A microcomputer automated recording spectropolarimeter

MANY analytical laboratories have available minicomputers or microcomputer systems which routinely find use for data analysis. Recent trends have been toward applying computers not only for computational capabilities, but also for on-line control and data .acquisition from actual analytical instru-mentation. Numerous analytical instruments are being designed to incorporate a computer system as an integral part. However it is possible, in many cases, to economically adapt existing instrumentation to a computer and gain the inherent advantages of on-line control, data acquisition, and rapid analysis of results. Reinbold and Pearson [1 described the modifications made to a Perkin-Elmer 141 polarimeter which enabled the acquisition of continuous optical rotatory dispersion data over the spectral region of 650-240 nanometers. The modifications basically consisted of replacing the existing light source of the Model 141 polarimeter with a double grating monochromator and a high intensity xenon light source. More recently, Simon and Pearson [2] .reported further modifications done to the Model 141 polarimeter system to convert it into a low cost recording spectropolarimeter. Their modifications include fitting the monochromator with a synchronous drive mechanism and coupling the Model 141 analyzer to a transmitting potentiometer for the continuous recording of optical rotatory dispersion spectra on a multi-speed, multi-millivolt strip chart recorder. In recent years, the Perkin-Elmer Model 141 polarimeter has been replaced on the market with a modernized Model 241 polarimeter. The Model 241 polarimeter incorporates solid state and digital circuitry for obtaining optical rotatory data which, unlike the vacuum tube circuitry of the Model 141, was ideally suited for interfacing to an on-line micro-*Author to whom correspondence shouM be addressed computer system. This paper describes the modifications made to a Perkin-Elmer Model 241 polarimeter to both interface it to an on-line microcomputer data system, and convert it to a microcomputer automated scanning optical rotatory dispersion spectropolarimeter with a range of 650-240 nm. Experimental Figure 1. shows, a block diagram of the computer automated scanning spectropolarimeter. Each of the major components shown in Figure will be discussed in detail. Figure 2 shows a photograph of the actual Model 241 polarimeter with some of the modifications visible.