Real-Time, On-Line Solvent Vapor Measurements
Using NIR Tunable Diode Laser Absorption Spectroscopy

Advantages

• ✔ Gas species specific
• ✔ Continuous, real-time, high detection sensitivity
• ✔ Absolute solvent concentration measurements
• ✔ Integrated lot measurement
• ✔ Less susceptible to sampling errors
• ✔ Sampling uses existing system pump and pressure differential
• ✔ Remote operator control
• ✔ Limits worker exposure to active pharmaceutical ingredients
• ✔ Reliable: solid-state diode laser and fiber optic transport

System Configuration for Solvent Drying Applications

Custom-Designed Industrial, Rack Mounted, PSI Solvent Vapor Monitor

TDLAS Principles

• Gas molecules absorb light at unique and discrete wavelengths
  • absorption lines
• Laser wavelength repeatedly scans across absorption lines
  • produces amplitude modulation in received power
• The modulated signal is processed and the output translates into:
  • molecules per cm³
  • parts per million, PPM
  • milligrams per liter

Typical Detection Limits*

William Kessler Physical Sciences Inc. 20 New England Business Center Andover, MA 01810-1077 Telephone: (978) 689-0003 Fax: (978) 689-3232 kessler@psicorp.com