Worried about Quenching? Don’t be! All is well when analyzing PAHs with Methanol Mobile Phase.

The acetonitrile shortage does not seem to have an end in sight. Finding solutions for reducing overall acetonitrile usage can decrease dependency on this now very costly solvent. In a previous post I recommended switching your HPLC mobile phase from acetonitrile to methanol for polycyclic aromatic hydrocarbon (PAH) analysis. The data from the previous post was using a UV detector with a sample concentration of 10 mg/L. Since then, I have received several requests for proof that sensitive analyses can still be performed using this alternate mobile phase. Typically, when looking for low levels of PAHs a fluorescence detector is used. With fluorescence detectors one has to be aware of any possible quenching effects that may reduce analyte sensitivity. Advanced Technology Laboratories was kind enough to share data they have acquired for PAH analysis using methanol mobile phase and a fluorescence detector. They have been able to achieve linear calibration curves down to 200µg/L.