Many people continue to use clear-walled micro cells without realising the problems caused by inadequate masking - using self-masking black-walled cells is a solution
Measurements at high absorbance are among the most demanding tasks for a UV-visible spectrophotometer, with factors such as instrument linearity, stray light and detector noise all conspiring to introduce potential errors.
This situation is exacerbated when very small samples are being measured.
An investigation at Starna, a manufacturer of spectrophotometer cells (cuvettes), compared results obtained using conventional clear-walled micro and semi-micro cells with those using cells with self-masking solid black walls.
Measurements in its Ukas accredited (ISO 17025) calibration laboratory revealed that light leakage through the cell walls of unmasked cells can introduce errors of over 40% at high absorbance levels (3A).
Significant errors were detected at absorbance levels well below 1A.
John Hammond, Starna's technical and marketing manager for analytical products, said: "Many people continue to use clear-walled micro cells without realising the problems caused by inadequate masking.
"Using self-masking black-walled cells is by far the safest and simplest solution".
Starna's self-masking micro and semi-micro cells are available with a variety of window materials and path lengths from 5 to 50mm, and are assembled using a fully fused method of construction pioneered by the company.
Experimental results obtained during the investigation can be supplied on request.
