Additional hints for worksheet 4.1: How to construct an absorption photometer on your own (2/4)

The cuvette

Besides the shown cuvettes made of plastic with inner dimensions of 1 cm × 1 cm × 5 cm, there are cuvettes made of optical glass as well. They are transparent in the spectral range of 350 to 3500 nm, and available in many various optical path lengths in between 0,1 mm and 10 cm.

If the spectral range is desired to reach 200 nm (deep ultraviolet), synthetic quartz cuvettes have to be used because optical glass absorbs radiation at wavelengths below 350 nm. Indeed, the transmission of some plastic cuvettes does reach the one of fused silica cuvettes in the UV.

Cuvettes made of synthetic quartz for the analysis of slightly absorbing liquids. The optical path length is 10 cm (left one) resp. 5 cm (right one). The lateral windows are opaque to reduce reflections from the passing light.

There are cuvettes which can be closed by a teflon plug, and so called flow-through cuvettes with connections for silicone tubes. This is useful when the liquid is meant to circulate through the cuvette or it shall be repeatedly filled through a funnel.

Cuvettes made of synthetic quartz for measurements in VIS and UV. On the left: Dimensions of 1 cm × 1 cm × 5 cm, with teflon plug. In the back: Dimensions of 1 mm × 1 cm × 5 cm, with teflon plug, for the analysis of highly absorbing liquids. In the front: flow-through cuvette, dimensions of 1 cm × 1 cm × 5 cm.