Quantitative Chromatographic Analysis - Data Processing from Quantitative Chromatographic Analysis

Data Processing

Chromatographic results were obtained originally by direct measurements taken from the chromatogram and involved the physical measurement of peak heights, retention distances, peak widths and, if integrators were available, peak areas. Despite the introduction of the computers, manual measurement is still carried out in some laboratories today where funds are limited or in university laboratories employing laboratory-made equipment. However, most contemporary chromatographs use computer data acquisition and data handling systems to automatically measure the chromatographic parameters, correct for response factors, calculate the results and prints out the analysis. The data is stored on disk that eliminates tedious book keeping and provides a high level of mathematical accuracy. Unfortunately, mathematical accuracy is the least important source of error in most chromatographic analysis. Nevertheless, if the peaks of interest are incompletely resolved, the protocol used for data processing needs to be known and its limitations understood.

Analytical Reports

The analysis report can be the simple entry of a date, a sample number and a percentage figure onto a standard printed form or it can take the form of a fifteen page report. The former could be a process control analysis, the latter a forensic or pollution report. In the former the procedure, the method of calculation and confidence levels would be firmly established and would not be reported on the form. However, in the latter analysis, the complete analytical details including the method, time and place of sampling and the accuracy and precision of the method would need to be reported. In cases where litigation is anticipated or in progress, every pertinent detail must be included and the preparation of the report may require the aid of an attorney. Most analytical reports will be similar to that of process control but between the two extremes, the analytical details that should be included will vary significantly from one type of report to another. An analytical report is designed to inform and not confuse or impress and thus pertinent information should be presented clearly and precisely. In addition, the report should be written using terms such that those unfamiliar with chromatography will still understand the significance of the results. To quote.

"Those who really understand, can speak in terms that everyone can comprehend".