Stable Isotope Dilution Assays

Semmelroch, P., Laskawy, G., Blank, I., Grosch, W., Determination of potent odorants in roasted coffee by stable isotope dilution assays, Flavour Fragrance J. 10(1), 1, 1995. 

Majcenovic, A. B., Schneider, R., Lepoutre, J.-P., Lempereur, V., and Baumes, R. (2002). Synthesis and stable isotope dilution assay of ethanethiol and diethyl disulfide in wine using solid phase microextraction. Effect of aging on their levels in wine. /. Agric. Food Ghem. 50, 6653-6658. 

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. 

As discussed in [1], precise quantitative results will be obtained when a stable isotope dilution assay (SIDA) is performed. In this procedure, stable isoto-pomers of the analytes are used as internal standards. Consequently, the major effort in the development of SIDA is the synthesis of the labelled standards since most of them are not commercially available. 

Schor DS, Struys EA, Hogema BM, Gibson KM, Jakobs C (2001) Development of a stable-isotope dilution assay for gamma-aminobutyric acid (GABA) transaminase in isolated leukocytes and evidence that GABA and beta-alanine transaminases are identical. Clin Chem 47 525-531... 

Aubry, V., Etievant, P.X., Ginies, C., and Henry, R. 1997. Quantitative determination of potent flavor compounds in Burgundy pinot noir wines using a stable isotope dilution assay. J. Agric. FoodChem. 45 2120-2123. 

Blank, I., Schieberle, P., and Grosch, W. 1993. Quantification of the flavour compounds 3-hy-droxy-4,5-dimethyl-2(5H)-furanone and 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone by stable isotope dilution assay. In Progress in Flavour and Precursor Studies (P. Schreier and P. Winterhalter, eds.). Allured Publishing, Wheaton, 111. 

H., and Schreier, P. 1996. Quantitative analysis of 2-aminoacetophenone in off-flavored wines by stable isotope dilution assay. JAOAC (J. Assoc. Off. Anal. Chem.) Int. 79 583-586. 

Fay, L.B., Metairon, S., and Blank, I. 2000. Stable isotope dilution assay mass spectometry in flavour research Internal standard and calibration issues. In Frontiers of Flavour Science (P. Schieberle and K.-H. Engel, Eds.) Deutsche For-schungsanstalt ftlr Lebensmittelchemie, Garching, Germany. 

Guth, H. and Grosch, W. 1990. Deterioration of soya-bean oil Quantification of primary flavour compounds using a stable isotope dilution assay. Lebensm.-Wiss. Technol. 23 513-522. 

Pfnuer, P., Matsui, T., Grosch, W., Guth, H., Hofmann, T., and Schieberle, P. 1999. Development of a stable isotope dilution assay for the quantification of 5-methyl-(E)-2-hepten-4-one Application to hazelnut oils and hazelnuts. J. Agric. Food Chem. 47 2044-2047. 

Schieberle, P. 1995b. Quantification of important roast-smelling odorants in popcorn by stable isotope dilution assays and model studies on flavor formation during popping. J. Agric. Food Chem. 43 2442-2448. 

The measurement of odor intensity using OAVs is described by Grosch (1993, 1994). It requires the determination of the concentration of each odorant in the sample, and for those present in trace quantities, a stable isotope dilution assay must be used (Guth, 1997). This may make the determination of OAVs very tedious if many values are required. OS Vs are normalized peak areas from an odor chromatogram and represent a more realistic representation of the importance of the odors in a sample as perceived by the nose. Their determination is described by Acree (1997). 

Concentration of odorants in sample being analyzed, determined by use of internal standards, GC-MS in selected ion monitoring (SIM) mode or a stable isotope dilution assay for trace quantities (see unitgu). 

Important food odorants, for which a quantification by a stable isotope dilution assay has been developed ... 

In the meantime, stable isotope dilution assays have been developed for nearly 60 important food odorants (Table 8). The OAV concept has been applied to characterize the... 

The caramel-like smelling HDF has been established as a main contributor to the flavors of several processed foods (Table 17). In addition, it should be noted that in all these foods, on the basis of a high FD-factor, HDF was also by far the most important caramel-like smelling odorant. In the following, the strategy in the HDF precursor analysis will be shown using wheat bread crust, popcorn [88] and malt as the examples. Quantitative measurements were performed by using a stable isotope dilution assay (cf. Section 3.2.). 

Kotseridis, Y., Baumes, R.L. Skouroumounis, G. (1999). Quantitative determination of free and hydrolytically liberated [J-damascenone in red grapes and wines using a stable isotope dilution assay. J. Chromatog., 849, 245-254. 

Rayne, S., Eggers, N.J. (2007a). Quantitative determination of 4-ethylphenol and 4-ethyl-2-methoxyphenol in wines by a stable isotope dilution assay. J. Chromatogr. A, 1167, 195-201. 

A suitable tool for the quantitation of trace compounds in foods is a stable isotope dilution assay (IVA) 16, 17). Allen et al. (18) used the IVA for the quantification of two methoxypyrazines in red wines, Guth (77) quantified wine lactone in various red and white wines and Aubry et al. (7P) used the technique for the determination of four esters (ethyl dihydrocinnamate, ethyl cinnamate, methyl anthranilate and ethyl anthranilate) in Pinot Noir wines. 

M. Lindenmeier, P. Schieberle, M. Rychlik, Quantification of OTA in foods by a stable isotope dilution assay using LC-MS-MS, J. Chromatogr. A, 1023 (2004) 57. 

Schneider, R., Kotseridis, Y., Ray, J., Augier, C. and Baumes, R. (2003) Quantitative determination of sulfur-containing wine odorants at sub parts per billion levels. Development and application of a stable isotope dilution assay, J. Agric. Food Chem., 51(11), 3243-3248. 

A stable isotope dilution assay using mass spectrometry to measure insulin, proinsulin, and C-peptide has been developed. The difference in mass among the three analytes allows specific measurement of each protein. Comparison of patient samples revealed that most, but not all, results were higher by immunoassay than mass spectrometry. Thus immunoassays may overestimate insulin, particularly at low concentrations. The high protein concentration in the serum requires extraction of proteins (e.g., by immunoaffinity) and purification by high-performance liquid chromatography (HPLC) before quantification by mass spectrometry. This method is not suitable for routine laboratory analysis. 

There are no convenient or reliable functional tests of pantothenic acid status, thus assessment is made by direct measurement of whole blood or urine pantothenic acid concentrations. Urine measurements are perhaps the easiest to conduct and interpret, and concentrations are closely related to dietary intake, Whole blood measurements are preferred to plasma, which contains only free pantothenic acid and is insensitive to changes in pantothenic acid intake. Concentrations of pantothenic acid in aU of the above fluids can be measured by microbiological assay, most commonly using Lactobacillus plantarum. Whole blood must first be treated with an enzyme preparation to release pantothenic acid fi om CoA. Other techniques that have been used to measure pantothenic acid in human samples include radioimmunoassay and gas chromatography, Other techniques that have been developed include gas chromatography-mass spectrometry and a stable isotope dilution assay. CoA and AGP can be measured by enzymatic methods. ... 

Rychlik M. Quantification of free and bound pantothenic acid in foods and blood plasma by a stable isotope dilution assay. J Agric Food Chem 2000 48 1175-81. 

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