from spoilage or adulteration which may be harmful and which is often controlled by governmental agencies, for example pesticides. Astrochemistry Several GC-MS have left earth. Two were brought to Mars by the Viking program. Venera 11 and 12 and Pioneer Venus analysed the atmosphere of Venus with GC-MS. The Huygens probe of the Cassini–Huygens mission landed one GC-MS on Saturn's largest moon, Titan. The MSL Curiosity rover's Sample analysis at Mars (SAM) instrument contains both a gas chromatograph and quadrupole mass spectrometer that can be used in tandem as a GC-MS. The material in the comet 67P/Churyumov–Gerasimenko was analysed by the Rosetta mission with a chiral GC-MS in 2014. Medicine Dozens of congenital metabolic diseases also known as inborn errors of metabolism (IEM) are now detectable by newborn screening tests, especially the testing using gas chromatography–mass spectrometry. GC-MS can determine compounds in urine even in minor concentration. These compounds are normally not present but appear in individuals suffering with metabolic disorders. This is increasingly becoming a common way to diagnose IEM for earlier diagnosis and institution of treatment eventually leading to a better outcome. It is now possible to test a newborn for over 100 genetic metabolic disorders by a urine test at birth based on GC-MS. In combination with isotopic labeling of metabolic compounds, the GC-MS is used for determining metabolic activity. Most applications are based on the use of 13C as the labeling and the measurement of 13C-12C ratios with an isotope ratio mass spectrometer (IRMS); an MS with a detector designed to measure a few select ions and return values as ratios. See also Capillary electrophoresis–mass spectrometry Ion-mobility spectrometry–mass spectrometry Liquid chromatography–mass spectrometry Prolate trochoidal mass spectrometer Pyrolysis–gas chromatography–mass spectrometry References Bibliography External links Golm Metabolome Database, a mass spectral reference database of plant metabolites Mass spectrometry Chromatography Laboratory techniques Explosive detection