Irinel Adriana Badea

Rapid HPLC method for the determination of paclitaxel in pharmaceutical forms without separation

A HPLC method has been developed for the in-process determination of the paclitaxel from dosage pharmaceutical forms. This method ensures the rapid determination of paclitaxel in the presence of polyoxyl castor oil--the main constituent of paclitaxels clinical formulation vehicle. The method is simple and rapid and does not require any preliminary treatment of the sample. The method was fully validated.

Rapid determination of total polyphenolic content in tea samples based on caffeic acid voltammetric behaviour on a disposable graphite electrode

The present paper describes the voltammetric behaviour and the quantitative determination of caffeic acid (CA) on a disposable pencil graphite electrode (PGE). The anodic peak current of CA recorded by differential pulse voltammetry (DPV) varies linearly with CA concentration in the range 1×10(-7)-3×10(-3) M. The detection and quantification limits were 8.83×10(-8) M and 2.94×10(-7) M caffeic acid, respectively. The mean recoveries of CA from Turkish green, white and black teas were 98.30%, 99.57% and 91.46%. For these three tea types the corresponding total polyphenolic contents (TPCs) evaluated by DPV on PGE were 35.81, 34.59 and 31.21 mg caffeic acid equivalent/g tea, respectively. These TPC values were in good accordance with those obtained by the Folin-Ciocalteu method. The developed DPV on PGE method constitutes a simple and inexpensive tool for the rapid assessment of TPC of tea samples.

A HPLC validated assay of paclitaxel's related impurities in pharmaceutical forms containing Cremophor EL.

A HPLC method has been developed for the determination of the paclitaxels related impurities in pharmaceutical forms. This method ensures the rapid determination of related impurities in the presence of polyoxyl castor oil--the main constituent of paclitaxels clinical formulation vehicle. The method is simple and does not require any preliminary treatment of the sample. The method was fully validated.

Development of a New HPLC Method Used for Determination of Zearalenone and Its Metabolites in Broiler Samples. Influence of Zearalenone on the Nutritional Properties of Broiler Meat

This paper presents the development, optimization and validation of a new HPLC method used for the separation and determination of zearalenone, ZON, and its metabolites in biological samples of Leghorn broiler. ZON and its metabolites can be separated with good resolution in 11 min, using a Hypersil Gold C18 column, a mobile phase mixture of 50 mM aqueous ammonium acetate:acetonitrile:methanol, 45:8:47 (v/v/v), flow rate 1 mL/min and column temperature 40 degrees C. Based on the results obtained by this method applied on biological samples one can conclude that liver is the site for zearalenone localization and detoxification. Influence of zearalenone on the nutritional properties of broiler meat (weight variation, gross chemical composition, fatty acids profile of the meat) was studied, also. Results obtained during 4 days of treatment with ZON showed minimal or no effects of the dietary zearalenone on broiler meat nutritional quality.

Chemical Composition and Antipathogenic Activity of Artemisia annua Essential Oil from Romania.

The essential oil extracted by hydrodistillation from Romanian Artemisia annua aerial parts was characterized by GC/MS analysis, which allowed the identification of 94.64% of the total oil composition. The main components were camphor (17.74%), α‐pinene (9.66%), germacrene D (7.55%), 1,8‐cineole (7.24%), trans‐β‐caryophyllene (7.02%), and artemisia ketone (6.26%). The antimicrobial activity of this essential oil was evaluated by determining the following parameters: minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), minimal fungicidal concentration (MFC), and minimal biofilm eradication concentration (MBEC). Moreover, the soluble virulence factors were quantified with different biochemical substrates incorporated in the culture media. The reference and resistant, clinical strains proved to be susceptible to the A. annua oil, with MICs ranging from 0.51 to 16.33 mg/ml. The tested essential oil also showed good antibiofilm activity, inhibiting both the initial stage of the microbial cell adhesion to the inert substratum and the preformed mature biofilm. When used at subinhibitory concentrations, the essential oil proved to inhibit the phenotypic expression of five soluble virulence factors (hemolysins, gelatinase, DNase, lipases, and lecithinases). Briefly, the present results showed that the A. annua essential oil contained antimicrobial compounds with selective activity on Gram‐positive and Gram‐negative bacterial strains as well as on yeast strains and which also interfere with the expression of cell‐associated and soluble virulence factors.

Voltammetric determination of B1 and B6 vitamins using a pencil graphite electrode

Due to the importance of B1 and B6 vitamins for human health it is useful to develop new cheap and rapid methods for their determination. Voltammetric behavior of these vitamins on a pencil graphite electrode was investigated using cyclic voltammetry in different media. Direct quantitative determination of the two vitamins, one in the presence of the other, was done by differential pulse voltammetry. Vitamin B1 was electroactive only in a NaOH solution generating two irreversible oxidation peaks; the first peak obtained at 250 mV is well-defined and was used in quantitative determinations. In case of vitamin B6, a well-defined oxidation peak was observed in all investigated supporting electrolytes except for HCl. The linear concentration ranges were 10−5–10−3 M for vitamin B1 in a NaOH solution and 5 × 10−6–10−3 M for vitamin B6 in an acetate buffer solution. The obtained detection limits were 5.34 × 10−6 M and 2.81 × 10−6 M for vitamin B1 and vitamin B6, respectively. The developed method is simple and rapid and it was successfully applied in the determination of the two vitamins in pharmaceuticals.

Cheap pencil graphite electrodes for rapid voltammetric determination of chlorogenic acid in dietary supplements

A disposable, cheap and easily available pencil graphite electrode (PGE) was used to develop, for the first time, a rapid voltammetric method for chlorogenic acid (CGA) determination. Cyclic voltammograms emphasised a quasi-reversible, diffusion controlled and pH dependent electrode process. Differential pulse voltammetry (DPV) applied to the anodic peak was used for the quantitative determination of CGA. The linear range, the limit of detection and the limit of quantification were 1 × 10−7 to 5 × 10−4 mol L−1 CGA, 7.14 × 10−8 mol L−1 CGA and 2.1 × 10−7 mol L−1 CGA, respectively, being similar to or even better than those reported in the literature. The developed DPV on PGE method was applied with good results to the quantitative determination of CGA in commercially available green coffee extract based dietary supplements. The results compared well with those obtained by the Folin–Ciocalteu method, a fact proved by the statistical analysis.

Redox Behavior of Zearalenone in Various Solvents

The redox equilibriums involving zearalenone were studied by cyclic and differential pulse voltammetry on a glassy carbon electrode. The cyclic voltammograms of zearalenone in DMSO at a glassy carbon electrode in the potential range from −600 to 1400 mV vs. the Ag/AgCl have two oxidation peaks and a reduction one. Zaralenone concentration may be determined by DPV at +1050 mV. The method was applied to the determination of zearalenone concentration in corn, barley, and maize. Studies performed in aqueous solution or in mixed solvents water-acetonitrile containing 1 M H2SO4 showed that the oxidation of ZEN with an aqueous solution of Ce(IV) at room temperature, in the dark, occurs with the destruction of ZEN molecule. Studies performed in aqueous solution or in mixed solvents water-acetonitrile containing 1 M H2SO4 showed that the oxidation of ZEN with an aqueous solution of Ce(IV) at room temperature, in the dark, occurs with the destruction of ZEN molecule.

Development of a New HPLC Method for Determination of Papaverine in Presence of Its Photooxidation Products

A new HPLC method was developed for determination of papaverine in a papaverine naturally photooxidized solution using a Duet C18/SCX column. The mobile phase used was a mixture of phosphate buffer (pH = 3.80) and acetonitrile in 40:60 ratio. The compounds identified were: papaverinol, papaveraldine, papaverine, and pyrrocolonium ion. Very good resolutions, peak shapes, and asymmetries were obtained. An ion exchange experiment was developed in order to identify and separate the pyrrocolonium ion. This was retained completely by a cation exchange resin in its Na+ form, while papaverine, papaverinol, and papaveraldine were retained more or less, due to a retention explained by a combined ion exchange-solvent extraction mechanism. Voltammetric studies showed that natural photooxidation of papaverine occurs in three irreversible steps and yields to stable compounds in solution.

A Derivative Spectrometric Method for Hydroquinone Determination in the Presence of Kojic Acid, Glycolic Acid, and Ascorbic Acid

A new, simple, and sensitive spectrometric method was developed for hydroquinone (HQ) determination in the presence of other depigmenting agents (kojic acid (KA), glycolic acid (GA), and ascorbic acid (AA)), commonly introduced in skin lightening products. The method is based on the oxidation of the depigmenting agents by potassium dichromate in sulfuric acid medium and subsequent measurement of the amplitude of the first-order derivative absorption spectrum at 268 nm. By applying the zero-crossing method, at this wavelength, the oxidation products of KA, AA, and GA do not interfere in the indirect determination of HQ. Beer’s law was obeyed in the range of 0.22–22 μg·mL−1 HQ, with a detection limit of 0.07 μg·mL−1. The developed method was applied with good results for the first time to the rapid determination of HQ in binary, ternary, and quaternary mixtures, thus proving that it could represent an effective tool for various skin lightening products analyses.