Sandwich-type flow-through fiber-optic cells for optical absorbance measurements

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Optical Instrumentation

Background:

• Conventional Z-type cells are susceptible to artifact absorbance signals from refractive index (RI) changes.
• Optical fiber-based cells offer potential improvements in light throughput and signal-to-noise ratio (S/N).

Purpose of the Study:

• To evaluate the performance of two sandwich cell configurations for absorbance detection.
• To compare their susceptibility to RI changes and light throughput against a conventional Z-type cell.

Main Methods:

• Investigated a Pavon et al. sandwich cell and a similar configuration with angled single-strand optical fibers.
• Utilized a conventional Z-type cell (6-mm path length) as a benchmark.
• Assessed performance based on artifact absorbance signals from RI changes and light throughput.

Main Results:

• Sandwich cells demonstrated an order of magnitude less susceptibility to RI artifact signals compared to the Z-cell.
• Incorporating an inert metallized reflector increased light throughput by an order of magnitude, improving S/N.
• Angled entrance single-strand fiber optic cells exhibited substantially greater overall light throughput than bifurcated fiber optic cells.

Conclusions:

• Sandwich cells, particularly those with angled optical fibers, provide enhanced performance for absorbance detection.
• The design improvements lead to reduced artifacts and higher signal quality.
• Detection limits are influenced by cell pathlength, suggesting optimization potential.