Sensitive, universal detection for capillary electrochromatography using condensation nucleation light scattering...

Condensation nucleation light scattering detection (CNLSD) was coupled with a pressurized capillary electrochromatography (pCEC) system using an electrospray interface. Supplementary pressure from a high-pressure pump was used to stabilize the electrospray and electrochromatography processes. Hydrodynamic injections were made with a 20 nl injection valve, and the inherent dead volume from the valve was successfully minimized, such that plate numbers in the range of 120,000 to 350,000/m were observed. Selectivity tuning using both pressure and voltage with the pressurized capillary electrochromatography system was demonstrated. Good reproducibility, comparable sensitivities for a wide range of compounds, including carbohydrates, and limits of detection down to the 50 ng/ml level, corresponding to 1-2 pg levels, were determined without the need for derivatization, demonstrating that condensation nucleation light scattering detection is a sensitive, universal detection method for pressurized capillary electrochromatography.