Get The Lead Out Part II

Hypothesis:

IF there is lead in either of the tea samples, the Chinese Dragonwell or the Japanese Sencha, or any of the waters being tested, a precipitate will form once potassium iodide liquid is added. 

Background Information:

Two teas and two waters have already been tested for possible lead contamination. See the first post HERE. 

Potassium iodide forms a precipitate with only three ions: mercury, silver and lead. We are assuming (and hoping!!!) there is no silver or mercury present in the teas or waters being tested. The potassium iodide is a much more specific test than the sodium carbonate used in the previous post. In that case, a precipitate forms with a number of ions, many of which are not toxic or concerning at all! So this test will tell us if something more sinister is lurking. 

Method:

The two teas will be prepared in exactly the same manner as before: using filtered fridge water, 80 degrees Celsius, steeped for 2 minutes. The same cups and infusers will be used. We will also test the same waters: the filtered fridge water and the President's Choice bottled water. Four drops of KI(l) will be added to each solution. If lead is present, a precipitate will form. 

 The Japanese Sencha is on the right. It is less clear before the potassium iodide is added. However, if a precipitate forms it will become quite milky and a solid will sink to the bottom. 

Let's add the potassium iodide!

Results:

No precipitate formed in either of the teas, the filtered fridge water or the bottled water!

BONUS:

Just for fun, I decided to use this bagged Twinings Green Tea

I made the tea, filtered it and added the KI(l). No precipitate there, either. Very impressive. 

CONCLUSION:

You and I can feel good about drinking our green teas. At least DAVIDsTEA and Twinings. They are officially lead free.