Quantification of multi-class antibiotics by UHPLC–MS/MS analysis combined with salt-assisted acetonitrile extraction: comparative evaluation of dairy and poultry manure

ABSTRACT

A comprehensive multiresidue method for the analysis of 33 antibiotics from 7 prevalent classes was comparably investigated for both dairy and poultry manure samples, which can be important pollution sources for the release of antibiotics into the environment. Following salting-out-assisted extraction with acetonitrile, the antibiotics were quantified with ultrahigh-performance liquid chromatography tandem mass spectrometry without a clean-up step. By changing the composition of the mobile phase for chromatography, a pronounced signal enhancement was achieved not only for tetracyclines (TCs) but also for other groups of antibiotics in the manure samples. Although the physicochemical properties of selected antibiotics were quite different, the apparent recovery values from dairy and poultry manure samples by using an extraction solvent comprising McIlvaine buffer and ethylenediaminetetraacetic solution at pH 3 were 86–121% and 89–113%, respectively. Apparent recovery of the antibiotics was not remarkably affected by the extraction solvent over a wide range of pH values, with the exception of the recovery of TC antibiotics from poultry manure, which was in the 53–55% range at pH 8. Furthermore, the poor performance of the analytical method for a few of the antibiotics in poultry manure was correlated with high metal and organic contents of the complicated matrix. The high suppression effects of co-eluted matrix components were compensated by constructing matrix-matched calibration curves and by using internal standards. Simultaneous quantification of seven different antibiotic classes with low limit of detection values varying from 0.38 to 31 μg kg^?1 for dairy manure and from 0.32 to 5.85 μg kg^?1 for poultry manure facilitated their monitoring. The application of the developed analytical method to dairy, broiler and layer-hen manure samples from confined animal feeding operations showed that a wide variety of antibiotics at high concentrations were found in broiler manure.     

Separation and preconcentration of mercury in water samples by ionic liquid supported cloud point extraction and fluorimetric determination

We have developed a cloud point extraction procedure based on room temperature ionic liquid for the preconcentration and determination of mercury in water samples. Mercury ion was quantitatively extracted with tetraethyleneglycol-bis(3- methylimidazolium) diiodide in the form of its complex with 5,10,15,20-tetra-(4-phenoxyphenyl)porphyrin. The complex was back extracted from the room temperature ionic liquid phase into an aqueous media prior to its analysis by spectrofluorimetry. An overall preconcentration factor of 45 was accomplished upon preconcentration of a 20?mL sample. The limit of detection obtained under the optimal conditions is 0.08?μg mL^?1, and the relative standard deviation for 10 replicate assays (at 0.5?g mL^?1 of Hg) was 2.4%. The method was successfully applied to the determination of mercury in tap, river and mineral water samples.

Use of pyrocatechol violet modified sodium dodecyl sulfate coated on alumina for separation and preconcentration of uranium(VI)

A sensitive and selective solid phase extraction procedure for the determination of trace of uranium(VI) has been developed. An alumina-sodium dodecyl sulfate coated on with pyrocatechol violet was used for preconcentration and determination of uranyl ions by spectrophotometry method using Arsenazo III reagent. Sorbed ions were quantitatively eluted using 5 mL of 0.25 mol L⁻¹ HNO₃. The effects of parameters such as pH, amount of alumina, amount of ligand, flow rate, type and concentration of elution agent were examined. The capacity of the sorbent for U(VI) was found to be 0.92 mmol g⁻¹. The relative standard deviation was 1.28% for 10 replicate determinations of U(VI) ion in a solution with a concentration of 1.0 μg mL⁻¹. The practical applicability of the developed sorbent was examined using synthetic and real samples such as standard reference material 2709 (San Joaquin Soil) and 2711 (Montana Soil).     

Fabrication and characterization of anhydrous polymer electrolyte membranes based on sulfonated poly(vinyl alcohol) and benzimidazole

In the present study, a new type of chemically cross-linked polymer blend membranes consisting of poly(vinyl alcohol) (PVA), sulfosuccinic acid (SSA) and benzimidazole (BnIm), as a dopant, at different stoichometric ratios were prepared and used as proton conducting polymer electrolytes. The proton conductivities of the membranes were investigated as a function of blending composition and the temperature. TGA indicated that the blend polymers were thermally stable up to approximately 175°C; differential scanning calorimetry (DSC) results illustrated the homogeneity of the materials. The local chain flexibility of the host polymer increased with BnIm concentration. The methanol permeability values of the membranes were much lower than that of a Nafion-membrane. The proton conductivity of these materials increased with BnIm and SSA concentration and the temperature.     

An EPR study of Cu doped diaquabis(nicotinamide)bis(o-sulfobenzimidato-N)-cadmium(II) single crystals

The electron paramagnetic resonance spectra of Cu²⁺ doped diaquabis(nicotinamide)bis(o-sulfobenzimidato-N)-cadmium(II) (hereafter, CdNAS) single crystals which were taken at room temperature are discussed. It was found from the analysis of the EPR data that the Cu²⁺ ions substitute for magnetically inequivalent Cd²⁺ ions. Two magnetically inequivalent Cu²⁺sites were observed. The principal values of the g and the hyperfine tensors were determined. The ground state wave functions of the unpaired electron of Cu²⁺ ions in two sites were constructed and type of the distortion was determined.     

Acylation of (<Emphasis Type="Italic">R,S</Emphasis>)-1-phenylethanol with ethyl acetate over an immobilized enzyme

Acylation of (R,S)-1-phenylethanol, which is a product of acetophenone hydrogenation, over a Pd-supported catalyst, was studied in ethyl acetate with an immobilized lipase. It was demonstrated that in the presence of hydrogen and Pd/C in the reaction medium the (R,S)-1-phenylethanol acylation rate is not hindered, whereas the selectivity was strongly altered in the latter case, leading to significant amounts of side products.     

Diabetes induces compositional, structural and functional alterations on rat skeletal soleus muscle revealed by FTIR spectroscopy: a comparative study with EDL muscle

Diabetes Mellitus (DM) is a metabolic disorder, characterized by abnormally high blood glucose levels due to decreased secretion or effectiveness in function of insulin. Having a role in carbohydrate and lipid metabolism, skeletal muscle is affected by the absence of insulin in diabetic conditions. This current study reports the application of Fourier transform infrared (FTIR) spectroscopy in the determination of macromolecular alterations in streptozotocin (STZ)-induced diabetic rat skeletal Soleus (SOL) muscles, which highlight the promise of this technique in medical research. The results revealed that DM induced several alterations in macromolecular content and structure of slow-contracting SOL muscles. In diabetic SOL muscles, a decrease in the content of lipids, proteins and nucleic acids together with an increase in lipid order was observed. The decrease in the level of unsaturation and acyl chain length of lipids demonstrated the increased lipid peroxidation in DM. There were alterations in protein secondary structure in DM with a decrease in α-helix and β-sheet content of proteins, whereas the content of aggregated β-strands increased, which is generally seen when proteins denature. Besides, the integrity of collagen molecules was found to be decreased, demonstrating the alterations in its triple helical structure in diabetic muscles. Furthermore, the same alterations mentioned above were also observed in diabetic fast-contracting Extensor Digitorum Longus (EDL) muscles. However, having a high content of mitochondria and relying on an oxidative pathway, SOL muscle was found to be more affected by DM.