New mini-computer automated linear photodiode array spectrometer system for high-resolution liquid chromatography

• Published in: Journal of Chromatography A 1976-01, Vol.126, p.347-368
• Main Authors: Dessy, R.E., Reynolds, W.D., Nunn, W.G., Titus, C.A., Moler, G.F.
• Format: Article
• Language: English
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(01)84085-1

A third generation multi-wavelength array spectrometer was developed as a detector for the high-resolution liquid chromatographic characterization of metabolites. The design features include a PDP-8/e mini-computer, a matched pair of linear photodiode (256 element) arrays (Reticon), holographically ruled gratings, fiber optics, flow cells, and a high-intensity xenon light source. The wavelength range is 256 nm differential with 1 nm resolution and can be independently adjusted in the spectral range of 200–800 nm. Correction for the quantum efficiency curve is made on both of the cooled (−30°) photodiode arrays by an assembly language subroutine. The system is capable of 20 spectra/sec (200–456 nm) in a dual-beam mode. The dynamic range and linearity of the photodiode arrays are approximately 4000:1. Special features include mini-computer driven signal enhancement via integration as a function of signal strength. The display output includes presentation of the total absorption chromatogram vs. elution time in both real and post-run time as well as selectable single absorption band ( e.g., 280 nm) vs. elution time (post-run time). Application of this dedicated mini-computer automated liquid chromatography-UV spectrometry system for the separation and characterization of the metabolites of a carcinogen, 4-ethylsulfonyl-1-naphthalenesulfonamide, will be discussed.