TTU GeoAnalytical Laboratory
Instrumentation & Overview| Analytical Techniques | Technique Notes
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Analytical Techniques and Sample Preparation
Whole rock glasses for LA-ICP-MS analysis
Glass discs by fusion with a Claisse Fluxer M4 are prepared for analyze in the TTU GeoAnalytical sample prep lab. [click here for detailed procedures]
Minerals in a polished thin section for LA-ICP-MS
Polished thin sections (27x48 mm) can be analyzed with or without carbon coating. Contact lab personnel about analyzing non-standard sized thin sections. It is recommended that photomicrograph and backscatter x-ray images are obtained before analysis and included with the sample submission. Coordinated markings on an image, the thin section (circles with a fine-point sharpie are best) and a spot location map assist in the mineral analysis. Our laser system has the ability to create maps however this does take time away from the actual analysis.
For data reduction, the SiO2 or CaO content of each mineral to be analyzed must be known. The oxide value is usually determined previously by electron-microprobe analysis of the actual mineral.
Backscatter x-ray images and electron-microprobe analysis can be preformed at University of Wyoming (http://mcl.gg.uwyo.edu/).
Analysis of Aqueous Solutions by ICP-AES and/or ICP-MS
Minimum sample size is a 10ml solution. Consultation with GeoAnalytical lab personnel will assist in determining the best analytical method.
Digestion for ICP-AES and ICP-MS
Microwave digestion of soil and biological samples following EPA procedure 3051 can be preformed in the metals laboratory at The Institution of Environmental and Human Health (link), Texas Tech University. Consult with GeoAnalytical lab personnel for this service. [click here for EPA procedure 3051]
Whole rock / soil sample fusions for ICP-AES
Whole rock fusion requires 1-2 g of sample powder be sent to the GeoAnalytical lab. Sample powder is mixed with LiBO2 in graphite crucible, melt into a molten bead, and then dissolved in a ~5% HCl solution. This solution is ready for trace element analysis and a portion is diluted for major element analysis. [click here for detailed whole rock/soil fusion procedure]
Loss on ignition procedure (LOI)
Loss on ignition requires a 4-5 g of sample powder. A sample is weighed into a dried porcelain crucible which is placed into a muffle furnace at 1000°C, dried for 20 min, then cooled and weighed. LOI is calculated from the wet and dry weights. [click here for detailed LOI procedure]
Iron Titration Procedure for ferrous iron analysis
The Fe titration method requires 2-3 g of sample powder. Ferrous Fe is analyzed by an iron titration ammonium meta-vanadate method. Sample powder is weighed, dissolved overnight, and titrated. Ferrous iron content is calculated using the sample weight and volume of titration solutions. [click here for detailed Fe titration procedure]