Preparation of solutions

Introduction

Most solutions in histology are made using water as a solvent. The agent dissolved in water to make an aqueous solution is the solute. Solutions typically are made as volume to volume or weight to volume. Concentrated formaldehyde is a 40% solution of formaldehyde (CH ₂ O) in water. This represents the maximum solubility of the molecule (solute), in water (the solvent) and the resulting solution is a 40% w/v (weight-to-volume) solution.

The majority of histology laboratories now purchase commercially produced solutions in a prepared form. This is largely to reduce user exposure to a variety of hazardous chemicals and stains, thus minimizing any associated risk. Additionally, the use of commercial solutions is beneficial in maintaining quality, as they produce standardization of the staining.