Accurate small-volume dispensing starts with matching the syringe to the expected range of your experiment. A syringe that is too large for the volume you need will have coarse graduations and higher relative error, while a syringe that is too small may not accommodate the full sample. Aim for a device whose maximum capacity is no more than three to five times the largest volume you will dispense.
This guide covers picking the instrument. How you handle it once you have it is a separate problem with its own failure modes, and it is covered in the companion guide on reducing error at the bench.
Syringe material and design
Consider the material and design of the syringe. Glass syringes provide excellent chemical resistance and low binding for many peptides and small molecules, but they are fragile and must be handled carefully. Plastic syringes are lighter and less breakable, but some polymers can adsorb hydrophobic compounds. Fixed-volume syringes (e.g., 5 µL or 10 µL) give the best precision for a narrow range, whereas variable-volume syringes with fine graduations are useful when you need flexibility across a broader range.
Barrel size and tip type
Barrel size and tip type are closely linked to accuracy. For volumes under 5 µL, a 10 µL Hamilton or equivalent glass syringe with a Luer slip tip offers the most consistent dead-space. Plastic syringes can be used for larger ranges (5-20 µL) but be aware that they may expand slightly with temperature changes.
Reading a tolerance figure
Pay attention to tolerance specifications and dead-volume. Manufacturers typically list a tolerance of ±1-2 % for microliter syringes; lower tolerances mean tighter control. Low-dead-volume tips reduce residual liquid and improve repeatability, especially when working with scarce reagents.
When you are measuring volumes below 10 µL, the syringe's tolerance becomes the dominant source of error. Look for syringes that specify a tolerance of ±1 % or better for the intended volume range, and verify that the manufacturer provides a calibration certificate.
For research use only. This guide covers bench handling of laboratory research materials. It does not describe an application, benefit, dose, route or outcome, and nothing in it is guidance for use in a person or an animal. Nothing sold by PepXtide has been evaluated by the FDA.