3,3',5,5'-Tetramethylbenzidine (CAS 54827-17-7): storage and disposal

Substrate solutions are the stock most people hold, and they usually live in a fridge in a university or pathology lab, next to antibodies and wash buffers. Spills there are common because the bottles are small, so keep them upright in a tray and away from open food or drink. The powder is better kept in a labelled cupboard with other dry reagents. The irritant classification covers skin, eyes and the respiratory tract, which is the reason to keep powder jars tightly closed. Write the date of receipt on each bottle, and keep a single labelled place for substrate so that a bottle is not lost behind plates and reagent boxes.

A clear, colourless solution is what normal looks like. When the liquid has turned blue in the bottle, something has already triggered the reaction, such as contamination from a pipette tip or a plate, so the bottle is no longer a sound reagent. A solution that is cloudy, has a deposit or has changed colour is stock to list. For the powder, caking, damp patches, staining on the shelf and a faded label are the checks. Bottles that have lost their date, or that are leaking at the cap in the fridge, belong on the collection list. A blue ring in a bottle neck shows liquid has crept and dried there.

By specialist collection only. It never goes down the drain or into general waste. It is normally packed in a non-regulated or low hazard laboratory pack with compatible chemicals.

Begin with what the container is: powder, or a ready-made substrate solution with the supplier name on the label. A university or pathology lab uses 16 05 06*, a clinic or other human healthcare setting 18 01 06*. The paperwork follows the hazardous route. Used substrate from plates and spare solution should be gathered in labelled containers and described as liquid waste, not left in the plate washer. Do not wash substrate away at a sink or treat it, and keep it out of general waste and clinical waste bins. The powder and the solution are listed separately, and a registered carrier collects them for a permitted facility.

Usually held as: substrate solutions.

Part-used bottles and full containers are both fine. Tell us the size and how many, and an estimate is enough for a first price.