Optical Detection Systems A unique multiple long pathlength sample cell for absorbance spectroscopy UltraPath™ Appearance of instruments presently in these systems differ from those pictured here. ● Process Control & Oceanography ● Rugged system for laboratory and onboard measuring ● Portable & easy to use ● User-selected optical path lengths: 2, 10, 50 & 200 cm ● Highly sensitive and stable SPEC TROS CO PY UltraPath™ is a unique high-performance spectrophotometer system offering user-selectable optical path lengths of 2, 10, 50 and 200 cm. The instrument operates in the wavelength range of 250 to 730 (UPUV) or 380 to 730 nm (UPVIS) and has an exceptional dynamic range. Designed for the detection of low absorbing species in aqueous solutions, UltraPath is an ideal tool for any study requiring precise and highly sensitive spectroscopic determination of analytes, either in the lab or in the field. Background UltraPath was developed by WPI under a collaborative agreement with NASA (Stennis Space Center) for the spectroscopic determination of colored dissolved organic matter (CDOM) in seawater and fresh water environments. It can be used in the laboratory and in the field (i.e., at sea). CDOM concentrations vary significantly between open ocean samples with low CDOM (e.g., 0.007 m-1 at 380 nm), and high CDOM freshwater environments (e.g., 10-20 m-1 at 380 nm). To address these problems the design requirements of UltraPath mandated the development of a rugged portable system capable of high sensitivity measurements across a wide dynamic range. The UltraPath system meets these stringent design criteria and enables reliable measurement of CDOM in the range of 0.002 m-1 to 200 m-1 (250 to 730 nm). substances to the cell wall. In particular, the design greatly minimizes the problems commonly found with flow cells of long optical pathlengths: the risk of trapping dust particles, fibers or particulate matter inside the cell. The UltraPath system includes a low noise photodiode array-based spectrometer module (TIDAS I: FWHM = 5 nm, noise <0.2 mAU) and a light source (D4H with UPUV; FO6000 with UPVIS) to measure sample absorption. Light is coupled from the light source to the sample cell and from the sample cell to the detector via two fused silica fibers. A peristaltic pump (PeriPro-4LS) is utilized to draw the sample into the UltraPath sample cell. 35 30 Sarasota Bay & Pond CDOM Sarasota Bay Pond Absorption [1/m] 25 20 15 10 5 0 -5 250 350 450 550 Design UltraPath has four optical pathlengths contained within a single sample cell (i.e., 2 cm, 10 cm, 50 cm and 200 cm). The pathlengths are userselectable, offering a very high sensitivity and an extended dynamic range for UV and VIS absorbance measurements. The fluid path of the sample cell is optimized to produce a laminar flow that is virtually free of interference from trapped air bubbles and adherence of dissolved 650 750 Wavelength [nm] Fig. 1 — Two typical absorption spectra measured using UltraPath. The sample labeled “Sarasota Bay” is a CDOM sample with 34 PSU salinity collected from Sarasota Bay (Nov. 2007), and the sample labeled “Pond” is a highly concentrated CDOM sample collected from a local pond in Sarasota, Florida (Nov. 2007). 186 UK: Tel: +44 (0)1462 424700 • wpiuk@wpi-europe.com World Precision Instruments www.wpiinc.com Germany: Tel: +49 (0)30-6188845 • wpide@wpi-europe.com US: Tel: 941-371-1003 • sales@wpiinc.com