Device and method for blood hemoglobin measurement without carboxyhemoglobin interference

Abstract

A method for blood haemoglobin measurement without carboxyhaemoglobin interference comprises converting oxyhemoglobin, deoxyhemoglobin and methemoglobin into a methemoglobin derivative, i.e. Imidazole-methemoglobin. Imidazole-methemoglobin and carboxyhemoglobin are collectively quantified by the reflectance spectroscopy of the matrix at 525 nm, the isobestic point between Imidazole-methemoglobin complex and carboxyhemoglobin molecule.

1 . A method for blood hemoglobin measurement comprising:
 preparing one or more layers of a strip placed in a detection area impregnated with at least one chemical reagent;   converting an oxyhemoglobin, a deoxyhemoglobin and a methemoglobin molecule into a common molecule; establishing an isobestic point of 525 nm between an imidazole-methemoglobin complex and a carboxyhemoglobin molecule;   placing at least one photosensor at one end of at least one optical barrier to allow reflection to reach at least one surface of said at least one photosensor;   reading of an analog potential in an analog signal form generated across said at least one photo-sensor due to falling reflected light rays upon said at least one photo-sensor; and   displaying a corresponding output value on a display screen.   
     
     
         2 . The method for blood hemoglobin measurement as claimed in  claim 1 , wherein the step of preparing one or more layers of said strip comprising a polymer, a matrix resting on a main base. 
     
     
         3 . The method for blood hemoglobin measurement as claimed in  claim 1 , wherein step of adding at least one chemical reagent selected from a group of reagents comprising, diocetyl sodium sulfosuccinate, sodium dodecyl benzene sulphonate, lauryl dimethylamine oxide, octylphenoxypolyethoxy ethanol, potassium ferricyanide, sodium lauryl sulfate, lithium dodecyl sulfate, sodium nitrite, sodium myristyl sulfate, cetyl tri-methyl ammonium bromide, sodium dodecylsulfate, sodium deoxycholate, N-lauroylsarcosine, triton-X  100 , hydrochloric acid, sodium nitrite or their mixtures present in a range of 0.1% to about 10% (w/v) and a ligand consisting of imidazole. 
     
     
         4 . The method for blood hemoglobin measurement as claimed in  claim 3 , wherein the step of converting oxyhemoglobin molecule, deoxyhemoglobin molecule into a methemoglobin molecule comprises using at least one said reagent. 
     
     
         5 . The method for blood hemoglobin measurement as claimed in  claim 1 , wherein step of coupling said ligand consisting of imidazole with methemoglobin forming said imidazole-methemoglobin complex. 
     
     
         6 . The method for blood hemoglobin measurement as claimed in  claim 1 , wherein the step of performing reflectance photometery at a single wavelength of said isobestic point of 525 nm involves placing said strip at one end of said light source of 525 nm and allowing a plurality of reflected rays through an optical slit to said strip and aligning at least one optical barrier at an angle of 60.degree. to said at least one optical barrier. 
     
     
         7 . The method for blood hemoglobin measurement as claimed in  claim 1 , wherein step of controlling said light source ( 8 ) by a processing unit comprising flashing said light source periodically for said period of 200 millisecond, frequenting at least one flash per second. 
     
     
         8 . The method for blood hemoglobin measurement as claimed in  claim 1 , wherein the step of reading of said analog potential in said analog signal form is by a control unit comprising a microcontroller based electronic unit. 
     
     
         9 . The method for blood hemoglobin measurement as claimed in  claim 8 , wherein step of converting said analog signal into at least one digital value is through an analog to digital converter. 
     
     
         10 . The method for blood hemoglobin measurement as claimed in  claim 9 , wherein step of recording and averaging said at least one digital value across said at least one photo-sensor ( 6 . a ,  6 . b ) is performed once at every ten millisecond in a 100 millisecond period. 
     
     
         11 . The method for blood hemoglobin measurement as claimed in  claim 10 , wherein step of averaging said ten consecutive tenth millisecond readings generating a 100 milliseconds average value. 
     
     
         12 . The method for blood hemoglobin measurement as claimed in  claim 11 , wherein the 100 millisecond average value of the 100 millisecond period preceding the period when the light source is turned off is stored as a V.sub.off value and two consecutive batches of said 100 millisecond average values are recorded during a period when the light source is turned on. 
     
     
         13 . The method for blood hemoglobin measurement as claimed in  claim 12 , wherein step of recording a second average value as a V.sub.on value. 
     
     
         14 . The method for blood hemoglobin measurement as claimed in  claim 13 , wherein step of noting a difference between V.sub.on and V.sub.off, as a Delta V value and recording a consecutive value of Delta V until the values of consecutive Delta V become substantially same. 
     
     
         15 . The method for blood hemoglobin measurement as claimed in  claim 15 , wherein step of comparing said last recorded Delta V value with said at least one digital value stored in said processing unit and displaying said corresponding output value on said display screen.