Search results for " Analytical"
showing 10 items of 1453 documents
Improving Fractionation of Human Milk Proteins through Calcium Phosphate Coprecipitation and Their Rapid Characterization by Capillary Electrophoresis
2018
This work describes a simple sample pretreatment method for the fractionation of human milk proteins (into their two main groups, whey and caseins) prior to their analysis. The protein-extraction protocol is based on the addition of calcium phosphate to nonadjusted pH human milk. The combination of calcium ions with phosphate results in an effective coprecipitation of caseins. To assess the suitability of this fractionation protocol, the protein extracts were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), LC-MS/MS, and capillary electrophoresis (CE) analysis. The results evidence a significant decrease in contamination of casein fraction with whey proteins…
Application of integrative cloud point extraction and concentration for the analysis of polyphenols and alkaloids in mulberry leaves
2018
Abstract A simple and efficient method based on cloud point extraction and concentration combined with high performance liquid chromatography was developed for the simultaneous separation and determination of five target compounds (deoxynojirimycin, chlorogenic acid, rutin, isoquercitrin and astragalin) in mulberry leaves samples. Firstly, to obtain a high extraction rate, the ultrasound assisted extraction was developed on acid modified Triton X-114 system. Under the optimal conditions, the total maximum extraction yields of five target compounds reached 20.80 mg/g, which was superior to conventional solvent extraction. After the cloud point extraction and concentration, the HPLC analysis …
Fluxapyroxad Haptens and Antibodies for Highly Sensitive Immunoanalysis of Food Samples
2017
Fluxapyroxad is a new-generation carboxamide fungicide, with residues increasingly being found in food samples. Immunochemical assays have gained acceptance in food quality control as rapid, cost-effective, sensitive, and selective methods for large sample throughput and in situ applications. In the present study, immunoreagents to fluxapyroxad were obtained for the first time, and competitive immunoassays were developed for the sensitive and specific determination of fluxapyroxad residues in food samples. Two carboxyl-functionalized analogues of fluxapyroxad were prepared, and antibodies with IC50 values in the low nanomolar range were generated from both haptens, though a dissimilar respo…
Phenolic profiles of raw mono- and polyfloral honeys from Latvia
2021
Abstract The phenolic compound profiles of 393 raw mono- and polyfloral Latvian honey samples were investigated using a targeted ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) method. This strategy allowed simultaneous determination of the content of 11 phenolic acids, 18 flavonoids, 2 plant hormones, and 3 water-soluble vitamins in honey samples of botanically diverse origin, including buckwheat (Fagopyrum esculentum), heather (Calluna vulgaris), linden (Tilia cordata), and rapeseed (Brassica napus). Honey samples were collected directly from the beekeepers and were analyzed in their natural, raw form. A selective high-throughput analysis was im…
Identification of Potential Distinguishing Markers for the Use of Cannabis-Based Medicines or Street Cannabis in Serum Samples
2021
Increasing prescription numbers of cannabis-based medicines raise the question of whether uptake of these medicines can be distinguished from recreational cannabis use. In this pilot study, serum cannabinoid profiles after use of cannabis-based medicines were investigated, in order to identify potential distinguishing markers. Serum samples after use of Sativex®, Dronabinol or medical cannabis were collected and analyzed for 18 different cannabinoids, using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Analytes included delta-9-tetrahydrocannabinol, 11-hydroxy-tetrahydrocannabinol, 11-nor-9-carboxy-tetrahydrocannabinol, cannabidiol, cannabinol, cannabigerol, …
An automated and self-cleaning nano liquid chromatography mass spectrometry platform featuring an open tubular multi-hole crystal fiber solid phase e…
2017
An open tubular (OT) sample preparation/separation platform was developed. A multi-channel polymer layer open tubular (mPLOT) solid phase extraction (SPE) column was prepared by wall-coating the 126 channels (8μm inner diameter (ID) each) of a crystal fiber capillary with an organic polymer, namely poly(styrene-co-octadecene-co-divinylbenzene) (PS-OD-DVB). The mPLOT SPE was coupled on-line with a 10μm×2m poly(styrene-co-divinylbenzene) (PS-DVB) OT liquid chromatography column with nanospray mass spectrometry (OTLC-MS). Compared to using monolithic/particle-packed SPEs, mPLOT-SPE-OTLC allowed both fast loading and sufficient refocusing on the OT analytical column of small model compounds (su…
Quantitative Analysis of Terpenic Compounds in Microsamples of Resins by Capillary Liquid Chromatography
2019
A method has been developed for the separation and quantification of terpenic compounds typically used as markers in the chemical characterization of resins based on capillary liquid chromatography coupled to UV detection. The sample treatment, separation and detection conditions have been optimized in order to analyze compounds of different polarities and volatilities in a single chromatographic run. The monoterpene limonene and the triterpenes lupeol, lupenone, &beta
Application of molecularly imprinted polymers in analytical chiral separations and analysis
2018
Over the last two decades the process of development and application of a new types of molecular imprinted polymer (MIP) sorbents in the field of analytical chemistry have been widely described in the literature. One of the new trends in analytical chemistry practice is the use of new types of MIP sorbents as specific sorption materials constituting the stationary phase in advanced separation techniques. The following review paper contains comprehensive information about the application of a specific and well defined MIP sorbents (with the data base in the paper about the reagents used in MIP preparation process) as stationary phases in separation techniques including high performance liqui…
Comparison of δ(13)C and δ(18)O from cellulose, whole wood, and resin-free whole wood from an old high elevation Pinus uncinata in the Spanish centra…
2016
δ(13)C and δ(18)O values from sapwood of a single Pinus uncinata tree, from a high elevation site in the Spanish Pyrenees, were determined to evaluate the differences between whole wood and resin-free whole wood. This issue is addressed for the first time with P. uncinata over a 38-year long period. Results are also compared with published isotope values of α-cellulose samples from the same tree. The differences in δ(13)C and δ(18)O between whole wood and resin-free whole wood vary within the analytical uncertainty of 0.3 and 0.5 ‰, respectively, indicating that resin extraction is not necessary for sapwood of P. uncinata. Mean differences between cellulose and whole wood are 0.9 ‰ (δ(13)C)…
Sensor Properties of Pristine and Functionalized Carbon Nanohorns
2016
Nanodispersions of pristine single-wall carbon nanohorns (i.e., p-SWCNHs) and oxidized-SWCNHs (i.e.; o-SWCNHs) were used to modify screen printed electrode (SPE). p-SWCNHs and o-SWCNHs were fully characterized by using several analytical techniques, as: HR-TEM (High Resolution-Transmission Electron Microscopy), FE-SEM/EDX (Field Emission-Scanning Electron Microscopy/Energy Dispersive X-ray Analysis), Raman spectroscopy, thermogravimetric analysis, differential thermal analysis (DTA), and the Brunauer-Emmett-Teller (BET) method. The chemically modified SPEs were also characterized with Cyclic Voltammetry (CV), using several different electro-active targets. In all cases, p-SWCNHs showed bett…