Quality control of fluorescein isothiocyanate-labeled reagents

Fluorescein-labeled reagents are not amenable to the same precision of definition as are chemical substances. Nonetheless extensive experimental evidence shows that certain preparative requirements and selected measurable chemical parameters of the product are of considerable predictive value in determining whether a reagent will be suitable in use. Adherence to these criteria and their continuous reappraisal combined with performance assessment and information on stability are all essential to ensure that reagents are of a quality acceptable to laboratory workers and legislative bodies. The need for manufacturers to document each procedural step and record the results is an essential element of good manufacturing practice now imposed by regulatory bodies. All reputable manufacturers adhere to these requirements, which serve not only to maintain standards but also to form a basis for corrective action.