=======Press Release======

In-Situ^® Inc. Announces the Technologically Advanced RDO^® Optical Dissolved Oxygen Sensor for Water Quality Monitoring

Next generation sensor lowers total cost of data acquisition and ownership

FORT COLLINS, COLORADO, September 3, 2008 — In-Situ Inc. announced today that it has released the next generation Rugged Dissolved Oxygen (RDO^®) sensor that uses the latest optical technology for dissolved oxygen (DO) measurement. For long-term and ambient water quality monitoring, the RDO sensor features a rugged, wiper-free design that excels in demanding environments. The sensor’s abrasion-resistant foil withstands fouling, high sediment loads, and rapid flow rates. The sensor cap’s pre-loaded calibration coefficients simplify set up and eliminate errors that can occur when manually programming other sensors. Designed to respond rapidly to changes in DO, the RDO sensor is an ideal tool for vertical profiling and applications with dynamically changing conditions.

“Water quality professionals will again benefit from In-Situ Inc.'s aggressive investment into new product development," said Bob Blythe, CEO and President of In-Situ Inc. "By improving upon the breakthrough optical DO sensor technology that In-Situ Inc. first brought to market in early 2004, our next generation RDO sensors provide higher quality data and more robust performance at a significantly lower cost than currently available optical DO sensors. Superior optical DO technology combined with the lower total cost of the new In-Situ RDO sensor will essentially render the membrane-based Clark cell electrode obsolete.”

Compared to Clark-cell type sensors, the new RDO sensor can lower the total cost of acquiring consistent, high-quality data. The In-Situ RDO sensor significantly reduces site visits for instrument checks and recalibration. The RDO sensor is factory-calibrated and requires a quick two-point calibration upon deployment. The calibration can last for several months if sensor fouling is minimal and if the foil is not mechanically damaged or removed. If fouling is high, the sensor can typically be cleaned and redeployed without recalibration. Field-replaceable caps streamline maintenance, reduce costs, and eliminate programming errors.

The In-Situ RDO sensor measures DO using the principle of “dynamic luminescence quenching.” Sensor optics include a lens, blue LED and filter, red LED and filter, and a photodetector or photodiode. When the blue LED emits light, it causes lumiphore molecules embedded in the gas-permeable sensing foil to emit red photons. The In-Situ RDO sensor measures the “phase” (or delay) of the returned signal compared to the excitation signal, and is thus based on the “lifetime” rather than the “intensity” of the luminescence. The presence of oxygen in the foil quenches the luminescence and causes a phase shift in the returned signal, detected by the photodiode. The phase difference between the blue excitation light and the return red light is measured, and the result is used to quantify DO.

While measuring the intensity of luminescence is easier to implement in optical DO sensors, it gives less robust data than measuring the lifetime of luminescence, which is a physical constant. In addition, instruments measuring intensity require more frequent calibration. Measuring lifetime luminescence requires more sophisticated signal processing and delivers higher accuracy over a wide operating range. Optical DO sensor readings are not affected by sample color or turbidity, and the method delivers highly accurate results in hypoxic conditions.

The new RDO optical dissolved oxygen sensor will be commercially available in September 2008. The sensor integrates seamlessly into the multi-parameter In-Situ TROLL^® 9500 water quality instrument. The TROLL 9500 instrument is available in either a sub-2 inch or sub-4 inch instrument body for groundwater and surface water monitoring.

ABOUT IN-SITU INC. — In-Situ^® Inc. designs, manufactures, distributes, and rents environmental equipment for monitoring the quantity and quality of groundwater and surface water. From advanced aquifer characterization to long-term monitoring to economical data collection, In-Situ instruments provide accurate results and reliable operation — even in harsh conditions. In-Situ Inc.'s headquarters are located at the foot of the Rocky Mountains in Fort Collins, Colorado, USA. In-Situ offers world-class technical support 24 hours a day, 7 days a week through its global network of regional offices and distributors. Visit www.in-situ.com or the RDO Media Center for more details on the RDO^® optical dissolved oxygen sensor.

In-Situ, RDO, and TROLL are registered trademarks of In-Situ Inc.

For more information, press only:
Rob Mooney
In-Situ Inc.
221 E. Lincoln Avenue
Fort Collins, Colorado 80524
Phone: 970-498-1655
Fax: 970-498-1598
rmooney@in-situ.com