Authors:L. Taujenis, V. Olšauskaitė, and A. Padarauskas
A reliable, sensitive and rapid method for determination of nicotine and three minor alkaloids (cotinine, anabasine and nornicotine) in tobacco by ultra-high performance liquid chromatography in hydrophilic interaction chromatography mode coupled with tandem mass spectrometry (HILIC-MS/MS) has been established. HILIC separation was performed on a BEH HILIC column using isocratic elution at 0.5 mL/min with acetonitrile:water (85:15, v/v) mobile phase containing 5 mmol/L ammonium acetate (pH 5.00). Separated analytes were determined by electrospray ionization MS/MS in the positive ion mode using multiple reaction monitoring. Alkaloids from tobacco were extracted in an ultrasonic bath for 10 min with acetonitrile:water mixture (8:2, v/v) containing 5 mmol/L ammonium acetate (pH 5.00). Limits of quantification were 10 μg/g for cotinine, 20 μg/g for anabasine and nornicotine, and 30 μg/g for nicotine. Mean recoveries from tobacco ranged between 94.8% and 104.1% for different analytes with relative standard deviations within 5%. The performance of the proposed method was tested for the extraction and determination of the four alkaloids in cigarette tobacco fillers, and satisfactory results were achieved.
Hydrophilic interaction chromatography (HILIC) is a liquid chromatography technique when a polar stationary phases — silica or polar bonded phases and aqueous mobile phase containing amount of a less polar solvent (often acetonitrile) is applied. HILIC is important for the separation of highly polar substances including biologically active compounds, such as drugs, amino acids, peptides, proteins, nucleosides, neurotransmitters, etc. HILIC is also the appropriate method for analysis of plant extract polar components such as carbohydrates, amino acids, peptides, phenolic acids, flavonoids and some alkaloids. Plant extracts are usually multicomponent mixtures of compounds of wide polarity range, which often cannot be analyzed by use of a single separation and detection method because of the high chemical diversity. Good results are obtained by use of coupled method, e.g., reversed-phase liquid chromatography (RP-LC) and HILIC mode separation. The elution order in HILIC is usually opposite to that in RP separations. This orthogonality determines one of the advantages of HILIC — the possibility of creating multidimensional separations. An important feature of HILIC is the improved sensitivity with electrospray mass spectrometry. This is significant for the analysis of components existing in small concentration in multicomponent mixtures. The high acetonitrile content also gives additional advantage of HILIC — faster separations due to the lower viscosity of HILIC eluents compared to standard RP ones. The presented review deals with the optimization of HILIC separations and application of the method for analysis of plant extracts components.
Authors:Aleksandra Radoičić, Helena Majstorović, Tibor Sabo, Živoslav Tešić, and Dušanka Milojković-Opsenica
The chromatographic behavior of twelve neutral, mixed cobalt(III) complexes of the
-edda-type has been investigated in six planar chromatographic systems. Four different stationary phases - unmodified silica gel, CN-silica, cellulose, and alumina - were combined with water-organic solvent (methanol or acetone) binary mobile phases. The effect of the water content of the mobile phases on retention of the complexes was investigation systematically. On the basis of the results obtained, possible separation mechanisms were considered. Hydrophilic-interaction chromatography was assumed to be the mechanism determining separation under normal-phase conditions, i.e. use of mobile phases containing small amounts of water. Reversed-phase chromatography occurs when water-rich mobile phases are used.
New polyacrylate-based monosized-porous polymer beads were proposed as a stationary phase for the separation of polar compounds by microbore reversed-phase chromatography. For this purpose, monosized-porous poly(glycerol dimethacrylate-co-glycerol-1,3-diglycerolate diacrylate), poly(GDMA-co-GDGDA), beads with hydroxyl functionality were synthesized by a modified seeded polymerization. The selected octadecylating agent, stearoyl chloride (SC), was covalently attached onto the hydrophilic beads via a direct, single stage reaction with a simple synthetic route. SC attached-poly( GDMA-co-GDGDA) beads were slurry-packed into the microbore columns and used as separation medium microbore reversed-phase chromatography. The stationary phase was used for separation of alkylbenzenes and polar analytes by micro reversed-phase chromatography, using mobile phases with low acetonitrile content. Theoretical plate number (TPN) values up to 12,000 plates m−1 and 10,000 plates m−1 for alkylbenzenes and polar analytes, respectively, were achieved. The results also showed that poly(GDMA-co-GDGDA) hydrogel beads are a promising starting material for a number of chromatographic applications like reversed-phase (RP) chromatography, hydrophilic interaction chromatography (HILIC), ion-exchange chromatography (IEC), and affinity chromatography with a single-stage surface modification.
-2018/28/19). References 1. Taujenis , L. ; Olšauskaitė , V. ; Padarauskas , A. Determination of nicotine and three minor alkaloids in tobacco by hydrophilicinteractionchromatography-tandem mass spectrometry . Acta Chromatogr. 2015 , 27 , 373 – 385 . 10