Homogeneous immunoassay method utilizing 5-300 mM magnesium

A homogeneous liquid phase immunoassay method for determining the concentration of an analyte in a body fluid, which comprises:

• treating the body fluid prior to an antigen antibody reaction by adding magnesium ions to provide a concentration of 5 to 300 mM at the time said antigen antibody reaction occurs, said magnesium ions being added:
• a) to a body fluid containing the analyte to be measured, followed by mixing with a buffer solution containing an antigen or antibody to the analyte to be measured, or
• b) to the buffer solution, followed by mixing with the body fluid, or
• c) to both the body fluid and the buffer solution, followed by mixing, the buffer serving to adjust the pH of the resulting solution,
• keeping the resulting solution standing for a period of time sufficient to allow said antigen antibody reaction to take place in the presence of magnesium ions at a concentration of 5 to 300 mM previously added, and
• measuring a change in turbidity specific to the analyte or change in scattering light intensity specific to the analyte, which is caused by the above antigen-antibody reaction, the magnesium ions present during the measurement serving to suppress non-specific turbidity,
• wherein said magnesium ions have a concentration of 5 to 300 mM in a reaction solution in which the antigen-antibody reaction is carried out.

A homogeneous liquid phase immunoassay method for measuring the concentration of an analyte component in a body fluid, which comprises:

• treating the body fluid prior to an antigen antibody reaction by adding magnesium ions to provide a concentration of 5 to 300 mM at the time said antigen antibody reaction occurs, said magnesium ions being added:
• a) to a body fluid containing the analyte to be measured, followed by mixing a buffer solution of antigen or antibody against the analyte, or
• b) to the buffer solution followed by mixing with the body fluid, or
• c) to both the body fluid and the buffer solution, followed by mixing, the buffer serving to adjust the pH of the resulting solution,
• keeping the resulting solution standing for a period of time sufficient to allow said antigen antibody reaction to take place in the presence of magnesium ions at a concentration of 5 to 300 mM previously added, and
• measuring a change in turbidity specific to the analyte or change in scattering light intensity specific to the analyte, which is caused by the above antigen-antibody reaction, the magnesium ions present during the measurement serving to suppress non-specific turbidity caused by the presence of rheumatoid factor or other substances causing non-specific turbidity.

A homogeneous liquid phase immunoassay method for measuring the concentration of an analyte component in a body fluid selected from the group consisting of C-reactive protein immunoglobulin G, immunoglobulin A, immunoglobulin M, Antistreptolysin O, albumin, complement C3, complement C4, transferrin, haptoglobin and afetoprotein, which comprises:

• treating the body fluid prior to an antigen antibody reaction by adding magnesium ions to provide a concentration of 5 to 300 mM at the time said antigen antibody reaction occurs, said magnesium ions being added:
• a) to a body fluid containing the analyte to be measured, followed by a mixing buffer solution of antigen or antibody against the analyte, or
• b) to the buffer solution, followed by mixing with the body fluid, or
• c) to both the body fluid and the buffer solution, followed by mixing, the buffer serving to adjust the pH of the resulting solution,
• keeping the resulting solution standing for a period of time sufficient to allow said antigen-antibody reaction to take place in the presence of magnesium ions at a concentration of 5 to 300 mM previously added, and
• measuring a change in turbidity specific to the analyte or change in scattering light intensity specific to the analyte, which is caused by the above antigen-antibody reaction, the magnesium ions present during the measurement serving to suppress non-specific turbidity caused by the presence of rheumatoid factor or other substances causing non-specific turbidity.