Packed hybrids of gold nanoparticles and layered double hydroxide nanosheets for microextraction of triazine herbicides from maize.

This work describes a nanohybrid material consisting of gold nanoparticles (AuNPs) and nanosheets of layered double hydroxides (NLDHs) of Mg(II) and Al(III). Mono-disperse AuNPs were immobilized on the surface of the LDHs via Au-O bonding. The nanohybrid sorbent was packed in an organic filter along with a syringe and applied to the microextraction of triazine herbicides with the help of an injection pump. The collected hexane eluate was concentrated and directly injected into a HPLC column for quantification. The effects of the amount of Au/LDH nanohydrobrids, type, flow rate, volume of washing and eluting solvent were optimized. The method was validated by detecting four triazine herbicides (prometryn, atrazine, terbumeton and secbumeton) in spiked maize. The limits of detection range between 35 and 108 pg g-1 . The relative standard deviations range from 1.0-6.9% for repeatability and 4.6-7.8% for reproducibility (for n = 5). Graphical abstract Schematic presentation of a nanohybrid material consisting of gold nanoparticles and nanosheets of layered double hydroxides of Mg(II) and Al(III) (Au/LDH) for use as an adsorbent for microextraction in a packed syringe. Organic filter heads were used as the container of Au/LDHs nanohybrids, and were connected with the syringes installed on the injection pump for the semi-automatic microextraction and preconcentration of triazines in maize.