Use of an ESR device for the differential characterization of at least two different states of a biological sample, wherein - in a first step, by means of ESR and a spin probe in the form of an uncharged or a cyclic hydroxylamine carrying negative groups, reactive oxygen species, reactive nitrogen species or both and/or, by means of compounds, which, due to the addition of oxygen, show different widths of the ESR absorption peak(s) with broadening with increasing oxygen concentration depending on the oxygen partial pressure, without chemical reaction, i.e. by purely physical interactions which arise due to the proximity of different quantities of oxygen, the oxygen concentration of the biological sample is measured without the addition of effectors and - in a second step, by means of ESR using a spin probe in the form of an uncharged or a cyclic hydroxylamine carrying negative groups, the ROS, the RNS or the ROS and the RNS of a same biological sample are measured in each case with the addition of effectors, wherein the sequence of the first and second steps can also be arbitrary; and/or - different measurement results are obtained due to at least two ESR measurements of the biological sample with different spin probes, which can reach extracellular fluid, intracellular fluid and the interior of mitochondria in different ways, with or without determination of the oxygen concentration by means of compounds which show broadening of a peak of the ESR absorption with increasing oxygen concentration due to the addition of oxygen depending on the oxygen partial pressure without chemical reaction, i.e. due to purely physical interactions which arise due to the proximity of different amounts of oxygen; and by comparing the different measurement results and calculating the difference, conclusions can be drawn about the vitality or health of a patient or healthy volunteer from whom the biological sample originates; wherein the measurement is set at a temperature in the biological sample in a range of 36 to 44°C and the oxygen partial pressure is set in a range of 2666.44-7332.71 Pa; and wherein "effectors", where mentioned, are to be understood as inhibitors or activators or other modulators of enzymes, enzyme systems or organelles which have an influence on the formation of ROS and/or RNS. - in a first step, by means of ESR and a spin probe in the form of an uncharged or a cyclic hydroxylamine carrying negative groups, reactive oxygen species, reactive nitrogen species or both and/or, by means of compounds, which, due to the addition of oxygen, show different widths of the ESR absorption peak(s) with broadening with increasing oxygen concentration depending on the oxygen partial pressure, without chemical reaction, i.e. by purely physical interactions which arise due to the proximity of different quantities of oxygen, the oxygen concentration of the biological sample is measured without the addition of effectors and - in a second step, by means of ESR using a spin probe in the form of an uncharged or a cyclic hydroxylamine carrying negative groups, the ROS, the RNS or the ROS and the RNS of a same biological sample are measured in each case with the addition of effectors, wherein the sequence of the first and second steps can also be arbitrary; and/or - different measurement results are obtained due to at least two ESR measurements of the biological sample with different spin probes, which can reach extracellular fluid, intracellular fluid and the interior of mitochondria in different ways, with or without determination of the oxygen concentration by means of compounds which show broadening of a peak of the ESR absorption with increasing oxygen concentration due to the addition of oxygen depending on the oxygen partial pressure without chemical reaction, i.e. due to purely physical interactions which arise due to the proximity of different amounts of oxygen; - different measurement results are obtained due to at least two ESR measurements of the biological sample with different spin probes, which can reach extracellular fluid, intracellular fluid and the interior of mitochondria in different ways, with or without determination of the oxygen concentration by means of compounds which show broadening of a peak of the ESR absorption with increasing oxygen concentration due to the addition of oxygen depending on the oxygen partial pressure without chemical reaction, i.e. due to purely physical interactions which arise due to the proximity of different amounts of oxygen; and by comparing the different measurement results and calculating the difference, conclusions can be drawn about the vitality or health of a patient or healthy volunteer from whom the biological sample originates; wherein the measurement is set at a temperature in the biological sample in a range of 36 to 44°C and the oxygen partial pressure is set in a range of 2666.44-7332.71 Pa; and wherein "effectors", where mentioned, are to be understood as inhibitors or activators or other modulators of enzymes, enzyme systems or organelles which have an influence on the formation of ROS and/or RNS.