Abstract: The invention concerns a method for the determination of an analyte in a sample containing free haemoglobin in which the determination is carried out by an optical measurement and the value measured for the analyte concentration is mathematically corrected. This method is in particular suitable for determining the parameters total protein, iron and albumin in a medical sample e.g. in a serum or plasma sample. The correction of the measured value for the analyte concentration is achieved by the steps (a) measuring the blank value of the sample to be analysed, (b) measuring the blank value of a haemoglobin-free reference sample, (c) measuring the uncorrected value for the analyte concentration and (d) correcting the value obtained in step (c) by correlation with the values obtained in step (a) and (b) in order to obtain the corrected value for the analyte concentration.

Abstract: The present invention provides a process for the specific determination of the serum fructosamine content in blood or samples derived from blood by reaction with an appropriate color reagent and measurement of the color change thereby brought about, wherein, before the color reaction, non-specific reducing-acting and/or turbidity-causing sample components are removed at approximately neutral pH value, subsequently the pH is adjusted to a value of from 10 to 12 and the color reagent is added thereto.The present invention also provides a reagent mixture for the specific determination of the serum fructosamine content in blood or samples derived from blood, wherein it comprises a reagent for the removal of non-specific reducing-acting and/or turbidity-causing sample components, a rebuffering reagent with a buffer which has a pH value in the range of from 10.5 to 12.5 and a color reagent for the detection of fructosamine.

Abstract: This invention teaches a process for reducing protein matrix effects in assays for serum fructosamine. Blood or blood derived samples are used, and one adds two reagents, one of which reduces interference caused by non-specific reducing substances, the other of which eliminates turbidity. Incubation follows, and then the pH of the sample is adjusted and color forming reagent is added. In one embodiment, the incubation time is only 1-15 minutes. In another embodiment, the first reagent contains peroxidase.

Abstract: A process for the determination of fructosamine in body fluids by the reaction of a sample solution with a color reagent, wherein the sample liquid is mixed with a buffer solution having a pH value of from 9 to 12, a color-forming reagent and uricase, as well as with at least one detergent, and the chronological change of the extinction is measured kinetically in a temperature range of from 20.degree. to 40.degree. C. at the earliest after 5 minutes.

Abstract: The present invention provides a process for the determination of iron in body fluids by liberation of the bound iron, reduction to Fe.sup.2+, addition of a color system appropriate for the detection of iron and photometric measurement in a tenside-containing sample solution, wherein a fatty acid polyethylene glycol ester, an alkanol polyglycol ether and at least 1 mole/liter quanidine hydrochloride are added to the sample solution. The present invention also provides a reagent for the determination of iron in serum, containing a reducing agent, a color material system appropriate for the detection of iron and guanidine hydrochloride and at least one tenside, wherein it contains a fatty acid polyethylene glycol ester and a alkanol polyglycol ether.