Medical Laboratory Automation, Inc.

North American Foreign Trading Corporation

Hugo Romero

Dietmar Nagel

Melvin R Kennedy

Avi Arad

Robert F Anderson

This invention provides a method and apparatus for correcting for the hydrostatic dead volume error which may occur in a pipette system and may also include method and apparatus for correcting for a lost fluid volume error. The technique involves determining the height of fluid in the tip for a desired fluid volume, determining the change in the dead volume resulting from having fluid of such height in the tip and determining the piston displacement required to achieve a volume equal to the sum of the desired volume and the determined change in dead volume, this determined displacement being the piston movement required to achieve the desired fluid volume. The height is determined from the volume multiplied by values which are constant for a given tip size and geometry. The change in dead volume varies as a function of the desired fluid height times a constant for a given fluid, pipette system and tip. Where a plurality of fluid samples are in the tip, and at least some of the samples are separated by a gas, the height, dead volume change and piston displacement determinations are made for each measured piston displacement to either intake or dispense. For multiple samples, height determinations for each sample are made utilizing only fluid heights. Where appropriate, a lost fluid volume correction value may also be added to the corrected volume utilized to perform piston displacement calculations.

Method and apparatus for performing hydrostatic correction in a pipette

A magnetic tape player has a stereo playback head for reproducing information from adjacent channels on a magnetic tape on which there is recorded a series of questions and answers in successive blocks. In a first portion of each block a given question and a plurality of possible answers are recorded in both channels, in a second portion of the block a coded indication of the correct answer to the question is recorded in one channel, and in a third portion of the block a correct indication is recorded in one channel and an incorrect indication is recorded in the other channel. The second portion of the block is marked by a first tone to indicate the start of the decision time during which one of a plurality of answer buttons is to be depressed to select an answer and the third portion of the block is marked by a second tone to indicate the end of the decision time. The coded indication of the correct answer as derived from the second portion of the block is then compared with the answer button which has been depressed, and the result of this comparison controls the passing of the one or the other channel to an audio output during reproduction of the information recorded in the third portion of the block.

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New Rochelle, NY, United States of America

Hugo Romero