In analytical chemistry, sample preparation refers to the ways in which a sample is treated prior to its analysis. Preparation is a very important step in most analytical techniques, because the techniques are often not responsive to the analyte in its in-situ form, or the results are distorted by interfering species. Sample preparation may involve dissolution, reaction with some chemical species, pulverizing, treatment with a chelating agent (e.g. EDTA), masking, Filtering, dilution, sub-sampling or many other techniques.