Useful Concepts for Data Analysis

In analytical chemistry, and indeed electroanalysis, a calibration curve is produced so that analysts can determine how their system responds towards the target analyte under investigation. In-particular the calibration curve gives the electrochemist a benchmark of their electroanalytical system, such as a graphene modified electrode towards sensing analyte X. 

When constmcting a calibration plot, the approach should be repeated to obtain statistically meaningful data. Reporting the analytical performance based upon one cahbration plot is unprofessional and not realistic of the electroanalytical system being developed yet such practices still carry on within the hterature. Note that the approach above will determine the intra-electrochemical response since the same electrode is being used, where ideally the inter-electrochemical response should also be explored. Useful definitions are as follows. 

Brownson and C. E. Banks, The Handbook of Graphene Electrochemistry, DOI 10.1007/978-1 71-6428-9, Springer-Verlag London Ltd. 2014 

This is also known as repeatability i.e. the ability to repeat the same procedure with the same analyst, using the same reagent and equipment in a short interval of time, e.g. using the same electrode with measurements made within a day and obtaining similar results. 

The ability to repeat the same method under different conditions, e.g. change of analyst, reagent, or equipment or on subsequent occasions, e.g. change of electrode, measurements recorded over several weeks or months, this is covered by the between batch precision or reproducibility, also known as inter-assay precision. 

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Scanning electrochemical microscopy (SECM the same abbreviation is also used for the device, i.e., the microscope) is often compared (and sometimes confused) with scanning tunneling microscopy (STM), which was pioneered by Binning and Rohrer in the early 1980s [1]. While both techniques make use of a mobile conductive microprobe, their principles and capabilities are totally different. The most widely used SECM probes are micrometer-sized ampero-metric ultramicroelectrodes (UMEs), which were introduced by Wightman and co-workers 1980 [2]. They are suitable for quantitative electrochemical experiments, and the well-developed theory is available for data analysis. Several groups employed small and mobile electrochemical probes to make measurements within the diffusion layer [3], to examine and modify electrode surfaces [4, 5], However, the SECM technique, as we know it, only became possible after the introduction of the feedback concept [6, 7],... 

Data analysis for this series was performed using MathCad and the statistical methods used are described in greater detail in Youden s monograph [7] and in Mark and Workman [8], We use the MathCad worksheets both to illustrate how the theoretical concepts can be put to actual use and also to demonstrate how to perform the calculations we describe. The worksheets will be printed along with the chapters in which they are first used. At a later date we are planning to enable you to go to the Spectroscopy home page (http //www.spectroscopymag.com) and find them. If, and when, the actual URLs for the worksheets become available, we will let you know. 

An interesting recent development is the application of an electron-nuclear-dynamics code [68] to penetration phenomena [69]. The scheme is capable of treating multi-electron systems and may he particularly useful for low-velocity stopping in insulating media, where alternative treatments are essentially unavailable. However, conceptional problems in the data analysis need attention, such as separation of nuclear from electronic stopping and, in particular, the very definition of stopping force as discussed in Section 5.2. 

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