Novel applications of broadband cavity enhanced absorption spectroscopy (BBCEAS) as a detector for HPLC at ultraviolet wavelengths from 250 - 400 nm.

The first application of broadband cavity enhanced absorption spectroscopy (BBCEAS) as a detection method for high performance liquid chromatography (HPLC) in the ultraviolet (UV) spectral range of 250-400 nm is reported. A custom-designed HPLC-BBCEAS system, incorporating a laser-driven light source (LDLS) and high reflectivity cavity mirrors (R ≥ 0.99), was employed for the separation and quantification of the polycyclic aromatic hydrocarbons (PAHs) anthracene and pyrene at near-UV wavelengths (300-400 nm). Minimum detectable absorption coefficients, αmin(t) of 9.8 × 10⁻⁶ cm⁻¹ Hz⁻½ and 9.6 × 10⁻⁶ cm⁻¹ Hz⁻½ were achieved for anthracene and pyrene at 338 nm and 333 nm, respectively, with 6.8 × 10⁻⁶ cm⁻¹ Hz⁻½ observed for anthracene at 356 nm. These values correspond to 25-fold and 18-fold improvements in sensitivity compared to a conventional Perkin-Elmer HPLC-UV system. In the deep-UV region (250-300 nm), the separation and detection of vitamin D₂ and D₃ were demonstrated using both the LDLS and a 280 nm LED with R ∼ 0.96 cavity mirrors. LDLS-based measurements yielded αmin(t) values of 5.1 × 10⁻⁴ cm⁻¹ Hz⁻½ and 4.0 × 10⁻⁴ cm⁻¹ Hz⁻½ for D₂ and D₃, respectively, while the LED measurements exhibited enhanced sensitivity with values of 7.7 × 10⁻⁵ cm⁻¹ Hz⁻½ and 5.8 × 10⁻⁵ cm⁻¹ Hz⁻½. These findings demonstrate that HPLC-BBCEAS enables broadband, multiplexed, and highly sensitive detection of UV-absorbing analytes and extends the practical detection range of HPLC into the deep-UV region.