Zelena priča o alkil poliglikozidima

Surfactants are substances of specific chemical structure which are capable of reducing the surface tension of liquid they are dispersed; they are basic ingredients of the widely used products such as detergents, cosmetics, paints and pesticides and many petroleum products. The green surfactants are surface active agens which are obtained from natural oils (for example palm or coconut oil) as well as plant carbohydrates (for example polysaccharides from marine algae) and they are main ingredients of both biodegradable and biocompatible products. Their use is a response to growing consumer demands for products that are 'greener', milder and more efficient, due to which green surfactants derivation from natural renewable resources is the concept that is increasingly used in industry of detergents and cosmetics. In this context, alkyl polyglucosides (APG) are key green surfactants whose use is an excellent solution for manufacturers who aim to combine efficiency and safety in the final product. In this paper, the author gave a short overview of alkyl polyglycosides as well as further perspective in their uses.Surfaktanti su supstance specifične hemijske strukture koje smanjuju površinski napon tečnosti u kojoj su rastvoreni ili dispergovani; oni su osnovni sastojci široko korišćenih proizvoda kao što su detergenti, kozmetički preparati, boje i pesticidi, a mnogi su naftni derivati. Zeleni surfaktanti su površinski aktivne materije koje se dobijaju iz biljnih ulja (npr. iz palminog ili kokosovog ulja) i biljnih ugljenih hidrata (npr. šećerne trske ili žitarica) i predstavljaju osnovne sastojke različitih biorazgradivih i biokompatibilnih proizvoda. Njihovo korišćenje je odgovor na sve veću potražnju potrošača za proizvodima koji su 'zeleniji', blaži i efikasniji, zbog čega je dobijanje zelenih surfaktanata iz prirodno obnovljivih izvora koncept koji se sve više koristi u industriji detergenata i kozmetici. U ovom kontekstu, alkil poliglikozidi (APG) su ključni zeleni surfaktanti čija upotreba predstavlja odlično rešenje za proizvođače čiji je cilj kombinovanje efikasnosti i bezbednosti u finalnom proizvodu. Ovo je priča o njima

Determination of piroxicam in pharmaceutical based on an oscillating chemical reaction

A novel procedure for kinetic determination of piroxicam (PX) by the concentration perturbations of the Bray-Liebhafsky (BL) oscillatory chemical system was proposed. The response of the BL matrix in a stable non-equilibrium stationary state close to the bifurcation point, to the perturbation by different concentrations of PX, is followed by a Pt-electrode. Under the optimized reaction conditions, the linear relationship between maximal potential shift ΔEm, and PX concentration was obtained in the concentration range 6.8 × 10−5 mol L−1 − 1.7 × 10−3 mol L−1 with a detection limit of 3.5 × 10−5 mol L−1 . The method had a rather good sample throughput (ST) of 45 samples h−1 with the recovery RCV = 103.7 %. Applicatibility of the proposed method to the direct determination of PX in pharmaceutical formulation (injections) was demonstratedPhysical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201

Perturbation of the Dushman reaction with piroxicam: experimental and model calculations

A novel method for the determination of piroxicam (PX) is proposed and validated. For this purpose, the Bray-Liebhafsky (BL) non-oscillating subsystem (mixture KIO3 and H2SO4), i.e. Dushman reaction (DR) was used. The proposed method relies on the linear relationship between maximal potential shift, ΔEm, and the logarithm of the injected PX amounts in the concentration range 2.0 × 10−5 mol L−1 − 2.0 × 10−4 mol L−1 . The sensitivity of the proposed method is 1.5 × 10−5 mol L−1 . Some aspects of the possible mechanism of UA action on the DR matrix system are discussed.Physical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201

Direct Spectrophotometric Determination of Hesperidin in Pharmaceutical Preparations

A simple, rapid and reliable direct spectrophotometric method for the determination of hesperidin is proposed and validated. The influence of wavelength, solvent, the ionic strength, pH and temperature on hesperidin determination were investigated. Under the optimum conditions, lambda = 283 nm, 60% methanol as the solvent, ionic strength, I = 2.5 x 10(-5) mol L-1, pH = 6.4 and T = 37.0 degrees C, the Beer's law is obeyed in the concentration range 1.83-24.5 mu g mL(-1). The molar absorptivity and Sandells sensitivity were found to be 1.8 x 10(4) L mol(-1) cm(-1) and 0.03 mu g cm(-2), respectively. The sensitivity of the proposed method was 0.9 mu g mL(-1) (as limit of detection) and 3.2 mu g mL(-1) (as limit of quantification). Applicability of the proposed method to the direct determination of total flavonoids as hesperidin equivalents in pharmaceutical formulation (Vitamin C with citrus bioflavonoids & Rose Hips) was demonstrated. Although the presence of ascorbic acid may cause problem in identification and measurements, hesperidin has been determined successfully

Termodinamika micelizacije heksadeciltrimetilamonijum-bromida u smeši propilen-glikol-voda - konduktometrijsko ispitivanje

Micellization of hexadecyltrimethylammonium bromide (syn. cetyltrimethylammonium bromide, CTAB) in propylene glycol-water (30% v/v) binary mixture, as well as the thermodynamic properties of the resulting micelles, were investigated by electrical conductivity measurements. The conductivity data were used to determine both the critical micellar concentration (CMC) and the micellar ionization degree (∞) of CTAB in the temperature range 298.2-310.2 K. The equilibrium model of micelle formation was applied in order to obtain the thermodynamic parameters (the standard molar Gibbs free energy, ∆Gmº, enthalpy, ∆Hm0 and entropy, ∆Smº) of the micellization process. The values of ∆Gmº and ∆Hmº were found to be negative at all investigated temperatures, while the values of ∆Smº were positive and became more positive as temperature increased. A linear dependence between ∆Smº and ∆Hmº, i.e. an enthalpy-entropy compensation effect, was observed.Konduktometrijski je ispitivana micelizacija heksadeciltrimetilamonijum-bromida (sinonim cetiltrimetilamonijum-bromid, CTAB) u binarnoj smeši propilen-glikol-voda (30%, v/v), kao i termodinamičke osobine nastalih micela. Merenjem specifične provodljivosti određeni su kritična micelarna koncentracija (KMK) i stepen jonizacije micele (∞) CTAB u opsegu temperatura 298,2-310,2 K određeni su. Primenom ravnotežnog modela za proces micelizacije izračunati su termodinamički parametri: promena standardne molarne Džibsove slobodne energije, (∆Gmº), entalpije (∆Hmº) i entropije (∆Smº) micelizacije. Vrednosti ∆Gmº i ∆Hmº su bile negativne na svakoj od ispitivanih temperatura, dok su vrednosti ∆Smº bile pozitivne i povećavale su se sa porastom temperature. Na osnovu linearne zavisnosti između ∆Hmº i ∆Smº utvrđen je tzv. entalpijsko-entropijski kompenzacioni efekat

МИЦЕЛАРНИ СВОЈСТВА НА ЦЕТИЛТРИМЕТИЛАМОНИУМ БРОМИД ВО СМЕСАТА ОД АЦЕТОНИТРИЛ ВОДА: КОНДУКТОМЕТРИСКИ И ФЛУОРЕСЦЕНТНИ СТУДИИ

The effect of acetonitrile (ACN) on the micellization of a cationic surfactant, cetyltrimethylammo-nium bromide (CTAB), in aqueous solutions at different temperatures was studied. The critical micellar concentration (CMC) as well as the degree of counter ion dissociation () of CTAB in aqueous ACN mixtures (1020 % v/v) at various temperatures (291.2298.2 K) were determined by electrical conduc-tivity measurements, while steady-state fluorescence measurements were used to determine several CMCs (for comparison) and a micellar aggregation number (Nagg) as well. At a fixed temperature, both an increase in CMC and a decrease in Nagg were observed for an increase in ACN in the solvent mixture. With a temperature increase, CMC values increased for 10 % (v/v) ACN, while for both 15 % and 20 % (v/v) ACN, CMC values were a minimum at T = 295.2 K with a temperature increase. In addition, some aspects related to the Krafft temperature behavior of CTAB in the examined micellar systems are dis-cussed.Беше испитано влијанието на ацетонитрилот (ACN) врз мицелизацијата на катјонски сурфактант, цетилтриметиламониум бромид (CTAB), во водна средина на различни температури. Со помош на мерења на електричната спроводливост, беа определени критичната мицеларна концентрација (CMC), и степенот на дисоцијација на спротивните јони () на CTAB во водни смеси на ACN (1020 % v/v) на различни температури (291,2298,2 K), додека за определување на неколку CMC (за споредба), како и на мицеларен агрегационен број (Nagg) беа употребени рамнотежни флуоресцентни мерења. На фиксна температура беше забележано зголемување на CMC и намалување на Nagg со зголемување на ACN во смесата на растворот. Со зголемување на температурата вредностите на CMC се зголемија за 10 % (v/v) ACN, додека за 15 % и за 20 % (v/v) ACN, вредностите на CMC при зголемување на температурата на T = 295,2 K беа минимални. Покрај тоа, дискутирани се некои аспекти што се поврзани со однесувањето на температурата на Krafft на CTAB во испитуваните мицеларни системи

Pulse perturbation technique for determination of piroxicam in pharmaceuticals using an oscillatory reaction system

A simple and reliable novel kinetic method for the determination of piroxicam (PX) was proposed and validated. For quantitative determination of PX, the Bray-Liebhafsky (BL) oscillatory reaction was used in a stable non-equilibrium stationary state close to the bifurcation point. Under the optimized reaction conditions (T = 55.0A degrees C, [H2SO4](0) = 7.60x10(-2) mol L-1, [KIO3](0) = 5.90x10(-2) mol L-1, [H2O2](0) = 1.50x10(-1) mol L-1 and j (0) = 2.95x10(-2) min(-1)), the linear relationship between maximal potential shift Delta E (m) , and PX concentration was obtained in the concentration range 11.2-480.5 A mu g mL(-1) with a detection limit of 9.9 A mu g mL(-1). The method had a rather good sample throughput of 25 samples h(-1) with a precision RSD = 4.7% as well as recoveries RCV a parts per thousand currency sign 104.4%. Applicability of the proposed method to the direct determination of piroxicam in different pharmaceutical formulations (tablets, ampoules and gel) was demonstrated

THERMODYNAMICS OF MICELLIZATION OF HEXADECYLTRIMETHYLAMMONIUM BROMIDE IN PROPYLENE GLYCOL-WATER MIXTURE: A CONDUCTIVITY STUDY

Micellization of hexadecyltrimethylammonium bromide (syn. cetyltrimethylammonium bromide, CTAB) in propylene glycol-water (30% v/v) binary mixture, as well as the thermodynamic properties of the resulting micelles, were investigated by electrical conductivity measurements. The conductivity data were used to determine both the critical micellar concentration (CMC) and the micellar ionization degree (a) of CTAB in the temperature range 298.2-310.2 K. The equilibrium model of micelle formation was applied in order to obtain the thermodynamic parameters (the standard molar Gibbs free energy, DGm0, enthalpy, DHm0 and entropy, DSm0) of the micellization process. The values of DGm0 and DHm0 were found to be negative at all investigated temperatures, while the values of DSm0 were positive and became more positive as temperature increased. A linear dependence between DSm0 and DHm0, i.e. an enthalpy-entropy compensation effect, was observed. TERMODINAMIKA MICELIZACIJE HEKSADECILTRIMETILAMONIJUM-BROMIDA U SMEŠI PROPILEN-GLIKOL-VODA: KONDUKTOMETRIJSKO ISPITIVANJE Konduktometrijski je ispitivana micelizacija heksadeciltrimetilamonijum-bromida (sinonim cetiltrimetilamonijum-bromid, CTAB) u binarnoj smeši propilen-glikol-voda (30%, v/v), kao i termodinamičke osobine nastalih micela. Merenjem specifične provodljivosti određeni su kritična micelarna koncentracija (KMK) i stepen jonizacije micele (a) CTAB u opsegu temperatura 298,2-310,2 K određeni su. Primenom ravnotežnog modela za proces micelizacije izračunati su termodinamički parametri: promena standardne molarne Džibsove slobodne energije, (DGm0), entalpije (DHm0) i entropije (DSm0) micelizacije. Vrednosti DGm0 i DHm0 su bile negativne na svakoj od ispitivanih temperatura, dok su vrednosti DSm0 bile pozitivne i povećavale su se sa porastom temperature. Na osnovu linearne zavisnosti između DHm0 i DSm0 utvrđen je tzv. entalpijsko-entropijski kompenzacioni efekat

Termodinamika micelizacije heksadeciltrimetilamonijum-bromida u binarnoj smeši propilenglikol-voda

The effect of cosolvent (propylen glycol, PG) on micellization of an cationic surfactant, hexadecyltrimethylammonium bromide (hereinafter cetylecyltrimethylammonium bromide, CTAB) in aqueous solution was studied. The thermodynamic of micellization and the aggregation behaviour of CTAB in PG-water mixture at different temperatures (from 298.2 K to 310.2 K) have been studied conductometrically. The conductivity data were used to determine the critical micellar concentration (CMC) and degree of micellar ionization (α) of CTAB in PG-water (20% v/v) binary mixtures at different temperatures (298.2 K, 306.2 K and 310.2 K). The equilibrium model of micelle formation was applied to obtain the thermodynamics parameters (the standard molar Gibs free energy (ΔGm 0), enthalpy (ΔHm 0) and entropy (ΔSm 0)) of micellization. Those parameters were determined using temperature dependance of CMC. Value of DGm 0 was found to be negative at all temperatures and becomes less negative as the temperature increases. Values of ΔHm 0 and ΔSm 0 were found to be negative in all cases, and increase dramaticaly with temperature in 20 % (v/v) PG. An entalpy-entropy compenzation effect was observed. Moreover, based on experimental data, it can be concluded that the micellization process in the examined system is substantially similar to the CTAB micellization in water, and the presence of PG has a negligible effect on the CTAB-water interactions.U radu je ispitan uticaj korastvarača (propilenglikola, PG) na micelizaciju katjonskog surfaktanta, heksadeciltrimetilamonijum-bromida (cetiltrimetilamonijum-bromida, CTAB) u vodenom rastvoru. Termodinamika micelizacije i agregaciono ponašanje CTAB u smeši PG-voda na različitim temperaturama (od 298,2 K do 310,2 K) ispitivani su konduktometrijski. Kritična micelarna koncentracija (KMK) i stepen jonizacije micele (α) CTAB u smeši PG-voda (20% (v/v)), na različitim temperaturama (298,2 K, 306,2 K i 310,2 K) određeni su merenjem specifične provodljivosti. Primenom ravnotežnog modela za proces formiranja micela i iz temperaturne zavisnosti KMK, izračunati su termodinamički parametri (promena standardne molarne Gibsove slobodne energije, (Δm 0), entalpije (ΔHm 0) i entropije (ΔSm 0)) micelizacije. Vrednost DGm 0 je negativna na svakoj od ispitivanih temperatura; ove vrednosti se smanjuju po apsolutnoj vrednosti sa povećanjem temperature. Vrednosti ΔHm 0 i ΔSm 0 su negativne na svakoj od ispitivanih temperatura i drastično se povećavaju po apsolutnoj vrednosti sa povećanjem temperature u smeši PG-voda. Za proces micelizacije CTAB u smeši PG-voda (20% (v/v)), dobijen je tzv. entalpijsko-entropijski kompenzacioni efekat. Štaviše, na osnovu eksperimentalno dobijenih podataka može se zaključiti da je proces micelizacije u ispitivanom sistemu suštinski sličan micelizaciji CTAB u vodi, i da prisustvo PG ima neznatan uticaj na interakcije između CTAB i vode