Detection of Phenols

Abstract

According to the present invention, phenols may be detected using an electrochemical sensor comprising a final compound, a working electrode and an electrolyte in contact with the working electrode, wherein the first compound operatively undergoes a redox reaction at the working electrodes to form a second compound which operatively reacts in situ with the phenol, wherein said redox reaction has a detectable redox couple and wherein the sensor is adapted to determine the electrochemical response of the working electrode to the consumption of said second compound on reaction with the phenol. The phenol may be, for example, cannabinoid or a catechin compound.

1 . An electrochemical sensor for the detection of a phenol, which comprises a first compound, a working electrode and an electrolyte in contact with the working electrode, wherein the first compound operatively undergoes a redox reaction at the working electrode to form a second compound which operatively reacts in situ with the phenol, wherein said redox reaction has a detectable redox couple and wherein the sensor is adapted to determine the electrochemical response of the working electrode to the consumption of said second compound on reaction with the phenol. 
   
   
       2 . The sensor according to  claim 1 , wherein said first compound is a 4-aminophenol. 
   
   
       3 . The sensor according to  claim 2 , wherein said first compound is a compound of the formula (I): 
     
       
         
         
             
             
         
       
       wherein
 m is 0, 1, 2, 3 or 4; 
 each R 1  is independently R 2 , or is hydrocarbyl or heterocyclyl, either of which is optionally substituted with 1, 2, 3, 4 or 5 R 2 ; 
 each R 2  is independently selected from halogen, trifluoromethyl, cyano, nitro, oxo, ═NR 3 , R 3 , —OR 35 —C(O)R 3 , —C(O)OR 3 , —OC(O)R 3 , —N(R 3 )R 4 , —C(O)N(R 3 )R 4 , —S(O) 1 R 3  and —C(R 3 ) 3 ; 
 R 3  and R 4  are each independently hydrogen, or are selected from C 1-6  alkyl, —(CH 2 ) k -carbocyclyl and —(CH 2 ) k -heterocyclyl, any of which is optionally substituted with 1, 2, 3, 4 or 5 substituents independently selected from halogen, hydroxy and C 1-6  alkyl; and 
 l is 0, 1 or 2; 
 
       and wherein the first compound is operatively oxidised at the working electrode to form a second compound which is of the formula (II): 
     
     
       
         
         
             
             
         
       
     
   
   
       4 . The sensor according to  claim 3 , wherein m is 0, 1 or 2. 
   
   
       5 . The sensor according to  claim 3 , wherein each R 1  is independently selected from —NR 3 R 4 , halogen, C 1 , C 2 , C 3  or C 4  alkyl, C 1 , C 2 , C 3  or C 4  haloalkyl, C 1 , C 2 , C 3  or C 4  alkoxy, and C 2 , C 3  or C 4  alkenyl, wherein R 3  and R 4  are each independently selected from hydrogen, —OH, C 1 , C 2 , C 3  or C 4  alkyl, C 1 , C 2 , C 3  or C 4  haloalkyl, C 1 , C 2 , C 3  or C 4  alkoxy, and C 2 , C 3  or C 4  alkenyl. 
   
   
       6 . The sensor according to  claim 5 , wherein each R 1  is halogen. 
   
   
       7 . The sensor according to  claim 6 , wherein the first compound is of the formula (IA): 
     
       
         
         
             
             
         
       
     
   
   
       8 . The sensor according to  claim 3 , wherein each R 1  is aryl. 
   
   
       9 . The sensor according to  claim 8 , wherein the first compound is of the formula (IB): 
     
       
         
         
             
             
         
       
     
   
   
       10 . The sensor according to  claim 1 , wherein the working electrode is a screen printed electrode, a metallic electrode, an edge plane pyrolytic graphite electrode, a basal plane pyrolytic graphite electrode, a gold electrode, a glassy carbon electrode, a boron doped diamond electrode, or a highly ordered pyrolytic graphite electrode. 
   
   
       11 . The sensor according to  claim 1 , wherein the sensor is adapted to determine the current flow between the working electrode and a counter electrode. 
   
   
       12 . (canceled) 
   
   
       13 . (canceled) 
   
   
       14 . (canceled) 
   
   
       15 . (canceled) 
   
   
       16 . (canceled) 
   
   
       17 . (canceled) 
   
   
       18 . (canceled) 
   
   
       19 . (canceled) 
   
   
       20 . (canceled) 
   
   
       21 . (canceled) 
   
   
       22 . The sensor according to  claim 1 , wherein the electrolyte comprises said first compound. 
   
   
       23 . The sensor according to  claim 1 , wherein the working electrode comprises said first compound. 
   
   
       24 . A method of detecting a phenol in a sample, comprising:
 (a) oxidising a first compound at a working electrode of an electrochemical sensor to form a second compound which is operatively reactive with the phenol;   (b) contacting the phenol with the second compound in the presence of an electrolyte, such that the second compound reacts with the phenol; and   (c) determining an electrochemical response of the working electrode to the consumption of the second compound on reaction with the phenol.   
   
   
       25 . The method according to  claim 24 , wherein the first compound is a 4-aminophenol. 
   
   
       26 . (canceled) 
   
   
       27 . (canceled) 
   
   
       28 . (canceled) 
   
   
       29 . (canceled) 
   
   
       30 . (canceled) 
   
   
       31 . (canceled) 
   
   
       32 . (canceled) 
   
   
       33 . The method according to  claim 24 , wherein the working electrode is a screen printed electrode, a metallic electrode, an edge plane pyrolytic graphite electrode, a basal plane pyrolytic graphite electrode, a glassy carbon electrode, a boron doped diamond electrode or a highly ordered pyrolytic graphite electrode. 
   
   
       34 . The method according to  claim 24 , wherein determination of the electrochemical response comprises measuring the current flow between the working electrode and a counter electrode to determine the amount of the phenol. 
   
   
       35 . The method according to  claim 34 , wherein the working electrode is maintained at a constant voltage. 
   
   
       36 . The method according to  claim 34 , wherein said current is measured using linear sweep or cyclic voltammetry, square wave voltammetry, or a pulsed voltammetry technique. 
   
   
       37 . The method according to  claim 24 , wherein the phenol is a para-substituted phenol. 
   
   
       38 . The method according to  claim 24 , wherein the phenol is phenol, 4-phenoxyphenol, p-methylphenol, m-methylphenol, nitrophenol or tetrahydrocannabinol. 
   
   
       39 . The method according to  claim 24 , wherein the phenol is a component or a metabolite of  cannabis.    
   
   
       40 . The method according to clam  24 , wherein the phenol is a natural or synthetic cannabinoid or a metabolite thereof. 
   
   
       41 . The method according to  claim 39 , wherein the phenol is a cannabis metabolite found in urine. 
   
   
       42 . The method according to  claim 39 , wherein the phenol is 11-nor-9-carboxy-9-tetrahydrocannabinol. 
   
   
       43 . The method according to  claim 24 , wherein the phenol is a catechin. 
   
   
       44 . The method according to  claim 43 , wherein the phenol is (−)-epigallocatechin gallate (EGCG) or (−)-epigallocatechin (ECG). 
   
   
       45 . The method according to  claim 24 , wherein the electrolyte comprises said first compound. 
   
   
       46 . The method according to  claim 24 , wherein the working electrode comprises said first compound. 
   
   
       47 . A method of forming an indophenol compound comprising electrochemically oxidising a 4-aminophenol compound to form a benzoquinone compound, and reacting the benzoquinone compound with a phenol to form an indophenol. 
   
   
       48 . The method according to  claim 47 , wherein the 4-aminophenol compound is of the formula (I): 
     
       
         
         
             
             
         
       
       wherein
 m is 0, 1, 2, 3 or 4; 
 each R 1  is independently R 2 , or is hydrocarbyl or heterocyclyl, either of which is optionally substituted with 1, 2, 3, 4 or 5 R 2 ; 
 each R 2  is independently selected from halogen, trifluoromethyl, cyano, nitro, oxo, ═NR 3 , R 3 , —OR 3 , —C(O)R 3 , —C(O)OR 3 , —OC(O)R 3 , —N(R 3 )R 4 , —C(O)N(R 3 )R 4 , —S(O) 1 R 3  and —C(R 3 ) 3 ; 
 
       R 3  and R 4  are each independently hydrogen, or are selected from C 1-6  alkyl, —(CH 2 ) k -carbocyclyl and —(CH 2 ) k -heterocyclyl, any of which is optionally substituted with 1, 2, 3, 4 or 5 substituents independently selected from halogen, hydroxy and C 1-6  alkyl; and
 l is 0, 1 or 2; 
 
       and is oxidised to form a benzoquinone compound of the formula (II): 
     
     
       
         
         
             
             
         
       
     
   
   
       49 . (canceled) 
   
   
       50 . (canceled) 
   
   
       51 . (canceled) 
   
   
       52 . (canceled) 
   
   
       53 . (canceled) 
   
   
       54 . (canceled) 
   
   
       55 . The method according to  claim 47 , wherein the phenol is phenol, 4-phenoxyphenol, p-methylphenol, m-methylphenol, nitrophenol, tetrahydrocannabinol, a component or metabolite of cannabis, or a natural or synthetic cannabinoid or a metabolite thereof. 
   
   
       56 . The method according to  claim 47 , wherein the phenol is a catechin. 
   
   
       57 . The method according to  claim 56 , wherein the catechin is (−)-epigallocatechin gallate (EGCG) or (−)-epigallocatechin (ECG). 
   
   
       58 . An electrode material comprising a 4-aminophenol compound. 
   
   
       59 . The material according to  claim 58 , wherein the compound is comprised on a surface of the material. 
   
   
       60 . The material according to  claim 58 , wherein the compound is comprised in the bulk of the material. 
   
   
       61 . The material according to  claim 58 , wherein said material is obtainable by screen printing. 
   
   
       62 . The material according to  claim 58 , wherein said material comprises a metallic material, edge plane pyrolytic graphite, basal plane pyrolytic graphite, gold, glassy carbon, boron doped diamond or highly ordered pyrolytic graphite. 
   
   
       63 . The material according to  claim 58 , wherein the compound is a compound of the formula (I): 
     
       
         
         
             
             
         
       
       wherein
 m is 0, 1, 2, 3 or 4; 
 each R 1  is independently R 2 , or is hydrocarbyl or heterocyclyl, either of which is optionally substituted with 1, 2, 3, 4 or 5 R 2 ; 
 each R 2  is independently selected from halogens trifluoromethyl, cyano, nitro oxo, ═NR 3 , R 3 , —OR 3 , —C(O)R 3 , —C(O)OR 3 , —OC(O)R 3 , —N(R 3 )R 4 , —C(O)N(R 3 R′, —S(O) 1 R 3  and —C(R 3 ) 3 ; 
 R 3  and R 4  are each independently hydrogen, or are selected from C 1-6  alkyl —(CH 2 ) k -carbocyclyl and —(CH 2 ) k -heterocyclyl, any of which is optionally substituted with 1, 2, 3, 4 or 5 substituents independently selected from halogen, hydroxy and C 1-6  alkyl; and 
 l is 0, 1 or 2: 
 
       and is oxidised to form a benzoquinone compound of the formula (II): 
     
     
       
         
         
             
             
         
       
     
   
   
       64 . (canceled) 
   
   
       65 . The material according to  claim 63 , wherein the compound is 2,6-diphenyl-4-aminophenol. 
   
   
       66 . (canceled) 
   
   
       67 . (canceled)