IDMS

Adams and Slack compared the electron densities and mobile bond orders of the parent molecule (21) with those of thiazole (22) and P50 idme (23). Overlap was neglected in these simplified calculations,... 

Reference methods are generally arrived at by consensus and fairly extensive testing by a number of laboratories. For example, the flame atomic absorption method for Ca in serum developed under the leadership of the agency fondly remembered as NBS, now NIST (Cali et al. 1972), was established after several inter-laboratory comparison exercises. The results were evaluated after each exercise and the procedure was changed as necessary. After five exercises, it was felt that the state-of-the-art had been reached, with the reference method being capable of measuring Ca in serum with an accuracy of 2% of the true value determined by IDMS (note that attainment of high accuracy and precision is not only a matter of the method, but is a function of both the method and analyst expertise). 

Conventional calibration MDRD equation [used only with those creatinine methods that have not been recalibrated to be traceable to isotope dilution mass spectrometry (IDMS)]... 

I DMS-Traceable MDRD Equation (Used Only with Creatinine Methods that Have Been Recalibrated to Be Traceable to IDMS)... 

Trace and ultratrace analysis SSMS, GD-MS, LA-ICP-MS, (IDMS) Chapter 8... 

Isotope analysis TIMS, ICP-MS, SIMS, (IDMS) Section 8.5.4... 

Isotope dilution mass spectrometry (IDMS) can be applied with most of the ionisation methods used in mass spectrometry to determine isotope ratios with greater or lesser accuracy. For calibration by means of isotope dilution, an exactly known amount of a spike solution, enriched in an isotope of the element(s) to be determined, is added to an exactly known amount of sample. After isotopic equilibration, the isotope ratio for the mixture is determined mass spectrometrically. The attraction of IDMS is its potential simplicity it relies only on the measurement of ratios. The... 

Applications The application of the isotope dilution technique is especially useful in carrying out precise and accurate micro and trace analyses. The most accurate results in mass spectrometry are obtained if the isotope dilution technique is applied (RSDs better than 1 % in trace analysis). Therefore, application of IDMS is especially recommended for calibration of other analytical data, and for certification of standard reference materials. The technique also finds application in the field of isotope geology, and is used in the nuclear industry for quantitative isotope analysis. 

ID-ICP-MS [425,426], Certified values for the 4 PE/Cd materials (VDA-001 to -004) with nominal Cd concentrations of 0.35 to 3.6mmolkg 1 were established by IDMS, using an enriched mCd spike [427]. The results did not show significant differences between bottles at the 300-mg level. For the sample with the highest Cd content (VDA-004 407 ppm) the measurement reproducibility was worse, which stands in relation to heterogeneity problems, as confirmed by GF-ZAAS results. 

HRLEELS plasma mass spectrometry High-resolution low-energy electron plasma-mass spectrometry (see TI-IDMS)... 

TI-IDMS Thermal ionisation-isotope dilution mass spectrometry (see ID-TIMS)... 

Isopropenylferrocene does not homopolymerize under free radical conditions using AIBN as an initiator, but it does copolymerize with styrene.Preliminary results indicate that the IDM monomer also copolymerizes with styrene using AIBN. In benzene solvent at 50°C in 24 h, a 10.6% yield of copolymer (IR vc=0 2020, 1945 cm , vN=0 1675 cm-- -, V q 1601 cm-- -, v 3020 cm-- -) resulted having an M f 5700 and containing 6.8% of IDM as determined by elemental analysis. The initial monomer mixture contained 17% of IDM. 

Blood and urine 206Pb addition and sample acid digestion lead coprecipitation by addition of Ba(N03)2, IDMS No data 98-99 Manton and Cook 1984... 

The isotopic distribution of lead (IDMS) in shed teeth from children has been shown to be useful in studies of the history of exposure to lead, including the definition of the source of the exposure, e.g., mine dust vs. food (Gulson and Wilson 1994), so IDMS certainly has important applicability, if not for routine determinations. ICP/MS, however, is easier, more sensitive, allows for multi-element analysis, and provides isotopic data. 

The primary methods of analyzing for lead in environmental samples are AAS, GFAAS, ASV, ICP/AES, and XRFS (Lima et al. 1995). Less commonly employed techniques include ICP/MS, gas chromato-graphy/photoionization detector (GC/PID), IDMS, DPASV, electron probe X-ray microanalysis (EPXMA), and laser microprobe mass analysis (LAMMA). The use of ICP/MS will become more routine in the future because of the sensitivity and specificity of the technique. ICP/MS is generally 3 orders of magnitude more sensitive than ICP/AES (Al-Rashdan et al. 1991). Chromatography (GC,... 

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