Does 1ml dosing syringe tip variances matter when testing?!?

[Project1004]

I’ve noticed I have two type dosing syringes. And I tend to use the ones with tip instead of flat ones for all the dosing and testing….

But, I think it’s the flat ones we get when we buy the new alk testing reagents?…

Hanna alk and calcium test unit requires 1ml of solution etc. And like to make sure I use the right one going forward.

I think it matters?!! Much appreciated <><

Edit: I know salifert test kit says not to worry about a tiny air bubble (0.05?) when testing etc. Maybe it don’t matter?!

 

[Dan_P]

I’ve noticed I have two type dosing syringes. And I tend to use the ones with tip instead of flat ones for all the dosing and testing….

But, I think it’s the flat ones we get when we buy the new alk testing reagents?…

Hanna alk and calcium test unit requires 1ml of solution etc. And like to make sure I use the right one going forward.

I think it matters?!! Much appreciated <><

Edit: I know salifert test kit says not to worry about a tiny air bubble (0.05?) when testing etc. Maybe it don’t matter?!

Doesn’t matter IF the barrels don’t become mixed up. The plunger with the protrusion pushes everything from the syringe at 0 while the other leaves a little bit. The scales on the syringe barrels might also differ.

Why don’t you dispense 0.5 mL water with plungers in the correct barrel then mixed up (4 trials). The water dispensed will be the same if it doesn’t matter. Measure each dispensed volume of water with a one mL syringe not used in the test. It might not be exactly what you dispensed, but the syringes with the correct plungers should be tha same volume.

 

[Fish Fan]

I would like to think whomever made the syringe accounted for the extra volume displaced by the longer tip. I would think.....

Please let us know what you find out

 

[Randy Holmes-Farley Verified Community Expert]

Tips sizes do not ever matter. In many syringes, no fluid ever enters the barrel so that it never gets dirty.

All that matters for fluid volume measurement is the travel distance of the plunger along the barrel.

DO NOT try to push out air and refill the syringe again. That will lead to mismeasurement.

 

[Project1004]

Thank you guys. That’s good to know. Based on the salifert test kits, approximately 0.05ml will be a small air bubble in 1ml syringe.

I guess as long as Im use the “same syringe tip” the test result should be the same or there maybe deviation (5%) which isn’t noticeable since we are looking at the trend.

 

[Randy Holmes-Farley Verified Community Expert]

Thank you guys. That’s good to know. Based on the salifert test kits, approximately 0.05ml will be a small air bubble in 1ml syringe.

I guess as long as Im use the “same syringe tip” the test result should be the same or there maybe deviation (5%) which isn’t noticeable since we are looking at the trend.

I think maybe you did not believe me based on that comment.

It will not matter what tip or no tip, as long as you measure volume by the barrel travel.

This is no random opinion. This is exactly how syringes are meant to work.

I describe this in detail here:
https://www.reef2reef.com/threads/reef-chemistry-question-of-the-day-161-using-a-syringe.226267/

 

[Project1004]

Got you. Don’t matter as long as it is measured upto the line indicated on the syringe. I guess I just use any of em :). Thank you!

There is 11pages of comment on above link from your question of the day.

I’m going to say answer is B! And now I see it from your picture reference :)

 

[Randy Holmes-Farley Verified Community Expert]

Yes, the answer is B. Here’s the explanation from post 85 of that thread:

And the answer is...B. 2.9 mL

Here's how to think about how a syringe works:

When the plunger is pushed all the way in, the leading edge of the plunger aligns with the zero mL marking. That is true of nearly every syringe I've seen. When you begin to use it, the tip and barrel are empty, with the tip containing air and the barrel occupied by the plunger.

As you draw back the plunger with the tip in a liquid, the plunger creates a vacuum between it and the liquid, drawing in the liquid. The movement of the plunger draws in exactly the amount of liquid equal in volume to the travel of the plunger backwards (or upwards). So you can track how much fluid is taken up exactly by the travel of the plunger against the volume markings, regardless of what you see with the fluid (assuming it is functioning properly).

Some of the drawn in liquid will be in the tip, and some (or perhaps none, if it is all in the tip) will be in the barrel of the syringe. If the volume of the tip is larger than the volume indicated by the movement of the plunger, none will show in the barrel. Many modern pipettes work this way to avoid contaminating the barrel of the device. The device stays clean and the tip is discarded after each use.

Now, when you go to dispense the liquid, the plunger is pushed in, and all of the liquid is dispensed and the air is pushed back into the tip.

If you mistakenly tipped the syringe upward during dispensing, and blew out the air before the liquid, then when you push the plunger all the way in, there will still be liquid in the tip, and you probably won't know how much so you end up with a mismeasurement.

In the medical world, it can be super important to not inject air into a patient's bloodstream. In that case, the syringe must first be overfilled. It is then tipped up and all of the air blown out and some liquid may be blown out until the end of the plunger is exactly aligned with the volume marking you want to dispense. The syringe in total now contains the amount you want to inject, plus the volume of the the needle. Then you inject and when done, the needle is still full of liquid in the exact amount as before injection, and like before, the amount dispensed is exactly determined by the movement of the plunger. So this situation is no different except that you start and end with a full tip/needle. In a non-injection setting, you start and end with an air-filled tip.

So it doesn't matter how much liquid you see in the barrel. Only the movement of the plunger is important, whatever the use. :)