A novel porphyrin-based conjugated microporous nanomaterial for solid-phase microextraction of phthalate esters residues in children's food.

A novel porphyrin-based conjugated microporous polymer (PCMP) with microporous structure and nitrogen-rich pyrrole building blocks was synthesized. The PCMP was used as a coating material to prepare solid-phase microextraction (SPME) fibers by sol-gel technique. Due to the toxicity of the phthalate esters (PAEs) and the necessity for their sensitive determinations in some food samples, the SPME fiber was investigated for the extraction of eleven PAEs from six different children's milk beverages prior to their detection by gas chromatography-mass spectrometry. Under the optimal conditions, the linear response range for the PAEs was in the range from 0.03 to 200 µg L-1 and the limits of detection (S/N = 3) for the analytes were 0.01-3.00 µg L-1. The method recoveries for the PAEs were between 80% and 120%, with the relative standard deviations varying from 1.3% to 9.8%. The method was successfully applied for the determination of PAEs in children's milk beverages.

Efficient solid-phase microextraction of twelve halogens-containing environmental hormones from fruits and vegetables by triazine-based conjugated microporous polymer coating.

A triazine-based conjugated microporous polymer (TCMP) was generated by introduced 1, 3, 5-triazine into conjugated microporous polymer network via Friedel-Crafts reaction. Under the optimum synthesis conditions, the obtained TCMP has a loose and porous structure. It was then used as a fiber coating material for solid-phase microextraction (SPME) of halogens-containing environmental hormones. It showed a strong adsorption capability due to the halogen bond, electrostatic, π-π stacking and hydrophobicity interactions. An analytical method combining the TCMP coated fiber-based SPME with gas chromatography-electron capture detection was developed to determine twelve halogens-containing environmental hormones in vegetable and fruit samples. A wide linear range (0.07-100.0 ng g-1) with the determination coefficients in the range of 0.9907-0.9996 and low limits of detection (0.02-0.04 ng g-1, S/N = 3) were achieved under optimized experimental conditions. The applicability of the established method was evaluated by the determination of the environmental hormones from three different fruit samples (apple, nectarine and pear) and five vegetable samples (Chinese cabbage, pakchoi, baby cabbage, rape and round lettuce). The resulting relative recoveries ranged from 76.6% to 123% with the relative standard deviations less than 10%. This research demonstrates the application potential of the TCMP coated fiber in the analysis of the halogens-containing environmental hormones in real vegetable and fruit samples.

Coordination of a fresh agricultural product supply chain with option contract under cost and loss disruptions.

This paper analyzes the option coordination problem of a fresh agricultural product supply chain under two supply chain structures, when the production cost and the loss rate are disrupted simultaneously. This paper provides the explicit option coordination conditions for the disrupted supply chain under two supply chain structures, and then explores the effects of the disruptions and supply chain structure on the option coordination conditions. The results suggest that it is unfavorable to apply the original coordinating contracts without disruptions to coordinate the disrupted supply chain. The coordination of the disrupted supply chain can be achieved with knowledge of the distribution of demand. In two coordinating contracts for the disrupted supply chain, the exercise price is still at the original level without disruptions while the option price deviates from the original level without disruptions. Moreover, the relationships of the coordination conditions in two supply chain structures depend on the value of the profit allocation coefficient. When the profit allocation coefficient exceeds (falls behind) a certain threshold, the option price is set at a higher (lower) value in the supplier-led supply chain structure than in the distributor-led supply chain structure, while the exercise price is set at a lower (higher) value in the supplier-led supply chain structure than in the distributor-led supply chain structure. Finally, the disrupted supply chain with any supply chain structure will perform better in the modified coordinating contracts than in the original coordinating contracts without disruptions.