Simultaneous Determination of Amphenicols in Animal-Derived Foods by Solvent and Solid Phase Extraction With Ultrahigh-Performance Liquid Chromatography Tandem Mass Spectrometry.

BACKGROUND: The consumption of foods containing amphenicols, a type of antibiotic, is a major concern for human health. A stable and accurate detection method can provide technical support for food-safety monitoring. OBJECTIVE: An effective and efficient method was established for determining amphenicols in animal-derived foods through the simultaneous use of solid-phase extraction (SPE) cleanup and ultrahigh-performance liquid chromatography/mass spectrometry (UPLC-MS/MS). METHOD: Samples were extracted using 1.0% ammoniated ethyl acetate solution, degreased with n-hexane, and then concentrated and cleaned using a C18 SPE column. Next, gradient elution was performed using methanol and 0.05% aqueous ammonia as the mobile phase, followed by separation using a C18 column. The target compound was detected using electrospray ionization, both in positive and negative modes, through multiple reaction monitoring, and quantified using an internal-standard method. RESULTS: The content of chloramphenicol (CAP), florfenicol (FF), and florfenicol amine (FFA) (content range: 0.2-8.0 µg/kg) as well as that of thiamphenicol (TAP; content range: 1.0-40.0 µg/kg) show a good linear relationship, with a correlation coefficient of r > 0.999. Furthermore, recoveries of 86.7-111.9% and relative standard deviations of <9.0% were achieved. The limits of detection and quantification are obtained as 0.03-0.33 and 0.1-1.0 µg/kg, respectively. CONCLUSIONS: The proposed method has excellent stability and accuracy, and can be successfully used for the qualitative and quantitative determination of amphenicols, i.e., CAP, TAP, FF, and FFA residues in 210 animal-derived food samples, of which FF and FFA were detected in four samples. HIGHLIGHTS: A stable and accurate method was successfully established for the simultaneous determination of CAP, TAP, FF, and FFA in animal-derived foods using UPLC-MS/MS. Effective sample pretreatment was established, lipids were removed using n-hexane, concentration and cleanup were achieved with the C18 SPE column, and matrix effects were effectively reduced, thus improving the method's accuracy and stability. The method was validated for eight common animal-source foods, including beef, lamb, pork, chicken, egg, milk, fish, and honey. This method has good applicability for CAP, TAP, FF, and FFA in animal-derived foods.

Toxin screening of Pseudosperma umbrinellum (Agaricals, Basidiomycota): First report of phalloidin in Inocybaceae mushroom.

Pseudosperma species are widely distributed worldwide. Many of them cause poisoning incidents every year, and the toxin responsible for poisoning is muscarine, which could stimulate the parasympathetic nervous system. This study established a method using multiwalled carbon nanotube purification and liquid chromatography-tandem mass spectrometry for the targeted screening of mushroom toxins (muscarine, isoxazole derivatives, tryptamine alkaloids, three amatoxins and three phallotoxins) from Pseudosperma umbrinellum, a common poisonous mushroom distributed in north and northwestern China. Surprisingly, in addition to muscarine, phalloidin was also detected in P. umbrinellum, and the contents were 3022.2 ± 604.4 to 4002.3 ± 804.6 mg/kg (k = 2; p = 95%) muscarine and 5.9 ± 1.2 to 9.3 ± 1.8 mg/kg (k = 2; p = 95%) phalloidin.

 Pseudospermaarenarium (Inocybaceae), a new poisonous species from Eurasia, based on morphological, ecological, molecular and biochemical evidence.

In this study, Pseudospermaarenarium is proposed as a new species, based on morphological, ecological, molecular and biochemical evidence. The new species grows on sandy ground under Populus and Pinussylvestris in north-western China and northern Europe, respectively. It is characterised by the combination of the robust habit, nearly glabrous pileus, large cylindrical basidiospores, thin-walled cheilocystidia and ecological associations with Populusalba × P.berolinensis and Pinussylvestris and unique phylogenetic placement. Additionally, a comprehensive toxin determination of the new species using ultra-high performance liquid chromatography-tandem mass spectrometry was conducted. Results showed that it was a muscarine-positive species. The content were approximately five times higher in the pilei [4012.2 ± 803.1-4302.3 ± 863.2 mg/kg (k = 2, p = 95%)] than in the stipes [850.4 ± 171.1-929.1 ± 184.2 mg/kg (k = 2, p = 95%)], demonstrating the severity of mushroom poisoning when patients consumed different parts of the poisonous mushroom. Amatoxins, phallotoxins, ibotenic acid, muscimol, psilocybin and psilocin were not detected.

Three-dimensional polymer mode (de)multiplexer with cascaded tapered couplers for on-board optical interconnects.

A three-dimensional polymer mode (de)multiplexer based on mode evolution is proposed. The proposed configuration is mainly composed of cascaded two tapered couplers where waveguides with different heights are inversely tapered to achieve mode conversions of the E11,E21, and E31 modes. The dimensional parameters and characteristics are analyzed by the beam propagation method. This mode (de)multiplexer exhibits the coupling ratio greater than 0.97, excess loss lower than 0.15 dB and extinction ratio higher than 20 dB for TE and TM polarizations over the wavelength range 1530∼1625nm (the C+L band). This design has weak wavelength dependence and polarization dependence, which is promising to be applied to broadband on-board mode multiplexing.