FAS/DPD drops

[kywildcats]

This is probably going to seem like a funny question, but when I use the R-0871 drops for FC test, it seems sometimes when inverting bottle, the drops will start on there own, and other times I have to squeeze the bottle to start. This definitely affects the test as far as I can tell, as the drops seem smaller without squeezing the bottle. Am I missing something?

 

[woodyp]

Have you just recently gotten a new supply of the drops?

 

[kywildcats]

No this is not a new batch, probably half a bottle used already.

 

[kywildcats]

 

[duraleigh]

Holding the bottle vertically, you allow the drops to "fall" off the tip. You should apply enough pressure on the bottle for the drop to start forming on the tip but not enough to force the drop off.

And, yes, often a drop will come out the instant you start to invert.

I hold the bottle inverted and make sure the drops will form correctly on the tip before I start my count. Like many things, practice is the best teacher

 

[tommyd123]

WHat I do is squeeze the bottle to let some air out and hold it that way as I invert it. Once inverted, I lessen my grip some, this way there is suction keeping gravity from making the drops come out. I feel like this method gives me maximum control over the drops, and eliminates that one errant drop that tends to come out when inverting the bottle.

 

[kywildcats]

Thank you!

 

[mikemass]

The same thing happens to me. I choose to waste the first few drops (3 or 4) off to the side as I have no control over them when I first invert the bottle. Once those first 3 or 4 pour out on their own I will move over to the tube and start my controlled drips.

Coincidentally this was recently discussed in another thread where I posted a video doing some Cl tests. Video was addressing issues with the DPD test, not the FAS/DPD test. But another member noticed me "wasting" the drops and offered the same suggestion as tommyd123 just did.

 

[kywildcats]

Very good info, I do appreciate it!!!