Resonance Light Scattering Method for Determination of Amikacin with Potassium Ferrioxalate as a Probe

In a weak acid medium, potassium ferrioxalate（PF） can react with some aminoglycoside（AGs） antibiotics, such as amikacin（AMK）, kanamycin（KANA）, tobramycin（TOB） and gentamicin（GEN）, to form ion-association complexes. It results in the enhancement of resonance light scattering（RLS） in different degrees. The maximum scattering peaks are all located at 345 nm. Among them, the relative scattering intensity（AIRLs） of AMK system is much higher than that of KANA, TOB or GEN. Therefore the method is more propitious to the determination of trace amounts of AMK. The optimum reaction conditions, influencing factors, and the relationship between scattering intensity and concentration of antibiotics were investigated by means of the proposed method. The enhancement of RLS signals is directly proportional to the concentration of antibiotics in a certain range of concentration. A new resonance light scattering method for the determination of AMK and other aminoglycoside antibiotics with [Fe（C2O4）3]^3- as a probe is thus established based on it. The method exhibits high sensitivity and good selectivity. The detection limit（3σ） for AMK is 1.8 ng/mL. The method can be applied to the determination of AMK in clinical serum samples. The reaction mechanism and the reasons for RLS enhancement are discussed in this paper.

A chronological review of photochemical reactions of ferrioxalate at the molecular level:New insights into an old story

Owing to its outstanding photoactivity,ferrioxalate is originally used as an actinometer and subsequent work has discovered that photochemistry of ferrioxalate is also fundamentally or technically important in atmospheric chemistry and water treatment.While the overall products generated from photolysis of ferrioxalate are known to include Fe(Ⅱ),a series of oxidizing(e.g.,·OH,O_(2)^(·-)/HO_(2)^(·-))or reducing(C_(2)O_(4)^(·-)/CO_(2)^(·-))radicals and H_(2)O_(2),however,at the molecular level,the primary step of the photoreaction of ferrioxalate remains as an unsolved mystery due to the difficulty in examining such ultrafast processes.Benefiting from the development of time-resolved spectroscopy,this old question has been studied with increasing vigor recently,by means of such ever-more-sophisticated techniques(e.g.,flash photolysis,time-resolved X-ray absorption spectroscopy(XAS),femtosecond infrared(IR)absorption spectroscopy,ultrafast photoelectron spectroscopy(PES)).There are two contrary views on the primary reaction mechanism:(1)Intramolecular electron transfer(ET)precedes the cleavage of the metal-ligand bond;(2)The dissociation of C-C or Fe-O bond occurs before intramolecular ET.Thus,this review presents a comprehensive summary about the overall reaction mechanism and molecular level mechanism of ferrioxalates.In chronological order,we have elaborated two predominant but controversial views from the perspectives of different experimental approaches.Some challenges and research opportunities in this active field are also briefly discussed.

Preparation of Ferrioxalate Submicrorods/Graphene Composites and Their Photocatalytic Properties

Ferrioxalate submicrorods/graphene composites were synthesized through a simple solvothermal process in a mixture of ethylene glycol and water. The in situ growth of ferrioxalate submicrorods and the reduction of graphene oxide （GO） were completed in a one-step reaction. Fourier transform infrared and Raman spectroscopy confirmed the reduction of GO. Uniform rod-like ferrioxalates with diameter of about 600 nm and length of several micrometers were well distributed on the graphene sheets. As-obtained composites exhibited better photocatalytic properties than pure ferrioxalate submicrorods. The influence of different contents of GO on photocatalytic performance was also investigated. A possible photocatalytic mechanism of ferrioxalate submicrorods/graphene composites was proposed.

A collaborative strategy for enhanced reduction of Cr(Ⅵ) by Fe(0) in the presence of oxalate under sunlight:Performance and mechanism

Nanometer-size zero-valent iron(NZVI)is an efficient reducing agent,but its surface is easily passivated with an oxide layer,leading to reaction inefficiency.In our study,oxalate(OA)was introduced into this heterogeneous system of NZVI,which could form ferrioxalate complexes with the NZVI surface-bound Fe3+and dissolved Fe3+in the solution.Photolysis of ferrioxalate complexes can facilitate the generation of Fe2+from Fe3+and CO2·-radical,both species have strong reduction capacity.Hence,a"photo-oxalate-Fe(0)"system through sunlight induction was established,which not only prohibited the formation of a surface passivation layer,but also displayed a synergetic mechanism of ferrioxalate photolysis to enhance reduction,exhibiting remarkably higher degradation activity(several times faster)toward the model pollutant Cr(Ⅵ)than the mechanism with NZVI alone.Factor tests suggested that both NZVI dosage and OA content markedly affected the reduction rate.Low pH was beneficial to the reduction efficiency.Moreover,recyclability experiment showed that the reduction rate decreased from 0.21706 to 0.03977 min-1 after three cycles of reuse due to the NZVI losing reaction activity generally,but the system still maintained considerable reduction capacity.Finally,a mechanism was revealed whereby NZVI would transform to Fe oxides after the exhaustion of its reductive power,and the photolysis of ferrioxalate to promote the cycling of iron species played the predominant role in providing extra reduction ability.These features confirm that introduction of OA into Cr(Ⅵ)reduction by NZVI through sunlight induction is advantageous and promising.