Novel filter-press single-step cleanup approach facilitated rapid screening and accurate quantification of 112 veterinary drugs in aquatic products

In this study, a novel filter-press cleanup column was developed as a single-step cleanup approach for the rapid screening and quantification of 112 veterinary drugs in fish samples. Fish muscle samples were extracted with acetonitrile and ethyl acetate, sequentially. After concentration and reconstitution, N-propylethylenediamine (PSA) sorbent, packed in filter-press column, allows rapid single-step cleanup operation, while UHPLC-Q-Orbitrap-HRMS provides high-precision mass information in multi-residue screening. Under optimum settings, the detection and quantification limits were validated at 0.5 and 2.0 μg·kg-1, for all analytes, respectively. The ranges of recoveries were from 35.3 to 138.4%. Most of these target analytes (82%) could be measured with recoveries between 60 and 130%, and intra-day RSDs ranging from 1.9 to 26.1%. This method was further applied to evaluate the residual of veterinary drugs in fish samples from four cities in China, and results demonstrated its practicability for multi-residue monitoring veterinary residues for food safety administration.

Positive and Negative Affinity Chromatography to Purify Norovirus P-Domain Protein

Affinity chromatography enables the separation and isolation of proteins of interest from complex milieu of biochemicals. Nickel-charged affinity resins and amylose resins are two commonly used matrices for the isolation of proteins with histidine tag (6× His-tag) and maltose binding protein (MBP) tag, respectively. Herein we describe the isolation of the Protruding domain (P-domain) of Norovirus's major capsid protein, VP1, through a highly efficient batch purification technique. By fusing the P-domain to a 6×His-MBP tag followed by a TEV cleavage site, we can effectively purify the P-domain in three chromatography steps (positive nickel affinity, negative nickel affinity, and negative amylose affinity).