Spectrophotometers encompass the majority of the instruments in our lab. For slower kinetics, there is a Perkin-Elmer Lambda 9 scanning instrument. For faster kinetics, there are several stopped-flow instruments (174). The newest instrument in the Margerum lab is the Applied Photo-Physics Model SX.18MV Sequential Stopped-Flow Spectrofluorimeter. This instrument is capable of measuring fast kinetics initiated by stopped-flow or by sequential-mixing stopped-flow with detection by absorbance or fluorescence. This instrument is particularly useful because its operation is fully automated. This instrument will be upgraded in the near future by installing a diode-array detector.
A novel development that originated in the Margerum lab has been the Pulsed-Accelerated Flow Spectrophotometer (PAF) (165, 176, 218, 236). These instruments are capable of measuring reactions that are too fast for the stopped-flow techniques. The PAF method integrates observation with continuous flow mixing over a decelerated velocity profile. Rate constants for these fast reactions can be abstracted from the data by mathematical analysis. In the newest model, the PAF - V, the mixing/observation cell has been designed to allow studies at non-abient temperatures, even below zero degrees Celsius, and to reduce problems with construction and with leaking (236). A different class of PAF instruments developed in our lab has been the PAF-PRO (Pulsed-Accelerated Flow with Position Resolved Observation).
Chromatographic methods utilized in our research include capillary ion and high performance liquid chromatography. Our lab possesses a Dionex DX - 500 chromatograph (with electrochemical and absorbance detectors), a Hewlett 3DCE system with a HP 3DCE Chemstation , a Varian 5000 HPLC liquid chromatography system with a variable wavelength UV detector and a Hewlett Packard Series 1050 Photodiode Array Detector to enable UV-vis scans of analytes in real-time as they elute from the HPLC.
An Electrochemical instrument employed in our research is the BAS-100 Electrochemical Analyzer used for Osteryoung Square Wave Voltammetry, bulk electrolysis of metal-peptides, and electron-transfer reactions in the studies of metal-peptide chemistry.
Other techniques routinely utilized for analysis in our research include mass spectrometry (MS), membrane introduction mass spectrometry (MIMS), circular dichroism (CD), Raman, and NMR. Instruments for these types of analysis are available in the chemistry department or in collaboration with other research groups in the chemistry department here at Purdue. Whether traditional wet-chemical methods or state of the art pulsed flow techniques are used, the Margerum Research Group continues to use innovative solutions for challenging analytical problems.
Last updated 25 May 2002.
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