I am developing method to identify drug using human saliva.The problem is should I prepare matrix calibration curve according to post spiked method or pre spiked method? Please explain me someone please.
In certain chemical analysis, the signal response behavior of the analyte, which is present in the system along with the other components ( termed as the matrix), is very different from that of the same analyte in pure solution, i. e. in absence of the matrix.
Therefore, in such chemical analysis, the calibration standards are prepared with a fixed amount of the "matrix" constituents added into the solutions... the calibration graph is thus obtained from the signal response of standards, which take into consideration the matrix effects.
You can find details of this methodology in the book: Measurement, Statistics and Computation, by David Mc Cormick and Alan Roach.
when preparing a pre-spiked matrix match calibration curve, there is a concern about calculating the matrix effect of our method. Because matrix effect is calculated as {post spiked sample con. /neat standard con.}*100.If we prepare a a pre-spiked matrix calibration curve, how can we calculate, the concentration of the post-spiked QC sample by using the pre-spiked matrix calibration curve? There will be an error.