Absolute Quantification of Gold Nanoparticles with Femtomolar Accuracy Using Inductively Coupled Plasma Atomic Emission Spectroscopy

Here we describe a label-free method for the detection and absolute quantification of gold nanoparticles (AuNPs). Inductively coupled plasma atomic emission spectroscopy (ICP-AES) is used to detect less than a nanogram of AuNPs from complex unpurified biological samples. This corresponds to approximately femtomolar concentration range of AuNPs. ICP-AES is a nonoptical analytical technique which is unaffected by optically active molecules, opaque solutions, and organic or inorganic contaminants. It is therefore superior to traditional methods of detecting AuNPs based on the distinctive extinction peak in the visible spectrum. This method is compatible with high-throughput automated applications in life science and environmental research.