All the studied analytes were simultaneously determined at isosbestic
point at 230 nm.
They either measure the absorbance of whole blood photometrically at the isosbestic
point--the wavelength in which the absorbance the two main hemoglobin derivatives, oxy-hemoglobin (HbO2) and deoxy-hemoglobin (Hb), is the same--or, more recently, use broad spectrum photometry with multiple wavelength to get an overall picture of the absorbance spectrum, while scattered light is prevented from arriving at the sensor.
Antioxidants themselves also absorbed in the UV range; however their difference "oxidized minus reduced" spectra had isosbestic
points close to 234 nm (Figure 4) and therefore could not notably contribute to the absorbance changes as monitored at 234 nm.
2+]-induced quenching of fura-2 fluorescence was estimated at 360 nm excitation wavelength (F360), which represents the isosbestic
wavelength and is not sensitive to the changes in the [[Ca.
The 805 nm wavelength is the isosbestic
point of the absorption coefficients of O2Hb and HHb.
Furthermore, spectroscopic titration studies for the interaction of these food additives with DNA showed that these dyes bind to calf thymus DNA and distinct isosbestic
points are observed clearly suggesting binding of the dyes to DNA.
Fura-2 fluorescence was alternately excited at the isosbestic
point (357 nm) and at the calcium-sensitive wavelength (.
A separate measurement at an isosbestic
point (815 nm for hemoglobin), a wavelength at which the absorption coefficients of the two species are equal, provides the total amount of reduced and oxidized forms, which is proportional to blood volume.
Overlapping the absorbance spectra for mixtures of ITX and MA having differing irradiation times between 0 and 60 min showed that a single isosbestic
point was produced at approximately 350 nm (Fig.
While in the presence of increasing concentration of CTAB in a fixed concentration of 5-FU, the signal at 206 nm showed increase in absorbance (hyperchromic effect) accompanied with red shift (bathochromic effect), generation of another signal at 296 nm and an isosbestic