Determination of caffeoylquinic acids in feed and related products by focused ultrasound solid–liquid extraction and ultra-high performance liquid chromatography–mass spectrometry

Targeted quantitative analysis of monoterpenoid indole alkaloids in Alstonia scholaris by ultra-high-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry

Monoterpene indole alkaloids exhibit structural diversity in herbal resources and have been developed as promising drugs owing to their significant biological activities. Confidential identification and quantification of monoterpene indole alkaloids is the key to quality control of target plants in industrial production but has rarely been reported. In this study, quantitative performance of three data acquisition modes of ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry including full scan, auto-MS2 and target-MS2 , was evaluated and compared for specificity, sensitivity, linearity, precision, accuracy, and matrix effect using five monoterpene indole alkaloids (scholaricine, 19-epi-scholaricine, vallesamine, picrinine, and picralinal). Method validations indicated that target-MS2 mode showed predominant performance for simultaneous annotation and quantification of analytes, and was then applied to determine monoterpene indole alkaloids in Alstonia scholaris (leaves, barks) after extraction procedures optimization using Box-Behnken design of response surface methodology. The variations of A. scholaris monoterpene indole alkaloids in different plant parts, harvest periods, and post-handling processes, were subsequently investigated. The results indicated that target-MS2 mode could improve the quantitative capability of ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry for structure-complex monoterpene indole alkaloids in herbal matrices. Alstonia scholaris, monoterpene indole alkaloids, quadrupole time of flight mass spectrometry, qualitative and quantitative analysis, ultra-high-performance liquid chromatography.

Pressurized hot water extraction of bioactive compounds from artichoke by-products

Artichoke by-products are a suitable source of health-promoting ingredients for the production of dietary supplements and food additives. A pressurized hot water extraction (PHWE) was developed to recover caffeoylquinic acids (CQAs) and flavone glycosides (FLs) from agro-industrial artichoke by-products. The main factors influencing PHWE efficiency and CQA isomerization (temperature, numbers of cycles, modifier, and extraction time) were carefully studied and optimized by response surface design. The proposed PHWE procedure provides an exhaustive extraction of CQAs and FLs (recoveries: 93-105% and 90-105%) from artichoke external bracts and leaves of different cultivars (p > 0.05), without significant formation of artefacts generated by high temperatures. PHWE extracts showed CQA and FL levels (14-37 mg/g and 3-19 mg/g, respectively) comparable to commercial products and marked antioxidative effects (EC50 11-83 μg/mL) by cellular antioxidant activity assay in human hepatocarcinoma HepG2 cells. These results proved that PHWE is an excellent green technique to recover bioactive compounds from artichoke agro-industrial residues.

Application of Focused Ultrasound-Assisted Extraction for the Quantification of Persistent Organic Pollutions in Liver Tissue of Giant Toad (Rhinella marina)

A simple and rapid focused ultrasound extraction method was developed for the determination of Persistent Organic Pollutants (POPs) in liver tissue obtained of giant toad (Rhinella marina) using a gas chromatography coupled to a mass detector with electron impact ionization. The performed method for POPs, was validated in fortified matrix, showing linearity from the LOQ up to 100 ng/mL; LODs and LOQs for each compound were between 1.7 and 4.8 and 3.5-7.5 ng/mL, respectively. Recovery rates were among 79%-116% for POPs determined. Finally, the method was applied in liver samples of giant toads found in a malarial area in Mexico. The sensitivity of the proposed method was good enough to ensure reliable determination of target analytes at concentration levels commonly found in this kind of samples.

Optimizing Mass Spectrometry Analyses: A Tailored Review on the Utility of Design of Experiments

Mass spectrometry (MS) has emerged as a tool that can analyze nearly all classes of molecules, with its scope rapidly expanding in the areas of post-translational modifications, MS instrumentation, and many others. Yet integration of novel analyte preparatory and purification methods with existing or novel mass spectrometers can introduce new challenges for MS sensitivity. The mechanisms that govern detection by MS are particularly complex and interdependent, including ionization efficiency, ion suppression, and transmission. Performance of both off-line and MS methods can be optimized separately or, when appropriate, simultaneously through statistical designs, broadly referred to as "design of experiments" (DOE). The following review provides a tutorial-like guide into the selection of DOE for MS experiments, the practices for modeling and optimization of response variables, and the available software tools that support DOE implementation in any laboratory. This review comes 3 years after the latest DOE review (Hibbert DB, 2012), which provided a comprehensive overview on the types of designs available and their statistical construction. Since that time, new classes of DOE, such as the definitive screening design, have emerged and new calls have been made for mass spectrometrists to adopt the practice. Rather than exhaustively cover all possible designs, we have highlighted the three most practical DOE classes available to mass spectrometrists. This review further differentiates itself by providing expert recommendations for experimental setup and defining DOE entirely in the context of three case-studies that highlight the utility of different designs to achieve different goals. A step-by-step tutorial is also provided.

Development of an analytical method for the determination of polyphenolic compounds in vegetable origin samples by liquid chromatography and pulsed amperometric detection at a glassy carbon electrode

A sensitive and accurate method for the determination of polyphenolic compounds in artichoke bract extracts and olive mill wastewaters by liquid chromatography coupled with pulsed amperometric detection at a glassy carbon working electrode was developed. Preliminary experiments were carried out by cyclic voltammetry to investigate the electrochemical behavior of polyphenols under different mobile phase compositions, and to test the detection and cleaning electrode potentials. Chromatographic separations were performed by using a core-shell C18 column, eluted with acetic acid and acetonitrile, by combined concave-linear binary gradients. Under the optimized experimental conditions, a good column efficiency and peak symmetry were observed, also for stereo and positional isomeric compounds. The developed three-step potential waveform for pulsed amperometric detection was successfully applied for the sensitive chromatographic determination of polyphenols in artichoke extracts and olive mill wastewaters. Linearity, precision and sensitivity of the proposed method have been evaluated. A wide linear range of response (up to 20 mg/L) has been obtained for all the investigated compounds. Detection and quantification limits in the vegetable origin sample extracts were in the range 0.004-0.6 mg/L and 0.01-2mg/L, respectively, while the injection-to-injection repeatability (n=6) ranged from 5 to 13%. The obtained results confirmed the excellent sensitivity of the electrochemical detection, and its suitability for the determination of electroactive polyphenolic compounds at low concentration levels.