Toc

Overall design and characterizations. a Schematic diagrams of the experimental workflow. b Size distribution of SiO2 and SiO2@Ag particles by DLS. c UV-Vis absorption spectra of SiO2 and SiO2@Ag particles. d SEM, and e TEM images of SiO2@Ag. f Elemental mappings of SiO2@Ag (red for Ag and yellow for Si). g SAED pattern and HR-TEM (inset of g) showing the silver crystal lattice

MALDI MS analysis. a Mass spectrum of 50 ng μL-1 lactose in a 5 mg mL-1 bovine serum albumin solution containing 0.5 M NaCl. b Mass spectrum of 6.25 nL of breast milk sample with 80-fold dilution. Tandem mass spectra of sodium adducted lactose at an m/z of 365.11 for [M+Na]+ in c standard sample, and d breast milk. Tandem mass spectra of silver adducted lactose at an m/z of 449.03 for [M+107Ag]+ in e standard sample, and f breast milk

Quantitation of small nutrients. a Representative mass spectrum of lactose with its isotope as the internal standard (IS). b The calibration curve obtained by plotting the experimental ratio of analyte/isotope (A/I) for sodium adducts as a function of the expected ratio of A/I for lactose. c Comparison of results obtained by the plasmonic MS and biochemical method for 20 breast milk samples. d Linear correlation of the quantification results from the plasmonic MS and biochemical method

Detection of toxins. a Plasmonic MS analysis of melamine prepared in a concentration gradient. Plasmonic MS analysis of raw milk samples spiked with melamine at a concentration of 0.5 ng μL-1, showing b an m/z range from 200 to 450, c an m/z range from 232 to 236, and d the tandem mass spectrum of melamine at an m/z of 232.96 for [M+107Ag]+