In this project I'm doing, I need to analyze the benzoic acid concentration from a meat sample. To increase the solubility of the benzoic acid, the meat was "soaked" in a solution containing a small amount of NaOH. After about half an hour, the solution was filtrated using normal gravity filtration. To remove fats and proteins, tert-buthyl methyl ether was added, mixed and separated from the aqueous layer. The slightly alkaline nature of the aqueous layer made sure that the benzoic acid should (at least for a good amount) stay in that layer. The last step was diluting the sample a bit further after which the samples were injected into the HPLC.
Now here's the problem: This sample preparation was done in duplicate. After separation of the two layers, something precipitates out of one of the two samples, but not the other. The same meat sample was taken, the same chemicals were used, the same time was spend between the steps. The only thing that differs between the two samples is the separation funnel used. When the rest of the sample preparation was done and the samples were injected into the HPLC, the peak area from the 'precipitation-sample' was way lower than the 'normal' sample.
Could this be explained by the precipitation and if so, what could it be?
Any help is appreciated!
p.s first time on this forum, feedback is always appreciated!