The limit of detection (LOD) was determined for three p-hydroxybenzoic acid esters at nine laboratories. The result of each laboratory was analyzed by computer software (called TOCO) which predicts the precision and LOD based on the baseline fluctuation without repeated measurements. In every laboratory, the shorter was the retention time of the analytes, the lower was the LOD. In each analyte, the peak-height measurement was more precise than the entire area measurement. The LOD obtained by the laboratories ranged from 0.16 to 30 μg/l. The validity of the TOCO, when applied in practical situations, has been proved.
