Mousheng Liu

Aluminium sensitized spectrofluorimetric determination of fluoroquinolones in milk samples coupled with salting-out assisted liquid–liquid ultrasonic extraction

An aluminium sensitized spectrofluorimetric method coupled with salting-out assisted liquid-liquid ultrasonic extraction for the determination of four widely used fluoroquinolones (FQs) namely norfloxacin (NOR), ofloxacin (OFL), ciprofloxacin (CIP) and gatifloxacin (GAT) in bovine raw milk was described. The analytical procedure involves the fluorescence sensitization of aluminium (Al(3+)) by complexation with FQs, salting-out assisted liquid-liquid ultrasonic extraction (SALLUE), followed by spectrofluorometry. The influence of several parameters on the extraction (the salt species, the amount of salt, pH, temperature and phase volume ratio) was investigated. Under optimized experimental conditions, the detection limits of the method in milk varied from 0.009 μg/mL for NOR to 0.016 μg/mL for GAT (signal-to-noise ratio (S/N)=3). The relative standard deviations (RSD) values were found to be relatively low (0.54-2.48% for four compounds). The calibration graph was linear from 0.015 to 2.25 μg/mL with coefficient of determinations not less than 0.9974. The methodology developed was applied to the determination of FQs in bovine raw milk samples. The main advantage of this method is simple, accurate and green. The method showed promising applications for analyzing polar analytes especially polar drugs in various sample matrices.

Cloud-Point Extraction and Reversed-Phase High-Performance Liquid Chromatography for the Determination of Synthetic Phenolic Antioxidants in Edible Oils

A cloud-point extraction (CPE) method using Triton X-114 (TX-114) nonionic surfactant was developed for the extraction and preconcentration of propyl gallate (PG), tertiary butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) from edible oils. The optimum conditions of CPE were 2.5% (v/v) TX-114, 0.5% (w/v) NaCl and 40 min equilibration time at 50 °C. The surfactant-rich phase was then analyzed by reversed-phase high-performance liquid chromatography with ultraviolet detection at 280 nm, using a gradient mobile phase consisting of methanol and 1.5% (v/v) acetic acid. Under the studied conditions, 4 synthetic phenolic antioxidants (SPAs) were successfully separated within 24 min. The limits of detection (LOD) were 1.9 ng mL(-1) for PG, 11 ng mL(-1) for TBHQ, 2.3 ng mL(-1) for BHA, and 5.9 ng mL(-1) for BHT. Recoveries of the SPAs spiked into edible oil were in the range 81% to 88%. The CPE method was shown to be potentially useful for the preconcentration of the target analytes, with a preconcentration factor of 14. Moreover, the method is simple, has high sensitivity, consumes much less solvent than traditional methods, and is environment-friendly. Practical Application: The method established in this article uses less organic solvent to extract SPAs from edible oils; it is simple, highly sensitive and results in no pollution to the environment.

Vortex-Assisted Acid-Induced Cloud Point Extraction Coupled With Spectrofluorometry for the Determination of Fluoroquinolones in Environmental Water Samples

ABSTRACT The present work describes a simple and rapid extraction approach based on vortex-assisted acid-induced anionic surfactant sodium dodecyl sulfate-mediated extraction (vortex-assisted acid-induced cloud point extraction) prior to spectrofluorometry for the determination of four fluoroquinolones, including norfloxacin, ciprofloxacin, sarafloxacin, and gatifloxacin, in water samples (hospital wastewater, river water, lake water, and water from the inlet of a wastewater treatment plant). Sodium dodecyl sulfate and concentrated hydrochloric acid (12 mol/L) were used as extractants. The four fluoroquinolones were concentrated in the surfactant-rich phase after phase separation and were determined by a spectrofluorophotometer. Some parameters affecting the extraction efficiency, such as the type and amount of surfactant, the amount of acid, vortex treatment, and centrifugation, were optimized systematically. Under the optimized conditions, the proposed method showed good analytical features with linearity for all analytes in a wide range of 0.045–0.90 µg/mL and coefficients of determination no less than 0.9901. The limits of detection (S/N = 3) were 0.007, 0.010, 0.009, and 0.013 µg/mL for norfloxacin, ciprofloxacin, sarafloxacin, and gatifloxacin, respectively; good precisions expressed as the relative standard deviations were in the range of 0.9–3.7% (n = 6); and average recoveries at three spiking levels ranged from 83.0% to 96.7%. The results of the proposed method are comparable to those obtained from the high-performance liquid chromatography method (t-test, p = 0.05) and are reliable for determination of fluoroquinolones in environmental water samples.

Utility of 4-chloro-7-nitrobenzofurazan for the spectrofluorimetric determination of butylated hydroxyanisole and propyl gallate in foodstuffs.

UNLABELLED A spectrofluorimetric method is presented for the determination of 2 synthetic phenolic antioxidants (SPAs), butylated hydroxyanisole (BHA), and propyl gallate (PG) in foodstuffs. The proposed method is based on the derivatization of SPAs with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in phosphate buffer of pH 9.0 to yield a highly fluorescent brown product. The optimum experimental conditions have been studied carefully. Linear calibration curves were obtained over the concentration range of 0.20 to 40 μg mL⁻¹ for BHA, and 0.80 to 50 μg mL⁻¹ for PG, using NBD-Cl reagent. The detection limits were 18 ng mL⁻¹ for BHA, 55 ng mL⁻¹ for PG. Intra-day and inter-day relative standard deviations at 3 different concentrations were determined. The high recovery values indicate the accuracy of the proposed methods, and low relative standard deviation values indicate good precision. The results presented in this report show that the applied spectrofluorimetric method is acceptable for the determination of the 2 SPAs in the foodstuffs. Other SPAs, tertiary butyl hydroquinone and butylated hydroxytoluene in foodstuffs do not interfere with the proposed method. PRACTICAL APPLICATIONS In this spectrofluorimetric method, NBD-Cl as a derivation agent is used to detect synthetic phenolic antioxidants. The method specificity has been greatly improved; there was no interference from other commonly used phenolic substances.