By Michael Judge
Updated Mar 24, 2022
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In synthetic chemistry, determining how much of your target compound survives a purification step is essential for evaluating efficiency and troubleshooting yields. Recrystallization, chromatography, or distillation can all leave residual solvent or solute in the final product, so a systematic calculation of % recovery helps you identify procedural gaps and maintain reproducibility.
Accurately record the mass of the chemical before any purification. Use a calibrated analytical balance and ensure the container is clean.
After purification, allow the product to dry completely. Let it sit at room temperature for several days or gently heat it (if thermally stable) to evaporate all solvent. Residual moisture will inflate the final weight.
Weigh the purified, dry material. If filter paper or other debris was used, subtract its weight or exclude it from the measurement.
Divide the dry mass of the recovered product by the initial mass (same units). In our example, 2.86 g ÷ 5.00 g = 0.572.
Multiply the ratio by 100 to obtain the percent recovery. 0.572 × 100 = 57.2 %.
A recovery above 100 % indicates a problem—typically a weighing error or incomplete drying. Keep your measurements precise and repeatable.
