Method and apparatus for conveying liquids to be analyzed to an automatic spectrophotometrical reading cuvette

Claim 2

Method for transferring a predetermined amount of sample liquid to be analyzed form a sample container to a closed cuvette chamber for carrying out spectrophotometrical and colorimetrical tests therein, comprising the steps of placing the interior of the cuvette chamber in communication with a probe and a syringe pump having a pressure stroke and a suction stroke, inserting said probe into said sample liquid in the sample container, withdrawing a predetermined amount of sample from the sample container and transferring said withdrawn sample to the cuvette chamber by actuating a suction stroke of said syringe pump to reduce the pressure in said chamber by a predetermined magnitude, removing the probe from the sample liquid, establishing communication between the bottom of said cuvette chamber and a source of vacuum to withdraw all of the liquid in the cuvette chamber, cutting off said communication between the cuvette chamber and vacuum source, and again withdrawing sample and transferring withdrawn sample to the cuvette chamber by actuating a suction stroke of the syringe pump while the probe is inserted in the sample liquid.

Claim 3

Method defined in claim 1, which includes the step of simultaneously actuating a pressure stroke of said syringe pump while said source of vacuum is in communication with the cuvette chamber.

Claim 4

Apparatus for carrying out spectrophotometrical and colorimetrical tests on successive samples of liquids, comprising a closed cuvette chamber having portions of opposing walls provided with means to permit transmission of radiant energy through a liquid contained therein, photodetector means including measuring means positioned to be responsive to radiant energy transmitted through said contained liquid, probe means to be inserted into a liquid to be sampled, reversible syringe pump means having a reciprocating piston, conduit means connecting said probe means and said syringe pump means in communication with the interior of said cuvette chamber to transfer liquid from a sample liquid container into said cuvette chamber when the probe means is inserted in said sample liquid and said syringe piston is moved in one direction to create suction in said conduit means and cuvette chamber, vacuum pump means, outlet conduit means including valve means having an open and a closed position and a closed flask connecting said vacuum pump means with the bottom of the interior of said cuvette chamber to withdraw all of the liquid from said cuvette chamber when said valve means is in said open position, electric motor means to reciprocate said syringe means piston, and switching means to connect said motor means with a source of energy, said switching means including means to maintain said valve means closed when said piston is moved by the motor means said suction stroke to maintain said valve means open when said piston is moved in the opposite direction and to energize said measuring means at a predetermined position of said piston.

Claim 5

Apparatus for carrying out spectrophotometrical and colorimetrical tests on successive samples of liquids, comprising a closed cuvette chamber having portions of opposing walls provided with means to permit transmission of radiant energy through a liquid contained therein, photodetector means including measuring means positioned to be responsive to radiant energy transmitted through said contained liquid, probe means to be inserted into a liquid to be sampled, reversible syringe pump means having a reciprocating piston, conduit means connecting said probe means and said syringe pump means in communication with the interior of said cuvette chamber to transfer liquid from a sample liquid container into said cuvette chamber when the probe means is inserted in said sample liquid and said syringe piston is moved in one direction to create suction in said conduit means and cuvette chamber, vacuum pump means, outlet conduit means including valve means having an open and a closed position and a closed flask connecting said vacuum pump means with the bottom of the interior of said cuvette chamber to withdraw all of the liquid from said cuvette chamber when said valve means is in said open position, electric motor means to reciprocate said syringe means piston, and switching means to connect said motor means with a source of energy, said switching means including means to maintain said valve means closed when said piston is moved by the motor means said suction stroke to maintain said valve means open when said piston is moved in the opposite direction and to energize said measuring means at a predetermined position of said piston.

Claim 6

Apparatus as defined in claim 3, wherein said electric motor means includes a rotary driving shaft, a reciprocable slide, crank linkage means connecting said rotary shaft and said slide, the piston of said syringe pump means including an elongated stem, and means connecting said slide with said stem to reciprocate said piston.

Claim 7

Apparatus as defined in claim 4, wherein said means connecting said slide with said stem includes adjustment means to vary the stroke of said piston.

Claim 8

Apparatus as defined in claim 5, wherein said means connecting said slide with said stem includes a pair of stop blocks positioned on said stem in longitudinally spaced relation, and a fork connected to said slide to engage alternately with a respective one of said pair of stop blocks when the slide is reciprocated.

Claim 9

Apparatus as defined in claim 6, wherein each o said stop blocks is longitudinally adjustably positioned on said stem to permit adjustment of the stroke of the piston.

Claim 10

Apparatus as defined in claim 2, wherein said valve means included in said outlet conduit means comprises a cylindrical chamber closed at one end by a reciprocable valve piston, said chamber being provided with an inlet opening in communication with the interior of said cuvette chamber and an outlet opening in communication with said vacuum pump means, said valve piston being reciprocable between a first position to block communication between said inlet and outlet openings and a second position to allow communication between the inlet and outlet openings.

Claim 11

Apparatus as defined in claim 8, wherein said switching means includes rotary cam-and-follower means, and means connecting said electric motor means to rotate said cam, said follower means being connected with said valve piston to reciprocate said valve piston between said first and second positions.