“…The most widely used commercial substrate, Klarite™ (Renishaw Diagnostics Ltd., Glasgow, UK), has a gold‐coated surface consisting of a regular pattern of inverted square pyramid subunits (Perney et al., ). Klarite has been on the market for more than 10 years and applied for detection of melamine (He et al., ), TBHQ (Pan et al., ), pesticides such as phosmet and carbaryl (Fan et al., , ), and banned and restricted drugs including chloramphenicol (Li et al., ), sulfamerazine (Li et al., ), furazolidone (Zhang et al., ), crystal violet (Li et al., ), and malachite green (Zhang et al., ; Zhang et al., ) in various foods. For colorants including crystal violet and malachite green, as low as single‐digit ppb levels could be detected due to the additional molecule resonance or SERRS effect using this substrate; but for noncolorant compounds, the detectible minimum concentration is normally around 0.1 to 10 ppm.…”