Abstract: A non-destructive method of estimating hematocrit (Hct) of whole blood from a dried blood sample prepared from the whole blood, the method comprising: a) determining the amount of hemoglobin derivatives comprising oxyhemoglobin, met-hemoglobin and hemichrome (total hemoglobin) in a dried blood sample, wherein the sum of the amounts of the hemoglobin derivatives remains constant in the dried blood sample in function of time, and b) estimating the hematocrit from the sum of the amounts of the hemoglobin derivatives, wherein the hematocrit is estimated using a calibration curve providing a correlation between hematocrit and the amount of the hemoglobin derivatives in a dried blood sample. The amount of the hemoglobin derivatives is preferably determined by measuring the reflectance, absorbance, or transmittance of the dried blood sample at the quasi-isosbestic point of the hemoglobin derivatives about 589 nm or at multiple wavelengths within the range of 450 to 750 nm.

Abstract: A non-destructive method of estimating hematocrit (Hct) of whole blood from a dried blood sample prepared from the whole blood, the method comprising: a) determining the amount of hemoglobin derivatives comprising oxyhemoglobin, methemoglobin and hemichrome (total hemoglobin) in a dried blood sample, wherein the sum of the amounts of the hemoglobin derivatives remains constant in the dried blood sample in function of time, and b) estimating the hematocrit from the sum of the amounts of the hemoglobin derivatives, wherein the hematocrit is estimated using a calibration curve providing a correlation between hematocrit and the amount of the hemoglobin derivatives in a dried blood sample. The amount of the hemoglobin derivatives is preferably determined by measuring the reflectance, absorbance, or transmittance of the dried blood sample at the quasi-isosbestic point of the hemoglobin derivatives about 589 nm or at multiple wavelengths within the range of 450 to 750 nm.

Abstract: A method and apparatus for dating a body sample, such as blood, includes taking at least one spectroscopic measurement of the sample at at least two predetermined positions in the spectrum having spectral characteristics corresponding to at least two predetermined substances present in the sample that have a time varying relationship with each other. A measured relative concentration of each of the predetermined substances is then determined from the measurement, and the measured relative concentrations of the two predetermined substances is compared with a known variation of the relative concentrations of the two predetermined substances over time. A good fit of the measured relative concentrations to the known variation of the relative concentrations is then determined, so as to provide an indication of the age of the sample. Alternatively, instead of measuring the relative concentrations of each of the predetermined substances, the rate of change of the relative concentrations is determined.

Abstract: A method and apparatus for dating a dating a body sample, such as blood, includes taking at least one spectroscopic measurement (37) of the sample at least two predetermined positions in the spectrum having spectral characteristics corresponding to at least two predetermined substances present in the sample that have a time varying relationship with each other. A measured relative concentration of each of the predetermined substances is then determined (41) from the measurement, and the measured relative concentrations of the two predetermined substances is compared (43) with a known variation of the relative concentrations of the two predetermined substances over time. A good fit of the measured relative concentrations to the known variation of the relative concentrations is then determined, so as to provide an indication of the age of the sample (44).