COMPUTERIZED DATA-ACQUISITION AND ANALYSIS APPLIED TO CHEMILUMINESCENCE DETECTION OF NITRIC-OXIDE IN HEADSPACE GAS

Nitric oxide (NO) is an important messenger molecule which is implicat ed in an ever increasing number of physiological, pharmacological, and pathological processes. Quantitative and qualitative analysis of NO h as been hindered by its extremely short half-life in biological system s, and thus there is a keen interest in developing accurate techniques to measure NO. We have employed a modification of the chemiluminescen ce NO detection technique used by J. F. Brien et al. (J Pharmacol Meth ods 1991;25:19-27) to measure the photo-induced release of NO from sev eral structurally unrelated drugs including streptozotocin (STZ) and s odium nitroprusside (SNP). We were unable to calibrate the instrument by measuring peak heights from an attached chart recorder in response to increasing amounts of injected nitric oxide. The extremely fast ris e times of peaks from the chemiluminescence detector exceeded the capa city of the pen-servomotor mechanism of the chart recorder to accurate ly measure nitric oxide response curves. We, therefore, digitized the detector's output with an analog-to-digital convertor board connected to an IBM PC. The signal was acquired and analyzed by a program called NOXIDE, Using the NOXIDE program we were able to accurately measure b oth the peak height and total integrated area of each peak and show th at the area, but not peak height, correlates extremely well (r = 0.999 1) with standard injections of 20.0-750.0 pmol NO.