Rapid Analysis of Seven Polyamines in Nephotettix cincticeps by Using Ultra-Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry.

A fast, simple, and sensitive method for the simultaneous determination of seven polyamines in Nephotettix cincticeps was developed based on ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-3Q-MS) together with liquid phase extraction. Polyamines in insect samples were extracted with HClO4 solution and then were separated and detected by UPLC-3Q-MS, which was equipped with a hydrophilic interaction liquid chromatography column, within 5 min without any derivatization procedure. The method has been successfully used to detect 7 polyamines in healthy and difluormethylornithine-treated adults of Nephotettix cincticeps with a method limit of detection and the method limit of quantitation of 24-139 pg/mg and 82-464 pg/mg, respectively, an intraday and interday relative standard deviation (RSD, n = 5) of 1.97-6.00% and 2.08-5.92% respectively, and a recovery of 86-115%. The success of this study provided a reliable method for the rapid and high-throughput detection of polyamines in the insect sample.

Regulating the Growth Rate of Gold Nanobipyramids via a HCl-NADH-Ascorbic Acid System toward a Dual-Channel Multicolor Colorimetric Immunoassay for Simultaneously Screening and Detecting Multiple Sulfonamides.

It is an urgent need to develop simple and high-throughput methods for simultaneously screening and detecting multiple or groups of sulfonamides (SAs) in animal-derived foods since various SAs were alternately used in animal husbandry to avoid generating drug resistance. We herein developed a novel HCl-reduced nicotinamide adenine dinucleotide I (NADH)-ascorbic acid (AA)-mediated gold nanobipyramids (AuNBPs) growth system, which can precisely regulate the growth rate of AuNBPs, to generate two colorful and stable AA-corresponding multicolor signal channels with different sensitivities. Based on the HCl-NADH-AA-mediated AuNBP growth system, we further developed a dual-channel multicolor immunoassay for simultaneously realizing rapid screening and detection of 5 SAs (sulfamethazine, sulfamethoxydiazine, sulfisomidine, sulfamerazine, and sulfamonomethoxine) by using a paper-based analytical device for sensitively and stably reading out the signal and a broad-specificity anti-SAs antibody as a bio-receptor. The developed immunoassay has more color changes, a wider linear range, excellent specificity and stability, and two multicolor signal channels (L-channel and H-channel) with different sensitivities. The H-channel exhibited 7-8 SAs-corresponding color changes and can be used to detect 5 target SAs with a visual detection limit of 0.1-0.5 ng/mL and a spectrometry detection limit of 0.05-0.16 ng/mL. The L-channel exhibited 7-9 SAs-corresponding color changes and can be used to detect 5 target SAs with a visual detection limit of 2.0-6.0 ng/mL and a spectrometry detection limit of 0.40-1.47 ng/mL. The developed immunoassay was successfully used to simultaneously screen and detect low-concentration and high-concentration of target SAs in milk and fish muscle samples with a recovery of 85-110% and an RSD (n = 5) < 8%. The visual detection limit of our immunoassay is much lower than the maximum residue limit of total SAs in edible tissue. All above features make our immunoassay a promising assay for simultaneously realizing the rapid screening and quantitative determination of multiple SA residues in food by bare eye observation. It must be mentioned that our immunoassay may be expended as a general method for the simultaneous visual screening and detection of other drugs using the corresponding antibody as a recognition probe.

Triazine-Cored Lanthanide-Based Metal-Organic Frameworks Featuring Unique Water Chains and Strong Characteristic Emissions.

A new triazine-cored tricarboxylic acid, N,N',N"-1,3,5-triazine-2,4,6-triyltris(cis-4-aminocyclohexane-carboxylic acid) (H3 L), has been prepared by replacing the chlorine atoms of cyanuric chloride with cis-4-aminocyclohexane-carboxylic acid, which has been used for the construction of a series of triazine-cored lanthanide-based metal-organic frameworks (MOFs). All these MOFs were structurally authenticated, revealing that they are isostructural and exist as two-dimensional (2D) coordination networks with the general formula [Ln(L)(H2 O)2 ]⋅5.5 H2 O (Ln=1⋅Gd, 2⋅Tb, 3⋅Eu). A unique one-dimensional water chain, composed of primary tetrameric cyclic rings and dodecameric cyclic rings, has been found entrapped in the lattice. Moreover, all these compounds display bright characteristic photoluminescence. Particularly, for 1, apart from the strong blue emission peak (Φf =20.6 %) corresponding to the intraligand transition under near-UV excitation, the characteristic emissions of Gd3+ cation (Φf =5.0 %) were unexpectedly observed upon excitation at 273 nm.

Preparation and evaluation of a hydrophilic poly(2-hydroxyethyl methacrylate-co-N,N'-methylene bisacrylamide) monolithic column for pressurized capillary electrochromatography.

A polar polymethacrylate-based monolithic column was introduced and evaluated as a hydrophilic interaction CEC stationary phase. The monolithic stationary phase was prepared by in situ copolymerization of a neutral monomer 2-hydroxyethyl methacrylate and a polar cross-linker N,N'-methylene bisacrylamide in a binary porogenic solvent consisting of dodecyl alcohol and toluene. The hydroxyl and amino groups at the surface of the monolithic stationary phase provided polar sites which were responsible for hydrophilic interactions. The composition and proportion of the polymerization mixture was investigated in detail. The mechanical stability and reproducibility of the obtained monolithic column preformed was satisfied. The effects of pH and organic solvent content on the EOF and the separation of amines, nucleosides, and narcotics on the optimized monolithic column were investigated. A typical hydrophilic interaction CEC was observed on the neutral polar stationary phase. The optimized monolithic column can obtain high-column efficiencies with 62,000-126,000 theoretical plates/m and the RSDs of column-to-column (n = 9), run-to-run (n = 5), and day-to-day (n = 3) reproducibility were less than 6.3%. The calibration curves of these five narcotics exhibited good linearity with R in the range of 0.9959-0.9970 and linear ranges of 1.0-200.0 µg/mL. The detection limits at S/N = 3 were between 0.2 and 1.2 µg/mL. The recoveries of the separation of narcotics on the column were in the range of 84.0-108.6%. The good mechanical stability, reproducibility, and quantitation capacity was suitable for pressure-assisted CEC applications.

Analysis of microcystins by capillary zone electrophoresis coupling with electrospray ionization mass spectrometry.

In this paper, a rapid and effective method based on capillary zone electrophoresis (CZE) coupled with electrospray ionization mass spectrometry (ESI-MS) was established for the trace analysis of microcystin (MC) isomers in crude algae sample. The experimental conditions including the composition, acidity and concentration of buffer, separation voltage, injection time, and MS detection parameters were investigated in detail. A capillary separation system was as follows: a uncoated fused-silica capillary tube (50 microm i.d. x 90 cm), 40 mmol L(-1) ammonium acetate solution (pH 9.86) as running buffer, 25 kV as separation voltage, 20 kV x 3s water first and 20 kV x 20s for sample injection. Mass analysis was performed in ESI source, with sheath gas temperature 150 degrees C, sheath gas pressure 10 psi, and sheath gas flow 6 L min(-1). And sheath liquid was 7.5 mmol L(-1) acetic acid in 50% isopropanol-water (3 microg L min(-1)). Protonation and ammonium adduct molecular ions m/z 506.9 (MC-LR) and 532.0 (MC-YR) were used for the quantification of MCs. Under these conditions, two MCs were baseline separated within 9 min, the calibration curves were obtained in the range of 0.11-10.0 microg mL(-1) and 0.16-10.5 microg mL(-1) for MC-LR and MC-YR, respectively. Meanwhile, limits of detection were 0.05 and 0.08 microg mL(-1) for MC-LR and MC-YR, respectively. The recoveries for the two MCs were in the range of 95.8-108%. The developed approach had been successfully applied to the analysis of MCs in crude algae samples.

Electrochromatographic characterization of methacrylate ester-based monolith and capillary electrochromatography separation of flavonoids.

A porous polymethacrylate ester-based monolithic column for capillary electrochromatography (CEC) was designed by mean of in situ co-polymerizing lauryl methacrylate (LMA), ethylene dimethacrylate (EDMA) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) in a ternary porogenic solvent including cyclohexanol, 1,4-butanediol and water. After investigating the influence factors of the CEC monolithic columns, four flavonoids (i.e., Rutin, Quercetin, Kaempferol, and Quercitrin) were separated and assayed to evaluate this monolithic column with CEC method. Under optimum conditions, the CEC method exhibited high separation efficiency, with rapid separation time of 3-4 min, for the four flavonoid samples using 10mM phosphate buffer containing 70% acetonitrile (pH 9.0). Importantly, the proposed method could provide a promising approach for rapid separation and detection in biomedicine.

pCEC coupling with ESI-MS for the analysis of beta(2)-agonists and narcotics using a poly-(1-hexadecene-co-TMPTMA) monolithic column.

A pressure-assisted CEC with ESI-MS based on poly(1-hexadecene-co-trimethylolpropane trimethacrylate) monolithic column for rapid analysis of two beta(2)-agonists and three narcotics was established in this article. After the organic polymer-based monolithic column was prepared by an in-situ polymerization procedure, a systematic investigation of the pressure-assisted CEC separation and ESI-MS detection parameters was performed. Baseline separation of the studied analytes could be obtained using the solution containing 75% ACN v/v and 20 mmol/L ammonium acetate with pH 8.0 as running buffer, when applying separation voltage of 20 kV and assisted pressure of 5 bar. Under the optimized conditions, two beta(2)-agonists and three narcotics could be completely resolved and accurately determined within 15 min. Finally, the proposed method was successfully used for real urine samples detection.