Normalized area percent analysis

Use Normalized Area Percent analysis for impurities and related substances testing. Index the area % to the parent drug (where parent = 100%). Apply a correction for relative response factors (RRF) if those are known. 

The aromatic hydrocarbon content of diesel fuel affects the cetane number and exhaust emissions. One test method (ASTM D-5186) is applicable to diesel fuel and is unaffected by fuel coloration. Aromatics concentration in the range 1-75 mass% and polynuclear aromatic hydrocarbons in the range 0.5-50 mass% can be determined by this test method. In the method, a small aliquot of the fuel sample is injected onto a packed silica adsorption column and eluted with supercritical carbon dioxide mobile phase. Mono- and polynuclear aromatics in the sample are separated from nonaromatics and detected with a flame ionization detector. The detector response to hydrocarbons is recorded throughout the analysis time. The chromatographic areas corresponding to the mononuclear aromatic constituents, polynuclear aromatic constituents, and nonaromatic constituents are determined, and the mass-percent content of each of these groups is calculated by area normalization. 

Normally the first two bars on the graph will cover very close to 80 percent of the issues plotted. This means that the first two problems will eliminate 80 percent of the issues when they get fixed or corrected. The value of a Pareto analysis is that it has the capability to help direct priorities to the most important areas first. Without this tool it is easy to get preconceived ideas of what the major problems are and go ahead and fix those while they may not be the big problems. This tool helps to create a focus on the correct problems to be resolving. 

Because only electrons from the top few atomic layers will have sufficient energy to escape, the technique is very surface specific and results are normally obtained from between 5 and 10 nm depth at a detection limit of around 0.1 atom percent. The analysis area is typically 3-10 mm and all the elements with the only exception of hydrogen can be detected. 

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