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A rapid, sensitive, and selective precolumn derivatization method for the simultaneous determination of eight thiophenols using 3-(2-bromoacetamido)-<i>N</i>-(9-ethyl-9<i>H</i>)-carbazol as a labeling reagent by high-performance liquid chromatography with fluorescence detection has been developed. The labeling reagent reacted with thiophenols at 50°C for 50 min in aqueous acetonitrile in the presence of borate buffer (0.10 mol/L, pH 11.2) to give high yields of thiophenol derivatives. The derivatives were identified by online postcolumn mass spectrometry. The collision-induced dissociation spectra for thiophenol derivatives gave the corresponding specific fragment ions at <i>m/z</i> 251.3, 223.3, 210.9, 195.8, and 181.9. At the same time, derivatives exhibited intense fluorescence with an excitation maximum at λ<sub>ex</sub> = 276 nm and an emission maximum at λ<sub>em</sub> = 385 nm. Excellent linear responses were observed for all analytes over the range of 0.033-6.66 μmol/L with correlation coefficients of more than 0.9997. Detection limits were in the range of 0.94-5.77 μg/L with relative standard deviations of less than 4.54%. The feasibility of derivatization allowed the development of a rapid and highly sensitive method for the quantitative analysis of trace levels of thiophenols from some rubber products. The average recoveries (<i>n</i> = 3) were in the range of 87.21-101.12%.
• A new low toxic dual-UADLLME coupled with microwave-assisted derivatization was proposed. • 4′-Carboxy-substituted rosamine was firstly used as derivatization reagent. • Simultaneous determination of PPD and PPT in rat plasma was achieved by UHPLC-MS/MS. • This method was successfully applied to pharmacokinetics study.<br>This paper, for the first time, reported a speedy hyphenated technique of low toxic dual ultrasonic-assisted dispersive liquid-liquid microextraction (dual-UADLLME) coupled with microwave-assisted derivatization (MAD) for the simultaneous determination of 20(<b>S</b>)-protopanaxadiol (PPD) and 20(<b>S</b>)-protopanaxatriol (PPT). The developed method was based on ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) detection using multiple-reaction monitoring (MRM) mode. A mass spectrometry sensitizing reagent, 4′-carboxy-substituted rosamine (CSR) with high reaction activity and ionization efficiency was synthesized and firstly used as derivatization reagent. Parameters of dual-UADLLME, MAD and UHPLC-MS/MS conditions were all optimized in detail. Low toxic brominated solvents were used as extractant instead of traditional chlorinated solvents. Satisfactory linearity, recovery, repeatability, accuracy and precision, absence of matrix effect and extremely low limits of detection (LODs, 0.010 and 0.015 ng/mL for PPD and PPT, respectively) were achieved. The main advantages were rapid, sensitive and environmentally friendly, and exhibited high selectivity, accuracy and good matrix effect results. The proposed method was successfully applied to pharmacokinetics of PPD and PPT in rat plasma.
A green, simple and sensitive method was developed for the analysis of volatile carboxylic acids (VFAs) and perfluorocarboxylic acids (PFCAs) in food packaging materials. The acidic compounds in food packaging materials were first extracted by gas purge microsyringe extraction (GP-MSE) with 1.0 mL 0.1 mol·L<sup>−1</sup> NaOH solution, then the analytes were dispersive liquid-liquid microextracted (DLLME) by 50 μL chloroform as extraction solvent and 200 μL acetonitrile as dispersive solvent. The 2-(5-Benzoacridine) ethyl-p-toluenesulfonate (BAETS) with excellent fluorescence property was applied to enhance the high performance liquid chromatography (HPLC) sensitivity. The obtained recoveries for the VFAs ranged from 92.0 to 101 %. The method LODs calculated at a signal-to-noise ratio (S/N) of 3 were in the range of 0.80-3.40 μg·kg<sup>−1</sup>, while the LOQs calculated at S/N of 10 were in the range of 2.5-10.2 μg·kg<sup>−1</sup>. All compounds were in good linearity with concentration coefficients of higher than 0.997. Perfluorooctanoic acid (PFOA) was found in all of the 15 kinds of samples analyzed with concentrations ranging from 4.86-7.56 μg·kg<sup>−1</sup>. Acetic acid, butyric acid, and caprylic acid were found in half of the samples analyzed. The other analytes were also found in more than 30 % samples with concentrations varied between 3.96 and 293 μg·kg<sup>−1</sup>.
In this study, a green, simple, and sensitive method was developed for the analysis of aliphatic aldehyde s from fried meat by using a modified gas purge-microsyringe extraction (GP-MSE) system in combination with high-performance liquid chromatography (HPLC) with fluorescence detection. The modified GP-MSE system possessed two gas channels and showed better recoveries for compounds with diverse density in comparison with one gas channel GP-MSE system. Target compounds in fried meat were effectively extracted without the traditional solvent extraction and lipid removing process, while the HPLC sensitivity of aldehyde s was enhanced by introducing 2-(12-benzo[b]acridin-5(12H)-yl)-acetohydrazide (BAAH) with excellent fluorescence property into the molecules. Parameters influencing the extraction efficiency and HPLC sensitivity were optimized. The limits of detection (LODs) ranged from 0.30 to 0.45 μg/kg, and the limits of quantification (LOQs) ranged from 1.0 to 1.5 μg/kg. The recoveries of the target compounds were in the range of 86.9 to 95.6%. The proposed method was successfully applied to the analysis of aldehyde s in fried meat samples. Formaldehyde, acetaldehyde, pentanal, hexanal, heptanal, octanal, nonaldehyde, and decanal were all found in fried meat samples with concentrations ranging from 0.05 to 17.8 mg/kg.
The goal of the presented work is to develop a simple and sensitive high-performance liquid chromatography in combination with fluorescence detection (HPLC-FLD) method for the determination of four nitrofurans (NFs) metabolites compounds (semicarbazide (SEM), 1-aminohydantoin (AH), 3-amino-2-oxazolidinone (AOZ) and 3-amino-morpholinomethyl-2-oxazolidinone (AMOZ)) in foodstuffs. For this goal, we synthesized a novel fluorescence labeling reagent, 4-(carbazole-9-yl)-benzyl chloroformate (CBBC) to label NFs metabolites compounds. NFs metabolites compounds can be labeled rapidly only within 5 min at the room temperature (25 °C). The labeled derivatives showed excellent fluorescence property with maximum excitation and emission wavelengths of 375 nm and 410 nm, respectively. The labeled derivatives were analyzed on a reversed-phase Eclipse XDB-C18 column within 10 min. Excellent linearity (R2 > 0.995) of all NFs metabolites compounds was achieved with the limits of detection (LODs) and the limits of quantitations (LOQs) in the low micrograms per kilogram range of 0.20-0.30 μg·kg−1 and 0.70-1.00 μg·kg−1, respectively. Satisfactory recoveries in the range of 92.5-98.0% were obtained for all NFs metabolites compounds. Using the proposed HPLC-FLD method, we successfully determined four NFs metabolites compounds in different foodstuffs. As promising, this highly sensitive and reliable method would also be extended for the quantitation of NFs metabolites compounds in other samples.<br><br>Display Omitted<br>• A novel fluorescence labeling reagent CBBC was synthesized to label nitrofurans (NFs) metabolites compounds. • A pre-column derivatization HPLC-FLD method was developed for the determination of NFs metabolites compounds in foodstuffs. • LODs were in the low micrograms per kilogram range of 0.2-0.3 μg·kg-1.
Sample pretreatment is a critical and essential step in almost all analytical procedures, especially for the analysis of biological and environmental samples with complex matrices. Dopamine molecules can easily self-polymerize under weak alkaline conditions, leading to a facile deposition of polydopamine (PDA) coatings on various surfaces. Since 2011, PDA chemistry has undergone significant expansion in its applications and is becoming one of the most attractive areas within the materials field. Here, recent advancements in the use of PDA-derived adsorbents for sample pretreatment were reviewed, with especial focus on surface modification strategies, extraction modes, and application fields. In addition, prospects of PDA-derived adsorbents for sample pretreatment are also proposed.<br>• Analytical applications of PDA-derived adsorbents are insightfully reviewed. • PDA has been directly used as an adsorbent for building extraction methods. • PDA has also been used as versatile mediums for fabricating various adsorbents. • PDA has greatly promoted the diversity of extraction modes because of its adhesion.
A new and sensitive pre-column derivatization method was developed for the analysis of melamine leached from tableware by high performance liquid chromatography (HPLC) with fluorescence detection. The HPLC sensitivity was greatly enhanced by introducing 10-methyl-acridone-2-sulfonyl chloride (MASC) with excellent fluorescence property into the melamine molecule. Meanwhile, derivatization also greatly increased the hydrophobicity of melamine. Therefore, the common reversed phase column can be used for the HPLC analysis of highly hydrophilic melamine. The detection limit obtained by the proposed method was lower than 0.40 μg/L. This is the first time that HPLC with fluorescence detection was applied to the analysis of melamine. The proposed method was successfully applied to the analysis of melamine leached from tableware. The results indicated that the leaching of melamine from tableware was obvious when hot water or milk was added.<br>• HPLC with fluorescence detection was applied to the analysis of melamine for the first time. • Reversed phase HPLC analysis of melamine was achieved with no ion-pair reagents needed. • HPLC sensitivity was greatly enhanced through derivatization.