This is defined as $$K=\frac{Q_{\text{T}}/Q_{\text{M}}}{Q_{\text{T}}^{\text{o}}/Q_{\text{M}}^{\text{o}}}$$ where $Q_{\text{T}}$ and $Q_{\text{T}}^{\text{o}}$ are the quantities of the microcomponent in the concentrate and in the sample, respectively (mass units or concentration units), and $Q_{\text{M}}^{\text{o}}$ and $Q_{\text{M}}$ and are the quantities of the matrix before and after preconcentration, respectively. If the recovery is 100%, $K=\frac{Q_{\text{M}}^{\text{o}}}{Q_{\text{M}}}$. The terms enrichment coefficient and enrichment factor are not recommended.