[dave8421]

Hello

Hope this is the right place to pose this question.

Suppose I have a microfiber towel that I have cleaned and now rinsed, and finally wrung out the rinse water and captured the rinse water in a clean container.

Is there some way to test the run-off water for detergent residue?  Is there some test I can run to see how much detergent is left in the water I have wrung out of a towel?

I'm trying to determine the most efficient methods of cleaning microfiber towels, and using as little water as is needed. 

You could say just rinse until the water runs clean, but sometimes that is hard to really see.  A chemical test to detect the reduction in detergent on each subsequent rinse would be excellent information to have towards this project.

Thank you

[Arkcon]

I have performed cleaning validation studies on swabs taken from pharmaceutical manufacturing equipment, searching for trace levels of cleaning agents.  I would use HPLC, of with a refractive index detector, or using ion chromatography.  This process is expensive and tricky.  What you're looking for is a way to generally determine if detergent remaining in a bulk fluid -- maybe you can determine it by conductivity?  If the detergent is charged, you may be able to get a general idea by comparing the conductivity of a rinse sample before and after, since the rinse water likely has some conductivity of its own to start with.

[Archer]

Arkon has provided a much (much) better method while I was writing this but I shall post it anyway as we don't know what instrumentation is available to you.

A very crude test, but one that is used to test water used in cement manufacture, is simply to put the sample in a measuring cylinder and shake it vigorously.

Any detergent present in significant amounts will form bubbles on the surface of the water.

This is not particularly technical but it is a British Standard (BSI) method for detergent in water.

Consider though that this is one of many tests (which includes conductivity) to test the suitability of water for use with cement.

Arkon's suggestions are far better!

[dave8421]

Thank you both!  Excellent suggestions.

Your comments led me to this study which I am now reading - http://www.doiserbia.nb.rs/img/doi/1451-9372/2011/1451-93721000051M.pdf

It leads me to another question.   At the moment, I clean microfiber by hand either by folding the towel and rubbing agaisnt itself, or using a soft brush.  I wonder what method / tools are most effective, and also at what point is further agitation of the fibers unlikely to do further cleaning.  Does a pre-soak of the towels add any benefit as well, and how long should it be.

I usually pre-soak for maybe 1/2 hour, but I think I go overboard in the scrubbing process just to be sure i've got everything.  A challenge is microfiber can get stained, but it doesn't appear the stains have that much effect on the performance of the towel.  The stains can make it difficult to know when enough is enough with the hand cleaning.

I think the above questions are harder to answer as accurately as the detergent residue.  I hope to heard advice where to research into further.  Thank you