What do "People in the Real World" do?

Linda from Rhode Island writes:

"Thought it would be useful for your folks to know what people in the real world are doing, despite instructions to the contrary. I run up against this all the time." (This involves our Dissolved Oxygen procedure which uses the azide modification of the Winkler method.)

"We are ending up our field training for new volunteers and re-supplying returning ones. As we put our supplies together I have discovered that although we seem to have enough of the new plastic DO syringes, we are short a lot (10-20) of the pink tips. I have also learned why we are short of them. Our volunteers have found that, at least at the start of the season, it is almost impossible to fill the plastic syringes without getting an air bubble in the barrel, when using the pink tip and using a sodium thio bottle that had been previously used with the glass syringe. Using the glass syringe enlarges the hole in the top of the sodium thio bottle. What I see our experienced and some new volunteers doing is removing the pink tip and then filling the barrel of the syringe and then replacing the tip. This morning I tried it myself and found that it does fill without an air bubble more readily. From what I can tell, if I fill the barrel as far as I can, then attach the tip, and then zero the sodium thio, the tip gets filled. Am I correct? Additionally, when then using the plastic tip and the sodium thio bottle inverted, we tend to get sodium thio leaking around the tip-hole, again with older sodium thio bottles."

"I like the smaller drop size of the pink tip for improving accuracy and precision of the measurement.... we do like the chemistry of the kits, their precision and safety and the ease of working with you good people."

Editorial Comments: Thanks, we like to work with customers and aim to please.

Our research chemist and instruction author, Liz, would like to reiterate what your experienced volunteers already know: Pink tips should never be removed from the titrators. If they hold the titrator to the bottle firmly with one hand, they shouldn't leak. If there is an air bubble in the titrator, it can be pumped back into the bottle while it is still being held upside down. Or the titrator can be held tip up and the bubble can be forced to the tip of the titrator by flicking the titrator with a finger and then squirting the bubble out of the titrator (a neat flick performed by many actors in medical dramas). Since you are replacing the reagents, the problem with the stretched out holes should be resolved. Please read the Direct Reading Titrator (DRT) instructions carefully.

Linda continues with a Deep sampling question and inexpensive low tech solution to a problem:

"Here's another thing we discovered. We use the deep sampler #3-0026. We have found that the inner tube that extends into the DO bottle sometimes tends to fall out and get lost. The perfect replacement is a round white Bic pen barrel, cut to the appropriate length!"

Thanks for the suggestion. It's an ingenious cost effective solution. We continue to try to improve our equipment but we never thought of this thrifty resolution.