Three-in-one via syringe needle-based device: sampling, microextraction and peroxidase-like catalysis for colorimetric detection of the change of biogenic amines levels with time in meat.

In this work, a syringe needle-based integrated method was designed for the detection of biogenic amines (BAs) in raw meat samples. Based on a sequential process, the needle-based sampling, micro liquid-phase extraction and peroxidase-like catalysis were adopted for the sample collection, target analytes extraction and colorimetric analysis, respectively. The proposed method exhibited high selectivity towards BAs (the total amount of histamine, putrescine and cadaverine was utilized to present the level of BAs), where the linear range is 5-50 μM and 50-1000 μM, and the limit of detection is 1.

Gold nanoprism/Tollens' reagent complex as plasmonic sensor in headspace single-drop microextraction for colorimetric detection of formaldehyde in food samples using smartphone readout.

In this work, an assay with high sensitivity and selectivity for the detection of formaldehyde (FA) is presented. The assay applied a gold nanoprism/Tollens' reagent (Au-np/TR) complex as the sensor used in headspace single-drop microextraction (HS-SDME). A surface plasmon resonance signal enhancement as well as color change was caused by the formation of Au@Ag-np after a redox reaction between FA and TR during the HS-SDME process.

Smartphone Nanocolorimetric Determination of Hydrogen Sulfide in Biosamples after Silver-Gold Core-Shell Nanoprism-Based Headspace Single-Drop Microextraction.

In this work, the sensitive detection of hydrogen sulfide (HS) was realized at low cost and high efficiency through the application of silver-gold core-shell nanoprism (Ag@Au-np) combined with headspace single-drop microextraction (HS-SDME). After SDME, smartphone nanocolorimetry (SNC), with the aid of a smartphone camera and color picker software, was used to detect and quantify the HS. The method took advantage of the inhibition of the ultraviolet-visible (UV-vis) signal caused by HS etching of the Ag@Au-np preadded to the SDME solvent to measure the HS concentration.