Maintenance of Soft Calibration Models in the Determination of Zinc, Cadmium, Lead and Copper by Differential Pulse Anodic Stripping Voltammetry

Abstract

A strategy for constructing a global multivariate calibration model that includes calibration samples measured over time on different days is developed and applied in electroanalysis. Both synthetic and real samples (tap, extracted and river water) are analyzed by differential-pulse anodic stripping voltammetry, showing the suitability of the global model constructed that provides successful results similar to those of the usual multivariate calibration. In addition the capability of discrimination of this model is evaluated in prediction for the mean of three replicates with estimation of probability of false noncompliance, a, and false compliance, b, being found 3.1, 11.2, 6.7 and 64.7 nM for nominal concentrations of zinc, cadmium, lead and copper of 96.0, 40.4, 37.3 and 328.0 nM respectively when a b 0.05. It has been proven that the use of the global calibration does not imply a loss of multivariate analytical sensitivity, using this parameter as quality index of the analytical procedure. The viability of using calibration maintenance strategies with electroanalytical techniques is shown, providing a way to save time and experimental effort when these techniques are used in routine analysis.

Performance characteristics according to Commission Decision 2002/657/EC in the fluorimetric determination of tetracycline in the absence and in the presence of magnesium

“…Some of these sets were joined to give sets that included inter-day variability, called joint sets. This procedure gives more robust calibrations (34)(35)(36). For the determination of tetracycline in the absence of Mg 2+ , three independent calibration sets (A, B and C) were measured.…”