Analytical Measurements (analytical + measurement)

Distribution by Scientific Domains


Selected Abstracts


Validation of Analytical Measurements by Single-trial and Collaborative Study

JOURNAL OF FOOD SCIENCE EDUCATION, Issue 1 2003
C.E. Carpenter
ABSTRACT: Validation of analytical measurements is necessary to report scientifically justifiable results. In this exercise, students validate the accuracy and precision of analytical instruments in single trials and in collaborative study, and validation results are used to report measurements in a scientifically justifiable manner. Tables are provided to guide data collection and to clarify reporting of results. A set of allied questions explores validation theory to develop student understanding, stimulate discussion, and provide feedback to the instructor regarding student comprehension. References are given that reinforce the validation concepts. [source]


On the modelling of publish/subscribe communication systems

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 12 2005
R. Baldoni
Abstract This paper presents a formal framework of a distributed computation based on a publish/subscribe system. The framework abstracts the system through two delays, namely the subscription/unsubscription delay and the diffusion delay. This abstraction allows one to model concurrent execution of publication and subscription operations without waiting for the stability of the system state and to define a Liveness property which gives the conditions for the presence of a notification event in the global history of the system. This formal framework allows us to analytically define a measure of the effectiveness of a publish/subscribe system, which reflects the percentage of notifications guaranteed by the system to subscribers. A simulation study confirms the validity of the analytical measurements. Copyright © 2005 John Wiley & Sons, Ltd. [source]


Disposable Gold Electrodes with Reproducible Area Using Recordable CDs and Toner Masks

ELECTROANALYSIS, Issue 1 2006
Denise Lowinsohn
Abstract The fabrication and characterization of very cheap disposable gold disk electrodes with reproducible area is reported. The innovation of the proposed procedure is the use of toner masks to define reproducible areas on uniform gold surfaces obtained from recordable compact disks (CD-R). Toner masks are drawn in a laser printer and heat transferred to gold surfaces, defining exactly the electrodes area. The electrochemical behavior of these disposable electrodes was investigated by cyclic voltammetry in Fe(CN)64, solutions. The relative standard deviation for signals obtained from 10 different gold electrodes was below 1 %. The size of the disk electrodes can be easily controlled, as attested by voltammetric responses recorded by using electrodes with radii varying from 0.5 to 3.0,mm. The advantages of using this kind of electrode for analytical measurements of substances that strongly adsorb on the electrode surface such as cysteine are also addressed. [source]


Cytochrome P4501A induction potencies of polycyclic aromatic hydrocarbons in a fish hepatoma cell line: Demonstration of additive interactions

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2000
Karl Fent
Abstract The relative CYP1A induction potencies, determined as ethoxyresorufin- O -deethylase (EROD) activity, and the cytotoxicities of 19 compounds with one to six benzene rings, mixtures of polycyclic aromatic hydrocarbons (PAHs), and contaminated landfill leachates have been determined in the permanent fish hepatoma cell line PLHC-1. No CYP1A induction was observed with benzene, naphthalene, anthracene, acenaphthene, benzo[g,h,i]perylene, and fluorene and low induction was found with fluoranthene and phenanthrene. All other PAHs with three and more benzene rings led to a concentration-related induction of CYP1A, with rebound decreases at high concentrations resulting in bell-shaped concentration,activity curves. Fish-related induction equivalency factors (IEFs) were estimated for all PAHs on the basis of EC50 values of their EROD activities and are reported here for the first time. The following order of decreasing IEFs was found: dibenz[a,h]anthracene > dibenzo[a,i]pyrene > benzo[k]fluoranthene > 3-methylcholanthrene > benzo[a]pyrene > benzo[e]pyrene > chrysene > 7,12-dimethylbenz[a]anthracene > perylene > benz[a]anthracene > pyrene. In contrast to the EROD activity, the immunodetectable protein content determined by ELISA showed a concentration-dependent increase. The interaction of PAHs in mixtures of up to eight individual compounds was additive based on their EROD activities. In landfill leachates, determined induction equivalents (IEQ) were significantly higher than calculated IEQs based on analytical measurements, which indicates additional unknown inducing compounds present in leachates. This study shows that the PLHC-1 cell in vitro system serves as an integrative bioanalytical tool in the ecotoxicological evaluation of aquatic environmental samples contaminated with CYP1A-inducing compounds. [source]


Physicochemical Properties of a New Multicomponent Cosolvent System for the pKa Determination of Poorly Soluble Pharmaceutical Compounds

HELVETICA CHIMICA ACTA, Issue 8 2007

Abstract A mixture of cosolvents is described that significantly improves the solubility of most pharmaceutical compounds. The mixture consists of equal volumes of MeOH, 1,4-dioxane, and MeCN, thereby containing polar and nonpolar solvents, and is referred to as MDM (from MeOH, dioxane, and MeCN). MDM is mixed with H2O until the required composition is reached. The utility of this system is that it enables analytical measurements to be performed on a wide range of compounds where measurements would be impaired in aqueous solution. We present the physicochemical characteristics of MDM/H2O mixtures (density, dielectric constant, psKw) and the principles of pKa measurement in this solvent/H2O mixture. We also present pKa values in H2O of several drug compounds determined from values measured in MDM/H2O mixtures. [source]


Bias-free results in the spectrophotometric determination of chemical oxygen demand in bleached textile mill effluents

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2002
Francesc Torrades
Abstract A calibration methodology that enables validation of the analytical procedure used in those cases where no placebo or standard reference material is available is applied here. The total Youden blank is used to eliminate the constant error component, and analytical measurements in the presence of the matrix at two different levels of the test portion, in order to avoid its interactive interference, are made. Moreover, the results obtained in the determination of chemical oxygen demand following a closed reflux spectrophotometric method are compared with those obtained when a definitive analytical method is applied, in order to show the absence of direct interference from the matrix. © 2002 Society of Chemical Industry [source]


Validation of Analytical Measurements by Single-trial and Collaborative Study

JOURNAL OF FOOD SCIENCE EDUCATION, Issue 1 2003
C.E. Carpenter
ABSTRACT: Validation of analytical measurements is necessary to report scientifically justifiable results. In this exercise, students validate the accuracy and precision of analytical instruments in single trials and in collaborative study, and validation results are used to report measurements in a scientifically justifiable manner. Tables are provided to guide data collection and to clarify reporting of results. A set of allied questions explores validation theory to develop student understanding, stimulate discussion, and provide feedback to the instructor regarding student comprehension. References are given that reinforce the validation concepts. [source]


FIRMNESS EVALUATION OF SWEET CHERRIES BY A TRAINED AND CONSUMER SENSORY PANEL

JOURNAL OF TEXTURE STUDIES, Issue 5 2009
CAROLYN 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]