Update:
In 2019, we prepared a new batch of the new botanical cleaner and evaluated its biological and physicochemical stability under refrigeration and room temperature. The cleaner water solution was stable for at least three months under both conditions, showing none of the signs of cloudiness caused by microbials or physical precipitation. We validated the effectiveness of the new batch in cleaning 2,4-D amine from the contaminated hose and proved it was more effective than tap water. We then tested the stable cleaner to remove the wettable powder herbicide atrazine in our miniature lab model. The rinsate was analyzed on HPLC to determine the concentration of atrazine. Tap water was used as a control. The cleaner removed 22 fold more atrazine than tap water. A question was asked at last year’s board meeting if the new cleaner can be used more than once, i.e., repeated uses of the same cleaner solution. Positive answer would improve the cost-effectiveness as the cleaner might be more expensive than some of the commercial tank cleaners such as Protank or WipeOut. We found a negative answer using 2,4-D amine as the test herbicide that the cleaner cannot be used once it was used. In fact, we discovered that the repeated use of the contaminated cleaner only added more residues back to the hose than it was supposed to clean, thus less out into the rinsate. We spent quite some time to find out why and whether the 2,4-D (1) had reacted with the cleaner to degrade , (2) had degraded in rinsate when it was stored for a week under room temperature, and (3) had become dead volume by repeated loading of 2,4-D residues because of the use of contaminated rinsates. The conclusion is none of these is the case and the repeated use of contaminated cleaner is a bad idea. Whether this phenomenon is exceptional to 2,4-D amine only or common to other herbicides, especially those in the EC formulations remains to be a question.