High-performance liquid chromatographic method for the rapid and simultaneous determination of sulfamonomethoxine, miloxacin and oxolinic acid in serum and muscle of cultured fish

Synthesis and Bioactivities of Novel Piperonylic Acid Derivatives Containing a Sulfonic Acid Ester Moiety

The crop loss caused by bacteria has increased year by year due to the lack of effective control agents. In order to develop efficient, broad-spectrum, and structurally simple agricultural bactericide, the structure of piperonylic acid was modified and a series of novel piperonylic acid derivatives containing a sulfonic acid ester moiety was synthesized. Bioassay results indicated the compounds exhibited significantly antibacterial activities. Among them, compound 41 exhibited excellent antibacterial activities against Pseudomonas syringae pv. Actinidiae (Psa), with inhibitory value 99 and 85% at 100 μg/ml and 50 μg/ml, respectively, which was higher than that of thiodiazole-copper (84 and 77%) and bismerthiazol (96 and 78%). In addition, some compounds also showed moderate insecticidal activity against Spodoptera frugiperda. The abovementioned results confirm the broadening of the application of piperonylic acid, with reliable support for the development of novel agrochemical bactericide.

The effect of sulfamonomethoxine treatment on the gut microbiota of Nile tilapia (Oreochromis niloticus)

To investigate the possible effects of sulfamonomethoxine (SMM) on Nile tilapia (Oreochromis niloticus), we quantitatively evaluated the microbial shifts in the intestines of Nile tilapia in response to different doses of SMM (200 and 300 mg/kg) using 16S rRNA gene sequencing. At the phylum level, the control group (0 mg kg^-1  SMM) was dominated by Actinobacteria, Proteobacteria, and Firmicutes. In the treatment groups, Firmicutes, Proteobacteria, and Chloroflexi were the dominant phyla. Cluster analysis indicated that the two groups treated with SMM clustered together. Similarly, the bacterial families that dominated the control group differed from those dominating the treatment groups. The changes in intestinal microbial composition over time were similar between the two SMM treatment groups. In both groups, the abundances of some families, including the Bacillaceae, Streptococcaceae, and Pseudomonadaceae, increased first and then decreased. Overall, the addition of SMM to the feed changed the structure of the intestinal microbiota in Nile tilapia. This study improves our understanding of the impact of SMM on the intestinal microenvironment of Nile tilapia. Our results provide guidelines for the feasibility of SMM use in aquaculture production.

Development of immunoaffinity restricted access media for rapid extractions of low-mass analytes

Restricted access media using antibodies as immobilized ligands were developed for the rapid and selective capture of small analytes by immunoextraction, giving rise to materials referred to as immunoaffinity restricted access media (IA-RAM). To make such a material, intact antibodies for the desired target were first immobilized onto porous silica, with antibodies at or near the outer surface of the support then being treated with papain (or a related agent) to release and remove their binding domains. The result was a support in which only antibodies deep within the pores remained intact and able to bind to the target. Items evaluated in the development of such media included the immobilization method used for the antibodies, the pore size of the support, and the amount of papain and time that were used for support treatment. A theoretical model was also developed to describe the extent of binding domain removal based on the measured polypeptide content of the IA-RAM support before and after treatment with papain. The final optimized conditions for making the IA-RAM supports were used to prepare columns that contained antifluorescein antibodies. Injections of fluorescein and fluorescein-labeled bovine serum albumin onto these IA-RAM columns gave selective and quantitative extraction of fluorescein in 1-2 s. This approach can be used with other antibodies and low-mass targets and should be valuable for such applications as the rapid separation of drugs from drug-protein complexes or the isolation of labeled/modified peptides from intact proteins that contain the same modification or label.

Restricted access materials and large particle supports for on-line sample preparation: an attractive approach for biological fluids analysis

An analytical process generally involves four main steps: (1) sample preparation; (2) analytical separation; (3) detection; and (4) data handling. In the bioanalytical field, sample preparation is often considered as the time-limiting step. Indeed, the extraction techniques commonly used for biological matrices such as liquid-liquid extraction (LLE) and solid-phase extraction (SPE) are achieved in the off-line mode. In order to perform a high throughput analysis, efforts have been engaged in developing a faster sample purification process. Among different strategies, the introduction of special extraction sorbents, such as the restricted access media (RAM) and large particle supports (LPS), allowing the direct and repetitive injection of complex biological matrices, represents a very attractive approach. Integrated in a liquid chromatography (LC) system, these extraction supports lead to the automation, simplification and speeding up of the sample preparation process. In this paper, RAM and LPS are reviewed and particular attention is given to commercially available supports. Applications of these extraction supports, are presented in single column and column-switching configurations, for the direct analysis of compounds in various biological fluids.

Application of shielded column liquid chromatography for determination of sulfamonomethoxine, sulfadimethoxine, and their N4-acetyl metabolites in milk

A hazardous-chemical free method for simultaneous determination of sulfamonomethoxine (SMM), sulfadimethoxine (SDM), and their N4-acetyl metabolites in raw milk using shielded column liquid chromatography is developed. The target analytes are extracted by mixing with ethanol-acetic acid (97:3, v/v) followed by centrifugation. The procedure uses a Hisep shielded hydrophobic phase (SHP) column, isocratic elution with 0.1% acetic acid solution (pH 3.1, in water)-ethanol (75:25, v/v), and a photo-diode array detector. Average recoveries from samples spiked at 25-500 ng/ml for each drug were >81% with relative standard deviations within 5%. The limits of quantitation were <25 ng/ml.

Direct injection HPLC method for the determination of selected benzodiazepines in plasma using a Hisep column

A direct plasma injection HPLC method has been developed for the determination of selected benzodiazepines (nitrazepam, clobazam, oxazepam, lorazepam). The method uses an analytical hydrophobic shielded phase (Hisep) column equipped with a Hisep guard column, are easy to perform and requires 20 ul of a filtered plasma sample. The chromatographic run time is less than 15 min using a mobile phase of 15:85 v/v acetonitrile-0.18 M ammonium acetate pH 2.5. The method is good for 175 injections before replacement of the guard column. The method was linear in the range 0.5-18 ug ml(-1) (r>0.99, n=6) for the analytes with R.S.D. less than 10.82%. Interday and intraday variability were found to be less than 14%. The limits of detection and quantitation were 0.16 (s/n>3) and 0.5 ug ml(-1) (s/n>10), respectively, for each of the four benzodiazepines.

Determination of residues of oxolinic acid and flumequine in freeze-dried salmon muscle and skin by HPLC with fluorescence detection

A procedure for the determination of residues of oxolinic acid (OA) and flumequine (FLU) in freeze-dried salmon muscle with attached skin, using reversed-phase high-performance liquid chromatography, is described. OA and FLU were extracted by a solid-liquid extraction procedure: after addition of hydrochloric acid, extraction used successively ethyl acetate, sodium hydroxide and chloroform. Liquid chromatography was performed on a 5 microm PuroSpher RP-18E cartridge using acetonitrile and 0.02 M aqueous orthophosphoric acid solution as mobile phase, with fluorescence detection. The performance of the method was established by spiking tissues with OA and FLU before the freeze-drying step. The method was linear over the concentration range 50-2000 ng/g freeze-dried tissue. Limits of detection and quantitation were 3.2 and 16 ng/g wet weight tissue respectively both for OA and FLU. Mean extraction recoveries of OA and FLU from freeze-dried tissue were 85.5 and 85.2% respectively. The method is suitable as a regulatory one for determination of residues of OA and FLU in freeze-dried salmon tissue.

Analysis of quinolone residues in edible animal products

A comprehensive review on the analysis of quinolone antibacterials is presented. The review covers most of the methods described for the determination of quinolone residues in edible animal products. Sample handling, chromatographic conditions and detection methods have been discussed. A summary of the most relevant information about the analytical procedures has been included.

High-performance liquid chromatographic determination of oxolinic acid and flumequine in the live fish feed artemia

A high-performance liquid chromatography (HPLC) analytical method for the determination of oxolinic acid and flumequine in Artemia nauplii is described. The samples were extracted and cleaned up by a solid-phase extraction (SPE) procedure using SPE C18 cartridges. Oxolinic acid and flumequine were determined by reversed-phase HPLC using a mobile phase of methanol-0.1 M phosphate buffer, pH 3 (45:55, v/v) and a UV detection wavelength of 254 nm. Calibration curves were linear for oxolinic acid in the range of 0.2-50 microg/g (r2=0.9998) and for flumequine in the range of 0.3-50 microg/g (r2=0.9994). Mean recoveries amounted to 100.8% and 98.4% for oxolinic acid and flumequine, respectively. The quantification limit was 0.2 microg/g for oxolinic acid and 0.3 microg/g for flumequine. Quantitative data from an in vivo feeding study indicated excellent uptake of both drugs by Artemia nauplii.

Determination of oxolinic acid in faeces and urine of turbot (Scophthalmus maximus) by high-performance liquid chromatography using fluorescence detection

A procedure for the determination of oxolinic acid (OA) in faeces and urine of turbot (Scophthalmus maximus), using reversed-phase high-performance liquid chromatography is described. Liquid chromatography was performed on a 5-microm PuroSpher RP-18E cartridge using acetonitrile and 0.001 M aqueous orthophosphoric acid solution as mobile phase, with fluorescence detection. After the addition of an internal standard, oxolinic acid was extracted by using a liquid-liquid extraction procedure. Linearity and precision were checked over the concentration ranges 1.0-1000 microg/g (faeces) and 0.06-10.00 microg/ml (urine). Limits of detection of OA in faeces and urine were 0.20 microg/g and 0.02 microg/ml respectively. Mean extraction recoveries of OA from faeces and urine were 102.0 and 91.6% respectively.

High-performance liquid chromatographic determination of oxolinic acid in the plasma of seabass (Dicentrarchus labrax) anaesthetized with 2-phenoxyethanol

A high-performance liquid chromatographic (HPLC) method for the determination of oxolinic acid (OA) in the plasma of seabass (Dicentrarchus labrax) anaesthetized with 2-phenoxyethanol is described. The samples were extracted and cleaned up by a solid-phase extraction procedure using C18 extraction cartridges. After the eluent was evaporated, the dry residue was dissolved in 1/15 M phosphate buffer. OA was determined by using an isocratic HPLC method with UV detection at 340 nm. Seabass drug-free plasma samples were spiked with OA at 0.2, 1.0, 5.0 and 25.0 microg/ml. Validation of the method showed good precision and accuracy. The mean recovery was 92.2%, with a relative standard deviation lower than 5%. The quantification limit was 0.2 microg/ml. The method was tested on 300 plasma samples of OA-treated seabass.