Gold nanoparticles bridging infra-red spectroscopy and laser desorption/ionization mass spectrometry for direct analysis of over-the-counter drug and botanical medicines

Anal Chim Acta. 2016 May 5;919:62-69. doi: 10.1016/j.aca.2016.03.023. Epub 2016 Mar 19.


With a coating of gold nanoparticles (AuNPs), over-the-counter (OTC) drugs and Chinese herbal medicine granules in KBr pellets could be analyzed by Fourier Transform Infra-red (FT-IR) spectroscopy and Surface-assisted Laser Desorption/Ionization mass spectrometry (SALDI-MS). FT-IR spectroscopy allows fast detection of major active ingredient (e.g., acetaminophen) in OTC drugs in KBr pellets. Upon coating a thin layer of AuNPs on the KBr pellet, minor active ingredients (e.g., noscapine and loratadine) in OTC drugs, which were not revealed by FT-IR, could be detected unambiguously using AuNPs-assisted LDI-MS. Moreover, phytochemical markers of Coptidis Rhizoma (i.e. berberine, palmatine and coptisine) could be quantified in the concentrated Chinese medicine (CCM) granules by the SALDI-MS using standard addition method. The quantitative results matched with those determined by high-performance liquid chromatography with ultraviolet detection. Being strongly absorbing in UV yet transparent to IR, AuNPs successfully bridged FT-IR and SALDI-MS for direct analysis of active ingredients in the same solid sample. FT-IR allowed the fast analysis of major active ingredient in drugs, while SALDI-MS allowed the detection of minor active ingredient in the presence of excipient, and also quantitation of phytochemicals in herbal granules.

Keywords: Botanical medicines; Drug; Gold nanoparticles; Infra-red spectroscopy; Laser desorption/ionization; Mass spectrometry.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Drugs, Chinese Herbal / analysis*
  • Gold / chemistry*
  • Medicine, Chinese Traditional*
  • Metal Nanoparticles / chemistry*
  • Molecular Structure
  • Nonprescription Drugs / analysis*
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization*
  • Spectroscopy, Fourier Transform Infrared


  • Drugs, Chinese Herbal
  • Nonprescription Drugs
  • Gold