UV Detector Flow Cell — Sales and Instrument Support

Analytical flow cell for an HPLC UV or PDA detector. The cell carries the column eluate through the light path between two quartz windows; absorbance rises in direct proportion to the path length, which is why a standard analytical cell is 10 mm and why changing cell type changes apparent sensitivity even though nothing about the method has changed.

An analytical cell keeps its illuminated volume small - single-digit microlitres on most designs - so that the peak leaving the column is not broadened again inside the detector. Semi-preparative and high-sensitivity cells trade that volume against path length deliberately.

What goes wrong

• Deposits or air in the cell give exactly the same baseline noise as a dying lamp; check the cell first, because it costs nothing.
• High-pH mobile phases etch quartz windows, and an etched window shows as permanently low energy.
• A leaking cell leaves a salt crust at the fittings and drifts with room temperature.
• Over-tightened fittings crack windows and distort the flow path.

Cleaning is done by pumping the manufacturer's recommended solvent sequence through the cell - commonly isopropanol, or dilute nitric acid where the manual allows it - never by dismantling and wiping the windows.