The analytical performance of micromachined μ-groove silicon ATR elements has been evaluated in a comparison of FTIR and QCL spectroscopy operating at MIR wavelengths. μ-Groove silicon ATR elements are highly efficient micromachined waveguides fabricated at a wafer scale at such low cost that they may be considered a consumable for single-time-use, e.g., in medical application scenarios. Herein, exemplary analytes haven been used for reliably evaluating their analytical performance (i.e., acetate and carbonate) in terms of sensitivity, noise level, and achievable limits of detection in a comparison of broadband vs. narrowband infrared spectroscopy.