Sample Preparation

The type of canned food we are going to use is Canned processed meat.
After we obtain a representative sample from the canned meat, we will now prepare a lab sample.

Chemicals and Reagents
Sodium nitrite
Saccharin
Potassium bisulfide
Monosodium Glutamate
Aspartame
Sorbic acid
Dehydroacetic acid

Materials and Methods
The canned meat is homogenized with cutter and a blender and immediately stored at -20⁰C in an air tight container (to prevent deterioration and change in composition) until use.


Preparation of Standard solutions 
 Stock standard solutions of individual compounds (100 mg) were prepared by exact weighing of powder and dissolution in 100 mL of acetone as standard solution.
Multi-analyte working standard solutions were prepared by diluting the standard solution to a series of concentration ranging from 0.2 to 6.0 ug/mL for use.

*Sample preparation is very important as inadequate preparation can cause matrix contamination.

Sample preparation
5g of homogenized canned meat samples were neutralised with 10% sodium hydroxide or 10% hydrochloride in a 100-mL beaker. 

This neutral solution was transferred to 500-mL round-bottomed flask containing 15mL of 15% tartaric acid, 60g sodium chloride and one drop of silicon resin. 

The solution was then diluted with water to the volume of 200mL and steam-distilled at a rate of 10mL/min. 50mL of distillate was transferred to the separation funnel, acidified with 10% sulphuric acid, saturated with sodium chloride, and extracted with 100mL (2x) of diethyl ether. The combined diethyl ether layer was washed with 30mL of saturated sodium chloride solution, added with anhydrous sodium sulphate to make free the solution of water, and then filtered through a filter. The residue was then added with acetone to a volume of 5mL for GC determination.

Recovery test
30g of extracted canned meat was spiked with 250ug of each preservative and mixed well.

The analysis was carried out carried out in triplicate and the sample blank unspiked with standards was also performed.

GC conditions
· Flame Ionisation detector
· Carrier gas flow rate: 30mL/min
· Temperature of detector: 250⁰C
· Temperature of injection port: 250⁰C
· Column: capillary support-coated open tubular 

   0.53mm x 30m, 0.5um film thickness
· Injection volume: 1uL

· Oven temperature: 105⁰C for 7min, raised to 160⁰C at 10⁰C/min, then kept at 160⁰C for 2.5min

*Before running the analysis, ensure that there is no gas leak. 

Optimize the chromatographic conditions for the best separations.

And we'll be using auto sampler for this analysis...

That's all for now! Hope i didn't leave out anything. :) 


Citation
Journal of Food and Drug Analysis, Vol. 9, No. 4, 2001, Pages 215-219