Preparing Tea Samples

Acid Washing Glassware

Since the experiment focuses on the concentration of metal ions, it was best to reduce any trace amounts that are not derived from the tea, such as in the glassware. To solve this, acid washing was performed. This was done using 50% v/v nitric acid, 10% v/v hydrochloric acid, tap water, and distilled water. The first acid wash was done by rinsing once with 10 mL nitric acid, followed by three rinses of tap water. The second wash was done by rinsing once with 10 mL hydrochloric acid, followed by three rinses of tap water and then two rinses of distilled water.

Tea Samples with Plastic Tea Bags

Three 400 mL beakers, three 250 mL Erlenmeyer flasks, three 100 mL volumetric flasks, three funnels, and three 10 mL volumetric pipettes were acid-washed using 50% v/v nitric acid and 10% v/v hydrochloric acid. Tea mass was calculated by cutting three tea bags, massing the plastic bags separately, and assuming that mass to be subtracted from the measured tea bags. All three 400 mL beakers were given a stir bar filled with 200 mL distilled water each. They were then stirred and heated until their desired temperature. A tea bag was fully immersed in each one before brewing for the desired time. After the time elapsed, the tea bags were immediately removed and the tea was filtered into an Erlenmeyer flask using a funnel and filter paper. Using a 10 mL volumetric pipette, tea from the Erlenmeyer flask was extracted and placed into a 100 mL volumetric flask. This solution was then diluted and shook with 0.2% v/v nitric acid. The rest of the samples were collected before being transferred to 50 mL Falcon Tubes for MP-AES analysis.

Tea Samples without Plastic Tea Bags

The process without the plastic tea bags was identical to the procedure with the tea bags except the tea was transferred into a reusable cloth tea bag. The mass was calculated the same way by subtracting the assumed mass of the plastic tea bag for consistency purposes.

Control Samples

Three 400 mL beakers, three 250 mL Erlenmeyer flasks, three 100 mL volumetric flasks, three funnels, and three 10 mL volumetric pipettes were acid-washed using 50% v/v nitric acid and 10% v/v hydrochloric acid. All three 400 mL beakers were given a stir bar filled with 200 mL distilled water each. They were then stirred and heated until 70℃. Loose tea was placed into one beaker, the plastic bag another, and a reusable tea bag in the third. Each sample was heated and stirred for 10 minutes before being prepared for MP-AES in the same fashion as the previous tea samples.