ViRoLac Industries
Instrument design for
real-time data collection and analysis
CAPTO. Dr. Robert LaCount
(rear center of photo) led the ViRolac Industries project team. Dave Walker
(front left) worked part-time with Bob
on this project from about 1988 through 1995. Dave assisted with some
of the hardware/ software design and implementation for the new instrument. Bob
called the instrument "CAPTO", short for Controlled-Atmosphere Programmed-Temperature
Oxidation. CAPTO is an oxidative degradation thermal method capable
of analyzing a wide range of materials. These include coals, high molecular
weight polymers, oil shales, and mineral sulfides and carbonates. In
fact, almost any solid that decomposes under thermal oxidative conditions
to evolve one or more gases can be analyzed by CAPTO. It handles up to four
samples at one time using as the detector a fourier transform infrared (FTIR)
spectrometer containing gas cells mounted on a table positioned by a linear
stepper motor. ViRoLac currently provides materials characterization
and analysis services.
Please contact ViRoLac by telephone at 724-627-3967 or visit www.ViRoLac.com.
Time-share a laboratory FTIR.
A spin-off project involved computer hardware and custom software enhancements,
making it possible for one FTIR to be "time-shared" between continuous
air monitoring and the usual laboratory measurements. The FTIR was equipped
with the same multiple sample cell positioning system used with CAPTO. ViRoLac
called this system "Enhancer" because it provided a substantial
enhancement over a standard (single use) laboratory FTIR. The system at the
right and below shows Enhancer mounted on a Bomem FTIR and outfitted with
four gas cells. A fifth gas cell could be added for reference spectra, effectively
providing the same long term stability as more expensive "dual-beam"
FTIRs. Additional sample cells (gas, liquid, etc.) could be mounted on the
table for general laboratory measurements. The ViRoLac custom software ran
on top of the standard FTIR software, providing control of the sample cell
table and FTIR, and coordinated the multiple data collection tasks, analysis,
and on-the-fly display. Since air monitoring activities require about 0.5
minutes per monitoring location (stream), full-time monitoring of all 4 locations
could occur as rapidly as once every 2 minutes. The more typical situation
is monitoring the 4 locations about once every 15 minutes, leaving approximately
13 minutes for other laboratory measurements. In general, after appropriate
sample cells have been mounted on the table, the FTIR workload can be shared.
For example, the work load could include random single measurements, a series
of measurements during a slow kinetics experiment, along with continuous air
monitoring.
Alternatively, the Enhancer could be devoted entirely to continuous monitoring. In that case, the maximum number streams can be increased by adding an external multiple-position valve to the system as shown below. Utilizing 5 gas cells, this could go as high as 60 different streams being monitored during every 15 minute period. Of course, overall capability depends upon cell type, size and clearing time. Clearing occurs while other cells are being monitored. For example, this translates into 9 to 12 different streams every 15 minute period, when using three long path gas cells mounted on the sample table along with external multiplexing. The software updates on-the-fly display curves showing concentration versus time for each extracted species. Spectra may be re-analyzed for the presence of additional species while the original montoring continues, and the ongoing monitoring and display curves may be modified to include them. Applications for such a system include emergency industrial monitoring involving accidental contaminants and chemical release into the air and water, and a host of multiple-stream laboratory applications.
The Enhancer project was presented at the Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy. Pittcon '94 abstract #929 (DW94PITTCON.doc). PIttcon '95 abstract #338 (DW95PITTCON.doc). PIttcon '97 abstract #1284 (DW97PITTCON.doc). Microsoft PowerPoint slide presentation (Enh97allv2.htm) or download 1.2 MB (Enh97allv2.ppt).