Chromatography Forum

Hi everyone,

I would like to ask some questions about matrix matched calibration.
My samples are vegetable and fruit.
As I know, matrix matched solution should be used.
However, my boss would like me to buy a pesticide matrix spiked POWDER (as CRM) instead of matrix blank solution.
I think I should buy both spiked powder (if available) and matrix blank solution in order to maintain fixed matrix content of each standard for calibration.
Would this increase the uncertainty of matrix solution? (because there are 2 matrix source, 1 from matrix blank and 1 from spiked powder.)
Also I would like to hear your opinion on whether I should use pesticide matrix spike or use matrix blank solution and spike with pesticide CRM myself.

Please share your suggestion, thank you so much.

think I should buy both spiked powder (if available) and matrix blank solution in order to maintain fixed matrix content of each standard for calibration.

I agree, you need to maintain a fixed matrix content in each standard.

Would this increase the uncertainty of matrix solution? (because there are 2 matrix source, 1 from matrix blank and 1 from spiked powder.)

I also agree, you don't know know if the matrix blank and spiked powder are from the same matrix source. However, if you can confirm from supplier that they are indeed from the same source I say go for it.

use matrix blank solution and spike with pesticide CRM myself.

YES, this is what we do!
We use a matrix blank that we spike using neat pesticide standard mix made up in either methanol or acetone. The neat pesiticde standard mix is made up of individual neat pesticide standards and is stable for 6months if stored in amber colored vials at temperature <4degC (some pesticides within the mix are stable for less, i.e. 1-Naphthol). The individaul neat pesticide standards are stable for 1year if stored at similar conditions as mix. We matrix match all of our sample sets, usually just buy organic and analyze a spiked and non-spiked sample to ensure that it is clean. We store matrix blank in freezer at <-40degC and thaw at room temperature before use.