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1

Simultaneous determination of gallic acid, protocatechuic acid, catechin, epicatechin, quercetin and kaempferol in Chinese chestnut (Castanea mollissima blume) kernel by high-performance liquid chromatography with diode array detection

Wang T., Yang Y. D., Du B., Yu S., Hou W. L.

Acta Chromatographica

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2014

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Vol. 26, no. 3

539--550

EN

Chestnut exhibits anti-inflammatory, styptic, anti-diarrhea, and analgestic effects as a traditional Chinese medicine. There is increasing evidence that shows that the consumption of chestnuts has become more important in human nutrition due to the health benefits provided by the antioxidants. The phenolic compounds are responsible for major bioactivities, such as anti-tumor and anti-oxidation. A high-performance liquid chromatography (HPLC) method with diode array detection (DAD) was established for the simultaneous determination of six phenolic compounds (gallic acid, GA; protocatechuic acid, PR; catechin, CA; epicatechin, EP; quercetin, QU; kaempferol, KA) in Chinese chestnut (Castanea mollissima blume) kernel. The sample followed by separation on Eclipse XDB-C18 column (150 × 4.6 mm, id., 5 μm) with gradient elution of methanol-1.0% acetate acid solution as a mobile phase, at a temperature of 30°C, under the ratio of 1.2 mL min-1, with 5 μL injection volume, and multi-wavelength synthesis was used with DAD. The correlation coefficients were larger than 0.999, the recoveries were 97.58% for GA, 100.41% for PA, 96.23% for CA, 101.38% for QU, 99.15% for EP, and 98.60% for KA, relative standard deviation (RSD) were 1.04% for GA, 1.21% for PA, 1.09% for CA, 1.19% for QU, 1.06% for EP, and 1.20% for KA. This method was applied for the determination of phenolics in chestnut kernel and was found to be fast, sensitive, and suitable.

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Fast and highly sensitive spectrophotometric determination of protein in urine applying novel spectrum probe

Wei Q., Li Y., Wang S., Li Z., Du B.

Chemia Analityczna

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2006

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Vol. 51, No. 1

159-171

EN

Molybdenurn(Vl)-trimethoxyphenylfluorone (TM-PF) complex has been used in spectro-photometric determination of protein in urine. At pH 2.43 and in the presence of Triton X-100 microemuision protein binds the complex within 2 min, which results in a maximum decrease of its absorbance at 527 nm. The presence of Triton X-100 microemuision significantly improves the sensitivity of the determination. The calibration plots for bovine serum albumin (BS A) and human serum albumin (HSA) were linear up to the analyte concentration of 11 μg mL-1> and 25 μgg ml-1>, respectively, with the corresponding molar coefficients of 1.13 x 107> L mol-1> cm-1> and 7.48 x 106> L mol-1> cm-1>. The proposed method is simple, practical, and relatively free from interference of coexisting substances, as well as much more sensitive than the Bradford method. Recovery of protein from human urine equals 96.7%-108% and the relative standard deviation is lower than 3.9%. The molar ratio method and the Rosenthanl graphic method have been employed to estimate the binding number and association constant of bovine serum albumin with the complex.

PL

Do oznaczania białek w moczu zastosowano kompleks molibdenu(Vl) z trimetoksyfenyloflu-oronem, do którego białko przyłącza się w ciągu 2 min przy pH 2.43 i \\ obecności Tritonu X-100. Największy spadek absorbancji następuje przy 527 nm. Obecność Tritonu X-100 znacznie poprawia czuiość oznaczania. Krzywe kalibrowania w pr/.ypadku albumin BSA i HAS były liniowe w zakresie, odpowiednio: do 11 μg mL-1> i 25 μg mL-1>, a współczynniki molowe absorbancji wynosiły 1,13 x 107> i 7,48 x I06> L mol-1> cm-1>. Zaproponowana metoda jest prosta, praktyczna i stosunkowo wolna od wpływu współobecnych substancji. Jest również bardziej czulą niż metoda Bradford'a. Odzysk białka/ moczu ludzkiego wynosił96.7-108 %. a względne odchylenie standardowe było mniejsze niż 3,9%. Do wyznaczenia stechiometrii tworzonych ukiadów i ich staiych trwałości zastosowano metodę stosunków molowych i graficzna metodę Rosenthanl'a.

3

Fast determination of ultra trace amounts of residual proteins in penicillin based on the enhancement in Rayleight light scattering spectra of phenylfluorone-Mo(VI) complex

Du B., Wu D., Zhang H., Li Y., Wei Q., Li Z.

Chemia Analityczna

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2005

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Vol. 50, No. 4

795-806

EN

Determination of protein - phenylfluorone (PF)-Mo(VI) complex using Rayleigh light scattering (RLS) method in the presence of the OP emulsifier microemulsion has been performed. At pH = 2.72 the RLS spectrum of PF-Mo(VI) complex is enhanced in the presence of proteins. Such a behaviour was utilised in a new method for the quantitative determination of proteins. An OP emulsifier microemulsion was used in this determination to increase the sensitivity. Four proteins, including bovine serum albumin (BSA), human serum albumin (HSA), Lysozyme (Lys), and λ-globulin (λ - G) have been determined. The dynamic range for BSA was 0-80 ng mL-1 and the corresponding detection limit equaled 1.57 ng mL-1. The method is characterised by high sensitivity and simplicity, and provides results of satisfactory stability. It can be used for the determination of residual protein in penicillin samples. The relative standard deviations for the investigated proteins were less than 4.48%. and the recoveries were in the range of 96.35%-100.9%.

PL

Przeprowadzono oznaczanie kompleksu białko-fenylofluoren (PF)-Mo(VI) stosując metodę rezonansowego rozproszenia światła (RLS) w obecności emulgatora OP. W obecności białek, przy pH 2,72 widmo RLS kompleksu PF-Mo(VI) ulega wzmocnieniu. Właściwość tę wykorzystano w nowej metodzie ilościowego oznaczania białek. Dodanie emulgatora OP znacznie poprawiało czułość. Oznaczono w ten sposób cztery białka: albuminę wolową (BSA). albuminę ludzką (HSA). lizozym (Lys) i λ λ-globulinę. Zakres dynamiczny BSA wynosił 0-80 ng mL-1, a granica wykrywalności - 1,57 ng mL-1. Metoda charakteryzuje się wysoką czułością! prostotą oraz dobrą powtarzalnością wyników. Względne odchylenie standardowe oznaczanych białek było niższe od 4,48% a odzyski zawierały się w granicach 96,35-100,9%.

4

Studies on the Electron Transfer reaction Mechanism Between NO2 and NO- 2 Complexes in the Gas Phase

Zhou Z., Gao H., Fu H., Du B.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 12

1849-1856

EN

The electron transfer (ET) reaction between NO2 and NO2 complexes in the gas phase is investigated by Density functional theory (DFT). The geometry optimization of the nitrogen dioxide complexes and the precursor state in the process of ET reaction was performed at 6-311+G* basis set level. The nitrogen dioxide molecule separation distances computed using DFT method were found to agree with second order Moller-Plesset perturbation theory level (MP2) results. The 351.1 nm (3.532 eV) photoelectron spectrum of the nitrite anion (NO2 ) is obtained. For the precursor complex of NO2….NO2 , eight reasonable geometries on the potential energy surface are considered with the most stable structure being T1-type. The activation barriers and the coupling matrix elements in the electron transfer process are also calculated for four different transition states. Results indicate that the structures and properties of the precursor complex directly affect the electron transfer reaction mechanism and rate. The reacting system in the T1-type structure has lower activation barriers and greater coupling matrix elements than those in other type of structures. It is indicate that the most possible path of the electron transfer is the collision of NO2 andNO2 to form the precursor complex with the T1-type structure, then the electron transfer and structure organization take place, the successor is obtained via the transition state with a Đ6 9-conjugated system. Finally the product is attained.