What TOC is and how it is measured.
A whole variety of organic matter can be present in water, which cannot be determined individually. At least not without considerable analytical effort and within a short time. This is why the so-called sum parameter TOC (total organic carbon) is used.
The TOC measures a samples organic loads and is thus an important indicator for water quality. Since it includes all carbon compounds as one mass, it is exactly defined and an absolute quantity. Therefore, it may be determined directly.
Read more about TOC measurement methods.