Tea Beverage Samples Research Articles

In-syringe dispersive liquid-liquid microextraction based on the solidification of ionic liquids for the determination of benzoylurea insecticides in water and tea beverage samples

A novel in-syringe dispersive liquid-liquid microextraction based on the solidification of ionic liquids (in-syringe SIL-DLLME) was coupled with high-performance liquid chromatography-ultraviolet detector (HPLC-UVD) to detect five benzoylurea insecticides (BUs) in water and tea beverage samples. In this method, the hydrophobic ionic liquid [N8881][PF6] was formed in situ by the metathesis reaction between [N8881]Cl and the anion-exchange reagent KPF6 to extract the target analytes. The whole extraction procedure was performed in a syringe. The solidified extractant could be separated from the aqueous phase by exposing the emulsified extraction solution to an ice bath and then easily collected by squeezing out the aqueous phase through the prepared NWPP-based needle. Various parameters affecting the extraction efficiency, such as the amount of [N8881]Cl, the molar ratio of [N8881]Cl to KPF6, salt addition, cooling time, solution temperature, sample pH and sample volume, were evaluated. Under the optimized conditions, the proposed method was validated with satisfactory results: good linearities with coefficients of determination greater than 0.99 were obtained in the range of 2–500µgL−1; the limits of detection varied between 0.29 and 0.59µgL−1; the recoveries of the five benzoylurea insecticides ranged from 85.93% to 90.52%; and the intra-day (n=3) and inter-day (n=3) relative standard deviations were less than 5.36%. Finally, the proposed method was successfully used for the determination of BUs in real water and tea beverage samples.

Method development for the analysis of phthalate esters in tea beverages by ionic liquid hollow fibre liquid-phase microextraction and liquid chromatographic detection

A novel method, termed ionic liquid-based hollow fibre liquid phase microextraction (IL-HF-PLME), coupled with high-performance liquid chromatography (HPLC) was developed for separation and preconcentration of three phthalate esters (PAEs) in tea beverage. In the present study, ionic liquid 1-butyl-3-methy-limidazolium hexafluorophosphate ([BMIm]PF6) was placed in the porous-walled polypropylene hollow fibre as the acceptor phase, and nonanol was used as the supported liquid membrane phase that accomplished extraction. Several important parameters influencing the extraction efficiency were investigated in detail. Under the optimized conditions, good linearity occurred in the range of 5–1000 ng mL−1 with the correlation coefficients values above 0.998. The limits of detection ranged from 0.67 to 1.73 ng mL−1. Recoveries of three PAEs in two kinds of spiked tea beverage samples (PAEs, 10.0–100.0 ng mL) were between 94.2 and 103.4%, with relative standard deviations (RSDs) ranged from 1.77 to 3.02%. The enrichment factors were 200. The developed IL-HF-PLME method allowed the simple, rapid, and sensitive determination of phthalate esters in tea beverage samples with an extraction time of just 4 min.

A porous carbon derived from amino-functionalized material of Institut Lavoisier as a solid-phase microextraction fiber coating for the extraction of phthalate esters from tea.

In this work, a porous carbon derived from amino-functionalized material of Institut Lavoisier (C-NH2 -MIL-125) was prepared and coated onto a stainless-steel wire through sol-gel technique. The coated fiber was used for the solid-phase microextraction of trace levels of phthalate esters (diallyl phthalate, di-iso-butyl ortho-phthalate, di-n-butyl ortho-phthalate, benzyl-n-butyl ortho-phthalate, and bis(2-ethylhexy) ortho-phthalate) from tea beverage samples before gas chromatography with mass spectrometric analysis. Several experimental parameters that could influence the extraction efficiency such as extraction time, extraction temperature, sample pH, sample salinity, stirring rate, desorption temperature and desorption time, were investigated. Under the optimal conditions, the linearity existed in the range of 0.05-30.00 μg/L for green jasmine tea beverage samples, and 0.10-30.00 μg/L for honey jasmine tea beverage samples, with the correlation coefficients (r) ranging from 0.9939 to 0.9981. The limits of detection of the analytes for the method were 2.0-3.0 ng/L for green jasmine tea beverage sample, and 4.0-5.0 ng/L for honey jasmine tea beverage sample, depending on the compounds. The recoveries of the analytes for the spiked samples were in the range of 82.0-106.0%, and the precision, expressed as the relative standard deviations, was less than 11.1%.

Application of mesoporous carbon as a solid-phase microextraction fiber coating for the extraction of volatile aromatic compounds.

A mesoporous carbon was fabricated using MCM-41 as a template and sucrose as a carbon source. The carbon material was coated on stainless-steel wires by using the sol-gel technique. The prepared solid-phase microextraction fiber was used for the extraction of five volatile aromatic compounds (chlorobenzene, ethylbenzene, o-xylene, bromobenzene, and 4-chlorotoluene) from tea beverage samples (red tea and green tea) prior to gas chromatography with mass spectrometric detection. The main experimental parameters affecting the extraction of the volatile aromatic compounds by the fiber, including the extraction time, sample volume, extraction temperature, salt addition, and desorption conditions, were investigated. The linearity was observed in the range from 0.1 to 10.0 μg/L with the correlation coefficients (r) ranging from 0.9923 to 0.9982 and the limits of detection were less than 10.0 ng/L. The recoveries of the volatile aromatic compounds by the method from tea beverage samples at spiking levels of 1.0 and 10.0 μg/L ranged from 73.1 to 99.1%.

Multi-walled carbon nanotube-impregnated agarose film microextraction of polycyclic aromatic hydrocarbons in green tea beverage

A new microextraction procedure termed multi-walled carbon nanotube-impregnated agarose film microextraction (MWCNT–AFME) has been developed. The method utilized multi-walled carbon nanotubes (MWCNTs) immobilized in agarose film to serve as adsorbent in solid phase microextraction (SPME). The film was prepared by mixing the MWCNTs in agarose solution and drying the mixture in oven. Extraction of selected polycyclic aromatic hydrocarbons was performed by inserting a needle through circular MWCNT-impregnated agarose films (5mm diameter) and the assembly was dipped into an agitated sample solution prior to micro high performance liquid chromatography–ultraviolet analysis. Back extraction was then performed using ultrasonication of the films in 100μL of solvent. The film was discarded after single use, thus avoiding any analyte carry-over effect. Due to the mesoporous nature of the agarose film, the MWCNTs were immobilized easily within the film and thus allowing for close contact between adsorbent and analytes. Under the optimized extraction conditions, the technique achieved trace LODs in the range of 0.1 to 50ngL−1 for the targeted analytes, namely fluoranthene, phenanthrene and benzo[a]pyrene. The method was successfully applied to the analysis of spiked green tea beverage samples with good relative recoveries in the range of 91.1 to 107.2%. The results supported the feasibility of agarose to serve as adsorbent holder in SPME which then minimizes the consumption of chemicals and disposal cost of organic wastes.

Magnetic retrieval of chitosan: Extraction of bioactive constituents from green tea beverage samples

A new solid-phase extraction mode for magnetic retrieval of chitosan combined with high-performance liquid chromatography-diode array detection was proposed for the pre-concentration and determination of flavonoids in green tea beverage samples. In the experiment, chitosan was used as sorbents for the extraction of target analytes; after completion of the extraction process, Fe(3)O(4) nanoparticles acted as carrier to retrieve chitosan from the sample solution. Some important parameters influenced extraction efficiency of flavonoids, including the extraction mode, amounts of chitosan, pH of sample solution, extraction time, salt addition, amounts of Fe(3)O(4) nanoparticles, desorption solvent and desroption time, were optimized. Under the optimum conditions, the recoveries of analytes done on samples spiked with the target analytes were between 96.4% and 108.6%; relative standard deviations ranged from 0.6% to 8.7%. The correlation coefficients varied from 0.9917 to 0.9988. The limits of detection ranged from 5.4 to 16.8 ng mL(-1) at a signal-to-noise ratio of 3. All four different brands of green tea beverage samples were successfully analyzed by the proposed method.

Effect of Catechins Extract of Green Tea on Quality Protection of Black Tea-bag During Storage

Green tea is one of the richest sources of antioxidants especially catechins, which are studied most because of their health benefits. These valuable compounds may lose their activity and oxidize to thearobigin during fermentation stage or black tea processing. The main objective of this research is applying antioxidant mixtures extracted from green tea on packaging material of black tea and determining the amount of antioxidants released from the tea bags by their immersion into boiling water. The green tea extracts prepared by a two-step extraction process in water at 50°C and 80°C in four individual time periods, i.e., 10min, 10min; 10min, 20min; 20min, 10min; 20min, 20min (1). Final extract from each process was analyzed by HPLC and DPPH tests and then sprayed on the tea bag packaging material.The activity and concentration of antioxidants (catechins) released from treated tea bags were investigated immediately and after 3 months storage. Sensory properties of the tea beverage samples were also studied. The results (Tables 1, 2) show that the concentration of antioxidants increases by 66–76% as compared to control i.e., untreated black tea. Tea beverage samples were more astringent as compared to untreated black tea. Under different time/temperature conditions the best results were obtained by the sample extracted by a two-step process (20min at 50°C) and (10min at 80°C) with the highest concentration of antioxidants, lowest astringency and best stability during 3 months storage.

Fast detection of catechin in tea beverage using a poly-aspartic acid film based sensor

A fast and convenient analytical method is presented for the determination of catechin. The electrochemical response of catechin in pH 6.8 phosphate buffer solution is significantly enhanced by immobilization of a film of poly-aspartic acid on the surface of the glassy carbon electrode. The enhancement mechanism and effect factors such as pH value, accumulation time and scan rate, were explored. Under optimum conditions, the differential pulse voltammetry peak current of catechin is proportional to the concentration in the range from 2.5 × 10−7 to 3.0 × 10−5 molL−1, with the detection limit of 7.2 × 10−8 molL−1. This method was also applied to the determination of catechin in tea beverage samples, and the recoveries were from 97.1% to 102.7%.

Analysis of Phosphorus-containing Amino Acid-type Herbicides by Capillary Electrophoresis/Mass Spectrometry Using a Chemically Modified Capillary Having Amino Groups

We describe a simple and practical method for the analysis of phosphorus-containing amino acid-type herbicides and their decomposition products without derivatization by capillary electrophoresis/mass spectrometry using a chemically modified capillary having amino groups. The compounds were glyphosate (GLYP), glufosinate (GLUF), bialaphos (BIAL), aminomethylphosphonic acid (AMPA) and 3-methylphosphinicopropionic acid (MPPA). AMPA and MPPA are the decomposition products of GLYP and GLUF, respectively. The optimum running conditions were found to be 100 mM formic acid adjusted to pH 3.4 with 100 mM ammonia with an applied voltage of −30 kV using an amino capillary (FunCap-CE/Type A) and mass spectrometry. The five compounds were separately determined within 10 min. Relative standard deviations of the migration times of analytes were less than 0.52%. Total analysis time of the proposed method was 1/6 to 1/3 of that of gas chromatography/mass spectrometry methods. The method was applicable for the analysis of these compounds in soil and tea beverage samples. The decomposition rates of GLYP, GLUF and BIAL in soil are discussed.