China Research


Rainy Day Update

A massive thunderstorm hit us today so I thought I use my time in my room to tell you about my research. I’ve been chlorinating three amino acids for different lengths of time to see what byproducts are formed. The amino acids we use are commonly found in algae from fresh water reservoirs so any byproducts formed by chlorinating these amino acids would has a high probablility of forming in drinking water supplies after chlorination of reservoir water. After chlorination we extract the disinfection byproduct (DBP) from the sample and put it in a small bottle for gas chromotography analysis.

We also perform a test called the ames test which uses salmonella to determine the mutagenic potential of a chemical. The salmonella is a special strain that only grows on histidine. We make agar plates containing no histidine and then place the bacteria in the DBP and put it on the dish. If growth occurs then a mutation has taken place so the salmonella can grow without histidine. We count the number of colonies that form to determine how mutagenic the chemical is.

All of these tests don’t take long to explain but take quite a while to perform. We have three different amino acids which are split in to two groups. Bromination (use of bromide) is another form of water disinfection that is often used along with chlorination so we have three amino acids with bromide and three amino acids without bromide. We have 9 time slots we chlorinate the samples with- 30 seconds, 1min, 2min, 5min, 10min, 30min, 1hr, 2hr, and 120hr (though the 120hr is not used as much). We split the chlorinated amino acid into 9 small bottles to extract different DBPs- HAA, HAN, and THM (which have long, fancy sounding names that you can google to find if you want). So that makes 486 bottles we take DBPs from. Then for the Ames test we put different concentrations of the DBP at each time slot- 6%, 12%, 25%, 50%, and 100%. So with 9 time slots per amino acid and 6 amino acids with 5 concentrations per time slot that makes 270 agar plates…except we run three plates per concentration for accuracy so it’s actually 810 agar plates.

As of now we are finished with extractions and only have about three more amino acids to run ames test on so I’m confident that by next week the lab work will have reached its conclusion.