Recycling of Reagents

All waste alcohol and formula 83 are to be poured into the appropriate “used” containers ‘to be recycled’. Used formula 83 and alcohols must be stored in the flammable cabinet. ALL formula 83 can be recycled. Used formalin will be placed in individual ‘used’ containers for storage until a chemical waste company removes them. Alcohols can be recycled with the exception of those used AFTER formula 83 (ie  alcohols used in the process of “hydrating” slides).

Notes

• Adequate volume of reagents must be maintained in the processor containers to ensure quality tissue sections
• The reagents must be rotated frequently, according to the lab’s established schedule
• Hydrometers should be used to check alcohol percentage to check for contamination
• Clearing agent should have purity checks performed after recycling and checked for cloudiness (discard)
• Paraffin infiltration containers should be changed frequently to avoid xylene contamination

Troubleshooting Processing

• The most common processing issues arise from incomplete fixation or incomplete dehydration of tissues
• Precipitate in processing chamber can be caused by the use of phosphate buffered formalin as a fixative when dehydration is begun using  >70% alcohol. CORRECT issue by:  Beginning dehydration <70% alcohol. To remove the precipitate, rinse the chamber and tubing with dilute acetic acid.
• Overdehydration– Seen in H&E as microchatter around the edges of the tissue sections microscopically. Caused by too much time in dehydration solutions. Corrected by: process smaller tissues such as biopsies separately from larger tissues- carefully controlling time in dehydration, decreasing dehydration time. [Partially rehydrating the faced block surface during microtomy may also help reduce the microchatter artifact. Soak trimmed blocks briefly (<contact 1 min) on a Kimwipe that has been saturated with warm water before cooling and sectioning.]
• Poor Processing: can be noted by uneven staining, poor nuclear staining on H&E or by absence of nuclear staining. Most common cause is water remaining in the tissue when it is placed in the clearing agent. Correct by: Ensure condensation is not forming on the lids during processing, check the percentages of alcohol to ensure water has not diluted the percentages and ensure reagents are being rotated and changed on a regular basis.  Dense or lipid-rich tissues should be processed on an extended program that allows sufficient time for complete reagent exchange.