Large-volume samples

Thorinm-232 is the only non-radiogenic thorium isotope of the U/Th decay series. Thorinm-232 enters the ocean by continental weathering and is mostly in the particulate form. Early measurements of Th were by alpha-spectrometry and required large volume samples ca. 1000 T). Not only did this make sample collection difficult, but the signal-to-noise ratio was often low and uncertain. With the development of a neutron activation analysis " and amass spectrometry method " the quality of the data greatly improved, and the required volume for mass spectrometry was reduced to less than a liter. Surface ocean waters typically have elevated concentrations of dissolved and particulate 17,3 7,62... 

Huang, H.Y. et al.. Analysis of food colorants by capillary electrophoresis with large-volume sample stacking, J. Chromatogr. A, 995, 29, 2003. 

He Y. and Lee H.K., Large-volume sample stacking in acidic buffer for analysis of small organic and inorganic anions by capillary electrophoresis, Anal. Chem. 71, 995, 1999. 

Various authors have described on-line LC-SFC coupling [947,948]. Coupling of LC to SFC with conventional-size LC columns, where only a small fraction of the peak of interest is transferred to the SFC, allows only for qualitative results, and does not address the need for improved sensitivity in cSFC. Cortes et al. [948] have described relatively large-volume sample introductions (>10 xL) into cSFC, using microcolumn LC in the first dimension. LVI-LC-cSFC provides enhanced sensitivity compared with conventional cSFC injection techniques. LC-cSFC is expected to be of utility in the characterisation of complex samples, and in the determination of components which are thermally labile do not contain significant chromophores or do not have sufficient volatility to be analysed by GC. 

Using nano LC-MS at submicroliter per minute flow rates requires special attention to plumbing, system dead volume, valve switching, large volume sample injection, precolumn methodology, automation, online sample clean-up, and multichannel parallel operation of a single MS. The techniques discussed below are particularly useful for nano LC-MS-MS applications. 

Light non-methane hydrocarbons (NMHCs) were measured using an automated GC-FID system with large volume sample collection onto a Peltier cooled carbon sieve trap followed by on-line thermal desorption, and separation on an aluminium oxide PLOT capillary column. The system deployed at Cape Grim has been described in more detail in a previous paper (Lewis et al., 2001). 

A great deal of discussion about elemental determination methods focuses on minor, trace, ultra-trace levels of analyte presence in relatively large volume samples. There is another area equally challenging and that involves elemental determination at major and minor concentration in very small volume/low mass samples. Lochmuller and Galbraith used PIXE to study the metal content of carbonic anhydrase... 

Chen, Y. R., Tseng, M. C., Chang, Y. Z., and Her, G. R. (2003). A low-flow CE/electrospray ionization MS interface for capillary zone electrophoresis, large-volume sample stacking, and micellar electroklnetlc chromatography. Anal. Chem. 75, 503 — 508. 

Source Adapted from K. Linker, Large-Volume Sampling and Preconcentration, 3rd Explosives Detection Technology Symposium and Aviation Security Technology Conference, Adan-tic City, NJ, USA, 26-27 November, 2001. 

There have been substantial changes in Raman sample interfaces recently. The approaches now can be divided broadly into two categories based on the sampling volume. The probes intended to sample small volnmes include the more traditional noncontact or standoff probes, immersion probes, and optical microscopes. Large volume sampling approaches are newer and include WAl and SORS probes and transmission confignrations. 

Besides the use of large volume samples, there are also other "brute force" approaches frequently used since the earlier reports of solid-state Mg NMR, including isotopic enrichment and the use of malefic fields as strong as possible.. 39.42,, 45-52 jg doubt that the increase in the... 

An Evaluation of the Preparation of Resin Samplers for Broad Spectrum Analysis of Large-Volume Samples... 

Low-volume sampling is typically used for quantitative analysis for specific compounds, such as pesticides, polychlorobiphenyls (PCBs), and organic acids. Large-volume sampling is used to simultaneously... 

Cleaning and blanking procedures, therefore, must be carefully evaluated to assure reliable results from broad spectrum analyses of large volumes of water. Many questions arise about the reliability of present methods because researchers have based large-volume sampling procedures on results from low-volume procedures. 

An alternative and relatively simple approach to the same analytical problem is to carry out the large volume sample extraction with a commercial SPE disk, e.g., Cl8 disk, and then elute the analyte from the Cl8 disk with a smaller volume of suitably selected solvent onto an MISPE column [39]. 

J. Staniewski, H.G. Janssen, C. A. Cramers and J. A. Rijks, Programmed-temperature injector for large-volume sample introduction in capillary gas chromatography and for liquid chromatography-gas chromatography interfacing , J. Microcolumn Sep. 4 331-338(1993). 

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