I am developing a SPE method as part of the sample preparation step in my analysis, but I’m not sure what is the best way to determine/calculate the matrix effect. I see a few different formulas online, can anyone help?
Hello Tony. The simplest thing I can recommend. prepare a clean sample and at the end get your solution, add a standard to it in the middle concentration of the calibration range and take the measurement. for example, calibration is in the range from 1 mg/ml to 1000 mg/ml, therefore the concentration in the matrix should be 100 mg/ml or 500 mg/ml. you made a measurement and got 500 mg/ml - the matrix does not affect, if 250 mg/ml or vice versa 700 mg/ml - the matrix does. This means that the coefficient of suppression or absorption by the matrix is introduced. 500 - 100%; 250 - x = 50%. Each result obtained will be calculated taking into account this 50%.
Also, when developing your method, you should take into account the degree of extraction. In SPE and any sample preparation, the extraction of the target substance may not be complete (this is why deuterated standards are used in chromatography). Before sample preparation and SPE, it is necessary to add an accurately known concentration of the standard sample, carry out all extractions and make measurements.
I don't know what you are measuring on. if you use chromatographic studies, then you first build a calibration on the matrix and then look at the recovery of the target analyte.
Hi Toni Jackson
there are several approaches (not just formulas).
For a basic view, have a look to the attached file
This is a older paper focused on LC-MS but Matuszewski et al. Anal Chem, 2003, 75, 3019-3030 outlines an approach used in many industries.
Here are a few approaches to account for matrix effects:
This is the ratio of the area of sample spiked after extraction B to the area of neat standard A i.e MF =B/A*100
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