With ICP emission spectrometry, many spectral lines are emitted for each element. The fact that spectral lines for samples containing several elements can overlap is well known as spectral interference. For this reason, it is necessary to use a spectrometer with a resolution over a certain level. Even then, spectral interference might be possible. This article describes a way to measure water samples using inductively coupled plasma–optical emission spectroscopy using a simultaneous instrument with a CCD detector and a software package that incorporates the knowledge of experienced analysts as a database, simplifying the selection and confirmation of wavelengths, to allow high precision and interference-free analytical results.