if you depress the plunger to the first stop, place the tip into a solution and then release the plunger, does it withdraw the sample, expel the sample, or eject the tip?

It withdraws the sample. The second stop ejects the tip.

thanks

It withdraws the sample.

To determine the action of depressing the plunger to the first stop, placing the tip into a solution, and then releasing the plunger, we need to understand the functioning of the specific device or tool in question.

Since you haven't mentioned a specific device, I'll explain the general procedure for a commonly used tool, such as a pipette. A pipette is often used in laboratories to measure and transfer precise volumes of liquid.

1. Depressing the plunger to the first stop: Most pipettes have a plunger with two stops. Depressing the plunger to the first stop often allows air to enter the pipette and establish equilibrium.

2. Placing the tip into a solution: After depressing the plunger to the first stop, you attach a disposable, sterile pipette tip to the pipette. Then, you gently place the tip into the liquid solution you want to withdraw or sample.

3. Releasing the plunger: Once the tip is submerged in the solution, you slowly release the plunger. This action creates a vacuum inside the pipette, which enables withdrawal or aspiration of the liquid into the pipette. The liquid will be drawn up into the pipette tip.

Based on this process, when you release the plunger after placing the tip into a solution, the most likely outcome is that the pipette will withdraw or aspirate the liquid sample into the pipette. It should not eject the tip unless there is a different mechanism or control involved.

Remember, the exact action may depend on the specific device being used, so it's always important to refer to the user manual or guideline provided by the manufacturer to ensure proper usage.