Hi Jamal!

You may need to clarify more on your question!

What is the initial form of your dried plant extract? powder, solid sticky or liquid.

Secondly, what type of food contamination test do you intend to carry out? Microbial or other constituents contamination?

When you talk of filtration to make a stock solution, I assume your sample is in thick liquid form, then in that case, i think your worry should be ''the determination of the concentration of that initial solution'' , provided your filtration does not involve addition of water or any substance that can affect concentration.

So, in that case, with the concentration of your extract well known you can proceed with your 1:10 dilution without hesitating, so i think.

Hope this can guide you

Regards!

Yes

Of course is needed more information. There are many methods for contaminants, and they depend on the matrix and on the cultivation. Without information about the type of contaminant you can find you will have to test many methods. If the food was dried you will not have to test thermolabile compounds, but is common to test for insecticides, fungicides or herbicides, and there are over 1,400 known pesticides. Pesticides can be misused during application (spray drift), storage or transportation or from environmental sources, such as contaminated water or soil. Both, gas chromatography and liquid chromatography are used, but the suggestion is firstly search the main contaminants in the origin of the food, and then use one standard method, such as ISO, OECD, USDA or other. Some type of publication can help you, as Jelinek, C. Occurrence and methods of control of chemical contaminants in foods, Environ Health Perspect, 1981, Mastovska, K. Modern Analysis of Chemical Contaminants in Food, Food Safety, 2013, FAO/WHO, WHO Evaluation of certain contaminants in food, 2017

Of course yes

Please let me know the type of contaminants you wish to check?

I would like to mention who will be the object of the evaluation. Who do you want to know if would accept your product? What kind of attribute do you want to check? Should you need to use one trained panel or not ?