The core principle of Hamilton's small volume injection needle is based on the negative pressure mechanism. When the operator pulls up the piston, a negative pressure environment is formed inside the syringe, which promotes the liquid to be measured to be sucked into the cavity through the needle tip; Then push the piston and use the pressure difference to inject an accurate amount of sample into the target device (such as a chromatograph or reaction vessel). This process relies on the airtightness of the "piston needle tube" system to ensure that the liquid is transferred in a leak free state; Modern automatic samplers further optimize this process by setting parameters such as injection volume and time to achieve full automation of the entire process. The system combines quantitative loop technology to strictly control the volume consistency of each injection, reducing errors caused by human factors; The application of high-quality materials such as stainless steel or special alloys enhances corrosion resistance and wear resistance, while the reinforced plunger design avoids bending deformation and ensures long-term reliability. In addition, clear scale markings facilitate real-time monitoring of liquid volume and enhance experimental controllability.

Measurement steps for Hamilton small volume injection needle:

1. Preparation work

-Check equipment integrity: Confirm that the injection needle is not damaged, deformed, or blocked, especially the needle tip should be kept sharp and unobstructed.

-Calibration instrument (if required): If high-precision quantitative analysis is required for the experiment, the injection system needs to be calibrated in advance to ensure that the actual injection amount is consistent with the set value.

2. Extract samples

-Slow operation to avoid bubbles: After immersing the needle in the sample solution, extract the liquid at a slower speed to prevent air from entering and forming bubbles due to rapid inhalation. For trace amounts (such as 10 μ l), there may be tiny bubbles inside the metal needle that are difficult to detect with the naked eye. It is recommended to inhale 1-2 μ l more and adjust the posture to move the bubbles up to the top for discharge.

-Repeated bubble discharge verification: Push and pull the piston multiple times to remove residual bubbles until a continuous and stable liquid column is observed flowing out without any interruption.

3. Sample injection operation

-Control speed and angle: During injection, the action should be fast but smooth, and the injection speed should be consistent each time; The needle tip should reach the middle of the target container before releasing the sample to reduce errors caused by positional deviation.

-Maintain residual consistency: During multiple consecutive injection processes, try to ensure that the amount of sample adhered to the inner wall of the needle is similar to improve repeatability.

4. Follow up processing

-Timely cleaning and disinfection: Immediately clean with warm water and non alkaline, phosphate free detergent after use, then rinse the inner and outer walls with solvents such as pure water or acetone, and dry with air; If necessary, use specialized disinfectants to prevent cross contamination.

-Status assessment: Determine whether the performance of the injection needle is normal by observing the liquid morphology (such as whether it is a vertical continuous liquid column) and the pressure feedback of the infusion pump.