Precipitate Formation in Wells Upon Substrate Addition

Symptom

Visible precipitate or cloudiness appears in wells immediately or shortly after substrate addition. Absorbance readings may be abnormally high or variable.

1. 1 Substrate concentration too high causing precipitation
2. 2 Sample concentration too high leading to protein aggregation
3. 3 Incompatibility between substrate components and sample matrix
4. 4 pH or ionic strength mismatch causing precipitation

1. 1 Decrease substrate working concentration
2. 2 Dilute samples further to reduce protein concentration
3. 3 Centrifuge samples before use to remove particulates
4. 4 Filter substrate solution through 0.22 µm filter before use

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