Syringe accuracy question.

[MisterSuperGod]

We've all seen the posts before where someone drawing 1 ml from a 10 ml vial comes up short on the last draw.

The answer is always that some oil remains in the needle and the needle hub and that small amount adds up to be close to 1 ml by the time the vial is completely tapped.

For science (and my own curiosity) i wanted to test a theory that i had. i pulled .5 ml from a vial using an insulin syringe with a fixed 27g, .5" needle with virtually no dead space.

i pulled the plunger down further after drawing to get all the oil and to make sure i had a precise .5 ml.

i transferred the .5 ml into a BD 3 ml syringe and pulled the plunger down to the 2 mark.

Below you will see that the volume is one slash higher than it's supposed to be.

Now before someone drones on about why anyone would worry about .1 ml, save your breath. That's not the point of this post.

The point is to come to a definitive conclusion for why so many people come up short. Could it be as simple as the markings on the syringe aren't accurate?

i apologize, the pic is cropped and pretty blurry, but you can still see the lines and oil level.

 

[LeoTC]

Honestly, I'd chalk most of it up to inconsistent or incorrect draws. Using the wrong park of the plunger to measure the dose.

 

[MisterSuperGod]

Honestly, I'd chalk most of it up to inconsistent or incorrect draws. Using the wrong park of the plunger to measure the dose.

That's possible, i know some people believe the peak of the rubber plunger is correct, but as you can blurrily see, i've got it measured correctly and there's still a discrepancy.

 

[The Terminator]

Pretty sure most pharmaceutical vials add extra to compensate. At least when I use to trt my 1ml vials had like .1-.2ml extra.

 

[ickyrica]

We've all seen the posts before where someone drawing 1 ml from a 10 ml vial comes up short on the last draw.

The answer is always that some oil remains in the needle and the needle hub and that small amount adds up to be close to 1 ml by the time the vial is completely tapped.

For science (and my own curiosity) i wanted to test a theory that i had. i pulled .5 ml from a vial using an insulin syringe with a fixed 27g, .5" needle with virtually no dead space.

i pulled the plunger down further after drawing to get all the oil and to make sure i had a precise .5 ml.

i transferred the .5 ml into a BD 3 ml syringe and pulled the plunger down to the 2 mark.

Below you will see that the volume is one slash higher than it's supposed to be.

Now before someone drones on about why anyone would worry about .1 ml, save your breath. That's not the point of this post.

The point is to come to a definitive conclusion for why so many people come up short. Could it be as simple as the markings on the syringe aren't accurate?

i apologize, the pic is cropped and pretty blurry, but you can still see the lines and oil level.

I've seen that with glassware. The markings will be incorrect and brews can end up 5/10ml off target.

 

[jJjburton]

We've all seen the posts before where someone drawing 1 ml from a 10 ml vial comes up short on the last draw.

The answer is always that some oil remains in the needle and the needle hub and that small amount adds up to be close to 1 ml by the time the vial is completely tapped.

For science (and my own curiosity) i wanted to test a theory that i had. i pulled .5 ml from a vial using an insulin syringe with a fixed 27g, .5" needle with virtually no dead space.

i pulled the plunger down further after drawing to get all the oil and to make sure i had a precise .5 ml.

i transferred the .5 ml into a BD 3 ml syringe and pulled the plunger down to the 2 mark.

Below you will see that the volume is one slash higher than it's supposed to be.

Now before someone drones on about why anyone would worry about .1 ml, save your breath. That's not the point of this post.

The point is to come to a definitive conclusion for why so many people come up short. Could it be as simple as the markings on the syringe aren't accurate?

i apologize, the pic is cropped and pretty blurry, but you can still see the lines and oil level.

Why worry about .1 ml in the end of the needle?

 

[MisterSuperGod]

Why worry about .1 ml in the end of the needle?

Cute.

 

[bob357sig]

The only thing that has kept me from coming up short on a cycle was using ampules. 30 ampules of say Deca, pinned 2X week and I know im going to get a 15 week cycle. I just used 30 ml of Deca in 3 vials and ended up with a 13 week cycle. Im always coming up short on the end, no pun intended lol.

 

[dokdonia]

It's hard to tell from the picture, where is the bottom of the meniscus? It looks like the top of the meniscus is at 1.4ml and bottom is at ~1.5ml. Technically measurement is to the bottom of the meniscus. The difference is ~0.1ml for oils in a 3ml syringe.

 

[MisterSuperGod]

It's hard to tell from the picture, where is the bottom of the meniscus? It looks like the top of the meniscus is at 1.4ml and bottom is at ~1.5ml. Technically measurement is to the bottom of the meniscus. The difference is ~0.1ml for oils in a 3ml syringe.

It's at the bottom of the rubber tip on the plunger is at the 2 mark, not at the peak.

 

[dokdonia]

It's at the bottom of the rubber tip on the plunger is at the 2 mark, not at the peak.

I am referring to the meniscus of the oil. The difference btw where the top and bottom are.

 

[MisterSuperGod]

I am referring to the meniscus of the oil. The difference btw where the top and bottom are.

Do you believe then that the syringe is accurate?

 

[SomeRandoGuy]

Why worry about .1 ml in the end of the needle?

If it’s primo that’s like 2 bucks worth! I want my two dollars!

 

[dokdonia]

Do you believe then that the syringe is accurate?

I do if the bottom of the meniscus is indeed at the ~1.5ml mark. Another place people are getting unexpected loss and discrepancies is the hub/needle dead space. The barrel markings take this into account as assumed loss. You think you are drawing say 1ml but you are really drawing in 1.x ml. You would inject 1ml and would leave .x in the dead space if you did nothing else besides draw to the marker.

This can be quickly verified by drawing water into a syringe to the 1ml mark with no air left in the needle or barrel and either drawing the plunger down to the 2ml mark or by dumping all the water including the dead space volume into an insulin syringe. You actually drew in close to 1.1ml of liquid.

 

[little]

Damn son that’s some real scientifically

 

[BigBaldBeardGuy]

This is pretty interesting. I’ll have to duplicate what you did and see if there’s a difference between my iPhone 7 picture and your iPhone 4 picture.

But back to your needle thing, 0.1 ml here and there quickly adds up. If you’re drawing 0.5 ml and it’s 0.1 ml off at the end of that vial you’ll be off. 20 draws x 0.1 ml = 2.0 ml.

 

[MisterSuperGod]

This is pretty interesting. I’ll have to duplicate what you did and see if there’s a difference between my iPhone 7 picture and your iPhone 4 picture.

But back to your needle thing, 0.1 ml here and there quickly adds up. If you’re drawing 0.5 ml and it’s 0.1 ml off at the end of that vial you’ll be off. 20 draws x 0.1 ml = 2.0 ml.

i actually took the picture naked and had to crop out all the dick and muscle because i figured it get too many people hot and bothered. Too many = you and Icky.

 

[JC Grifter]

It’s irritating and I really noticed it when I started trt. You’re still injecting the actual dose of what’s in the syringe, but the tip steals .1ml every time. There’s a brand of syringe called excel that has a tip that gets pressed into the plastic part of the needle and you get every last drop. So you actually end up injecting .1ml more than you were planning actually

 

[BigBaldBeardGuy]

It’s irritating and I really noticed it when I started trt. You’re still injecting the actual dose of what’s in the syringe, but the tip steals .1ml every time. There’s a brand of syringe called excel that has a tip that gets pressed into the plastic part of the needle and you get every last drop. So you actually end up injecting .1ml more than you were planning actually

Life hack:

(And this is going to blow your mind.)

You don’t have to worry about air in the barrel so I always draw 0.2 cc of air. That way when you’re injecting that air pushes that last little bit out of the needle.

Plus the “thrruppp” sound it makes tells you that you’re done.

Never had an embolism in 3 years. You’re injecting into muscle, not a vein - no issues.

 

[JC Grifter]

Life hack:

(And this is going to blow your mind.)

You don’t have to worry about air in the barrel so I always draw 0.2 cc of air. That way when you’re injecting that air pushes that last little bit out of the needle.

Plus the “thrruppp” sound it makes tells you that you’re done.

Never had an embolism in 3 years. You’re injecting into muscle, not a vein - no issues.

Interesting [emoji848]. Maybe we should have a thread dedicated to tips and tricks Like this