Facile synthesis of magnetic hypercrosslinked polymer for the magnetic solid-phase extraction of benzoylurea insecticides from honey and apple juice samples.

In this work, a novel knitting aromatic polymer (KAP) was fabricated for the first time by knitting ferrocene with 1,3,5-tris(bromomethyl)-2,4,6-trimethylbenzene via Friedel-Crafts reaction, and then the KAP was magnetically functionalized with Fe3O4 nanoparticles to produce a magnetic KAP (M-KAP). Combining M-KAP based magnetic solid-phase extraction with high performance liquid chromatography-ultraviolet detection, a simple and sensitive method was developed for simultaneous determination of six benzoylurea insecticides (BUs) in honey and apple juice samples. In the optimized conditions, a good linearity for the BUs existed in the range of 1.67-1000 ng g-1 for honey sample and 0.500-100.0 ng mL-1 for apple juice sample. The limits of detection were 0.500-1.50 ng g-1 and 0.150-0.400 ng mL-1 for honey and apple juice sample, respectively. Satisfactory recoveries were in the range of 85.5-105.5% with RSDs ≤ 8.3%. The developed method demonstrated an excellent practicability for sensitive analysis of the BUs.

Facile fabrication of tyrosine-functionalized hypercrosslinked polymer for sensitive determination of nitroimidazole antibiotics in honey and chicken muscle.

The preparation of tyrosine-functional novel hypercrosslinked polymer (HCP@Tyr) was achieved by knitting 1,3,5-triphenylbenzene with l-tyrosine via simple Friedel-Crafts reaction. The HCP@Tyr displayed large surface area (1220 m2 g-1) and high adsorption capacity (30 mg g-1) for nitroimidazoles (NDZs). With HCP@Tyr as potent sorbent, an efficient extraction method was developed to simultaneously extract five NDZs from honey and chicken muscle samples before high performance liquid chromatography-diode array detection. Under optimized conditions, the proposed method provided a good linearity in the range of 0.75-200.0 ng g-1 for honey and 1.5-100.0 ng g-1 for chicken muscle sample. Low detection limits (S/N = 3) were obtained to be 0.10-0.24 ng g-1 for honey and 0.15-0.30 ng g-1 for chicken muscle. The method recovery was 80.7-120% with relative standard deviations below 9.2%. The HCP@Tyr based method can serve as a reliable and sensitive tool for detection of NDZs in honey and chicken muscle samples.

Green synthesis of novel magnetic porous organic polymer for magnetic solid phase extraction of neonicotinoids in lemon juice and honey samples.

Natural rutin with abundant hydroxyl groups was used as a green monomer to synthesize hydroxyl-functional magnetic porous organic polymer (named Rut-MOP) through environmentally-benign diazo-coupling reaction for the first time. The Rut-MOP displayed high extraction capability for neonicotinoid insecticides (thiamethoxam, imidacloprid, acetamiprid and thiacloprid). Thus, a Rut-MOP based magnetic solid-phase extraction method combined with high performance liquid chromatography was established for sensitive determination of neonicotinoid insecticides in lemon juice and honey samples. Under optimized conditions, the linear response of neonicotinoids was 0.1-100.0 ng mL-1 for lemon juice and 8.0-1000.0 ng g-1 for honey. The limits of detection (S/N = 3) were 0.03-0.04 ng mL-1 and 2.5-3.0 ng g-1 for lemon juice and honey, respectively. The method recoveries were 82-118% with the relative standard deviations of 1.9-7.6%. The results demonstrate that the Rut-MOP based method can be served as a good alternative for the sensitive analysis of neonicotinoid insecticides in lemon juice and honey.

Rapid fluorescent color analysis of copper ions on a smart phone via ratiometric fluorescence sensor.

A smartphone-assisted fluorescence color sensing system for rapid, convenient, and on-site detection of copper ions was developed. The ratiometric fluorescence sensor was fabricated by using silica-coated blue-light-emitting carbon dots and surface-grafted red-light-emitting cadmium-telluride quantum dots. After exposure to Cu2+ in 20 s, the red fluorescence was quenched obviously, while the blue fluorescence remained unchanged, and the sensor color changes continuously from red to blue under the ultraviolet lamp. The concentration (50-1200 nM) of copper ions could be measured by the fluorescence spectrum (excitation at 360 nm, dual-emission at 441 and 640 nm) with a detection limit of 7.7 nM. The fluorescence colors were converted to digital RGB values to calculate the concentration of copper ions by a smartphone with a detection limit of 9.6 nM. The method was applied to detecting copper ions spiked in real samples with recovery from 97.9 to 108.0% and RSD from 3.8 to 8.9%. Thus, this convenient and practical fluorescence color sensing system presents a new strategy for rapid, sensitive, and on-site determination of copper ions in environmental or biological samples.

A low-cost and high-efficiency carbazole-based porous organic polymer as a novel sorbent for solid-phase extraction of triazine herbicides in vegetables.

In this study, a porous organic polymer (denoted as Car-DMB) was fabricated by a simple one-step crosslinking polymerization of carbazole and p-dimethoxybenzene for the first time. Then the Car-DMB was served as adsorbent of solid phase extraction to enrich triazine herbicides from white gourd, tomato and soybean milk samples prior to their determination by high performance liquid chromatography. Under the optimal conditions, the response linearity was in the range of 0.3-100.0 ng g-1 for white gourds and tomato samples, and 0.5-100.0 ng mL-1 for soybean milk, with the coefficient of determination higher than 0.996. The detection limits were 0.1-0.2 ng g-1 for white gourd and tomato samples, and 0.15-0.3 ng mL-1 for soybean milk. The adsorption mechanism of the Car-DMB for the triazines was attributed to the strong H-bonding and weak π-π interactions. The efficient extraction for several other compounds demonstrated that Car-DMB holds great potential for diverse analysis applications.

Preparation of nickel-doped nanoporous carbon microspheres from metal-organic framework as a recyclable magnetic adsorbent for phthalate esters.

In this work, magnetic Ni doped nanoporous carbon (Ni-C) microspheres were prepared by directly calcinating Ni based metal-organic framework at 400 °C in nitrogen. The morphology and surface area of Ni-C microspheres were characterized by electron microscopy and N2 adsorption-desorption isotherms. The results demonstrated that Ni nanoparticles were wrapped by the carbon matrix, resulting in the Ni-C microspheres with a strong magnetic response. The Ni-C microspheres also showed high surface area and micro/meso-porous structure, which make them efficient and recyclable magnetic adsorbent. The Ni-C microspheres were employed for magnetic solid phase extraction of phthalate esters from juice and water samples before high performance liquid chromatographic analysis. The limits of detection (S/N = 3) of the method were 0.2-0.3 ng mL-1 for juice sample and 0.02-0.03 ng mL-1 for water sample. The recoveries of all analytes were between 90.0%-100.6%. The Ni-C microspheres showed a great deal of potential to be an adsorbent for enrichment of other organic pollutants in different samples.

Solid phase extraction of carbamate pesticides with porous organic polymer as adsorbent followed by high performance liquid chromatography-diode array detection.

A solid phase extraction (SPE) method with a porous organic polymer as adsorbent was established for the extraction of five carbamate pesticides (metolcarb, carbaryl, isoprocarb, bassa and diethofencarb) from milk, white wine and juice samples prior to high performance liquid chromatography-diode array detection. The main factors affecting the SPE were optimized, including sample volume, sample loading rate, sample solution pH, desorption conditions and cartridge reusability. Under the optimal conditions, a good linearity existed in the range from 1.0 to 320.0 ng mL-1 for milk and white wine samples and from 0.5 to 160.0 ng mL-1 for juice sample with the correlation coefficients between 0.9956 and 0.9998. The method recoveries of the carbamates were 82.0%-110.0%. The limits of detection were 0.12-0.40 ng mL-1 for milk and white wine samples, and 0.06-0.20 ng mL-1 for juice sample. The adsorption mechanism of the adsorbent was investigated by the extraction of different types of organic compounds (carbamates, benzoylurea insecticides, endocrine disrupting chemicals and polycyclic aromatic hydrocarbons) with the adsorbent. The results showed that the existence of the hydrogen-bonding between the adsorbent and the analytes is favorable for the adsorption and strong hydrophobicity seems to have an adverse effect.

(E)-N'-(4-Hy-droxy-benzyl-idene)-3-nitro-benzohydrazide.

The mol-ecule of the title compound, C(14)H(11)N(3)O(4), assumes an E conformation about the C=N double bond. The benzene rings form a dihedral angle of 3.9 (2)°. The crystal structure is stabilized by N-H⋯O, O-H⋯N, O-H⋯O and C-H⋯O hydrogen bonds, forming layers parallel to (101). In addition, intra-layer π-π stacking inter-actions [centroid-centroid distance = 3.635 (2) Å] are observed.

2-Fluoro-N'-[(2-hydroxynaphthalen-1-yl)methylidene]benzohydrazide.

In the title mol-ecule, C(18)H(13)FN(2)O(2), the hy-droxy group is involved in an intra-molecular O-H⋯N hydrogen bond. The naphthyl ring system and the benzene ring form a dihedral angle of 31.0 (2)°. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into chains propagating in [101].

2-Bromo-4-chloro-6-(cyclo-hexyl-imino-meth-yl)phenol.

The title compound, C(13)H(15)BrClNO, was prepared by the condensation of equimolar quanti-ties of 3-bromo-5-chloro-salicyl-aldehyde with cyclo-hexyl-amine in methanol. There is an intra-molecular O-H⋯N hydrogen bond in the mol-ecule. The cyclo-hexyl ring adopts a chair conformation.

N'-[(2-Methoxynaphthalen-1-yl)methyl-idene]-4-methyl-benzohydrazide.

In the title compound, C(20)H(18)N(2)O(2), the mean planes of the naphthyl system and the benzene ring form a dihedral angle of 88.48 (10)°. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into C(4) chains, which propagate along the b-axis direction.