Materials needed: 1 mg/mL thymol standard in methanol, foil, small beaker, filter paper, glass funnel, volumetric pipette, four 10.00 mL volumetric flasks, Falcon tube, 50 mL beaker, syringe, four HPLC vials, marker

CAUTION: Keep your samples covered with foil when you are not working with them because methanol evaporates readily.

1. Filter the thyme leaves extracted in methanol into a small beaker through gravity filtration using filter paper and a glass funnel.

2. Add 5.00 mL of your extract to each of four clean 10.00 mL volumetric flasks using a volumetric pipette. Transfer any unused extract in a Falcon tube, for the Thymol Antibacterial lab.

3. Obtain 6 mL of 1 mg/mL thymol standard in a 50 mL beaker.

4. Use a syringe to add 0.0, ~0.5, ~1.5, ~2.0 mL of thymol standard, respectively, to each of the four volumetric flasks containing 5.00 mL of extract. Do not forget to record the actual volume of standard you added to each flask.*

5. Fill each flask up to the mark with methanol. Mix by inverting the capped flask several times.

6. Transfer a small amount of each sample to a separate HPLC vial, up to the mark. Add the insert and press it into the vial slowly until the bottom of the blue cap is approximately 3mm from the lip of the vial. Label each vial with a marker (do not use tape).

*Volumes will be provided in the next section.