Guidelines for selecting the right syringe to reliably dispense microliter-scale liquids in the lab.
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.
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.
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. Before each use, expel any trapped air and pre-wet the barrel with the same solvent to minimize adsorption and volume shifts.
Store syringes in a clean, dry environment away from direct sunlight and extreme temperatures. If you reuse a syringe, clean it according to the solvent compatibility chart and verify that the plunger moves smoothly before the next measurement. Regularly inspect the barrel for scratches or residue, as these can affect accuracy over time.
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