Development of Micellar HPLC-UV Method for Determination of Pharmaceuticals in Water Samples.

Method for extraction and determination of amoxicillin, caffeine, ciprofloxacin, norfloxacin, tetracycline, diclofenac, ibuprofen, nimesulide, levonorgestrel, and 17α-ethynylestradiol exploiting micellar liquid chromatography with PDA detector and solid-phase extraction was proposed. The usage of toxic solvents was low; the chromatographic separation of the medicaments was performed using a C18 column and mobile phases A and B containing 15.0% (v/v) ethanol, 3.0% (m/v) sodium dodecyl sulfate (SDS), and 0.02 mol·L-1 phosphate at pHs 7.0 and 8.0, respectively. The method is simple, selective, and fast, and the analytes were separated in 23.0 min. For extraction, 1000 mL of sample containing 2.0% (v/v) ethanol and 0.002 mol·L-1 citric acid at pH 2.50 was loaded through a 1000 mg of C18 cartridge. The analytes were eluted using 3.0 mL of ethanol, which were evaporated and redissolved in 0.5 mL of mobile phase. Concentration factors better than 1200, except amoxicillin (224), were obtained. The analytical curves were linear (R2 better than 0.992); LOD and LOQ (n=10) presented values in the range of 0.019-0.247 and 0.058-0.752 mg·L-1, respectively. Recoveries of 99% were obtained, and the results are in agreement with those obtained by the comparative methods.

Determination of trans-resveratrol in Solanum americanum Mill. by HPLC.

Solanum americanum Mill. is a plant that belongs to the Solanaceae family, its respective ripe fruit is dark purple. Ripe S. americanum Mill. fruits were submitted to physicochemical characterisation, and their trans-resveratrol contents were quantified by high-performance liquid chromatography. Such determination was executed with fruits at different stages of ripeness and freeze-stored fruits as well. In natura ripe fruit pulp and peel presented average trans-resveratrol amounts of 1.07 and 0.7960 µg per gram of sample, respectively. These amounts are significantly higher when compared to freeze-stored fruit (0.1353 µg of trans-resveratrol per gram of sample) and to other berries. All ripe fruits showed significant amounts of total anthocyanins and total antioxidants. Thus, for the first time, trans-resveratrol has been identified and quantified in S. americanum Mill. fruit samples.

Characterization of residual oils for biodiesel production

Background: Residual oils were characterized according to their physicochemical properties, i.e. acidity, iodine value, peroxide value and saponification number, to evaluate the degradation level and viability for biodiesel production. Results: The methyl esters of fatty acids (FAME) from samples of residual bovine, chicken and soybean oils were quantified by using four transesterification methods, using acidic and basic catalysis and, gas chromatography with flame ionization detector (GC-FID). Methods that used acidic catalysis at a lower temperature were the most efficient. Methyl biodiesel samples were synthesized by basic catalysis (KOH) for all quantified oils and the physicochemical properties of the biofuel were evaluated, i.e. viscosity, flash and fire points, density, water content, iodine and acidity numbers. Conclusions: The obtained results suggesting that it is possible to take advantage of these residues for biodiesel production as the obtained products were approved according to the rules established by the National Association of Petroleum (ANP); the bovine samples were the exception regarding moisture and acidity.

Optimised photocatalytic degradation of a mixture of azo dyes using a TiO(2)/H(2)O(2)/UV process.

The aim of the present study was to optimise the photocatalytic degradation of a mixture of six commercial azo dyes, by exposure to UV radiation in an aqueous solution containing TiO(2)-P25. Response surface methodology, based on a 3(2) full factorial experimental design with three replicates was employed for process optimisation with respect to two parameters: TiO(2) (0.1-0.9 g/L) and H(2)O(2) (1-100 mmol/L). The optimum conditions for photocatalytic degradation were achieved at concentrations of 0.5 g TiO(2)/L and 50 mmol H(2)O(2)/L, respectively. Dye mineralisation was confirmed by monitoring TOC, conductivity, sulfate and nitrate ions, with a sulfate ion yield of 96% under optimal reactor conditions. Complete decolorisation was attained after 240 min irradiation time for all tested azo-dyes, in a process which followed a pseudo-first kinetic order model, with a kinetic rate constant of approximately 0.018 min(-1). Based on these results, this photocatalytic process has promise as an alternative for the treatment of textile effluents.

Optimization of the selectivity of a cyanopropyl stationary phase for the gas chromatographic analysis of trans fatty acids.

The quantification of monounsaturated and polyunsaturated trans fatty acids in partially hydrogenated fats by gas-liquid chromatography on a CP-Select CB-FAME capillary column was optimized using equivalent chain length values of fatty acids methyl esters that could coelute in the temperature range from 155 to 200 degrees C. The most appropriate temperature for the simultaneous determination of these trans isomers is around 197 degrees C. It is proposed a system to discriminate trans from cis octadecenoic fatty acid methyl esters based on the angular coefficient values of the equivalent chain length curves. The limits of detection and quantification were 0.28 and 0.93 mg g(-1). Quantification was performed in the range from 0.93 to 280 mg g(-1). Quantification accuracy was estimated by spike recovery of elaidic and trans-13-octadecenoic acids in hydrogenated fat samples. The obtained levels were from 97.60 to 103.28% for elaidic acid and from 98.12 to 99.27% for trans-13-octadecenoic acid. These results indicate that the accuracy of the methodology proposed for the quantification of monounsaturated and polyunsaturated trans fatty acids in hydrogenated fats is adequate.

Trans polyunsaturated fatty acid contents in Brazilian refined soybean oil.

This study examined the concentration (mg/g) of trans polyunsaturated fatty acid (TPFA) in five soybean oil brands by gas-liquid chromatography. Tricosanoic acid methyl ester was used as the internal standard. All samples analyzed presented trans 18:2 fatty and trans 18:3 acids in detectable amounts. The concentration of TPFA ranged from 5.8 to 30.2 mg/g, with a mean concentration value of 18.4 mg/g. Trans 18:3 fatty acids had the highest TPFA group concentrations, which ranged from 3.9 to 16.3 mg/g. The main isomer of this group presented the 9c, 12c, 15t configuration. For trans 18:2 fatty acids, concentrations ranged from 1.9 to 14.0 mg/g with a mean value of 8.1 mg/g. Alpha-linolenic acid (all cis) concentrations ranged from 30.7 to 60.6 mg/g and their degree of isomerization ranged from 6.0 to 31.5, indicating that the deodorization process varies from one producer to another. From per capita consumption of soybean oil brands in Brazil and their TPFA concentrations, it is possible to conclude that their contribution to the average TPFA intake per person in Brazil is 0.4 g/d.