Data Quality

To maintain high data quality, instrument performance is routinely monitored using one or more secondary standards, typically at the beginning and end of each analytical session.

Concord's EPMA lab regularly participates in interlaboratory exercises. This includes G-probe (one or two test glasses per year) and the 2011 INTAV intercomparison of tephrochronology laboratories (Kuehn et al., 2011). These provide a source of ongoing external quality testing. 

The lab's results on such samples are routinely excellent in terms of both accuracy and precision. Below is an example from analysis of the INTAV reference glasses and two USGS glasses using the routine procedure for tephra glasses:

 

 

EPMA data table

EPMA Data table

G-probe website

Kuehn, S.C., Froese, D.G., and Shane, P.A.R., 2011, The INTAV intercomparison of electron-beam microanalysis of glass by tephrochronology laboratories, results and recommendations: Quaternary International. doi:10.1016/j.quaint.2011.08.022 Article online