I had to design an experiment to extract BPA from water stored in different types of plastic containers. I used these procedures and didn't obtain anything in week 1, so I'm hoping someone can tell me if there is any type of issue with my experimental procedures. Here is what I wrote for the method section of my research paper:
A #3 plastic bottle, a #1 plastic bottle, and a glass jar were filled with distilled water, capped, and sealed with a thin strip of paraffin to prevent evaporation. The containers were then stored in a dark, cool cabinet for one week before being tested for the presence of BPA.
1) 40mL of water from one of the containers was measured into a graduated cylinder and poured into a separatory funnel. Then, 5mL of dichloromethane and 5mL of anhydrous sodium chloride were added to the funnel to extract the BPA.
2) The contents of the funnel were gently mixed, stopping occasionally to vent, until two distinct layers formed. The bottom organic layer was dispensed into a clean pre-weighed flask.
3) Two additional extractions were made with 3mL each of dichloromethane and anhydrous sodium chloride and the organic layer was dispensed into the same flask.
4) Magnesium sulfate was added to the flask to dry the solution until the “snow globe” effect was obtained. The solution was then poured into a funnel fitted with a piece of fan-folded filter paper.
5) In the fume hood, the filtrate was gently warmed over a Bunsen burner and dried with a mild stream of air.
6) The flask was then weighed and the weight of the sample obtained was used to determine the molarity of BPA in the bottle of water.
The above procedures were repeated for all containers at week one.
Notes: Dicholoromethane was chosen to extract BPA based on previous lab work done on this topic.
Thanks for any feedback!