Patent GB-1465002-A (GB)
Title: Method of and an apparatus for distributing a liquid in the form of a multiplicity of doses
IPC: G01N35/10
Filed: 1974-03-19
Abstract: 1465002 Drop-delivery apparatus CENTRE NATIONAL DE TRANSFUSION SANGUINE 19 March 1974 [22 March 1973] 12136/74 Heading B8N A method for sequentially discharging into a multiplicity of containers 10 fractions of a liquid material sampled from a liquid containing receptacle T comprises: dipping a probe 60 forming a first end of a tube 51a into the receptacle; sucking liquid material L to be sampled into the tube 51a through the probe by first pump means 51; removing the probe from the receptacle T; sucking in a rinsing liquid R at the end of the tube opposite the probe by second pump means 53; displacing the probe above and along the containers 10 while continuing to suck in the rinsing liquid whereby the liquid to be sampled is pushed toward the outlet of the probe where it forms a micro-drop attached to the probe; and suddenly subjecting the probe to a sharp impact force to effect discharging of the micro-drop into a container which registers with the actual position of the probe when the same is subjected to the sharp impact. As described apparatus for performing the method comprises a frame 12, Fig. 1, on which is pivoted a plate body 16, and a carriage 20 slidable along rails 19, 19a on the body 16 by a chain 41 pivotally attached to a T-shaped member 25 slidable on rods 24, 24a on the carriage 20. A plate 29 is mounted on the body 16 via pins 31, 31a and co-operating slots 30, 30a and carries saw teeth 33, and a rack 35. Pumps 45, 51, and 53 are carried by the frame 12, and carriage 20. The probe 60 is carried by a plate 26 slidable on the rods 24, 24a, and the plate 26 has pawl 28 co-operable with the saw teeth 33. The probe 60, Fig. 3, is connected via pipe 53a and pump 53, and via pipe 51a and pump 51 to a washing liquid reservoir R. A washing ring 62 is connected via pipes 45a, 45b and pump 45 to reserovir R and waste respectively, and a channel 63 is also emptied by pump 45 and pipe 45c. In operation the carriage 20 is moved to the extreme right of the plate body 16 by chain 41 and the members 25 and 26 lowered by the vertical run of the chain to pass the probe 60 through the ring 62 into a tube T containing liquid L. At this time pumps 45 and 51 are operated to cause external washing of probe 60 in the ring 62 and to cause liquid to be sucked into the probe. The probe is then raised and the carriage 20 moved to the left, pumps 45 and 51 being inoperative at this stage. When the probe 60 is located above the first one in a line of receptacles 10 the pawl 28 engages the saw teeth 33 and the rack 35 is raised by a pawl 57 on the carriage 20 to mesh with a toothed flange 56 on the pump 53. Hence this pump is driven, as the carriage advances, to eject liquid from the probe 60, and the probe is reciprocated jerkily by the pawl 28 co-operating with the teeth 33 so as to shake a drop from the probe into each receptacle 10. At the end of its movement carriage 20 is returned, with the plate 29 now lowered to disengage rack 35 from pump 53, and teeth 33 from pawl 28. The plate body 16 is then tilted to align the probe 60 with a further row of receptacles and the carriage again advanced. On subsequent return of the carriage the pump 51 is driven by engagement of its flange 52 with a surface 53 on frame 12 so that washing liquid is supplied to the probe and collected in channel 63.