Electrochemiluminescence flow cell and flow cell components

Abstract

An electrochemiluminescence cell comprising an electrode capable of inducing an electrochemiluminescence-active species to electrochemiluminesce. The electrode is preferably made of rhodium, iridium or an alloy of platinum, rhodium or iridium alloyed with an alloy material comprising a transition element. The electrode may be used as counter electrode and/or as a working electrode in the electrochemiluminescence cell. The cell preferably includes a counter electrode and a support attached to the counter electrode. The support comprises a transparent portion in optical registration with the working electrode. The counter electrode may include one or more field extending elements interposed between the transparent portion and the working electrode. The field extending element is preferably a ladder or a grid.

1 . An electrochemiluminescence cell comprising a working electrode capable of inducing an electrochemiluminescence-active species to electrochemiluminescence, the electrode comprising a platinum alloy comprising: a first weight percent of platinum; and a second weight percent of iridium; wherein the first weight percent and the second weight percent are greater than zero;
 and wherein at a pH in the range 6.5 to 8.0 at the electrode, tripropylamine is oxidized at a lower potential than water.   
   
   
       2 . The cell of  claim 1  wherein the working electrode comprises a first weight percent of platinum of about 90 percent, a second weight percent of iridium of about 10 percent, 50 ppm Cu, 75 ppm Au, 250 ppm Fe, 100 ppm Ag, less than 100 ppm Ni, and less than 50 ppm Si. 
   
   
       3 . The cell of  claim 1  wherein the working electrode comprises a second weight percent of iridium within a range of about 1 to 50 percent. 
   
   
       4 . The cell of  claim 1  wherein the working electrode comprises a first weight percent of platinum of 70 percent. 
   
   
       5 . An electrochemiluminescence cell comprising:
 a working electrode formed from a platinum alloy, iridium, rhodium, a rhodium alloy or an iridium alloy; and   a light detector and/or transparent portion of the cell in optical registration with the working electrode;   wherein the working electrode is capable of inducing a ruthenium-tris-bipyridine moiety to electrochemiluminesce in the presence of tripropylamine.   
   
   
       6 . The cell of  claim 5 , wherein at an electrode potential of 1.3 V (vs. Ag/AgCl) the current density for the oxidation of tripropylamine is at least twice as large as the current density for the oxidation of water. 
   
   
       7 . The cell of  claim 5  wherein the working electrode is formed from an alloy which includes a weight percent of rhodium in a range of about 1 to 50 percent. 
   
   
       8 . The cell of  claim 5  wherein the working electrode is formed from an alloy which further comprises 50 ppm Cu, 75 ppm Au, 250 ppm Fe, 100 ppm Ag, less than 100 ppm Ni, and less than 50 ppm Si. 
   
   
       9 . An electrochemical cell comprising (a) a working electrode; and (b) a light detector and/or a transparent portion of the cell in optical registration with the working electrode;
 wherein the working electrode is formed from an alloy comprising a first weight percent of platinum and second weight percent of rhodium; and   at a pH in the range of 6.5 to 8.0 at the working electrode, tripropylamine is oxidized at a lower potential than water.   
   
   
       10 . The cell of  claim 9  wherein the second weight percent of rhodium is within a range of about 1 to 50 percent. 
   
   
       11 . The cell of  claim 9  wherein the working electrode is formed from an alloy which further comprises 50 ppm Cu, 75 ppm Au, 250 ppm Fe, 100 ppm Ag, less than 100 ppm Ni, and less than 50 ppm Si. 
   
   
       12 . An electrochemical cell comprising (a) a working electrode; and (b) a light detector and/or a transparent portion of the cell in optical registration with the working electrode;
 wherein the working electrode is formed from an alloy comprising a first weight percent of platinum and second weight percent of rhodium; and   the working electrode is capable of inducing a ruthenium-tris-bipyridine moiety to electrochemiluminesce in the presence of tripropylamine.   
   
   
       13 . The cell of  claim 12  wherein the electrochemical cell exhibits less downward drift in detected ECL signal from a ruthenium-tris-bipyridine moiety than a corresponding cell with a pure platinum working electrode. 
   
   
       14 . The cell of  claim 12  wherein at an electrochemical potential of 1.3 V vs. Ag/AgCl, the cell exhibits a current density of less than 5 mA/cm 2  during oxidation of water in a phosphate-buffered aqueous solution having a pH of 6.5-8.0. 
   
   
       15 . An electrochemical cell comprising (a) a working electrode; and (b) a light detector and/or a transparent portion of the cell in optical registration with the working electrode;
 wherein the working electrode is formed from an alloy comprising a first weight percent of platinum and second weight percent of rhodium; and   the electrochemical cell exhibits less downward drift in detected ECL signal from a ruthenium-tris-bipyridine moiety than a corresponding cell with a pure platinum working electrode.   
   
   
       16 . The cell of  claim 15  wherein the alloy of the working electrode comprises a first weight percent of platinum of about 90 percent, a second weight percent of rhodium of about 10 percent, 50 ppm Cu, 75 ppm Au, 250 ppm Fe, 100 ppm Ag, less than 100 ppm Ni, and less than 50 ppm Si. 
   
   
       17 . The cell of  claim 15 , wherein at an electrode potential of 1.3 V (vs. Ag/AgCl) the current density for the oxidation of tripropylamine is at least twice as large as the current density for the oxidation of water. 
   
   
       18 . The cell of  claim 15  wherein the second weight percent of rhodium is about 1 to 50 percent. 
   
   
       19 . An electrochemical cell comprising (a) a working electrode; and (b) a light detector and/or a transparent portion of the cell in optical registration with the working electrode;
 wherein the working electrode is formed from an alloy comprising a first weight percent of platinum and second weight percent of rhodium; and   at a pH in the range of 6.5 to 8.0 at the working electrode, a ruthenium-tris-bipyridine moiety is oxidized at a lower potential than water.   
   
   
       20 . The cell of  claim 19  wherein the alloy of the working electrode further comprises about 50 ppm Cu, 75 ppm Au, 250 ppm Fe, 100 ppm Ag, less than 100 ppm Ni, and less than 50 ppm Si. 
   
   
       21 . The cell of  claim 19 , wherein at an electrode potential of 1.3 V (vs. Ag/AgCl) the current density for the oxidation of tripropylamine is at least twice as large as the current density for the oxidation of water. 
   
   
       22 . The cell of  claim 19  wherein the second weight percent of rhodium is within a range of about 1 to 50 percent. 
   
   
       23 . The cell of  claim 19  wherein the electrochemical cell exhibits less downward drift in detected ECL signal from a ruthenium-tris-bipyridine moiety than a corresponding cell with a pure platinum working electrode. 
   
   
       24 . An electrochemical cell comprising (a) a working electrode; and (b) a light detector and/or a transparent portion of the cell in optical registration with the working electrode;
 wherein the working electrode is formed from an alloy comprising a first predetermined weight percent of platinum and second predetermined weight percent of rhodium, iridium, tungsten or a combination thereof; and   at a pH in the range of 6.5 to 8.0 at the working electrode, tripropylamine is oxidized at a lower potential than water.   
   
   
       25 . The cell of  claim 24  wherein the electrochemical cell exhibits less downward drift in detected ECL signal from a ruthenium-tris-bipyridine moiety than a corresponding cell with a pure platinum working electrode. 
   
   
       26 . The cell of  claim 24  wherein at an electrochemical potential of 1.3 V vs. Ag/AgCl, the cell exhibits a current density of less than 5 in mA/cm2 during oxidation of water in a phosphate-buffered aqueous solution having a pH of 6.5-8.0. 
   
   
       27 . An electrochemical cell comprising (a) a working electrode; and (b) a light detector and/or a transparent portion of the cell in optical registration with the working electrode;
 wherein the working electrode is formed from an alloy comprising a first weight percent of platinum and second weight percent of rhodium, iridium, tungsten or a combination thereof; and   the working electrode is capable of inducing a ruthenium-tris-bipyridine moiety to electrochemiluminesce in the presence of tripropylamine.   
   
   
       28 . The cell of  claim 27  wherein the working electrode is formed from an alloy which includes at least about 70 weight percent platinum and a range of about 5 to 30 weight percent iridium. 
   
   
       29 . The cell of  claim 27  wherein the working electrode is formed from an alloy which includes at least about 70 weight percent platinum and a range of about 5 to 30 weight percent rhodium. 
   
   
       30 . The cell of  claim 27  wherein the working electrode is formed from an alloy which includes at least about 70 percent weight platinum and a range of about 1 to 50 weight percent tungsten.