Synthesis of a novel polydopamine and C18 dual-functionalized magnetic core-shell mesoporous nanocomposite for enrichment and analysis of widely abused illegal drugs in urine samples on site and in the laboratory.

In this study, a novel polydopamine and C18 dual-functionalized magnetic core-shell mesoporous silica (Fe3O4@nSiO2@mSiO2@PDA-C18) nanocomposite was designed and synthesized, which was employed as an adsorbent to extract illegal drugs from urine samples by magnetic solid-phase extraction (MSPE) procedures. The as-prepared nanocomposite was fully characterized and combined with ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to monitor 12 trace illegal drugs and metabolites, including 6-monoacetylmorphine (6-MAM), morphine (MOR), codeine (COD), amphetamine (AMP), methamphetamine (MAMP), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), ketamine (KET), norketamine (NK), cocaine (COC), benzoylecgonine (BZE) and methcathinone (MC). Optimal MSPE procedures were achieved by fully investigating parameters of activation, adsorption, washing and desorption steps. The MSPE-UHPLC-MS/MS method offered high sensitivity with limit of detection (LOD) range of 0.005-0.05 ng mL-1 and good linearity with the concentration of 0.01-1000 ng mL-1. Also, the intra- and inter-day recovery respectively ranged in 90.2-105.0% and 89.8-107.4%, and the intra- and inter-day precision was in the range of 0.5-14.0% and 1.2-10.0%, respectively. By application to real urine samples, the proposed method could not only be equally sensitive for quantifying 12 illegal drugs in urine but also significantly reduce the pretreatment time when comparing with methods based on solid-phase extraction. Furthermore, the designed dual-functionalized adsorbents could also be applied for on-site determination of MAMP in urine coupled with urine test kit, and the detection threshold of MAMP urine test kit remarkably reduced from 1000 ng mL-1 to 50 ng mL-1. Therefore, the present method was a convenient, economic and sensitive approach for determining illegal drugs in urine samples both on site and in the laboratory.

Synthesis of a metal oxide affinity chromatography magnetic mesoporous nanomaterial and development of a one-step selective phosphopeptide enrichment strategy for analysis of phosphorylated proteins.

Protein phosphorylation is one of the most vital protein post-translational modifications, which regulates numerous biological processes including protein structure transformation, molecular interaction, cell proliferation and apoptosis, as well as various malignant diseases. Though mass spectrometry (MS)-based technologies provide a feasible strategy to analyze phosphorylated proteins, label-free quantitative analysis for phosphopeptides in biological samples is still a challenging task due to sample losses from complicated preparation and necessary phosphopeptide enrichment. In this study, magnetic mesoporous TiO2 microspheres, Fe3O4@nSiO2@mSiO2@TiO2, a metal oxide affinity chromatography material, were synthesized with uniform particle size of 500 nm. The synthesized material exhibited good selectivity (molar ratio of ß-casein:BSA = 1:2000, great sensitivity (0.5 fmol µL-1ß-casein), and good adsorption capacity (120 mg g-1). Moreover, the proper mesopores on the surface of the enrichment material displayed the unique property of size-exclusion, which could 'capture' the trypsin and form a temporary immobilized enzyme reactor, reducing the tryptic digestion procedure from at least 16 h to 2 h. Based on the synthesized material, a facile one-step selective phosphopeptide enrichment method was successfully developed and consisted with protein digestion and phosphopeptide enrichment, which was further applied to selectively enrich phosphopeptides from the complex biological samples of nonfat milk and HepG2 cells, indicating its great feasibility and potential of applications in real sample analysis. More importantly, combining with MS, a label-free phosphoproteomic quantitative strategy was established and performed for determination of the mixture samples containing BSA and various concentrations of ß-casein. The results showed that the obtained calibration curve was linear with R = 0.9987 by plotting the intensities of unique phosphopeptide of ß-casein (m/z 2061.77) versus the concentrations of ß-casein. Our study will provide a novel analytical strategy for selective enrichment of phosphopeptides and facile label-free relative quantitative analysis of phosphorylated proteins.

Preparation of polydopamine-functionalized mesoporous silica-coated core/shell magnetic nanocomposite for efficiently extracting five amphetamine-type stimulants from wastewater followed by UPLC-MS/MS determination.

Wastewater-based epidemiology (WBE) was a near-real-time monitoring strategy for illegal drugs. However, solid-phase extraction (SPE) widely used in WBE was time-consuming and labor-intensive to extract ultra-trace target compounds from wastewater. In this study, a convenient magnetic solid-phase extraction (MSPE) approach based on newly designed and synthesized polydopamine functionalized core-shell magnetic mesoporous silica (Fe3O4@nSiO2@mSiO2@PDA) nanocomposite was synthesized and firstly utilized for simultaneously extracting five amphetamine-type stimulants (ATSs) from wastewater samples. Subsequently, ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method coupled with optimal MSPE was developed for determination of ultra-trace ATSs in wastewater. The validation results indicated a favorable linearity ranging from 1 to 200 ng L-1, low limit of detection (0.5-2.5 ng L-1), and qualified recovery (95.1-106.6%) and repeatability (0.6-6.2%). In addition, the Fe3O4@nSiO2@mSiO2@PDA nanoparticles could be reused for at least ten times without significant loss of the adsorption efficiencies of ATSs. Finally, the MSPE-UPLC-MS/MS method was successfully applied to real wastewater samples with the results that the preparation procedure was shrunk from 2 h to 30 min without obvious decline of extraction efficiency compared with the SPE. Hence, based on merits of the novel Fe3O4@nSiO2@mSiO2@PDA nanocomposite, the proposed method is convenient and reliable for determination of ATSs in wastewater.

Automatic analytical approach for the determination of 12 illicit drugs and nicotine metabolites in wastewater using on-line SPE-UHPLC-MS/MS.

In this study, we developed a novel on-line solid phase extraction (SPE)-ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS)-based analytical method for simultaneously quantifying 12 illicit drugs and metabolites (methamphetamine, amphetamine, morphine, codeine, 6-monoacetylmorphine, benzoylecgonine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine, cocaine, ketamine, norketamine, and methcathinone) and cotinine (COT) in wastewater samples. The analysis was performed by loading 2 mL of the sample onto an Oasis hydrophilic-lipophilic balance cartridge and using a cleanup step (5% methanol) to eliminate interference with a total run time of 13 min. The isotope-labeled internal standard method was used to quantify the target substances and correct for unavoidable losses and matrix effects during the on-line SPE process. Typical analytical characteristics used for method validation were sensitivity, linearity, precision, repeatability, recovery, and matrix effects. The limit of detection (LOD) and limit of quantification (LOQ) of each target were set at 0.20 ng/L and 0.50 ng/L, respectively. The linearity was between 0.5 ng/L and 250 ng/L, except for that of COT. The intra- and inter-day precisions were <10.45% and 25.64%, respectively, and the relative recovery ranged from 83.74% to 162.26%. The method was used to analyze various wastewater samples from 33 cities in China, and the results were compared with the experimental results of identical samples analyzed using off-line SPE. The difference rate was between 19.91% and -20.44%, and the error range could be considered acceptable. These findings showed that on-line SPE is a suitable alternative to off-line SPE for the analysis of illicit drugs in samples.