Determination of veterinary drug residues in chicken meat using corona discharge ion mobility spectrometry

A positive corona discharge ion mobility spectrometry (CD-IMS) has been evaluated for the determination of three residual veterinary drugs including furazolidone (FUR), chloramphenicol (CAP), and enrofloxacin (ENR) in poultry for the first time. Pretreatment included extraction of the drugs from samples and further treatment of the extracts by solid phase extraction (SPE) using C₁₈ sorbents. The limits of quantification (LOQs) were less than 20 μg kg⁻¹ for all compounds. The calibration plots for these compounds were linear to about three orders of magnitude. The validity of the method was demonstrated by the analysis of spiked and real samples.     

Mcm-41 Materials as Catalysts for the Synthesis of Alkyl Fructosides

ABSTRACT

Alkylation of saccharides combines the essential characteristics of two major renewable classes, viz. triglycerides and carbohydrates, while leading to biofriendly surfactants and emulsifiers. The development of alkylated derivatives of fructose has lagged because no efficient synthesis was available. We have found that mesoporous materials of the MCM-41 type are active and selective catalysts for the alkylation of fructose. Quantitative yields were obtained in the reaction of fructose with lower alcohols, up to C4. For long chain alcohols yields were moderate but the alkyl fructopyranosides could be easily purified. The other isomers could be isolated by chromatography.     

(+)-Sorangicin A: evolution of a viable synthetic strategy

An effective, asymmetric total synthesis of the antibiotic (+)-sorangicin A (1) has been achieved. Central to this venture was the development of first- and second-generation syntheses of the signature dioxabicyclo[3.2.1]octane core, the first featuring chemo- and stereoselective epoxide ring openings facilitated by a Co₂(CO)₆-alkyne complex, the second involving a KHMDS-promoted epoxide ring formation/opening cascade. Additional highlights include effective construction of the dihydro- and tetrahydropyran ring systems, respectively, via a stereoselective conjugate addition/α-oxygenation protocol and a thioketalization/hydrostannane reduction sequence. Late-stage achievements entailed two Julia-Kociénski olefinations to unite three advanced fragments with high E-stereoselectivity, followed by a modified Stille protocol to introduce the Z,Z,E trienoate moiety, thereby completing the carbon skeleton. Mukaiyama macrolactonization, followed by carefully orchestrated Lewis and protic acid-promoted deprotections that suppressed isomerization and/or destruction of the sensitive (Z,Z,E)-trienoate linkage completed the first, and to date only, total synthesis of (+)-sorangicin A (1).     

Cu(II) and Zn(II) complexes with a fluoroquinolone antibiotic: Spectroscopic and X-ray absorption characterization

The synthesis of two complexes with the antibiotic flumequine, [Cu(Flumequine)₂(OH₂)₂] (1) and [Zn(Flumequine)₂(OH₂)₂]·H₂O (2) is reported. Their molecular structure was elucidated by combining various spectroscopic techniques. The EPR parameters combined with XAS data underline a tetragonal distorted octahedral geometry for the two complexes. The coordination occurs through the carbonyl and carboxylate oxygen atoms in the equatorial plane. The coordination sphere is completed by two water molecules in axial position.     

反相高效液相色谱法直接拆分舒必利对映体

以反相高效液相色谱法,建立了舒必利在大环抗生素类固定相(chirobiotic T)上手性拆分的方法。考察了不同流动相组成对分离的影响。推荐流动相条件为V(甲醇)：V(磷酸)：V(三乙胺)=100：1．5：3。     

Preconcentration of rifampicin prior to its efficient spectroscopic determination in the wastewater samples based on a nonionic surfactant

Every year, tuberculosis affects the lungs of millions of people and rifampicin is the commonly used medicine for its treatment due to its antibiotic nature. The frequent use of rifampicin may lead to its increased concentration in the water resources. This research work is focused on the cloud point extraction (CPE) procedure for the preconcentration of rifampicin prior to its determination in water. The UV/vis spectrophotometric method was adapted for the measurement of rifampicin content after the phase separation. Triton-X 100 was used as the nonionic surfactant which contains hydrophilic polyethylene chain feasible for the extraction of analyte. Various analytical parameters that can affect the extraction efficacy were optimized to achieve linearity of the proposed method in the concentration range of 3.54–81.41 mgL^–1. The Limit of detection and quantification were 1.261 and 4.212 mgL^–1, respectively. The Preconcentration factor was 40 with relative standard deviation (%RSD) of 2.504%. The standard addition methodology was adopted for the validation of this procedure and effectively applied for the determination of rifampicin in real wastewater samples.     

A Multifunctional Fluorescence Europium-Organic Framework for Turn-On Sensing of pH and Turn-Off Sensing of 2-Thiazolidinethione-4-carboxylic Acid and Aztreonam

A luminescent lanthanide-organic framework [Eu₂(adip)(H₂adip)(DMF)₂]·CH₃OH ( 1 ) was synthesized by a solvothermal method using anthracene-based ligand 5,5’-(anthracene-9,10-diyl)diisophthalic acid (H₄adip). 1 possesses a 3D coordination framework, which could be rationalized as a 4,8-connected 2-nodal (4¹⁶6¹²)(4⁴6²) topological network. 1 shows an excellent linear increase in fluorescence intensity as the pH value rises from 4.8 to 7.1. Particularly, the fluorescence enhancement percentage reaches 588% for each increase of pH value, which is the highest value recorded for fluorescence pH sensing materials, promoting the sensitivity of pH detection within the physiological pH range. In addition, 1 can also specifically recognize carbon disulfide biomarkers 2-thiothiazolidine-4-carboxylic acid (TTCA) and antibiotic aztreonam (ATM) by fluorescence quenching, with the K_SV values of 1.02 × 10⁵ L·mol^–1 (0—10 μmol·L^–1) and 4.67 × 10⁵ L·mol^–1 (0—50 μmol·L^–1), the limit of detection (LOD) of 86 nmol·L^–1 and 19 nmol·L^–1, respectively. Among only a few cases reported, the detection sensitivities of 1 for both TTCA and ATM are the highest. The sensing mechanisms of pH, TTCA, and ATM are also discussed in detail.      

An Isotope-Labeled Single-Cell Raman Spectroscopy Approach for Tracking the Physiological Evolution Trajectory of Bacteria toward Antibiotic Resistance

Understanding evolution of antibiotic resistance is vital for containing its global spread. Yet our ability to in situ track highly heterogeneous and dynamic evolution is very limited. Here, we present a new single-cell approach integrating D₂O-labeled Raman spectroscopy, advanced multivariate analysis, and genotypic profiling to in situ track physiological evolution trajectory toward resistance. Physiological diversification of individual cells from isogenic population with cyclic ampicillin treatment is captured. Advanced multivariate analysis of spectral changes classifies all individual cells into four subsets of sensitive, intrinsic tolerant, evolved tolerant and resistant. Remarkably, their dynamic shifts with evolution are depicted and spectral markers of each state are identified. Genotypic analysis validates the phenotypic shift and provides insights into the underlying genetic basis. The new platform advances rapid phenotyping resistance evolution and guides evolution control.