Ultra-high Performance Liquid Chromatography Analysis Research Articles

Ultrahigh Performance Liquid Chromatography Analysis of Volatile Carbonyl Compounds in Virgin Olive Oils

The enzymatic and chemical oxidation reaction in olive oil produces many volatile carbonyl compounds that contribute to the complex flavor of olive oil. A novel ultrahigh performance liquid chromatography (UHPLC) method with dynamic headspace sampling and 2,4-dinitrophenylhydrazine (DNPH) derivatization were established to determine the volatile carbonyls in virgin olive oil. Quantification of nine characteristic carbonyls (acetone, hexanal, E-2-hexenal, octanal, E-2-octenal, nonanal, E-2-nonenal, E,E-2,4-nonadienal, and E,E-2,4-decadienal) was achieved using cyclopentanal as an internal standard. This method provides comparable linearity (R(2) = 0.9917-1.0000) and repeatability (less than 7.6% relative standard deviations) with solid phase microextraction gas chromatography (SPME-GC). The relative standard deviations (%RSD) of all applied carbonyl standards were lower than 7.6%. The limits of detection (LOD) and quantification (LOQ) were in the ranges of 1.6-150.1 and 4.8-906.1 μg/kg. The recoveries obtained for olive oil samples were in the range of 81.0-115.3%. To show the potential of this method on the quantification of other volatile carbonyls that were not included in this study, GC-electron ionization mass spectrometry (GC-EI/MS) was employed to identify the derivatized carbonyls (carbonyl (2,4-DNPH) hydrazones) while peak assignments were made on the basis of elution sequences and peak areas. This method provided feasibility of using LC to determine volatile carbonyls in oil matrices, which can be applied to exam the degree of lipid oxidation and evaluate the sensory properties of VOO and other edible oils.

Comparison of a new high-resolution monolithic column with core-shell and fully porous columns for the analysis of retinol and α-tocopherol in human serum and breast milk by ultra-high-performance liquid chromatography†

The reduction of analysis time, cost, and improvement of separation efficiency are the main requirements in the development of high-throughput assay methods in bioanalysis. It can be achieved either by ultra-high-performance liquid chromatography (UHPLC) using stationary phases with small particles (<2 μm) at high back pressures or by using opposite direction--monolithic stationary phases with low back pressures. The application of new types of monolithic stationary phases for UHPLC is a novel idea combining these two different paths. The aim of this work was to test the recently introduced second-generation of monolithic column Chromolith® HighResolution for UHPLC analysis of liposoluble vitamins in comparison with core-shell and fully porous sub-2 μm columns with different particle sizes, column lengths, and shapes. The separation efficiency, peak shape, resolution, time of analysis, consumption of mobile phase, and lifetime of columns were calculated and compared. The main purpose of the study was to find a new, not only economical option of separation of liposoluble vitamins for routine practice.

Biochemical Composition, Antimicrobial Activities,and Anti–Quorum-Sensing Activities of Ethanol and Ethyl Acetate Extracts fromHypericum connatumLam. (Guttiferae)

We studied the polyphenol composition and antioxidant activity of the ethanolic and ethyl acetate extracts of Hypericum connatum (Guttiferae), in addition to their antimicrobial and antiquorum-sensing (AQS) properties. The extracts exhibited a similar polyphenol content and a notable antioxidant activity, which was stronger in the ethanolic extract (EC50=3.2 μg/mL). Ultrahigh-performance liquid chromatography analyses revealed different polyphenol profiles, with rutin and apigen being the main components of the ethanolic extract and caffeic acid, (-)-epicatechin and p-coumaric acid being abundant in the ethyl acetate extract. The ethyl acetate extract exhibited a more effective antimicrobial activity than the ethanolic extract against the pathogens Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa. For the first time, AQS activity was detected in H. connatum: the ethanolic extract inhibited the production of violacein, a quorum-sensing-regulated pigment, in a Chromobacterium violaceum tester strain, without interfering with its growth.

UHPLC as a suitable methodology for the analysis of carotenoids in food matrix

The purpose of this paper was to optimize an ultra-high performance liquid chromatography (UHPLC) method for the determination and quantification of carotenoid pigments in food products and compare it with a HPLC method in terms of resolution, selectivity, sensitivity, time and reagent saving. Less analysis times, solvent consumption and better peak resolution were achieved when the UHPLC methodology was used. Ultra-high performance liquid chromatography analysis was performed on Zorbax Eclipse Plus C18 column (2.1 × 50 mm; 1.8 μm) using a gradient solvent system and diode array detector. A total of seven carotenoids were separated and quantified in <8.5 min. For all components, the resolution was higher than 1.5 and LOD was below 1.0 μg mL−1. To determine the intraday and reproducibility, assays were conducted in 10 continuous days for method validation achieving recuperation rates ranging between 85 and 100 % and no significant differences among the results obtained in same and different days. The proposed methodology was applied for the determination of the carotenoid contents in honeybee pollen samples, pumpkin and nectarine flesh with satisfactory recovery.

ChemInform Abstract: Analytical Tools for the Analysis of Carotenoids in Diverse Materials

AbstractReview: 99 refs.

&amp;lt;i&amp;gt;In Vitro&amp;lt;/i&amp;gt; Characterization of the Efficacy and Safety Profile of a Proprietary Ajuga Turkestanica Extract

Ajuga Turkestanica, an herbaceous flowering species in the mint family, has been traditionally used in Turkeyand Uzbekistan for heart disease, muscle aches and stomach problems. Due to its high levels of phytoecdysteroids (particularly the characteristic C-11-hydroxylated Turkesterone), anabolic properties have also been reported. The aim of our study was to screen for early signs of efficacy and safety of a proprietary Ajuga turkestanica extract (ATE) using in vitro models. C2C12 mouse myotube cell line was used to study potential effects on viability and gene modulation. Cell viability was evaluated with different concentrations [0.2 - 200 ppm (mg/L)] of ATE. Gene modulation was assessed by quantitative polymerase chain reaction (qRT-PCR) after 6h incubation (ATE vs. the androgenic anabolic steroid methandrostenolone). Total androgenic activity was measured using the A-SCREEN bioassay. Ultra-high performance liquid chromatography analysis showed good correlation between the phytochemical profile of the native plant and our ATE. C2C12 mouse myotube cells treated with ATE experienced no significant loss of viability (concentrations 0.2 - 200 ppm, 1 - 24 hs, p > 0.05). qRT-PCR array analysis showed significant (p regulation of Caspase-3 (2-fold) and Myostatin (4-fold). The extract showed no androgenic activity within the dose range used. Our results indicate the potential for an ATE to support muscle mass without typical androgenic side effects of synthetic anabolic drugs.

Suitability of ultra-high performance liquid chromatography for the determination of fat-soluble nutritional status (vitamins A, E, D, and individual carotenoids)

Our aim was to assess the suitability of ultra-high performance liquid chromatography (UHPLC) for the simultaneous determination of biomarkers of vitamins A (retinol, retinyl esters), E (alpha- and gamma-tocopherol), D (25-OH-vitamin D), and the major carotenoids in human serum to be used in clinical practice. UHPLC analysis was performed on HSS T3 column (2.1 x 100 mm; 1.8 microm) using gradient elution and UV-VIS detection. The system allows the simultaneous determination of retinol, retinyl palmitate, 25-OH-vitamin D, alpha- and gamma-tocopherol, lutein plus zeaxanthin, alpha-carotene, beta-carotene, alpha- and beta-cryptoxanthin and lycopene. The method showed a good linearity over the physiological range with an adequate accuracy in samples from quality control programs. Suitability of the method in clinical practice was tested by analyzing samples (n = 286) from patients. In conclusion, UHPLC constitutes a reliable approach for nutrient/biomarker profiling allowing the rapid, simultaneous and low-cost determination of vitamins A, E, and D (including vitamers and ester forms) and the major carotenoids in clinical practice.