Construction of a Replacement VPC Syringe Glass barrel 10 pL syringes are commonly used in undergraduate VPC experiments. They are often of short life due to their fragile needles and glass barrels. Minimum replacement east averages $16 per syringe. An inexpensive replacement syringe can be constructed from the remains of a broken syringe. The plunger is cut to the length of a 21 gauge hypodermic needle. As the figure illustrates a piece of VPC septum is cut and inserted into the Luer huh to form a leak-tight seal. The plunger can be inserted through a serum cap and the septum to give a rugged, student grade syringe. The syringe is low cost ($1.91 for needle, septum, and serum cap), and the parts are nonbreakable. When the plunger is cut to exact length, the~yringehas negligible dead volume. If, after the plunger is cut the tip is not filed smooth, there is a resistance felt a t theend of the stroke when the plunger is withdrawn. This allows filling with a reproducible volume of 1.35 pL when a 1.5-in. needle is used. Change in needle length will allow injection of other volumes. Reproducibility of injected volume with the replacement syringe was compared to that of a standard Hamilton 10 pL syringe, Peak areas by VPC far injections each of hexane were measured. With the replacement syringe a mean of 1.35pL was injected with a standard deviation of 0.05pL. With the Hamilton syringe a mean of 1.00 uL iniected had a standard deviation of 0.07 pL. Possible explanations for the better performance of the reolacem-ent svrinee are its low dead volume and its reduced blow-hy due t o the tight fit hetween plunger and internal septum ~
C m l r a l M i c h i g a n I:niversity Mount I'lrasnnt. MI IhR59
~
Glenn S. Lewandos
Volume 57, Number 8,August 1980 1 551
