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α-Tocopherol and α-tocopherol acetate are separated using HPLC in reversed phases and determined with a fluorescence detector or a UV detector.

Total carbon (TC) and total inorganic carbon (TIC) are converted into carbon dioxide through oxidation (TC) or acidification (TIC). The CO₂ is transferred from the digestion cuvette through a membrane into the indicator cuvette. The color change of the indicator is measured in a photometer. TOC (total organic carbon) is determined as the difference between the values for TC and TIC.

The organically bound carbon in water is converted into carbon dioxide through combustion. Inorganic carbon is eliminated through acidification or is determined separately. The carbon dioxide formed by oxidation is determined either directly or after reduction, e.g., to methane. The final determination of CO₂ is achieved using various methods, e.g., infrared spectrometry, CO₂-sensitive sensors or – after reduction of the CO₂ to yield methane – with a flame ionization detector.

The basis for these O₂ measurements is the detection of photoluminescence produced by an oxygen-sensitive layer. The change in photoluminescence depends on the partial pressure of the oxygen. Given the values for the partial pressure of the oxygen and the temperature, the amount of oxygen gas dissolved in the liquid can be calculated. The oxygen sensor determines the O₂ content of the liquid by means of optical detection through a photoluminescent process, in which an oxygen-sensitive layer is exposed to blue light. In doing so, the molecules in this layer become excited and reach a higher energy state. In the absence of oxygen, the molecules emit a red-colored light. If oxygen is present, it collides with the molecules in the oxygen-sensitive layer. The molecules in the oxygen-sensitive layer, which have collided with oxygen, cease to emit light (refer to figure 1). For this reason, a relationship exists between the oxygen concentration and the intensity of the emitted light as well as the intensity and the rapidity with which the intensity of the light diminishes. The intensity of the light is reduced at higher oxygen concentrations, although the rate at which it does so increases. The temperature of the product and the time interval between the light signal and the emission of light (phase shift) are both measured and used to calculate the oxygen content.

The device’s construction enables the state of the blue LED to be monitored using a photodiode. Another photodiode – with a red filter – measures the oxygen-dependent red light (refer to figure 2). This light is emitted by the luminophores due to photoluminescence (fluorescence) after they reach an excited state through exposure to the blue light. As a result of this exposure, the electrons of the luminophores are elevated to a higher energy level. As they return to their original energy level, they emit a red light.

The CO₂ content is determined as inorganic carbon using a device that measures the total organic carbon, known as a TOC analyzer. Through the addition of caustic, CO₂ in the sample enters the system as carbonate or bicarbonate and then through the addition of phosphoric acid is released and fed into an NDIR detector (non-dispersive infrared sensor) by means of a carrier gas.