Fluid analyzer for measuring magnesium ions and method of calibrating potentiometric magnesium ion sensor therein

Abstract

A fluid analyzer for analyzing fluid samples comprising one or more analytes and a method of calibrating such. The fluid analyzer includes a control system to control at least one automated valve to pass at least three calibration reagents through a fluid channel to a secondary ion selective electrode, a primary ion selective electrode, and a reference electrode, and determine calibration information using calibration logic from signals generated by a meter, control the at least one automated valve to selectively pass different subsets of the at least three calibration reagents through the fluid channel to the secondary ion selective electrode, the primary ion selective electrode, and the reference electrode, and determine re-calibration information using the signals generated by the meter and at least one of the calibration information and re-calibration logic.

1 . A fluid analyzer for analyzing a plurality of analytes present in biological fluid samples, comprising:
 a fluid channel;   a potentiometric sensor for sensing at least a first analyte in a fluid sample, the potentiometric sensor comprising:
 a secondary ion selective electrode in fluidic communication with the fluid channel; 
 a primary ion selective electrode in fluidic communication with the fluid channel; 
 a reference electrode in fluidic communication with the fluid channel; 
 a meter receiving signals generated by the secondary ion selective electrode, the primary ion selective electrode, and the reference electrode and transforming the signals into information indicative of the electric potential of the one or more analytes; 
   at least one additional sensor for sensing at least a second analyte in the fluid sample, the at least one additional sensor being in fluidic communication with the fluid channel;   at least one calibration reagent injection port in fluidic communication with the fluid channel, the at least one calibration reagent injection port adapted to receive at least one predetermined calibration reagent;   at least one automated valve positioned between the at least one calibration reagent injection port and fluid channel, the at least one automated valve being openable and closable to provide one or more samples of the at least one predetermined calibration reagent to the fluid channel; and   a control system having a processor executing processor executable code that causes the processor to:
 control the at least one automated valve to pass at least three calibration reagents through the fluid channel to the potentiometric sensor and the at least one additional sensor and determine calibration information using calibration logic from signals generated by the meter, wherein each of the at least three calibration reagents has a magnesium ion concentration independently selected from a range of from about 0.1 mM to about 1.5 mM and a calcium ion concentration independently selected from a range of from about 0.2 mM to about 2.0 mM, wherein the at least three calibration reagents each comprise a different amount of magnesium ions and a different amount of calcium ions, and wherein at least one of the calibration reagents is utilized with both the potentiometric sensor and the at least one additional sensor present in the fluid analyzer; 
 control the at least one automated valve to selectively pass different subsets of the at least three calibration reagents through the fluid channel to the potentiometric sensor and the at least one additional sensor and determine re-calibration information using the signals generated by the meter and at least one of the calibration information and re-calibration logic. 
   
     
     
         2 . The fluid analyzer of  claim 1 , further comprising at least one of:
 (i) a sample injection port, whereby at a predetermined time a sample is injected into the fluid channel; and/or   (ii) at least one automated valve positioned between the sample injection port and the fluid channel, the at least one automated valve being openable and closable to provide one or more samples of the sample to the fluid channel.   
     
     
         3 . The fluid analyzer of  claim 2 , wherein the sample is manually injected into the fluid channel. 
     
     
         4 . (canceled) 
     
     
         5 . The fluid analyzer of  claim 2 , wherein the processor of the control system executes processor executable code that causes the processor to control the at least one automated valve positioned between the sample injection port and the fluid channel to inject the sample into the fluid channel. 
     
     
         6 . The fluid analyzer of  claim 1 , wherein the primary ion selective electrode is a magnesium ion selective electrode, and wherein the secondary ion selective electrode is a calcium ion selective electrode. 
     
     
         7 . (canceled) 
     
     
         8 . The fluid analyzer of  claim 1 , wherein the subsets of the at least three calibration reagents may be selected from the group consisting of: (i) one of the at least three calibration reagents, (ii) two of the at least three calibration reagents, and (iii) all of the at least three calibration reagents. 
     
     
         9 . (canceled) 
     
     
         10 . The fluid analyzer of  claim 1 , further comprising a cartridge comprising the at least three calibration reagents, the cartridge in fluidic communication with the at least one calibration reagent injection port. 
     
     
         11 . The fluid analyzer of  claim 1 , further comprising:
 at least one quality control reagent injection port in fluidic communication with the fluid channel, the at least one quality control reagent injection port adapted to receive at least one predetermined quality control reagent; and   at least one quality control automated valve positioned between the at least one quality control reagent port and the fluid channel, the at least one quality control automated valve being openable and closable to provide one or more samples of the at least one predetermined quality control reagent,   
       wherein the control system comprises processor executable code that causes the processor to control the at least one automated quality control valve positioned between the at least one quality control reagent injection port and the fluid channel to pass the at least one predetermined quality control reagent through the fluid channel to the potentiometric sensor and the at least one additional sensor. 
     
     
         12 . A method of calibrating a fluid analyzer, comprising the steps of:
 (A) at a first time period:
 (i) causing at least three calibration reagents to contact a potentiometric sensor and at least one additional sensor, the potentiometric sensor comprising a secondary ion selective electrode, a primary ion selective electrode, and a reference electrode, wherein the secondary ion selective electrode, the primary ion selective electrode, and the reference electrode generate signals receivable and transformable by a meter into first information indicative of the electric potentials of the at least three calibration reagents, and 
 (ii) using calibration logic of a control system having a processor executing processor executable code to determine calibration information using the first information, wherein the calibration information comprises a slope, an offset, and a selectivity coefficient; 
   (B) at a second time period after the first time period:
 (i) causing one of the at least three calibration reagents to contact the the potentiometric sensor and the at least one additional sensor, wherein the secondary ion selective electrode, the primary ion selective electrode, and the reference electrode of the potentiometric sensor generate signals receivable and transformable by the meter into second information indicative of the electric potential of said one calibration reagent, and 
 (ii) using recalibration logic of the control system to determine first re-calibration information using (a) the second information, and (b) at least a portion of the calibration information from step (A), wherein the re-calibration information comprises one or more of a slope, an offset, and a selectivity coefficient; and 
   (C) at a third time period after the first time period:
 (i) causing two of the at least three calibration reagents to contact the the potentiometric sensor and the at least one additional sensor, wherein the secondary ion selective electrode, the primary ion selective electrode, and the reference electrode of the potentiometric sensor generate signals receivable and transformable by the meter into third information indicative of the electric potentials of the two calibration reagents, and 
 (ii) using the re-calibration logic of the control system to determine second re-calibration information using (a) the third information, and (b) at least a portion of the calibration information from step (A), wherein the second re-calibration information comprises one or more of a slope, an offset, and a selectivity coefficient. 
   
     
     
         13 . The method of  claim 12 , wherein at least one of:
 (i) step (B) occurs prior to step (C) and wherein step (B) is repeated at least two more times prior to step (C);   (ii) the time between the repetitions of step (B) occurs at time intervals of about 30 minutes;   (iii) after step (C), the method re-performs the series of steps (B) and (C) at least two more times before re-performing step (A), and wherein the re-calibration logic of the control system causes the processor to determine re-calibration information for each repetition of step (B) using (a) information indicative of electric potentials of the secondary ion selective electrode, the primary ion selective electrode, and the reference electrode sent to the control system by signals generated by the meter, and (b) at least a portion of the re-calibration information obtained in the immediately preceding step (C);   (iv) wherein in (iii) above, the time between the first time period and subsequently performing step (A) is about 8 hours;   (v) steps (A), (B), and (C) are repeated for at least 28 days;   (vi) the second time period is about 30 minutes after the first time period; and   (vii) the third time period is about 2 hours after the first time period.   
     
     
         14 - 19 . (canceled) 
     
     
         20 . A method of calibrating a fluid analyzer, comprising the steps of:
 (A) at a first time period:
 (i) causing at least three calibration reagents to contact a potentiometric sensor and at least one additional sensor, the potentiometric sensor comprising a secondary ion selective electrode, a primary ion selective electrode, and a reference electrode, wherein the secondary ion selective electrode, the primary ion selective electrode, and the reference electrode generate signals receivable and transformable by a meter into first information indicative of electric potentials of the at least three calibration reagents, and 
 (ii) using calibration logic of a control system having a processor executing processor executable code to determine calibration information using the first information, wherein the calibration information comprises a slope, an offset, and a selectivity coefficient; 
   (B) at a second time period after the first time period:
 (i) causing two of the at least three calibration reagents to contact the the potentiometric sensor and the at least one additional sensor, wherein the secondary ion selective electrode, the primary ion selective electrode, and the reference electrode of the potentiometric sensor generate signals receivable and transformable by the meter into second information indicative of the electric potentials of the two calibration reagents, and 
 (ii) using re-calibration logic of the control system to determine first re-calibration information using (a) the second information, and (b) at least a portion of the calibration information from step (A), wherein the first re-calibration information comprises at least one of a slope, an offset, and a selectivity coefficient; and 
   (C) at a third time period:
 (i) causing one of the at least three calibration reagents to contact the the potentiometric sensor and the at least one additional sensor, wherein the secondary ion selective electrode, the primary ion selective electrode, and the reference electrode of the potentiometric sensor generate signals receivable and transformable by the meter into third information indicative of the electric potential of said one calibration reagent, and 
 (ii) using the re-calibration logic of the control system to determine second re-calibration information using (a) the third information, and (b) at least a portion of the first re-calibration information, wherein the second re-calibration information comprises at least one of a slope, an offset, and a selectivity coefficient. 
   
     
     
         21 . The method of  claim 20 , wherein step (C) is repeated at least two more times. 
     
     
         22 . The method of  claim 21 , wherein after step (C), the method re-performs the series of steps (B) and (C) at least two times before re-performing step (A). 
     
     
         23 . The fluid analyzer of  claim 1 , wherein the at least one additional sensor comprises a potentiometric sensor for sensing an analyte selected from potassium ions, sodium ions, bicarbonate ions, and/or a pH level. 
     
     
         24 . The fluid analyzer of  claim 1 , wherein the at least one additional sensor comprises an amphoteric sensor for sensing an analyte selected from partial oxygen pressure (pO 2 ), glucose, and/or lactate. 
     
     
         25 . The method of  claim 12 , wherein the at least one additional sensor comprises a potentiometric sensor for sensing an analyte selected from potassium ions, sodium ions, bicarbonate ions, and/or a pH level. 
     
     
         26 . The method of  claim 12 , wherein the at least one additional sensor comprises an amphoteric sensor for sensing an analyte selected from partial oxygen pressure (pO 2 ), glucose, and/or lactate. 
     
     
         27 . The method of  claim 20 , wherein the at least one additional sensor comprises a potentiometric sensor for sensing an analyte selected from potassium ions, sodium ions, bicarbonate ions, and/or a pH level. 
     
     
         28 . The method of  claim 20 , wherein the at least one additional sensor comprises an amphoteric sensor for sensing an analyte selected from partial oxygen pressure (pO 2 ), glucose, and/or lactate.