Chemometrics computer programs

Once again, specific algorithms and computer programs have not been included. The wide range of mathematical software now available makes implementation relatively simple and the reader is encouraged to experiment and play with their data to appreciate and understand the techniques and treatments discussed. It is even more important now than at the time of publication of the first edition that analysts and spectroscopists have an understanding of the basics of chemometrics. 

A number of computer programs have been developed for chemometrics in order to serve the special needs of non-specialized users in chemistry. The most well known and widely distributed products today are PIROUETTE, SCAN, SIMCA, SIRIUS, and UNSCRAMBLER (alphabetically ordered, all run on personal computers under MSDOS/Windows). 

A mass spectral classifier is a part of a computer program that uses the peak list of a low resolution mass spectrum as input and produces information about the chemical structure as output. For such a classification procedure a number of methods are available in multivariate statistics. Many of them have already been applied to various problems in chemistry classification of mass spectra (with the aim of recognizing chemical compound classes) was one of the pioneering works in chemometrics. 

Chemometrics Computer-assisted data manipulation Expert systems and intelligent instruments Resolution improvement programs for chromatography to speed analyses Pattern recognition systems... 

Computation and practical use are further important concerns, and thus the R package chemometrics has been developed, including data sets used in this book as well as implementations of the methods described. Although some programming skills are required, the use of R has advantages because it is freeware and is continuously updated. Thus interested readers can go through the examples in this book and adapt the procedures to their own problems. Feedback is appreciated and it can lead to extension and improvement of the package. 

Advances in data manipulation and availability of mathematical, statistical, and chemometric analytical software programs have greatly assisted extraction of useful information from IR spectra. This area, in particular, has greatly benefited from the wide spread use of personal computers. 

Luke BT (1994) Evolutionary Programming Applied to the Development of Quantitative Structure-Activity Relationships and Quantitative Structure-Property Relationships. J Chem Inf Comput Sci 34 1279-1287 Massart DL, Vandeginste BGM, Buydens LMC, De Jong S, Lewi PJ, Smeyers-Verbeke J (1997) Handbook of Chemometrics and Qualimetrics Part A, Amsterdam, Chapter 26 pp 783-803... 

Using chemometrics in data processing further increases the quality and reliability of the analytical information. There are certain programs constructed for specific types of analytical methods. Data acquisition directly by the computer followed by data processing considerably decreases the uncertainty of the last main step in the analytical process (data processing). 

The demand on the computer system is increased if chemometric methods are to be used for data evaluation. Because these programs are often written for workstations running under VMS or UNIX, an open data format for the stored spectra is mandatory in these cases. 

Another chemometric technique that has been applied to GCxGC-MS data is PARAFAC2, which differs from PARAFAC in that one dimension need not be strictly trilinear [27,28]. This allows for analysis of data where there is shifting of peak profQes or changes in retention time in one separation dimension due to, for example, temperature programming, which affects the second-column retention times, or misalignment across samples [4,29]. PARAFAC2 can be used in most cases where PARAFAC is used, but is computationally more complex and expensive. 

We worked with the NIR spectrometer NIRVIS (Buchi Labortechnik AG, Switzerland). The spectrometer is interfaced to a computer for data acquisition. The software used for data acquisition, data preatreatment and chemometrics was the program NIRCAL (Biichi Labortechnik AG,... 

The rapid growth of chemometrics - the application of mathematical methods to the solution of chemical problems of all types - is due to the ease with which large quantities of data can be handled, and complex calculations done, with calculators and computers. These devices are available to the analytical chemist at several levels of complexity and cost. Hand-held calculators are extremely cheap, very reliable, and capable of performing many of the routine statistical calculations described in this book with a minimal number of keystrokes. Pre-programmed functions allow calculations of mean and standard deviation (see Chapter 2) and correlation and linear regression (see Chapter 5). Other calculators can be programmed by the user to... 

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