Stable Isotopic Analysis Using Mass Spectrometry and Laser Based Techniques: A Review
Stable isotope ratios of hydrogen and oxygen are widely used in hydrology, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, ecology, oceanography, and paleoclimatology. In water cycle proce
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Abstract Stable isotope ratios of hydrogen and oxygen are widely used in hydrology, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, ecology, oceanography, and paleoclimatology. In water cycle processes, it is used in getting the information on groundwater circulation, discharge components in rivers, lake hydrology, sources of moisture in precipitation, recycling and transport of atmospheric moisture, glaciology at local, regional and continental scales. The isotope ratio mass spectrometer (IRMS) invented in 1940s led to the measurement of isotopes of water. The technological advancement led to the development of new range of IRMS that functions as programed operation provides high throughput with high precision and accuracy and uses microliters of sample analysis. However, their high cost and required operational skills have a wider limited use of these systems and applications of isotopes in hydrological science by researchers in general. Over the last one decade, less expensive and easy-to-operate spectroscopic methods for isotope analysis using lasers have emerged. The present paper provides insight into this advancement along with performance of these systems. Keywords Mass spectrometry • Stable isotopes • Laser • International atomic energy agency
1 Introduction Isotopes can be classified in two important categories: (1) stable isotopes and (2) unstable isotopes (also called radioactive isotopes). Stable isotopes are the atoms that do not decay with time. On the other hand, radioactive isotopes disintegrate by giving out alpha (α), beta (β) particles and/or gamma (γ) radiation, etc., and transform into another type of atom.
M. Someshwar Rao (*) National Institute of Hydrology, Roorkee, India e-mail: [email protected]
S. Sathiyamoorthy et al. (eds.), Emerging Trends in Science, Engineering and Technology, Lecture Notes in Mechanical Engineering, DOI: 10.1007/978-81-322-1007-8_48, © Springer India 2012
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The mass spectrometer is used for detection of stable isotopes that do not decay with time. It is not used for detection of unstable isotopes (also called radioactive isotopes) that decay and disintegrate by giving out alpha (α), beta (β) particles and gamma (γ) radiation, etc., and transform into daughter nucleus. If the daughter nucleus if radioactive, the process of disintegration with emission of radiation continues till it reaches to stable nuclear form and the process of disintegration stops. The radioactive isotopes are usually measured through detection of their emitted radiation or by counting parent or daughter isotopes using Accelerator Mass Spectrometer. The present paper limits its scope mainly in the measurement of stable isotope concentration.
2 Units of Measurement To avoid system dependent and procedure dependent biases, measured isotope abundance ratios are compared to those of a standard material of known isotope composition using delta (δ) notation. The δ provides deviation of the iso
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