Single-drop microextraction for the determination of manganese in seafood and water samples

A novel direct-immersion single-drop microextraction combined with digital colorimetry applied to the determination of vanadium in water

In this study, a method based on direct-immersion single-drop microextraction was developed for the determination of vanadium in water. The detection system uses digital images obtained directly from the solvent drop after the sorption of V(V). The extraction solvent used was the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C₆MIM][PF₆]). The images were obtained directly from the solvent drop, with the aid of a camera. The digital images were stored, and the RGB (red, green, and blue) data were obtained. The data collected by the red channel were used to construct the analytical curve since it showed higher sensitivity compared with green and blue channels. Under optimized conditions, the method presented an enrichment factor of 50 and a limit of detection of 0.6 μg L^-1 for 3.5 mL sample volume. The limit of quantification and the relative standard deviation (50.0 μg L^-1) obtained were 1.8 μg L^-1 and 4.8%, respectively. Certified reference material (Plankton) was used to assess the accuracy of the method. The simple, fast, efficient, and low-cost procedure was successfully applied to the determination of V(V) in water samples. The proposed method is also following the principles of green chemistry since it uses minimal volumes of samples, reagents, and solvents and yields a small amount of waste.

Miniaturized sample preparation techniques and ambient mass spectrometry as approaches for food residue analysis

Analytical methods such as liquid chromatography (LC) and mass spectrometry (MS) are widely used techniques for the analyses of different classes of compounds. This is due to their highlighted capacity for separating and identifying components in complex matrices such food samples. However, in most cases, effective analysis of the target analyte becomes challenging due to the complexity of the sample, especially for quantification of trace concentrations. In this case, miniaturized sample preparation methods have been used as a strategy for analysis of complex matrices. This involves removing the interferents and concentrating the analytes in a sample. These methods combine simplicity and effectiveness and given their miniaturized scale, they are in accordance with green chemistry precepts. Besides, ambient mass spectrometry represents a new trend in fast and rapid analyses, especially for qualitative and screening analysis. However, for complex matrix analyses, sample preparation is still a difficult step and the miniaturized sample preparation techniques show great potential for an improved and widespread use of ambient mass spectrometry techniques. . This review aims to contribute as an overview of current miniaturized sample preparation techniques and ambient mass spectrometry methods as different approaches for selective and sensitive analysis of residues in food samples.

Ultrasound-assisted synthesis of thermosensitive nanovesicle for direct trap and release of analgesic drugs in biofluid and sewage

An environmentally friendly thermosensitive nanovesicle-cloud point microextraction technique has been developed with the assistant of ultrasonic waves to determine analgesic drugs with a broad range of polarity in field water and human urine. Based on thin-film hydration, the conformation of nanovesicles formed by a binary mixing system with the nonionic surfactants was evaluated using regular and cryogenic transmission electron microscopy. The multilayered nano-spherical structure was able to capture polar and nonpolar compounds simultaneously. Analgesic drugs (acetaminophen, salicylic acid, ketoprofen, diclofenac, indomethacin, ibuprofen, and mefenamic acid) were detected by ultra-performance liquid chromatography coupled to photodiode array detection. Under optimal conditions including the type and ratio of surfactants, sonication time and sonication temperature, linear calibration curves were obtained over the range of 50-8000 μg L^-1. The coefficient of determination (R²) ranged from 0.9953 to 0.9995, with detection limits of 10-100 μg L^-1. The relative standard deviations ranged from 3.2% to 12.7% for intraday precision (n = 5) and 2.5% to 14.1% for interday precision (n = 15). The relative recoveries obtained from one industrial wastewater sample and two field water samples ranged from 86.1% to 108.1%. In the human urine analysis, three volunteers ingested 1500 mg of acetaminophen. After 4 h, the concentration of acetaminophen in the urine was found to range from 87.0 to 197.9 mg L^-1.

Large volume of water samples introduced in dispersive liquid-liquid microextraction for the determination of 15 triazole fungicides by gas chromatography-tandem mass spectrometry

A novel method of large volume of water samples directly introduced in dispersive liquid-liquid microextraction was developed, which is based on ultrasound/manual shaking-synergy-assisted emulsification and self-generating carbon dioxide gas (CO2) breaking down the emulsion for the determination of 15 triazole fungicides by gas chromatography-tandem mass spectrometry. This technique makes low-density extraction solvent toluene (180 μL) dissolve in 200 mL of samples containing 0.05 mol L(-1) of HCl and 5 % of NaCl (w/v) to form a well emulsion by synergy of ultrasound and manual shaking, and injects NaHCO3 solution (1.0 mol L(-1)) to generate CO2 achieving phase separation with the assistance of ultrasound. The entire process is accomplished within 8 min. The injection of NaHCO3 to generate CO2 achieves phase separation that breaks through the centrifugation limited large volume aqueous samples. In addition, the device could be easily cleaned, and this kind of vessel could be reconfigured for any volume of samples. Under optimal conditions, the low limits of detection ranging from 0.7 to 51.7 ng L(-1), wide linearity, and enrichment factors obtained were in the range 924-3669 for different triazole fungicides. Southern end of the Beijing-Hangzhou Grand Canal water (Hangzhou, China) was used to verify the applicability of the developed method. Graphical Abstract Flow chart of ultrasound/manual shaking-synergy-assisted emulsification and self-generating carbon dioxide gas breaking down the emulsion.