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Analytical Determinations (analytical + determination)
Selected AbstractsUtilization of a Copper Solid Amalgam Electrode for the Analytical Determination of AtrazineELECTROANALYSIS, Issue 22 2005Djenaine De, Souza Abstract A copper solid amalgam electrode was prepared and used for the voltammetric determination of atrazine in natural water samples by square wave voltammetry. This electrode is a convenient substitute for the hanging mercury electrode since it is selective, sensitive, reliable and inexpensive and presents low toxicity characteristic. The detection limit of atrazine obtained in pure water (laboratory samples) was shown to be lower than the maximum limit of residue established for natural water by the Brazilian Environmental Agency. The relative standard deviation for 10 different measurements was found to be only 3.98% in solutions containing 8.16×10,6,mol L,1 of atrazine. In polluted stream water samples, the recovery measurements were approximately 70.00%, sustaining the applicability of the proposed methodology to the analysis of atrazine in such matrices. [source] Electrocatalytic Reduction and Determination of Iodate and Periodate at Silicomolybdate-Incorporated-Glutaraldehyde- Cross-Linked Poly- L -lysine Film ElectrodesELECTROANALYSIS, Issue 10 2010Yu-Ching Pan Abstract The present work describes reduction of iodate (IO3,), and periodate (IO4,) at silicomolybdate-doped-glutaraldehyde-cross-linked poly- L -lysine (PLL-GA-SiMo) film coated glassy carbon electrode in 0.1,M H2SO4. In our previous study, we were able to prepare the PLL-GA-SiMo film modified electrode by means of electrostatically trapping SiMo12O404, mediator in the cationic film of PLL-GA, and the voltammetric investigation in pure supporting indicated that the charge transport through the film was fast. Here, the electrocatalytic activity of PLL-GA-SiMo film electrode towards iodate and periodate was tested and subsequently used for analytical determination of these analytes by amperometry. The two electron reduced species of SiMo12O404, anion was responsible for the electrocatalytic reduction of IO3, at PLL-GA-SiMo film electrode while two and six electron reduced species were showed electrocatalytic activity towards IO4, reduction. Under optimized experimental conditions of amperometry, the linear concentration range and sensitivity are 2.5×10,6 to 1.1×10,2,M and 18.47,,A mM,1 for iodate, and 5×10,6 to 1.43×10,4,M and 1014.7,,A mM,1 for periodate, respectively. [source] Multi-residue method for the analysis of pharmaceutical compounds in sewage sludge, compost and sediments by sonication-assisted extraction and LC determinationJOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2010Julia Martín Abstract A method for the simultaneous determination of 16 pharmaceutical compounds in three types of sewage sludge (primary, secondary and anaerobically digested dehydrated sludge), compost and sediment samples is described. Pharmaceutical compounds evaluated were nonsteroidal anti-inflammatory drugs (acetaminophen, diclofenac, ibuprofen, ketoprofen, naproxen and salicylic acid), antibiotics (sulfamethoxazole and trimethoprim), an anti-epileptic drug (carbamazepine), a ,-blocker (propranolol), a nervous stimulant (caffeine), estrogens (17,-ethinylestradiol, 17,-estradiol, estriol and estrone) and lipid regulators (clofibric acid, metabolite of clofibrate and gemfibrozil). The method is based on the ultrasonic-assisted extraction, clean-up by SPE and analytical determination by HPLC with diode array and fluorescence detectors. The best extraction recoveries were achieved in a three-step extraction procedure with methanol and acetone as extraction solvents. Extraction recoveries of several pharmaceutical compounds as caffeine were highly dependent on the type of sample evaluated. The applicability of the method was tested by analyzing primary, secondary and anaerobically digested dehydrated sludge, compost and sediment samples from Seville (Southern Spain). Ten of the sixteen pharmaceutical compounds were detected in sludge samples and five in compost and sediment samples. The highest concentration levels were recorded for ibuprofen in sewage samples, whereas salicylic acid and 17,-ethinylestradiol were detected in all of the samples analyzed. [source] QSARs for aromatic hydrocarbons at several trophic levelsENVIRONMENTAL TOXICOLOGY, Issue 2 2006Walter Di Marzio Abstract Quantitative structure,activity relationships (QSARs) with aromatic hydrocarbons were obtained. Biological response was measured by acute toxicity of several aquatic trophic levels. The chemicals assayed were benzene, toluene, ethylbenzene, o -xylene, m -xylene, p -xylene, isopropylbenzene, n -propylbenzene, and butylbenzene. Acute toxicity tests were carried out with Scenedesmus quadricauda, as representative of primary producers; Daphnia spinulata, a zooplanctonic cladoceran; Hyalella curvispina, a benthic macroinvertebrate; and Bryconamericus iheringii, an omnivorous native fish. The EC50 or LC50 was calculated from analytical determinations of aromatic hydrocarbons. Nonlinear regression analysis between the logarithm of the octanol,water partition coefficient (log Kow) of each compounds and the toxicity end points was performed. QSARs were positively related to increases in log Kow at all trophic levels. Intertaxonomic differences were found in comparisons of algae with animals and of invertebrates with vertebrates. We observed that these differences were not significant with a log Kow higher than 3 for all organisms. Aromatic hydrocarbons with log Kow values of less than 3 showed different toxicity responses, with algae more resistant than fish and invertebrates. We concluded that this was a result of the narcotic mode of action related to liposolubility and the ability of the compound to reach its target site in the cell. The bioconcentration factor (BCF) achieved to start nonpolar narcosis fell almost 1 order of magnitude below the BCF expected from the log Kow. Predicted critical body residues for nonpolar narcosis ranged between 2 and 1 mM. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 118,124, 2006. [source] Determination of banned Sudan dyes in food samples by molecularly imprinted solid phase extraction-high performance liquid chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 19 2009Claudio Baggiani Abstract A method for molecularly imprinted SPE of banned Sudan azo-dyes from food samples was investigated. The molecularly imprinted polymer was obtained by suspension polymerization using 1-(4-chlorophenyl)azonaphthalen-2-ol as the mimic template. The molecular recognition properties of imprinted beads were evaluated for use as a SPE sorbent, in order to develop a selective extraction protocol for the Sudan class of dyes. The optimized extraction protocol resulted in a reliable molecularly imprinted SPE (MISPE) method suitable for HPLC analysis. It was selective for the main analyte, Sudan I, and the related azo-dyes Sudan II, III, IV, Sudan Red B, and Sudan Red 7B, while the permitted azo-dyes Allura Red AC, Neococcin, and Sunset Yellow FCF were not extracted. The method was tested for Sudan I, II, III, and IV in five different food samples (hot chilli pepper, hot chilli tomato sauce, sausage, tomato sauce, and hard boiled egg yolk) at three concentration levels (15, 100, and 300 ,g/g). It demonstrated itself to be insensitive to the presence of different complex matrices, precise, accurate, and with good recovery rates (85,101%). The LOD and LOQ were satisfactory for most analytical determinations. [source] FIRMNESS EVALUATION OF SWEET CHERRIES BY A TRAINED AND CONSUMER SENSORY PANELJOURNAL OF TEXTURE STUDIES, Issue 5 2009CAROLYN F. ROSS ABSTRACT The objective of this study was to examine cherry firmness and the ability of a trained and consumer panel to differentiate between cherries of different firmness values. For the trained panel (n = 12) and consumer panel (n = 100) evaluations, two late-maturing, commercially important cherry cultivars were evaluated, "Selah" and "Skeena." For trained panel evaluations, the analytical firmness value of each cherry was determined, although for the consumer panel, cherries were characterized into different firmness categories (low, intermediate and high), after which, a series of paired comparisons were made. "Selah" was the less-firm cultivar by approximately 20 g/mm and consumers could distinguish the more-firm cherry in all comparisons (P < 0.05). For "Skeena," consumers could only distinguish soft versus firm. Trained panelists were able to distinguish between cherries of a minimum analytical firmness value of ,40 g/mm. A model was developed to predict sensory firmness from analytical determinations of firmness (r = 0.63). PRACTICAL APPLICATIONS Developing prediction models to estimate sensory response from analytical data will benefit the fruit industry by potentially allowing the use of analytical measurements as a proxy for sensory evaluation. In addition, understanding the importance of firmness on cherry acceptance and knowing the specific firmness values at which individuals can perceive a difference in sensory firmness is useful for cherry growers to produce a cherry with acceptable texture. [source] | ||||||||||