LA-TOF-ICP-MS

The purposes of this paper are to report on our efforts to evaluate the real world precision of laser ablation time of flight ICP-MS (LA-TOF-ICP-MS) replicate measurements on NIST standards and archaeological materials, and to... 

While we think we have arrived at the right combination of sample introduction and system and ion counting parameters, it remains an empirical challenge to produce reliable isotope measurements using LA-TOF-ICP-MS. Adjusting for an appropriate instrumental count rate is key to approaching... 

LA-TOF-ICP-MS may be a useful tool for distinguishing different sources of lead found in low-lead, alkaline-based and lead-based glazes from Mesopotamia. Even with the limitations of the present study, lead-isotope ratios determined by TOF-ICP-MS indicate that multiple ore sources were utilized by makers of Islamic lead-glazed pottery. With the further refinements of Dudgeon et al. (this volume), LA-TOF-ICP-MS promises to be a rapid, cost-effective approach to lead-isotope ratio analysis of glazed pottery. 

The following section focuses on the variability of the clay bodies or pastes of the glazed ceramics previously characterized by LA-ICP-MS and LA-TOF-ICP-MS. The purpose of this study is to compare the variation in the ceramic pastes with the different glaze decorative technologies through time. The variability in the ceramic pastes will be characterized through instrumental neutron activation analysis (INAA) and petrographic analysis. 

Glass beads from central California, lead isotope analysis by LA-TOF-ICP-MS, 305-307/... 

LA-TOF-ICP-MS can also be used for elemental-mapping applications that would be difficult or impossible to perform with quadrupole LA-ICP-MS. In one study [83], ceramics from the Sepik Coast of New Guinea at the Field Museum revealed some clear associations between find spot and chemical group. This study raised the possibility that diagenetic enrichment of barium may contribute to some of the apparent discrimination. In order to test this possibility, microscale mapping of elemental concentrations in Sepik Coast sherds was undertaken with LA-TOF-ICP-MS. The microprobe capabilities of the TOF allowed quantitative data to be obtained from spots less than lOO-pm diameter. Elements other than barium showed no trends across sherd cross sections. Similarly, in low barium, there were no trends in barium concentrations. High-barium sherds, however, showed enrichment near one or both surfaces. These observations are consistent with diagenetic enrichment of barium [83]. 

Some effort has also been focused on the determination of other isotope ratios, particularly St/ St with TOF-ICP-MS and LA-TOF-ICP-MS [104].These efforts have not, however, yielded precision and accuracy useful for the characterization of human tooth enamel for population movement studies. Part of the problem probably arises from interferences produced by the calcium phosphate matrix [106], but there also appears to be TOF detector-related fractionation akin to but more extreme than that observed for Pb/ Pb. 

Tables 8.57 and 8.61 compare the performance of GD-MS to other inorganic mass-spectrometry techniques, including LA-ICP-MS which acts as a strong competitor. GD and laser ablation techniques offer the possibility to obtain information about the distribution of analyte within the sample, but on quite a different scale. Pulsed GD requires ToF-MS [374].

Bings77 quantified 11 trace metals in lubricating oil with the aid of solution based calibration in LA-ICP-MS using a ToF mass spectrometer. It has been shown that good analytical performance in terms of precision (6 % on average) and low detection limits in the ng g-1 range can be obtained with this easy and fast quantification procedure in LA-ICP-MS.77... 

With LA-ICP-ToF-MS, using the 193 nm ArF laser (laser energy lOOmJ at 120(xm laser beam diameter), a depth resolution of 200 nm per laser shot was measured.121 LA-ICP-MS was utilized for depth profiling of copper coatings on steel with certified copper coating thicknesses from about... 

Another approach to selenized yeast is to characterize Se-containing proteins. The application of polyacrylamide gel electrophoresis (PAGE) has been proposed with the introduction of the protein spot to ICP-MS via LA or ET atomization [62, 93]. The feasibility of matrix-assisted laser desorption ionization (MALDI)D timeDof-Bight mass spectrometry (TOF-MS) prior to ES tandem MS as applied to tryptic protein digests has also been explored [135, 136]. 

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