Isotopic dilution, and

Th, Th and Po, all decay by alpha emission and are thus measurable by isotope dilution and alpha spectrometry (Ivanovich and Murray 1992). However, " Th is produced by the alpha decay of and in turn decays by beta emission to via the short-lived intermediate " Pa (half-life 1.18 m) ... 

If, nevertheless, uncertainties remain, there are some theoretical and experimental possibilities to guarantee reliably the identity. Such procedures are, e.g. addition of the analyte in a definite form, isotope dilution, and isotope substitution (e.g. deuterization of characteristic groups). 

Isotope Dilution and Quantification (the Jelly Bean Experiment)... 

Part—VI has been solely devoted to Miscellaneous Assay Methods wherein radioimmunoassay (RIA) (Chapter 32) has been discussed extensively. Various arms of theoretical aspects viz., hapten determinants and purity importance of antigenic determinants and analysis of competitive antibody binding of isotopically labeled compounds. The applications of RIA in pharmaceutical analysis, such as morphine, hydromorphone and hydrocordone in human plasma clonazepam, flurazepam in human plasma chlordiazepoxide in plasma barbiturates, flunisolide in human plasma have been described elaborately. Lastly, the novel applications of RIA-techniques, combined RIA-technique-isotope dilution and stereospecificity have also been included to highlight the importance of RIA in the analytical armamentarium. 

Ryan, D., Watkins, R, Smith,)., Allen, M., Marriott, P. (2005) Analysis of methoxypyrazines in wine using headspace solid phase microextraction with isotope dilution and comprehensive two-dimensional gas chromatography. J. Sep. Sci. 28 1075-1082. 

Kuhara T (2002) Diagnosis and monitoring of inborn errors of metabolism using urease-pretreatment of urine, isotope dilution, and gas chromatography-mass spectrometry. J Chro-matogr 781 497-517... 

Magera MJ, Helgeson JK, Matern D, Rinaldo P (2000) Methylmalonic acid measured in plasma and urine by stable-isotope dilution and electrospray tandem mass spectrometry. Clin Chem 46 1804-1810... 

In some applications like newborn screening and filter paper blood spots, the internal standard that is labeled cannot be mixed with blood. It can only be present in the extraction solvents. Therefore, only the extracted metabolites can be quantitatively measured. I have denoted a term called pseudo-isotope dilution to account for the differences between traditional isotope dilution and the technique commonly used in newborn screening by MS/MS. A special analysis is capable using this technique, however, in terms of an extraction efficiency experiment. With isotope-labeled standards you can perform an experiment whereby a traditional isotope-dilution technique (internal standard added to liquid blood and spotted) is compared to pseudo-isotope dilution techniques (internal standard is added to the extraction matrix). The ratio of the results of these two analysis (pseudo/traditional) is the extraction efficiency. 

Yoshinaga and Morita used isotope dilution in conjunction with ICP-MS to measure mercury in biological and environmental samples [45]. The same group used microwave-induced plasma mass spectrometry for the isotope dilution analysis of selenium in biological materials [46]. Analysis of nickel via isotope dilution and ICP-MS has been reported by Patriarca et al [47]. 

C. Pin, B. Le Fevre, S. Joannon, Isotope dilution and plasma source mass spectrometry An optimal combination for high precision analysis of trace elements. Can. 

Ahnoff M, Persson BA (1990) Chromatography of calcium channel blockers. J Chromatogr 531 181-213 Review Carvalho M, Oliveira CH, Mendes GD et al. (2001) Amlodip-ine bioequivalence study quantification by liquid chromatography coupled to tandem mass spectrometry. Bio-pharm Drug Dispos 22 383-390 Fischer C, Heuer B, Heuck K, Eichelbaum M (1986) Quantification of nitrendipine by stable isotope dilution and electron-capture negative ion chemical ionization. Biomed Environ Mass Spectrom 13 645-650... 

Techniques for demonstrating channeling behavior include enzyme buffering, ligand exchange kinetics, isotope dilution, and estimation of the transition time. One of the most... 

Improved determination of regenerated sarin (GB) in minipig and human blood by gas chromatography-chemical ionization mass spectrometry using isotope dilution and large volume injection. Toxicologist 78(1) 354. 

Evans, R.A., Jakubowski, E.M., Muse, W.T., Matson, K., Hulet, S.W., Mioduszewski, R.J., Thomson, S.A., Totura, A.L., Retmer, J.A., Crouse, C.L. (2008). Quantification of sarin and cyclosarin metabolites isopropyl methylphosphonic acid and cyclohexyl methylphosphonic acid in minipig plasma using isotope-dilution and liquid chromatography-time-of-flight mass spectrometry. J. Anal. Toxicol. 32(1) 78-85. 

The SAAM (Simulation, Analysis And Modeling) computer program developed by Berman and Weiss (8) was used to analyze the isotope dilution and balance data. The observed time dependent dilution of both calcium tracers in plasma, as reflected in urine at longer times, coupled with their cumulative appearance in urine and feces is used to calculate kinetic parameters of the model. The balance data are then used to calculate the steady state... 

Harrison, W. G., and Harris, L. R. (1986). Isotope-dilution and its effects on measurements of nitrogen and phosphorus uptake by oceanic microplankton. Mar. Ecol. Prog. Ser. 27, 253—261. 

DeLaune, R. D., Lindau, C. W., Srdaeman, E., and ugsujinda, A. (1998). Nitrification and denitrification estimates in a Louisana swamp forest soil as assessed by N isotope dilutions and direct gaseous measurements. Water Air Soil Pollut. 106, 149—161. 

The most common method of determining the U-Pb date of an accessory mineral is the determination of uranium and lead isotopic abundances via isotope dilution and thermal ionization mass spectrometry (ID-TIMS). Most measurements in the 1970s and 1980s required that an aliquot of the dissolved mineral solution be made, with one portion being spiked with an enriched U and ° Pb tracer solution, and the... 

It is apparent that, for the majority of studies undertaken with stable isotopes, ion monitoring GC-MS affords the best compromise solution in the inter-relationship between accuracy, isotope dilution and sample size. A degree of structural information and specificity in terms of isotope location in the molecule is also retained as several fragment ions may be monitored in each analysis. 

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