Deuterium-labelled internal standard

Analytical accuracy. The mixture of all deuterium-labeled internal standards is added to each water sample before extraction. This does not prevent the loss of the unlabeled herbicides from the sample in subsequent processing steps, but a proportional loss of the deuterated internal standard precludes the need to correct for recovery. Although referring to recovery in this type of analysis is inappropriate, the accuracy of this method should be monitored. 

Despite the very desirable performances of SIL internal standards, they are not always available or are very expensive, especially when seeking exclusively non-deuterium-labeled internal standards. Then, structural analogues can be used. In this case, coelution of an analyte and its internal standard is preferred in order to reduce matrix effect [11] or to expand linearity range [12],... 

O Halloran S, Ilett KF (2008) Evaluation of a deuterium-labeled internal standard for the measurement of sirolimus by high-throughput HPLC electrospray ionization tandem mass spectrometry. Clin Chem 54 1386-1389... 

Simultaneous Quantification of Cyclophosphamide and its Metabolites in Human Urine by Sample Dilution and High-Performance Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry, Using a Deuterium Labeled Internal Standard... 

Benazepril, benazeprilat, and the corresponding deuterium-labelled internal standards (I.S.) were supplied by Novartis (Basle, Switzerland). All the chemicals were of analytical grade. Hexane and toluene (Pestipur SDS) were obtained from Solvants Documentation Synthese (Pepin, France). Methyl tert. -butyl ether and 2 mol/L trimethylsilyldiazomethane solution in hexane were purchased from Fluka (Saint-Quentin Fallavier, France). Hydrochloric acid (0.1 mol/L),... 

In order to study the metabolism of arachidonic acid by the cytochrome P450 complex, Nithipatikom et al. [38] developed a negative-ion LC-ESI-MS method for the quantitative determination of 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids (EET), their corresponding diHET, and 20-HETE. The analytes and their deuterium-labelled internal standards were measured as [M-H] in selected-ion monitoring (SIM) mode. The detection limit was 1 pg (2-mm-ID column). 

W.S. Powell, D. Boismenu, S.P. Khanapure, J. Rokach, Quantitative analysis of 5-oxo-6,8,II,I4-ETE by ESI-MS using a deuterium-labeled internal standard. Anal. Biochem., 295 (2001)262. 

Very few collaborative studies between accredited doping laboratories are available to determine their variances. As such determinations are rather complex, some of the experimental parameters are most of the time left uncontrolled. Great attention should be given to standardization of the methods. Matrix problems are known during calibration and best results can be obtained with the systematic use of good quality deuterium-labeled internal standards. The... 

Bortolomeazzi et al. (1994) used GC/EI/MS with an ion trap to identify the thermal oxidation products of cholesteryl acetate as the 7P-hydroperoxy and 7a-hydroperoxy cholesteryl acetate, 7keto-cholesteryl acetate, the a and P isomers of 7-hydroxycholesteryl acetate, the a- and P-5,6-epoxy isomers and several derivatives arising from the loss of acetate and water. Dzeletovic et al. (1995b) have observed that saponification during sample preparation did not hydrolyse all of the oxysterol esters completely and that separation of oxysterols from cholesterol by HPLC was tedious and incomplete. They developed a stable isotope dilution GC/EI/MS SIM method for the determination of cholesterol oxidation products in human plasma. Nine oxysterols were determined by using deuterium-labelled internal standards. 

Analysis of Salsolinol and Salsoline in Biological Samples Using Deuterium-Labeled Internal Standards and Gas Chromatography-Mass Spectrometry... 

Simultaneous Determination of 4-Hydroxy-3-methoxyphenylacetic Acid and 4-Hydroxy-3-methoxyman-delic Acid in Human Plasma by Mass Fragmentography Using Deuterium-labeled Internal Standards Ann. Pharm. Fr. 38(5) 439-446 (1980) CA 94 170438g... 

Deuterium labeled internal standards Total run time, including injection and equilibration time was 5.7 min LODs ranged between 0.0010 and 0.0026 pg mL ... 

Because of the challenges of extracting and analyzing THC and its metabolites, most methods incorporate deuterium-labeled internal standards. These compounds are chemically quite similar to THC and its metabolites and, therefore, extract, ionize, and can be detected with essential equivalent efficiency as the target analytes. Deuterated analogues such as THC-Dj and THC-COOH-Dj are commercially available and are especially recommended for quantification of the cannabinoids. 

Mononucleotides are less of a problem in mass spectrometric analyses and are often accessible by conventional EIMS or CIMS of volatile derivatives. Even with derivatization, the in beam technique of DCI was needed to detect (83) the cytokinin 9- 3-D-ribofuranosylzeatin-5 -phosphate (17) in a partially purified extract from Datura innoxia crown gall tissue and to quantify it using a deuterium-labelled internal standard (18). 

We will now use cheese, coffee, apple, a fabric softener, and soap by way of example to show that the use of isotope dilution analysis permits exact, trouble-free quantification of fragrance and flavor compounds in the ppm and ppb range. To this end, the deuterium-labeled internal standards (isotopomers) shown in Fig. 31 were synthesized. Given the scope of this chapter, we have intentionally omitted a discussion of the synthesis of labeled flavor compounds. 

Table 2 Chemical and Isotopic Purities, Ion Masses, Retention Times, and MS Response Factors of Analytes and Deuterium-Labeled Internal Standards...

Figure 40 El and PCI mass spectra of skatole along with mass traces of analyte and deuterium-labeled internal standard (m/z 132 and m/z 135).

---