Hollow-Fiber Liquid-Phase Microextraction Followed by Gas Chromatography Flame Ionization Detection for the Determination of Amitraz in Honey and Water Samples

Covalent organic framework reinforced hollow fiber bar for extraction and detection of bisphenols from beverages

Bisphenols (BPs) can migrate from packaging materials into foods, resulting in potentially harmful residues. For example, accumulation of BPs is associated with endocrine disorders. Owing to matrix effects, development of an effective and eco-friendly sample pretreatment would be helpful for BPs detection in beverages packed in plastic containers. In this work, an extraction bar, composed of hollow fiber (HF) functionalized with covalent organic frameworks (COF@Tp-NDA) and 1-ocanol, was prepared for extraction of five BPs simultaneously. The synergistic effect of COF@Tp-NDA and 1-octanol improved the extraction efficiency of BPs from milk-based beverage, juice, and tea beverage. Under optimal conditions, limits of detection ranged from 0.10 to 2.00 ng mL-1 (R2 ≥ 0.9974) and recoveries ranged from 70.1 % to 106.8 %. This method has the potential to enrich BPs, supporting their accurate determination in complex beverages.

Three-phase hollow fiber liquid-phase microextraction combined with HPLC for determination of three trace acidic plant growth regulators in Anoectochilus roxburghii (Wall.) Lindl

The analysis of plant growth regulators presents a challenge due to their trace quantities and complex matrices. A novel, simple, and effective analytical method for the determination of three trace acidic plant growth regulators in Anoectochilus roxburghii (Wall.) Lindl was developed to address this issue. Three-phase hollow fiber liquid-phase microextraction combined with high-performance liquid chromatography was applied for the enrichment, purification, and determination of three acidic plant growth regulators, namely, indole-3-acetic-acid, indole-3-butyric-acid, and (+)-abscisic acid. The factors affecting extraction performance, including extractant species, pH of donor and acceptor phases, salt addition dosage, extraction time, temperature, and stirring rate, were investigated and optimized. Under optimum conditions, the proposed method provided good linearity (R² , 0.9994-0.9999), low limit of detection (0.038-0.12 ng/mL), and acceptable relative recoveries (56.7-117.6%). The enrichment factors were between 153 and 328. The developed method was successfully applied to the enrichment and determination of plant growth regulators in Anoectochilus roxburghii (Wall.) Lindl and exhibited increased purification capacity, higher sensitivity, and decreased organic solvent consumption compared with conventional sample preparation methods. This method may provide a testing platform for the monitoring of plant growth regulator residues, ensuring the safe and effective use of traditional Chinese medicine.

Hollow fiber liquid-phase microextraction based on the use of a rotating extraction cell: A green approach for trace determination of rhodamine 6G and methylene blue dyes

In this work, a novel mode of hollow fiber liquid-phase microextraction (HF-LPME) technique namely rotating extraction cell solvent bar microextraction (REC-SBME) was introduced. The proposed method was applied for the preconcentration of methylene blue (MB) and rhodamine 6G (RG) in some real samples, including soft drink, lipstick, environmental water, and wastewater samples. In the extraction setup, two pieces of hollow fibers were fixed on a mechanical support and immersed in a rotating extraction cell containing the sample solution during the extraction process. The rotation of the extraction cell by using an electric motor led to an enhancement in the mass transfer of the dyes from the sample solution into the organic acceptor phase. In the developed procedure, the UV-Vis spectrophotometry and HPLC-UV/Vis were employed as detection methods for the analysis of the acceptor phase and the obtained results were compared. Optimization of the extraction factors affecting the method, including organic solvent type, sample solution pH, extraction time, rotational rate, the volume of sample and acceptor solutions, salt addition, and temperature was performed in order to obtain the best preconcentration factor. Linear dynamic range obtained by HPLC-UV/Vis and spectrophotometry was observed in the ranges of 2.5-1200 ng mL^-1 for RG and 1.6-600 ng mL^-1 for MB with R² more than 0.9971. Also, relative standard deviation (RSD) values (n = 3) less than 3.8% were obtained. The good conformity of the obtained results makes UV-Vis spectrophotometric method an ideal tool for routine analysis of trace dyes in the complex matrices after REC-SBME.

Simultaneous determination of amitraz, chlordimeform, formetanate and their main metabolites in human urine by high performance liquid chromatography-tandem mass spectrometry

A rapid, simple and reliable high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for simultaneous determination of amitraz, chlordimeform, formetanate and their main metabolites, N-(2,4-dimethylphenyl)-N-methyl-formamidine (DMPF), 2,4-dimethylformamidine (DMF), 2,4-dimethylaniline (DMA), 4-chloro-2-methylaniline and 3-hydroxyacetanilide in human urine. The urine samples were mixed with buffer solutions (pH 8) and subsequently cleaned up by solid supported liquid/liquid extraction (SLE). The target analytes were efficiently separated with a Waters Atlantis T3 column (150mm×4.6mm, 5μm), ionized with electrospray ion source in positive mode, and quantitatively determined by tandem mass spectrometry in the multiple reaction monitoring (MRM) mode. In order to minimize matrix effects, the matrix-matched calibration curves of eight analytes were adopted with correlation coefficients (R²) above 0.99. The method were further validated by determining the limits of detection (LODs, 0.3-0.6ng/mL), the limits of quantitation (LOQs, 1.0-2.0ng/mL) and recoveries (89.1%-108.4%) with intra-day and inter-day relative standard deviation (RSD, <11%). The established method was applied and demonstrated in a real case by assaying a urine sample from a female poisoned by formetanate. The achieved results proved this method to be rapid, sensitive and accurate for simultaneous quantitation of eight analytes in human urine for intended forensic cases of human poisoning.