When using a photometer it is important to insert the cuvette in the same position when performing a blank measurement (zero) and a read with reacted sample in order to maintain a consistent path length in accordance with the Beer-Lambert Law (see below). The HI731336N have a locking index tab in the cap that fits with the HI977xx series photometers to ensure that the cuvette is inserted in the same orientation each time.
The quantity of radiation absorbed is given by the Beer-Lambert Law:
A = log Io/I
Absorbance is also given by: A= ?? ? C ? l where:
A is a dimensionless number
?? the proportionality constant, is called the molar extinction coePMcient or molar absorptivity; it is a constant for a given substance, provided the temperature and wavelength are constant [L/(mol?cm)]
C is the concentration of the substance (mol/liter)
l is theoptical distance light travels through sample (cm)
The HI731336N are the replacement caps for glass cuvettes that are supplied with all HI977xx series portable photometers. The are also designed to keep any stray light from entering the sample cuvette holder of the optically based system.
