Quick question about reading syringes please!

Hi, it’s me again.

Usually I just draw up the liquid into the syringe and take the reading from the first plunger line. However I wondered how accurate this is because if there is still liquid in the nozzle when drawing it up, it’s a little more than where the first mark of 0.0mg starts on a 1ml syringe. I’ve been going with getting it as accurate as possible so have been measuring from the first line on the syringe (0.0mg) rather than from the nozzle. Is this correct?

Many thanks!

If you submerge the tip in liquid, and pull back the plunger, the amount of liquid pulled in will be exactly the amount shown in the scale on the barrel of the syringe.  There will be some in the tip, and there will be an air gap between the bottom of plunger, and the liquid in the barrel.  The volume in the tip will be exactly the same as the volume in the air gap.

To get the full dose that you pulled up, you need to fully discharge the syringe several times (and rinse and discharge cycle is recommended) and use/drink everything that is discharged.

i've always knocked out the air bubble and pushed the solution up through the tip until the plunger was at my dosage line.

i also never rinsed out the plunger to drink.  Only to clean it at the end for my next dose usage.  I do drink and rinse and re-drink from the cup with my solution 3 x's.

nobody ever mentioned about the bubble in the syringe to me when sharing how to do MLT. 

does this make a big difference?

When a syringe is "empty", and the plunger fully depressed, there is an area between the end of the tip, and the bottom of the plunger.  I put "empty" in quotes because that space is actually filled with air.

If you submerge the tip, then that air is trapped between the end of the tip, and the bottom of the plunger.  And when you begin to retract the plunger, 1) liquid displaces the air in the tip, and 2) the air moves up  and stays between the liquid, and the bottom of the plunger.

And the actual amount of liquid drawn up will be exactly the amount shown on the barrel of the syringe.  There will be air gap between the plunger and the liquid, and there will be liquid in the tip.  But the total amount of liquid (barrel + tip) is the amount shown on the scale of the barrel. If you want really want to use the full amount that you drew up (and is shown on the syringe), then you must discharge ALL of that liquid.

But...as I post over and over again, consistency is much more important than accuracy.  Just because we do calculations and spreadsheets that show tenths or hundredths of a milligram does NOT mean you actually need to measure to tenths of hundredths of a mg.  So whatever procedure you use for filling and discharging your syringe(s), as long as you do it the same way each time, you will be OK.

The concept of a "microtaper" is NOT that it will be more precise and accurate, but that is will be more gradual.

Thank you, builder.