Standard

Description

external

= Default setting. Calibration is via one or several standard samples. Via the amount values entered in the Amount column, a ratio is established between the area and the amount. On this basis, the amount in samples of unknown concentration is determined via the peak area.

An increasing number of different amounts allows determining the area/amount ratio (=calibration curve) more exactly.

If different amounts are obtained by diluting the original substance, a Dilution Series is resulting. The amount of each concentration appears in a separate amount column in the corresponding line of the amount table.

If calibration is performed with a single standard sample by injecting different volumes (Var.InjectVol.), only the amount of the original sample is stored in an amount column. Chromeleon calculates the remaining amount values (for the different injection volumes).

internal/
external

Choose a substance as Internal Standard ("ISTD") whose retention time behavior is similar to the behavior of the substances to be analyzed. Before the sample is prepared, add exactly the same amount of internal standard to all samples (unknown and standard samples) so that its concentration is identical in all samples. For example, diluting the sample or performing a pre-column derivatization later will change the concentration of the internal standard. During calibration, the internal standard and the substances to be determined are calibrated.

internal

Instead of using absolute areas and amounts, area and amount ratios are used for calibration. This procedure requires that a constant amount of the Internal Standard ("ISTD") is injected, i.e., that the standard is added after sample preparation, but that, for example, it is not diluted in a dilution series (Const. Internal Standard). Due to the equivalent amount of added internal standard, the same ISTD result should be resulting for all samples. Forming the ratio of ISTD values allows you to draw conclusions about the precision of the analysis and to calculate the actual result.

Due to the intense experimental procedure, this type of calibration is rarely used in HPLC.