What syringe should I use?
For the best possible injection reproducibility and accuracy, the smallest injectable volume from any syringe should generally be no less than 20% of its total capacity, (the smallest recommended injection volume from a 10µL syringe would be 2µL). For capillary injection, a microvolume plunger-in-needle syringe is recommended. The standard full-scale length on a 0.5-10µL syringe is 54.1mm. The standard scale length on a 25µL-25mL syringe is 60mm.
What is adequate washing and flushing of a syringe?
A syringe should be flushed with approximately 5-10 times its total capacity to eliminate carryover between samples. This is achieved by drawing and expelling the solvent/sample from the syringe several times. To avoid contaminating the sample, the first 2-3 washes should be discarded to waste.
How do I eliminate air from the syringe and needle?
Small air bubbles can be removed by drawing the sample into the barrel and rapidly expelling the sample while keeping the needle tip immersed in the solution. Repeat this activity several times. Turning the syringe barrel upright while expelling the sample may also help remove bubbles.
What technique is recommended for accurate and reproducible injection?
After removing the air bubbles, overfill the syringe. Holding it vertically at eye level, with the needle pointing upwards, press the plunger until the desired injection volume is reached. Draw the plunger back slightly and then wipe the needle tip with a lint-free tissue making sure that the sample is not drawn from the needle. Inject the sample.
Are there temperature limits to consider?
SGE syringes have been designed to withstand temperatures up to 120°C. However, rapid changes in temperature can lead to splitting the glass barrel. Plungers should be removed for autoclaving procedures.
How should I inspect my syringe?
Syringes should be routinely checked for damage to the barrel and needle. Look for hairline cracks in the barrel. Replace a cracked barrel with a new syringe. Needles should also be checked for burrs and rough surfaces that may cause tearing and excessive wear on the septum. Burrs may tear GC septa leading to sample loss or poor peak shape.
Under most circumstances, methanol, methylene chloride, acetonitrile, or acetone is suitable for routine cleaning of a syringe. The selection of a solvent for cleaning a syringe should be made with consideration to the contaminating material in the syringe. Under no circumstances should the entire syringe be immersed in solvent. The adhesive used to bond the metal flange and front needle fittings to the glass barrel can be damaged. Clean the outside surfaces of the syringe by simply wiping with a cleaning material. After use and before storing, always thoroughly rinse the syringe with solvent. Ensure that the syringe is dried so that there is no residual solvent in the barrel.
Never force the plunger. Replacement plungers for standard syringes are not available. Plungers fitted to these syringes are individually fitted to the barrels to achieve a perfect seal. This means that plungers are not interchangeable.
The ease with which a plunger slides in a glass barrel is not an indication of the quality of seal between the glass barrel and metal plunger. A perfectly sealing plunger may appear to be loose in the barrel.