Isotopic analyses quadrupole

Becker JS, Dietze H-J, McClean JA, Montaser A (1999) Ultratrace and isotope analysis of long-hved radionuclides by inductively coupled plasma quadrupole mass spectrometry using a direct injection high efficiency nebulizer. Anal Chem 71 3077-3984... 

The ICP/MS is an elemental and isotopic analysis method that was first developed in the early 1980s. The ICP had been used only as a source for emission spectroscopy until it was adapted for producing ions for a mass analyzer (Douglas and French, 1981 Houk et al., 1980 Houk et al., 1981 Houk and Thompson, 1982). Since 1983, several manufacturers have sold ICP/MS instruments that incorporate various mass analyzer systems, such as quadrupole mass filter, magnetic sector field, time-of-flight, Paul ion trap, and ion detection systems such as the electron... 

At the heart of the TIMS ion source are one or more hot filaments that serve to vaporize and ionize atoms or molecules of interest. Once generated, the ions are accelerated, focused, and directed into the mass analyzer for measurement. The classic TIMS instrument consists of an ion source, a single magnetic sector mass separator, and an ion detector. Such an instrument is capable of measuring isotope ratios as small as 1 x 10 6, sufficient for the isotopic analysis of most elements. For radionuclide analysis, smaller isotope ratios are often encountered. Specialized mass spectrometers include multiple magnetic and electric sectors and sector instruments with retarding quadrupole lenses (Smith, 2000) to measure down to the 10-9 range. 

Kylander, M.E., Weiss, D.J., Jeffries, T.E., Kober, B., Dolgopolova, A., Garcia-Sanchez, R., Coles, B.J. (2007) A rapid and reliable method for Pb isotopic analysis of peat and lichens by laser ablation-quadrupole-induc-tively coupled plasma-mass spectrometry for biomonitoring and sample screening. Analytica Chimica Acta, 582,116-124. 

Although the conclusions of this study are sound, it is also dear that it is a pioneering work in the field. From an analytical point of view, the predsion [better than 1% relative standard deviation (RSD)] and accuracy (better than 2% deviation) reported for Pb isotopic analysis are rather poor and would hardly be acceptable nowadays. In part, this is due to the sequential nature of the process of detection and quantification of ions when quadrupole-based ICP-MS is deployed. Still, it is possible to improve these results with an updated data acquisition methodology and a better correction for instrumental mass bias, as is discussed later. 

Subsequent work proved this point, while also profiting from new instrumental developments. For instance, Ulrich et al. [4] compared the performances of quadrupole-based ICP-MS and sector field (SF)-ICP-MS for the isotopic analysis of Pb in the context of two real crime scene investigations. They concluded that the latter showed better performance in terms of precision. This aspect is well known and is due to the fiat-topped (trapezoidal) peaks obtained at low mass resolution with a double-focusing SF mass spectrometer (see also Chapter 2). The authors also stressed that, although qualitative comparison of isotope ratios could be achieved without proper instrument calibration, it is better practice to measure absolute ratios by normalizing the measured raw ratios to an isotope ratio standard, preferably an isotopic reference material (IRM). 

Already in 1997, Augagneur et al. compared the performance of quadrupole-based ICP-MS with that of TIMS for Pb isotopic analysis of wine samples. They concluded that there was good agreement between the results provided by the two techniques, and reported a precision for quadrupole-based ICP-MS ranging between 0.1 and 0.3% RSD for ratios involving ° Pb, ° Pb, and ° Pb [38]. 

Barbaste et al. compared the performance of different types of instruments, including quadrupole-based ICP-MS, ICP-TOF-MS, and MC-ICP-MS for Pb isotopic analysis of wine [41]. They concluded that ICP-TOF-MS provides the worst sensitivity, as already mentioned in the previous section, an observation further aggravated by matrix suppression due to the presence of ethanol. Therefore, Pb separation from the matrix and preconcentration were necessary, steps that are also typical if the highest accuracy is aimed for when deploying MC-ICP-MS instrumentation. Under these conditions, ICP-TOF-MS provided a precision very similar to that offered by MC-ICP-MS, and significantly better than that realized by quadrupole-based ICP-MS quadrupole ICP-MS 0.14-2.7% RSD, ICP-TOF-MS 0.04-0.17% RSD, and MC-ICP-MS 0.01-0.12% RSD for ° Pb/ Pb and ° Pb/ Pb ratios. 

In a study entitled Nuclear archeology in a bottle, Schwantes et al. [41] utilized quadrupole-based ICP-MS to investigate the isotopic composition and age of a sample of several hundred milligrams of Pu excavated from a waste burial trench at Hanford (WA, USA) in 2004. Isotopic analysis of three independent parent-daughter pairs, " Pu- " Am, Pu- U, and °Pu- U, conducted on the... 

Diemer et al. [281] compared the performances of different types of ICP-MS instrumentation for copper isotopic analysis, namely a quadrupole-based... 

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