On the mycotoxins determination methods, in terms of sample preparation procedures, some methods dilute the sample extract before analysis (or before clean up) while some others do not. Why is this? The solvent type (used for dilute the sample extracts) and volumes are also different, what do these depend on?
Hello, I think that dilution of sample extract helps to minimize the possible matrix effects that can occur, the solvent used should be the same as the standard reference for the calibration curve, so it depends on how you prepare your standards for the analysis.
depends on the sensitivity of the method of analysis one has to dilute the sample to get in the linear absorption range (Beer-Lambert law (or Beer's law) is the linear relationship between absorbance and concentration of an absorbing species)
It all depends on quality, specificity of the antibodies to reduce or avoid any matrix effects in the test. Antibodies produced in different labs exhibit variation in specificity as well as titers, that lead to use the diluted samples in test. More over antibody quality depends on purity of the antigen that has injected in to animal system and in case of monoclonal it depends on selection process.
To dilute before analysis is to 1) reduce matrix effect for LC/MS, 2) if add water to sample befor LC separation, you would make the compound stick to the head of the column to get a sharp peak before running gradient, 3) yes, to make it in the linear range if your sample is concentrate (not likely in the residue analysis). If you dilute before sample prep, I would guess that you do it before cleanup with SPE. the sample may be diluted with water so again your compound will stick to SPE before the cleanup process. To better explain, I would need to see the cleanup protocol.
Matrix dilution has been proposed as a simple strategy to reduce or eliminate matrix
effects on LC-ESI-MS detection. There are some investigations published on the relationship between dilution factor and matrix effects.
http://www.ncbi.nlm.nih.gov/pubmed/22243135
http://pubs.acs.org/doi/abs/10.1021/ac402567w
Wish this helps.
Sciex has been showing that you need to dilute 200 times and inject to the new 6500 Q-Trap to eliminate matrix effect to the manageble level (20% or less).
in ELISA method dilution is important because the limited of detection for the kit is limited between the lower concentration for detection and higher concentration for detection, and the concentration toxin in sample should be between these two concentration to give the right read.
I think Barbara Amato is write that the dilution of sample extract helps to minimize the possible matrix effects and the solvent used should be the same as the standard reference for the calibration curve.
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