INTRODUCTION

Plasma-based instrumental techniques, which are useful for pharmaceutical analyses, fall into two major categories: those based on the inductively coupled plasma, and those where a plasma is generated at or near the surface of the sample. The inductively coupled plasma (ICP) is a high-temperature excitation source that desolvates, vaporizes, and atomizes aerosol samples and ionizes the resulting atoms. The excited analyte ions and atoms can then subsequently be detected by observing their emission lines, a method termed inductively coupled plasma–optical emission spectroscopy (ICP–OES; also referred to as inductively coupled plasma–atomic emission spectroscopy), or the excited or ground state ions can be determined by a technique known as inductively coupled plasma–mass spectrometry (ICP–MS). ICP–OES and ICP–MS may be used for either single- or multi-element analysis and used for either sequential or simultaneous analyses with good sensitivity over an extended linear range.