Salifert Test Kit Syringe Question

[Reefrock]

Hello. I am still using Salifert test kits although it seems they are going out of business. In any case, I have a question regarding the syringe, which is the same for many test kits such as Alk, Cal,etc. My question is does everyone use the tip that is attachable to the syring or do you just use the syringe without the tip? I think the test is more accurate when you do not use the tip attachment and just fill the syring up to 1.0 with the solution being tested. Is this what some of you are also doing?

Thanks!
Joe
Reefrock

 

[sirreal63]

I have always used the tip but my dexterity is way above normal.

 

[aquaman67]

I use the tip...

 

[xraydoc]

I personally still use the syringe tip. It doesn't matter if you dont as long as you draw up the additional volume of reagent to match what would have been in the tip.

The only issue I can conceive of is that the individual drops will be larger from the syringe tip compared with the pipette tip, potentially adding a small amount of inaccuracy (which I am sure is within the margin of error).

 

[OneReef]

I think that I remember reading in the instructions that they factor in the air volume in that skinny tip in what measurements they tell you to use, so not using it may have some impact on your measuring and reading.....

 

[Randy Holmes-Farley]

Yes, you should use the tip, but only because you can get smaller drops that way. Smaller drops means greater precision. The air volume in the tip makes no difference at all.

Sucking up water until the black part of the plunger reads 1.0 ml and then dispensing until the black part of the plunger reads 0.2 mL delivers exactly 0.8 mL of liquid, regardless of whether you use a tip or not. In fact, you could use a tip 50 feet long and never get any water into the visible part of the syringe, and you'll still deliver 0.8 mL if the syringe plunger is moved by that amount.

 

[Reefrock]

I clearly see the syringe provides a more accurate measurement. So I have one more question then. When filling the syringe with the tip installed, where should the liquid stop at? When the bottom of the black plunger is at 1.0, the liquid stops sometimes at .8 and sometimes at .75. To get the most accurate measurement, where should the liquid measurement fill up to..?...is .8 correc?...or should there be liquid up to 1.0?

Thanks for any feedback,...trying to make sure my measurements are accurate...

 

[Randy Holmes-Farley]

The end of the liquid and the beginning of the air inside the barrel reflects the volume of air in the tip between the tip end and the end of the plunger. Depending on the exact tip used and how far it is forced on, the value may be different. But it makes no difference where it comes to since the volume of liquid taken up and dispensed reflects the travel of the plunger end only.