever significant changes in the RT or Area % observed, then we have to take the corrective steps to improve the column performance or to change the column by new ones.

About the author:
Prashantkumar Kudli Shrinivas has a vast experience of Aroma chemicals,Essential oils,Perfumery and Flavour industries.

E-mail: prashantkudli@yahoo.co.in


Prabhakar Rao Mallavarapu has a vast experience of quality control,quality assurance and regulatory affairs in Aroma chemicals,Perfumery and Flavour industries.

E-mail: mallavarapu38@yahoo.com


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