Tip on cheaper alkalinity testing

[tenurepro]

Hi all, just wanted to share with you a very simple tip that i use to cut my titration testing costs down.
I typically test alkalinity (salifert) twice a week on two tanks, and any saving of reagents will obviously lead to some cost savings over time. It is often the titration reagent that runs out first.
While you can do a 'low resolution' test, i feel like this defeats the purpose of buying a titration test... and because i use the test for adjusting 2 part dosing, i really want to get the most accurate answer. You can always return unused reagents back to the bottle, but i don't recommend this as well because returning unused reagents back to the stock solution is a cardinal sin in analytical chemistry - you are potentially (and likely) introducing contaminates to your stock reagents which can compromise the accuracy of your testing.

So my tip is really simple, and one that you can use for any titration test, provided you know the 'ball park' amount of reagents you typically need to use to see the end-point color change on your titration test. The tip is - > only use enough titration reagent to get to the expected endpoint + a 0.1 ml or two ; you then need to do some very simple math on the back end to read off the result from the table. For the salifert ALK kit... if your alk is typically 7 or 8; you can safely only do the test with 0.6 / 0.7 / 0.8 mls of reagents (instead of 1 ml; which saves you 40%/30%/20% of reagents respectively)... once you find the end point, you need to compensate for the fact that you didn't start at 1.0 ml of reagent by adding 0.4/0.3/0.2 to the value that you got, before looking it up on the table.

Super easy! you get the benefits of both full resolution testing and using less reagents.

here is vid explanation of this here

 

[GoVols]

Thank You!!

 

[tenurepro]

and just a quick response to a few questions that are bound to come up here..
What is wrong with returning the unused liquid back to the solution? 'i've been returning the liquid to the stock solution all my life and i haven't had any problems', etc etc.

Again, if you've been trained to do analytical chemistry or molecular biology in a lab setting - you would have received instructions to never return any solution in a pipette / or syringe back to stock solution (in most circumstances); here is an excerpt from an analytical chemistry guide:

"Unless specifically directed to the contrary, never return any excess reagent or solution to a reagent bottle. Contamination of the entire bottle by returning excess reagent is a false economy - considerable time can be spent determining the source of any contamination (and consequent poor results), and the entire bottle then has to be disposed of and a new bottle obtained. "
source: INTRODUCTION TO GOOD LABORATORY PRACTICES (GLPs) https://web.viu.ca/krogh/chem311/Intro to GLPs 2008.pdf

If you return unused solution to stock, then you run the risk of contamination... while you may still be able to run the test and get 'results', you will not be sure of how accurate these results are. Now you may say 'this is a hobbyist kit', or 'is this going to make a difference', etc. etc. ; it may or may not, but i rather do the technique properly then compromise the integrity of the kit. Also, as i mention above, there is a safer way to save reagents without running the risk of contamination

 

[saltyhog]

Good tip! Unfortunately I use Hanna for Alk and with Salifert Ca and Mg you use almost the entire 1 ml if you are in range, so it won't help me. I would never have thought of this.

 

[tenurepro]

Good tip! Unfortunately I use Hanna for Alk and with Salifert Ca and Mg you use almost the entire 1 ml if you are in range, so it won't help me. I would never have thought of this.

Thanks @saltyhog I also recently got a hanna for Alk but I only use to test accuracy of new salifert Alk kits. I like the salifert kit for cost as I test often

 

[Cory]

Cool video thanks. Apparently fuchsia (purplish) is the endpoint not pink. But i always go to pink. Also i always close my acid bottle. One is for evaporation or accidentally spilling a drop into it and two is because ive actually hit and spilled the whole jar.

 

[tenurepro]

Cool video thanks. Apparently fuchsia (purplish) is the endpoint not pink. But i always go to pink. Also i always close my acid bottle. One is for evaporation or accidentally spilling a drop into it and two is because ive actually hit and spilled the whole jar.

Thanks. Yeah the end point is tricky. I recently double checked my endpoint on the salifert with a Hanna checker. I get 7.7 on the salifert and 7.78 on the Hanna when I call the endpoint = pink with no blueish undertones
Yes also a great idea to cap the reagent bottle right away. I usually do that but got carried away with the vid setup