Quantification, isotope dilution

McCann MT, Thompson MM, Gueron IC et al. (1996) Methyl malonic acid quantification by stable isotope dilution gas chromatography-mass spectrometry from filter paper urine samples. Clin Chem 42 9io-9i4. 

The development of new fiber coatings in the near future should further improve the specificity of SPME and overcome some of the observed matrix effects. Quantification by stable isotope dilution gas chromatography/mass spectrometry (GC/MS) may assist in improving analytical performance. Along with the possible application of micro LC and capillary LC columns to in-tube SPME, the development of novel derivatization methods and the potential for the analysis of fumigant pesticides, SPME appears to be a technique with a future in the analysis of pesticide residues in food. 

Crowley, J.R., Yarasheski, K., Leeuwenburgh, C., Turk, J., and Heinecke, J.W., Isotope dilution mass spectrometric quantification of 3-nitrotyrosine in proteins and tissues is facilitated by reduction to 3-aminotyrosine, Anal. Biochem., 259, 127, 1998. 

The main advantages of plasma-source mass spectrometry (PS-MS) over other analytical techniques, such as PS-AES and ETAAS, are the possibilities of quantitative isotope determination and isotope dilution analysis the rapid spectral scanning capability of the mass spectrometer and semiquantitative determinations to within a factor of two or three. Several labelling methods are used for the quantification of analytes present in complex mixtures. In these methods, the sample is spiked... 

Chao M. et al., 2005. Rapid and sensitive quantification of urinary N7-mthelguanine by isotope-dilution liquid chromatography/electrospray ionization tandem mass spectrometry with online solid-phase extraction. Rapid Commun Mass Spectrom 19 2427. 

Quantification is usually achieved by a standard addition method, use of labeled internal standards, and/or external calibration curves. In order to allow for matrix interferences the most reliable method for a correct quantitation of the analytes is the isotope dilution method, which takes into account intrinsic matrix responses, using a deuterated internal standard or carbon-13-labeled internal standard with the same chemistry as the pesticide being analyzed (i.e., d-5 atrazine for atrazine analysis). Quality analytical parameters are usually achieved by participation in interlaboratory exercises and/or the analysis of certified reference materials [21]. 

TI is a very precise and accurate method in stable isotope ratio measurements and quantification of inorganic elements, for example, by isotope dilution mass spectrometry [8]. Because TI is a continuous ion source, it could be coupled to any analyzer that is suitable for such sources. However, because the strength of TI lies in the quantitative precision and accuracy, sector analyzers are preferred to ensure maximum quality. 

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

This demonstration is intended to show how quantification is achieved using isotope dilution principles in mass spectrometry (Fig. 14.5). It also shows the issue of error in clinical measurements, such as precision accuracy and the use of relative relationships of one compound to another. 

In normal RIA-procedures the labelled drug or metabolite not only serves as the tracer for recovery but also for RIA quantification. However, the isotope dilution method categorically makes a clear separation of the drug and its metabolites. Consequently, a non-specific antiserum is employed to actually quantify the total amount of both unlabelled and labelled substance present. 

Fig. 12.4. RICs and TIC of an LC-ESI-MS quantification of a drug (M) and its metabolite (M ) by isotope dilution. The numbers on the give the absolute intensity value for each trace. Reproduced from Ref. [25] by permission. Elsevier Science, 2001.

Grace, P.B., Taylor, J.I., Bolting, N.P., et al. (2003). Quantification of isoflavones and lignans in serum using isotope dilution liquid chromatography/tandem mass spectrometry. Rapid Commun. Mass Spectrom., 17, 1350-1357. 

Polatajko, A., Encinar, J. R., Schaumloffel, D., and Szpunar, J., Quantification of a selenium-containing protein in yeast extract via an accurate determination of a tryptic peptide by species-specific isotope dilution capillary HPLC-ICP MS, Chemia Analityczna 50(1), 265-278, 2005. 

Freisleben, A., Sehieberle, P, Ryehlik, M. (2003 May). Specific and sensitive quantification of folate vitamers in foods by stable isotope dilution assays using high-performance liquid chromatography-tandem mass speetrometry. Anal. Bioanal. Chem., 376 2), 149-156. 

ID-TIMS 0.000 005-0.1 by isotope dilution + + +/ + + excellent quantification possibility, highest precision no multi-element capability, time consuming sample preparation... 

Trace impurities in noble metal nanoclusters, used for the fabrication of highly oriented arrays on crystalline bacterial surface layers on a substrate for future nanoelectronic applications, can influence the material properties.25 Reliable and sensitive analytical methods are required for fast multi-element determination of trace contaminants in small amounts of high purity platinum or palladium nanoclusters, because the physical, electrical and chemical properties of nanoelectronic arrays (thin layered systems or bulk) can be influenced by impurities due to contamination during device production25 The results of impurities in platinum or palladium nanoclusters measured directly by LA-ICP-MS are compared in Figure 9.5. As a quantification procedure, the isotope dilution technique in solution based calibration was developed as discussed in Chapter 6. 

V.V-dicthyl-V -bcnzoy I thiourea (DEBT). The palladium complex formed was eluted with methanol and introduced into an ICP-SFMS via microconcentric nebulization with membrane desolvation. Isotope dilution analysis was employed for quantification purposes.80... 

Isotope dilution techniques T racer experiments Quantification of analytical data Process control - any material e.g., iodine determination u using... 

Volatiles (GC-FID) Alternate Protocol Quantification of Aroma Compounds by Isotope Dilution Gl.3.1... 

QUANTIFICATION OF AROMA COMPOUNDS BY ISOTOPE DILUTION ASSAY (IDA)... 

Quantification of aroma compounds by isotope dilution assays... 

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