PEAXACT Tour Part 1 - Getting Started

This is part 1 of a tour through PEAXACT - Sotware for Quantitative Spectroscopy from S-PACT. It explains the concept of models and data sets, introduces the main window, and demonstrates the interactive what-you-see-is-what-you-get model editor.

Models and Data Sets

PEAXACT is an interactive Windows App for the quantitative analysis of UV/VIS/IR/Raman/NMR spectra. Its central element is a model. You create, edit, and calibrate models, and then apply models to analyze measured samples. A PEAXACT model contains four sub-models: Data Pretreatment Model, Integration Model, Hard Model, and Calibration Model.

The Data Pretreatment Model provides settings for the manipulation of a sample's signal; the Integration Model specifies ranges for peak integration; the Hard Model is a parametric representation of spectra used by Indirect Hard Modeling and Hard Modeling Factor Analysis; the Calibration Model quantitatively converts the spectral signal into features of interest, e.g. concentrations.

The second-most important elements of PEAXACT are data sets. A data set consists of a measured sample and features known about it, e.g. concentrations, temperature, measurement time, ... Data sets are used for data visualization, model building, and of course, for analysis.

The PEAXACT Desktop

The main window is called the Desktop. Here you manage your models, create and edit new models, and conduct analyses to squeeze information out of your spectra.

  • The Model Tree Panel (top-left) displays models as trees. Use it to navigate through the model strcuture.
  • The Data Sets Panel (bottom-left) holds a list of loaded data sets.
  • The Properties Panel (top-right) displays model parameters and lets you edit them.
  • The Plot Panel (bottom-right) displays the selected model and spectrum and offers a way to interactively edit the model with the mouse.

What you see is what you get

A nice concept of PEAXACT is its what-you-see-is-what-you-get editor. For instance, if you make changes to the Pretreatment Model you immediately see the effect on the selected spectrum. And if you drag an integration range with the mouse, you immediately see how the peak area gets re-calculated. You will learn more about Integration Models in a later part.

You can even interactively build and modify peak models - so called Hard Models - to deconvolve complex overlapping signals. You will learn more about Hard Models in a later part.

Many of the modeling steps are also automated, but just being able to see how a model fits your spectra is a great way to learn more about the measured system. It also makes modeling with PEAXACT a pleasant experience.

Part 2: Organizing Data

 

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