Table 1. Analytic Details Concerning the Limits of Quantification, Linearity of the Tested Assay, and Recovery Rates of the Various Opioids

The internal standard fentanyl-d⁵was used to quantify sufentanil, fentanyl, and alfentanil. 3-Methylfentanyl served as a marker for identification of chromatographic or detection problems. The recovery rate ± coefficient of variation (%) in relation to Fentanyl-d⁵was measured from spiked opioid levels extracted from 1.0 ml serum.