GB1209182A - Injectors for injecting measured micro-quantities of liquid samples - Google Patents

Abstract

1,209,182. Syringes. PYE Ltd. March 14, 1968 [March 15, 1967], No. 12122/67. Heading F1R. An injector for injecting measured microquantities of liquid samples into chromatographic equipment, comprising a sampling tube 1, Fig. 2, with a close-fitting wire-like plunger 6 therein, has means for substantially preventing rotation of the plunger in a gland 7 at one end of the sampling tube. The rotation may be prevented by a tube 9 co-operating with members 8, 10 fixed to the plunger and sampling tube respectively, or by making the co-operating surfaces of tubes 3 and 5 of non-circular cross-section, e. g. hexagonal. A screw 11 prevents accidental withdrawal of the plunger from the sampling tube. A resilient scale member 12, Fig. 4, is locked by a finger screw (not shown) in a channel in the member 8 in a position corresponding to the volume of sample required, and normally rests on the side of the member 10. However, during filling of the sampling tube, the scale member moves clear of the member 10, See Fig. 4, and can therefore be flexed into a position in which, on subsequent movement of the members 8 and 10 towards one another, the bottom of the scale member will abut the top of member 10. Thus the required volume of sample in left in the sampling tube and can be discharged therefrom when the scale is released from its flexed position. In an alternative embodiment, Fig.5 (not shown), the scale member is located in slots in both members (8 and 10), and the lower end of the scale is bent inwardly below the member (10) to form an abutment (15) which, after locking of the scale in its required position to the member (8) and during filling of the sampling tube, contacts the bottom of the member (10) to prevent further filling when the sampling tube contains the required sample volume. The injector may have a compression spring surrounding the tube 9 between the member 8, 10, have finger grips, and be made wholly of metal.