I am using the published method to extract paraquat/diquat from potato. I used 10 g sample shake with 1:1 MeOH:0.1 N HCl for 10 min and heat in a water bath at 80 C for 15 min and shake more for 10 min. I determined the analytes by LC/MS. Diquat is good with recovery around 100%, but I got low recovery for paraquat (around 40%) constantly. I use matrix matched standard and with internal standard.
Below is the method I used. It is from a well-known source. However, I cannot repeat it.
It is not the cleanup (SPE), it is the extraction from the sample. I will dilute and shoot with matrix-matched standard with IS. I do not have sample cleanup so the loss does not occur at this point. It is the bining between the analytes and may be with starch molecule (per the explanation of the paper).
Dear Mr. Narong,
Please find the attachment may be helpful for your work.
@Sondhiya I have this paper and it is the same condition as the method that II posted previously (1 day ago). It is written by the same author (Michelangelo Anastassiatdes).
@Tran the AOAC is old and takes a long time, that is why Anasstassiades modified it. Per his paper, he cited that the analyte is bound with starch molecule. That is why he cooked to create gelatinization and allow water to penetrate to the analyte. However, I like the idea of re-extract again. Let face it, even with high concentration of HCl at high temperature and long extraction time, the AOAC still needs two extractions. I will try it today. Thanks a lot.
I finally fixed it and get better recovery of paraquat by increasing solvent:sample ratio. Instead of 1:1 (10 g with10 mL), I use 4:1 (5 g with 20 mL).
- Badges
- Science topic
- Similar topics
- Biological Science
- Biochemistry
- Biochemical Techniques