Minimum procedure system for the determination of analytes

A reagent strip for measuring glucose in a whole blood sample wherein said reagent strip is adapted for emplacement in a reflectance reading apparatus, said reagent strip comprising:

• a porous hydrophilic membrane having poles in the range of about 0.6 microns to about 1.0 microns;
• a signal producing system of glucose oxidase, peroxidase and a dye indicator embedded in said membrane for reaction with said whole blood sample;
• and
• a tab attached to said porous matrix for handling of said reagent strip after emplacement of said blood sample on said porous matrix.

A reagent strip for measuring glucose in a whole blood sample, said reagent strip adapted for emplacement in a reflectance reading apparatus, said reagent strip comprising:

• a tab adapted for emplacement in said reflectance reading apparatus, said tab including a thin rectangular plate having two ends on either side of a centralized hole of about 2 mm to about 10 mm diameter, one of said ends having a notch about midway along said end;
• a porous hydrophilic membrane having two smooth sides, a first of said sides attached to said tab at said centralized hole, said membrane containing pores having openings in the range of about 0.6 microns to about 1.0 microns;
• and
• a dye solution embedded in said porous membrane including glucose oxidase, peroxidase and an MBTH-DMAB indicator, said dye solution maintained in said hydrophilic membrane at a pH of less than about 4.8 and in a 10% citrate solution,
• said reagent strip capable of measuring whole blood samples without separating said sample into components, once a threshold volume of blood sample is placed within said hydrophilic membrane.

A method of timing of a measurement in a reflectance reading device, which comprises:

• taking at least one first optical reflectance reading from a first surface of a porous matrix on a reagent strip prior to application of a sample to a second surface of said matrix;
• taking at least one additional reflectance reading from said first surface;
• and
• comparing said additional reflectance reading to said first reflectance reading and initiating time measurement upon a predetermined drop in reflectance resulting from said sample reaching said first surface.

In a reflectance switching system having an optical reader capable of reading the reflectance of light emitted from a plurality of light emitting diodes (LED), said light reflected to said optical reader from a porous membrane, a method of normalizing said reflectance switching system comprising:

• scanning said porous membrane for an intensity reflectance reading of said LEDs prior to the emplacement of an assay sample;
• inputting said reading into a control means, said control means capable of storing readings of the intensity of said LED:, said control means further capable of equating the difference between a pair of initial and subsequent LED readings;
• and
• using said control means to boost the power to adjust the intensity of said LEDs to give the same reflectance reading for each LED.

A method for determining glucose levels in blood comprising:

• placing a drop of blood on a reagent strip;
• placing said strip in a reflectance scanning meter wherein said meter is sensitive to the presence of said blood sample on said reagent strip, said reflectance scanning meter initiating a timing sequence upon sensing the presence of said blood sample in said reagent strip;
• taking reflectance measurements:
• (1) from the background within said meter (Rb);
• (2) before said reagent strip contains blood (Rdry);
• and (3) at a predetermined time (Rt), then computing R*t wherein
• R*t=(Rt−Rb)/(Rdry−Rb);
• using R*t to compute K/S-t, wherein K/S-t is defined as
• (1−R*t)2/(2×R*t);
• and
• computing glucose levels from said K/S-t value.

A method for determining glucose levels in blood comprising:

• placing a drop of blood on a reagent strip;
• placing said strip in a reflectance scanning meter, wherein said meter is sensitive to the presence of said blood sample on said reagent strip, said reflectance scanning meter initiating a timing sequence upon sensing the presence of said blood sample in said reagent strip;
• taking reflectance measurements:
• (1) from the background within said meter (Rb);
• (2) before said reagent strip contains blood (Rdry);
• (3) at 15 seconds after said reagent strip contains blood (R15);
• and (4) at a predetermined endpoint (Rt);
• using said readings to compute R*15 and R*t according to the following properties:
• 1 R * 15 = ( R 15 - R b ) / ( R dry - R b ) R * t = ( R t - R b ) / ( R dry - R b ) ;
• computing K/S15 and K/St levels where said levels are defined as:
• K/S15=(1−R*15)2/(2×R*15) K/St=(1−R*t)2/(2×R*t);
• normalizing said K/S15 value to arrive at a K/S15n value defined as
• K/S15n=(1.54×K/S15)−0.1333;
• arriving at a K/St/15 value defined as
• K/St/15=K/St−K/S15n;
• and
• using said K/St/15 value to compute said glucose levels.