1. A method for detecting an analyte, wherein the analyte is labelled with one or more labels relatable to the analyte which are suitable for optical detection, which method comprises: (a) applying an oscillating voltage having a first frequency across the labelled analyte and simultaneously performing an optical detection method on the labelled analyte to obtain data from the one or more labels; (b) applying an oscillating voltage having a second frequency across the labelled analyte and simultaneously performing an optical detection method on the labelled analyte to obtain data from the one or more labels; and (c) determining the identity and/or quantity of the analyte from the data obtained in step (a) and step (b).