3. Sample preparation

Sample preparation is an essential step in any analytical process, particularly if high sensitivity is required. Correct sample preparation increases the sensitivity and selectivity of the method, and can help reduce matrix effects.

Before analysis begins, the seal (usually a hair envelope) is described (photographed, measured), then opened. The strand it contains is also described (color, length, weight...). It is then sewn onto paper in a straight line, with the root and tip indicated.