Abstract: Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is used for the multiplex detection and characterization of diverse analytes over a wide mass range directly from tissues. However, analyte coverage with MALDI MSI is typically limited to the more abundant compounds, which have m/z values that are distinct from MALDI matrix-related ions. On-tissue analyte derivatization addresses these issues by selectively tagging functional groups specific to a class of analytes, while simultaneously changing their molecular masses and improving their desorption and ionization efficiency. We evaluated electrospray deposition of liquid-phase derivatization agents as a means of on-tissue analyte derivatization using 2-picolylamine; we were able to detect a range of endogenous fatty acids with MALDI MSI. When compared with airbrush application, electrospray led to a 3-fold improvement in detection limits and decreased analyte delocalization. Six fatty acids were detected and visualized from...

Abstract: 2-amino-6-(piperazin-1-yl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (NPz) was rationally designed and synthesized as a rapid and facile fluorimetric derivatization reagent for detecting formaldehyde Compared with the other fluorimetric derivatization reagents, NPz possessed a marked advantage on the time consumption Upon addition of formaldehyde, NPz showed an obvious fluorescence enhancement at room temperature within 4 min The fluorescent test papers loaded with NPz were prepared and applied in the detection of formaldehyde qualitatively

Abstract: A sensitive and reliable method for the extraction, preconcentration, and determination of non-steroidal acidic anti-inflammatory drugs (ibuprofen, naproxen, and diclofenac) from biological samples has been developed using simultaneous derivatization and air-assisted liquid–liquid microextraction followed by gas chromatography–flame ionization detection. In this method, a mixture of an extraction solvent (chloroform) and a derivatizing agent (butyl chloroformate) is added into a glass test tube containing an aqueous sample of the analytes and picoline (catalyst). The mixture is dispersed by repeatedly aspirating and dispensing via a syringe. By this action, derivatization and extraction of the selected analytes is performed simultaneously. Under the optimal conditions, enrichment factors and extraction recoveries were obtained in the ranges 364–412 and 72–82 %, respectively. The linear ranges were broad with correlation coefficients higher than 0.995. Limits of detection were obtained in the ranges 0.06–3.30 and 0.24–13 ng mL−1 in urine and plasma samples, respectively. Limits of quantification were 0.21–9.2 ng mL−1 in urine and 0.84–37 ng mL−1 for plasma sample. Relative standard deviations were lower than 5.2 % for six repeated determinations at a concentration of 25 ng mL−1 of each analyte. Finally, the developed method was successfully applied to determine the selected analytes in urine and plasma samples.

Abstract: An HPLC method coupled to pre-column derivatization with 2,4-dinitrofluorobenzene (DNFB) was developed for simultaneous determination of 19 amino acids in tea infusion. The amino acid-derived samples were separated on a reversed-phase C18 column (4.6 × 250 mm) at 35 °C and monitored by an ultraviolet detector at 360 nm. Separation analysis showed a good resolution (Rs > 1.5) for most amino acids with a gradient elution of mobile phases at a flow rate of 1 ml min-1. Precision analysis revealed low repeatability errors with relative standard deviation (RSD) ranging from 0.11 to 1.53 % for retention times and 0.60 to 2.84 % for peak areas, and recovery rate ranged from 70.60 to 108.80 %. Linear calibration curves were well established at the concentrations ranging from 0.57 to 57.38 μg ml−1, with correlation coefficients R 2 ≥ 0.9918 for 19 detected amino acids. The superior stability of the amino acid derivatives at room temperature gave an advantage to simultaneous preparation of many samples and continuous analysis using auto sampler. The established method was successfully applied to separate and quantify amino acids in three tea cultivars, and the results indicated that the albino tea cultivars contained higher contents of total amino acid, theanine, γ-aminobutyric acid (GABA), glutamic acid (Glu), aspartic acid (Asp), and serine (Ser) than normal tea cultivar.

Abstract: Accurate and specific analysis of target molecules in complex biological matrices remains a significant challenge, especially when ultra-trace detection limits are required. Liquid chromatography with mass spectrometry is often the method of choice for bioanalysis. Conventional sample preparation and clean-up methods prior to the analysis of biological fluids such as liquid-liquid extraction, solid-phase extraction, or protein precipitation are time-consuming, tedious, and can negatively affect target recovery and detection sensitivity. An alternative or complementary strategy is the use of an off-line or on-line in situ derivatization technique. In situ derivatization can be incorporated to directly derivatize target analytes in their native biological matrices, without any prior sample clean-up methods, to substitute or even enhance the extraction and preconcentration efficiency of these traditional sample preparation methods. Designed appropriately, it can reduce the number of sample preparation steps necessary prior to analysis. Moreover, in situ derivatization can be used to enhance the performance of the developed liquid chromatography with mass spectrometry-based bioanalysis methods regarding stability, chromatographic separation, selectivity, and ionization efficiency. This review presents an overview of the commonly used in situ derivatization techniques coupled to liquid chromatography with mass spectrometry-based bioanalysis to guide and to stimulate future research.

Abstract: Hydrothermal liquefaction is a promising technique for the production of bio-oil. The process produces an oil phase, a gas phase, a solid residue, and an aqueous phase. Gas chromatography coupled with mass spectrometry is used to analyze the complex aqueous phase. Especially small organic acids and nitrogen-containing compounds are of interest. The efficient derivatization reagent methyl chloroformate was used to make analysis of the complex aqueous phase from hydrothermal liquefaction of dried distillers grains with solubles possible. A circumscribed central composite design was used to optimize the responses of both derivatized and nonderivatized analytes, which included small organic acids, pyrazines, phenol, and cyclic ketones. Response surface methodology was used to visualize significant factors and identify optimized derivatization conditions (volumes of methyl chloroformate, NaOH solution, methanol, and pyridine). Twenty-nine analytes of small organic acids, pyrazines, phenol, and cyclic ketones were quantified. An additional three analytes were pseudoquantified with use of standards with similar mass spectra. Calibration curves with high correlation coefficients were obtained, in most cases R 2 > 0.991. Method validation was evaluated with repeatability, and spike recoveries of all 29 analytes were obtained. The 32 analytes were quantified in samples from the commissioning of a continuous flow reactor and in samples from recirculation experiments involving the aqueous phase. The results indicated when the steady-state condition of the flow reactor was obtained and the effects of recirculation. The validated method will be especially useful for investigations of the effect of small organic acids on the hydrothermal liquefaction process.

Abstract: A simple, rapid, sensitive, selective, and environmentally friendly method, based on in situ derivatization ultrasound-assisted dispersive liquid–liquid microextraction (in situ DUADLLME) coupled with ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) using multiple reaction monitoring (MRM) mode has been developed for the simultaneous determination of food-related biogenic amines and amino acids. A new mass-spectrometry-sensitive derivatization reagent 4′-carbonyl chloride rosamine (CCR) was designed, synthesized, and first reported. Parameters and conditions of in situ DUADLLME and UHPLC-MS/MS were optimized in detail. Under the optimized conditions, the in situ DUADLLME was completed speedily (within 1 min) with high derivatization efficiencies (≥98.5%). With the cleanup and concentration of microextraction step, good analytical performance was obtained for the analytes. The results showed that this method was accurate and practical for quantification of biogenic amines...

Abstract: Carboxyl coatings are extensively used for adhesion promotion, bio-immobilization and surface reactions thanks to their reactivity towards nucleophilic groups and high wettability. The deposition of relatively stable carboxyl rich coatings using low-cost atmospheric pressure plasma processes is still challenging. This work is aimed at the investigation of the plasma copolymerization of maleic anhydride (MA) and C2H2 by atmospheric pressure dielectric barrier discharge. The quantification of the carboxyl groups is performed by X-ray photoelectron spectroscopy (XPS) C1s curve fitting and by derivatization with trifluoroethanol. The layer synthesized at optimized monomer flow rate and plasma power contains 5 at.% of carboxyl groups (determined by derivatization combined with XPS) and exhibits the thickness loss below 5% after 128 h in water. The influence of the MA:C2H2 ratio on the layer chemistry, morphology and stability is analyzed. (C) 2015 Elsevier B.V. All rights reserved.

Abstract: Fatty aldehydes are crucial substances that mediate a wide range of vital physiological functions, particularly lipid peroxidation. Fatty aldehydes such as acrolein and 4-hydroxynonenal (4-HNE) are considered potential biomarkers of myocardial ischemia and dementia, but analytical techniques for fatty aldehydes are lacking. In the present study, a comprehensive characterization strategy with high sensitivity and facility for fatty aldehydes based on derivatization and high-performance liquid chromatography-multiple reaction monitoring (HPLC-MRM) was developed. The fatty aldehydes of a biosample were derivatized using 2,4-bis(diethylamino)-6-hydrazino-1,3,5-triazine under mild and efficient reaction conditions at 37 °C for 15 min. The limit of detection (LOD) of the fatty aldehydes varied from 0.1 to 1 pg/mL, depending on the structures of these molecules. General MRM parameters were forged for the analysis of endogenous fatty aldehydes. “Heavy” derivatization reagents with 20 deuterium atoms were synthesi...

Abstract: A pre-column derivatization high-performance liquid chromatography (HPLC) method was developed and optimized to characterize and quantify the monosaccharides present in tea polysaccharides (TPS) isolated from Yingshuang green tea. TPS sample was hydrolyzed with trifluoroacetic acid, subjected to pre-column derivatization using 1-phenyl-3-methyl-5-pyrazolone (PMP), and separated on an Agilent TC-C18 column (4.6 mm × 250 mm, 5 μm) with UV detection at 250 nm. A mixture of ten PMP derivatives of standard monosaccharides (mannose, ribose, rhamnose, glucuronic acid, galacturonic acid, glucose, xylose, galactose, arabinose, and fucose) could be baseline separated within 20 min. Moreover, quantitative analysis of the component monosaccharides in Yingshuang green tea TPS was achieved, indicating the TPS consisted of mannose, ribose, rhamnose, glucuronic acid, galacturonic acid, glucose, xylose, galactose, and arabinose in the molar contents of 0.72, 0.78, 0.89, 0.13, 0.15, 0.36, 0.39, 0.36, 0.36, and 0.38 μM, respectively. Recovery efficiency for component monosaccharides from TPS ranged from 93.6 to 102.4% with RSD values lower than 2.5%. In conclusion, pre-column derivatization HPLC provides a rapid, reproducible, accurate, and quantitative method for analysis of the monosaccharide composition and contents in TPS, which may help to further explore the relationship between TPS monosaccharides isolated from different tea varieties and their biological activity.