Gas chromatography–mass spectrometry
The design was complex. The time interval between different compounds flowing out of the chromatograph was hard to control. So, the mass spectrometer had to finish working on one compound before the next one flowed out of the chromatograph.  In the early models, the measurements from the mass spectrometer was recorded on graph paper. Highly-trained chemists studied the patterns of peaks to identify each compound.  By the 1970s, analog-to-digital converters were added to mass spectrometers. This allowed computers to store and to interpret the results. As computers grew faster and smaller, GC-MS became faster and spread from laboratories into every day life.  Today, computerized GC-MS instruments are widely used in environmental monitoring of water, air, and soil. It is also used in the regulation of agriculture, food safety and in the discovery and production of medicine.