Design, construction, and evaluation of an integrating transient recorder for data acquisition in capillary gas chromatography/time-of-flight mass spectrometry

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Abstract
An integrating transient recorder (ITR) has been designed, constructed, and evaluated to accomplish time‐array detection in gas chromatography time‐of‐flight mass spectrometry (GC‐TOFMS) applications. The ITR consists of a 200‐MHz flash analog‐to‐digital converter, 16 high‐speed 100K emitter‐couple logic (ECL) summing boards, three parallel processors for real‐time data reduction, instrument control and routing functions, and a 300‐Mbyte mass storage device. The ITR is capable of recording 80 μs bursts of transient information with a time resolution of 5 ns. For each transient, up to 16 384 sequential time‐resolved channels may be recorded. An operator‐selectable number of sequential transients may be summed in a locked time registry creating a summed scan file while maintaining the integrity of the transient time resolution. The information from each transient is read, summed, and stored in one of two summing registers (16×1024×24 bits). While incoming information is being stored in one summing register, the information in the other summing register is processed and read out to disk, thus permitting high‐speed data collection continuously for long periods of time. The information from successive transients is summed in order to improve signal‐to‐noise, dynamic range, and sensitivity, and produces scan files at a rate sufficient to maintain all of the chromatographic information. GC‐MS data collected at 1, 20, and 50 spectra per second are presented for a nine‐component aliphatic/aromatic mixture. Although the ITR was specifically designed for GC‐TOFMS studies, the overall design concepts of the ITR are universal and apply to any situation where information from two or more phenomena occur at the output of a single detector and occur over vastly different time domains.