Method and apparatus for chemical analysis

Claim 2

In a chemical analyzing system for determining the concentration of a component in a sample, wherein said sample, upon being introduced into solution with a reagent, reacts therewith, the rate of the reaction being indicative of said concentration, such system comprising sensor means for monitoring a characteristic of said solution or a component or a product of said reaction and for producing a first electrical output signal proportional thereto, and differentiator circuit means for producing a second electrical signal propOrtional to the time derivative of said first signal, said time derivative signal being indicative of said concentration of said component in said sample, the improvement comprising: means for inhibiting operation of said differentiator circuit means for a predetermined, fixed time interval from introduction of said sample into said reagent, said time interval being sufficient to permit thorough mixing of said sample with said reagent.

Claim 3

In a chemical analyzing system for determining the concentration of a component in a sample, wherein said sample, upon being introduced into solution with a reagent, reacts therewith, the rate of the reaction being indicative of said concentration, such system comprising sensor means for monitoring a characteristic of said solution or a component or a product of said reaction and for producing a first electrical output signal proportional thereto, differentiator circuit means for producing a second electrical signal proportional to the time derivative of said first signal, said time derivative signal being indicative of said concentration of said component in said sample, and means responsive to said second signal for generating an output signal indicative of the value thereof, the improvement comprising: means for inhibiting the generation of said output signal for a predetermined, fixed time interval initiated automatically upon introduction of said sample into said reagent, said time interval being sufficient to eliminate the effect of transients occurring upon introduction of said sample into said reagent.

Claim 4

In a chemical analyzing system according to claim 4, the improvement wherein said inhibiting means inhibits the operation of said differentiator circuit means during said fixed time interval.

Claim 5

In a chemical analyzing system according to claim 4, the improvement wherein said inhibiting means inhibits the operation of said generating means during said fixed time interval.

Claim 6

In a chemical analyzing system for determining the concentration of a component in a sample, wherein said sample, upon being introduced into solution with a reagent, reacts therewith, the rate of the reaction being indicative of said concentration, such system comprising sensor means for monitoring a characteristic of said solution or a component or a product of said reaction and for producing a first electrical output signal proportional thereto, differentiator circuit means for producing a second electrical signal proportional to the time derivative of said first signal, said time derivative signal being indicative of said concentration of said component in said sample, and means for measuring the value of said time derivative signal, the improvement comprising: means for inhibiting the measurement of said time derivative signal for a predetermined, fixed time interval from introduction of said sample into said reagent, said time interval being sufficient to eliminate the effect of transients occurring upon introduction of said sample into said reagent.

Claim 7

In a chemical analyzing system according to claim 7, the improvement wherein said fixed time interval is long enough to permit thorough mixing of said sample with said reagent.

Claim 8

In a chemical analyzing system according to claim 7, the improvement wherein the rate of said reaction is not necessarily linear.

Claim 9

In a chemical analyzing system according to claim 7, the improvement wherein said inhibiting means inhibits the operation of said differentiator circuit means during said fixed time interval.

Claim 10

In a chemical analyzing system according to claim 7, the improvement wherein said inhibiting means inhibits the operation of said measuring means during said fixed time interval.

Claim 11

A chemical analyzer comprising: means for receiving a sample and a reagent; sensor means operatively associated with said receiving means for monitoring the concentration of a component or product of the reaction between said sample and said reagent and for producing a First output signal proportional to said concentration; differentiator circuit means coupled to said sensor means and responsive to said first output signal for producing a second output signal proportional to the time derivative of said first output signal and thus proportional to the time rate of change of concentration of said component or product; means coupled to said differentiator circuit means for measuring the value of said second signal; and means coupled to said sensor means for inhibiting the measurement of the value of said second signal for a predetermined, fixed time interval from introduction of said sample and said reagent into said receiving means, said time interval being sufficient to eliminate the effect of transients occurring upon introduction of said sample and said reagent into said receiving means.

Claim 12

A chemical analyzer according to claim 12 wherein said inhibiting means comprises: timing means responsive to an abrupt change in said first output signal for producing a control signal, a characteristic of which changes after said predetermined, fixed time interval; and wherein said measuring means comprises: means responsive to said second output signal and operative upon the occurrence of said change in said characteristic of said control signal for determining the value of said second output signal.

Claim 13

A chemical analyzer according to claim 13 wherein said control signal is applied to said differentiator circuit means for inhibiting the operation thereof during said fixed time interval and wherein said measuring means measures the maximum value of said second output signal.

Claim 14

A chemical analyzer according to claim 13 wherein said timing means produces a second control signal, a characteristic of which changes before the termination of said fixed time interval, wherein said second control signal is applied to said differentiator circuit means for inhibiting the operation thereof during a first portion of said fixed time interval, and wherein said first-mentioned control signal is applied to said measuring means for inhibiting the operation thereof during said fixed time interval.

Claim 15

A chemical analyzer according to claim 12 wherein said sensor means comprises: first and second electrodes extending into said receiving means for monitoring the conductance of the solution therein, wherein: said second output signal is proportional to the rate of change of conductance of said solution, and wherein: said measuring means measures the value of said rate of change of conductance after said predetermined, fixed time interval.

Claim 16

A chemical analyzer according to claim 16 further comprising: oscillator means operatively coupled to one of said electrodes of said sensor means, said oscillator means generating an AC output signal; and demodulator means operatively coupled to the other of said electrodes of said sensor means, said demodulator means receiving an amplitude modulated signal and producing a DC signal which comprises said second output signal.

Claim 17

A chemical analyzer according to claim 16 wherein said sensor means includes a surface which is exposed to said solution, and wherein said electrodes comprise first and second conductive areas positioned on said surface, said conductive areas being spaced apart.

Claim 18

A chemical analyzer according to claim 16 wherein said sensor means includes a surface which is exposed to said solution, said surface conforming to a segment of a sphere, and wherein said electrodes comprise first and second conductive areas positioned on said surface.

Claim 19

A chemical analyzer according to claim 19 wherein said conductive areas have the shape of half circles and are positioned with their straight sides parallel and spaced apart.

Claim 20

In a chemical analyzing system for determing the concentration of a component in a sample, wherein said sample, upon being introduced into solution with a reagent, reacts therewith causing an instantaneOus change in a characteristic of said solution or a component or a product of said reaction, the rate of the reaction being indicative of said concentration, such system comprising sensor means for monitoring said characteristic, component or product and for producing a first electrical output signal proportional thereto, said change being sensed by said sensor means producing an abrupt change in said first output signal, and differentiator circuit means for producing a second electrical signal proportional to the time derivative of said first signal, said time derivative signal being indicative of said concentration of said component in said sample, the improvement comprising: timing means responsive to an abrupt change in said first signal for producing a control signal, a characteristic of which changes after a predetermined, fixed time interval after said abrupt change in said first signal; and means responsive to said second output signal and operative upon the occurrence of said change in said characteristic of said control signal for determining the value of said second signal.

Claim 21

In a chemical analyzing system according to claim 21, the improvement wherein said control signal is applied to said differentiator circuit means for inhibiting the operation thereof during said fixed time interval and wherein said determining means measures the maximum value of said second signal.

Claim 22

In a chemical analyzing system according to claim 21, the improvement wherein said determining means measures the instantaneous value of said second signal upon termination of said fixed time interval.

Claim 23

In a chemical analyzing system according to claim 21, the improvement wherein said determining means measures the peak value of said second signal after termination of said fixed time interval.

Claim 24

In a chemical analyzing system according to claim 21, the improvement further comprising: means for displaying the determined value of said second signal.

Claim 25

In a chemical analyzing system according to claim 21, the improvement wherein said timing means produces a second control signal, a characteristic of which changes before the termination of said predetermined fixed time interval, wherein said second control signal is applied to said differentiator circuit means for inhibiting the operation thereof during a first portion of said fixed time interval, and wherein said first-mentioned control signal is applied to said determining means for inhibiting the operation thereof during said fixed time interval.

Claim 26

In a chemical analyzing system according to claim 26, the improvement wherein said determining means measures the instantaneous value of said second signal upon termination of said fixed time interval.

Claim 27

In a chemical analyzing system according to claim 26, the improvement wherein said determining means measures the value of said second signal at a known time after termination of said fixed time interval.

Claim 28

In a chemical analyzing system according to claim 21, the improvement wherein said sensor means comprises first and second conductive elements for monitoring the conductance of said solution, wherein said second electrical signal is proportional to the rate of change of conductance of said solution, and wherein said determining means measures the value of said rate of change of conductance after said predetermined, fixed time interval from introduction of said sample into said reagent.

Claim 29

In a chemical analyzing system according to claim 29, the improvement wherein said conductive elements are substantially planar and are positioned in said sample coplanar to minimize capacitance effects on the measurement of conductance.

Claim 30

In a chemical analyzing system according to claim 29, the improvement wherein said sensor means includes a surface which is exposed to said solution, said surface conforming to a segment of a sphere, and wherein said conductive elements comprise first and second conductive areas positioned on said surface.

Claim 31

In a chemical analyzing system according to claim 31, the improvement wherein said conductive areas have the shape of half circles which are positioned with their straight sides parallel and spaced apart.