Why do the enzyme tubes appear discolored (yellow or brownish) or gelled?

This issue may occur if the instrument is not fully purged of the residual enzyme left in the supply lines, especially Trizma. ANKOM recommends flushing the enzyme supply lines with alcohol weekly when enzymes are being used. Further, we recommend flushing the supply line immediately after an analysis is performed using Trizma, due to the high probability of crystallization of Trizma in the lines. Residue in supply lines will cause discoloration, gelling, and complete blockage of the supply lines.  

If enzyme tubes have become discolored (turned yellow or brownish) or if the enzyme has begun to gel in the tubes, they will require replacement. Refer to TDF Service Procedure Tube Replacement Enzymes (TS004) for instructions on replacement. Contact ANKOM Technology at https://www.ankom.com/contact/technical-services or call (315) 986-8090 to purchase the Enzyme Tubing Replacement Kit (Part #: TDF67).