Interlaboratory comparison of the intensity of drinking water odor and taste by two-way ordinal analysis of variation without replication.

A case study of ordinal data from human organoleptic examination (sensory analysis) of drinking water obtained in an interlaboratory comparison of 49 ecological laboratories is described. The recently developed two-way ordinal analysis of variation (ORDANOVA) is applied for the first time for the treatment of responses on the intensity of chlorine and sulfurous odor of water at 20 and 60 °C, which is classified into the six categories from 'imperceptible' to 'very strong'. The one-way ORDANOVA is used for the analysis of the 'salty taste' intensity of the water.

Total risk of a false decision on conformity of an alloy due to measurement uncertainty and correlation of test results.

Total risk (probability) of a false decision on conformity of an alloy due to measurement uncertainty and correlation of test results is quantified. As an example, a dataset of test results of a PtRh alloy is studied when contents of four components of the alloy composition are under control. There are specification limits for contents of 1) Pt and 2) Rh; 3) three precious impurities - Au, Ir and Pd, and 4) eight impurities, both precious Au, Ir, Pd, and non-precious Fe, Pb, Si, Sn, Zn.

Risk of a false decision on conformity of an environmental compartment due to measurement uncertainty of concentrations of two or more pollutants.

Risks of false decisions in conformity assessment of an environmental compartment due to measurement uncertainty of concentrations of two or more pollutants are discussed. Even if the assessment of conformity for each pollutant in the compartment is successful, the total probability of a false decision concerning the compartment as a whole might still be significant. A model of the total probability of a false decision, formulated on the base of the law of total probability, is used, for example, for a study of test results of total suspended particulate matter (TSPM) concentration in ambient air near to three independent stone quarries located in Israel, as the sources of the air pollution.

Risk of false decision on conformity of a multicomponent material when test results of the components' content are correlated.

The probability of a false decision on conformity of a multicomponent material due to measurement uncertainty is discussed when test results are correlated. Specification limits of the components' content of such a material generate a multivariate specification interval/domain. When true values of components' content and corresponding test results are modelled by multivariate distributions (e.

Conformity assessment of multicomponent materials or objects: Risk of false decisions due to measurement uncertainty - A case study of denatured alcohols.

Risk of a false decision on conformity of a multicomponent material or object due to measurement uncertainty is discussed. Even if conformity assessment for each component of a material sample is successful, the total probability of a false decision (total consumer's risk or producer's risk) concerning the sample as a whole might still be significant. A model of the total probability of such false decisions is formulated based on the law (theorem) of total probability.

Monte Carlo simulation of expert judgments on human errors in chemical analysis--a case study of ICP-MS.

Monte Carlo simulation of expert judgments on human errors in a chemical analysis was used for determination of distributions of the error quantification scores (scores of likelihood and severity, and scores of effectiveness of a laboratory quality system in prevention of the errors). The simulation was based on modeling of an expert behavior: confident, reasonably doubting and irresolute expert judgments were taken into account by means of different probability mass functions (pmfs). As a case study, 36 scenarios of human errors which may occur in elemental analysis of geological samples by ICP-MS were examined.

Redox-potentiometric determination of peroxide value in edible oils without titration.

Standard methods for peroxide value determination in edible oils, which are based on KI oxidation by the hydroperoxides and volumetric titration of the liberated iodine, have been improved using redox-potentiometric iodine determination without titration. Stages of the KI oxidation and redox-potentiometric measurements were combined in the same electrochemical cell. The limit of quantitation of the new method is 0.

pH-Metric method for acid number determination in hydraulic oils without titration.

A heptane-mediated extraction of acids from hydraulic oils is proposed for pH-metric acid number determination without titration. The acids are extracted in the reagent consisting of triethanolamine and potassium nitrate dissolved in water and isopropanol. The use of heptane allows us to overcome the influence of additives in the hydraulic oil on the glass electrode.

pH-Metric determination of acid values in oilseeds without titration.

A new pH-metric method for determination of acid values in oilseeds without titration has been developed in the range 0.6-10 and more mg KOH/g. The method is based on a rapid (1-2 min) selective and complete extraction of free fatty acids from an oilseed test portion into a special reagent A, separation of the solution from the solid oilseed material by centrifugation or filtration, transfer of an aliquot of the solution into a pH-metric cell with reagent B for measurement of conditional pH(1)' of the formed mixture, addition of standard acid (HCl or H(2)SO(4)) and pH(2)' measurement.

pH-Metric determination of acid numbers in petroleum oils without titration.

A new pH-metric method without titration has been developed for determination of acid numbers lower than 0.1 mg (KOH) g(-1) (oil) in petroleum oils such as White, Transformer and Basic oils. The method is based on rapid and complete extraction of acids from an oil test portion into the novel reagent and measurement of the conditional pH in the ;oil-reagent' mixture by a glass electrode.

Simultaneous voltammetric determination of uric and ascorbic acids in urine.

Anodic voltammetric method for simultaneous determination of uric acid (UA) and ascorbic acid (AA) in urine has been developed with the use of a commercial working rotating glassy carbon electrode. UA may be determined in a sample diluted by the buffer supporting electrolyte (HOAc+NH(4)OH; pH 5.1-5.

Distributions of results of cetirizine dihydrochloride assay in bulk material.

The distribution of the cetirizine dihydrochloride assay results in correlation with the pharmacopoeia limits is analyzed. The data for analysis were obtained at Chemagis Ltd., Israel, for 13 batches during a year in two laboratories by five analysts using three different titroprocessors (total 114 results of the determination).

pH-metric determination of acid numbers of petroleum oils without titration.

A pH-metric method was developed for determination of the acid numbers of oils containing organic and inorganic acids at levels <0.1 mg KOH/g oil. The method is based on rapid and complete extraction of acids from a test portion of oil into a special reagent, and measurement of the conditional pH of the mixture "oil-reagent" by a glass electrode.

Water determination in drugs containing thiols.

A new rapid analytical method is applied for water determination in alpha-Mono-thioglycerol and Captopril tablets containing thiols, and therefore, not amenable for direct Karl Fischer titration. The method is based on the consecutive titration first of thiol by a novel reagent, and then of water by a conventional K. Fischer reagent in the same sample and cell with the electrometric 'dead-stop' location of the end point in both titrations.

Water determination in drugs containing ascorbic acid.

A new rapid analytical method was applied for water determination in tablets of vitamin C, Ce De Calcium Veterinary, and C-Tamin-500 containing ascorbic acid and therefore is not amenable for direct Karl Fischer (KF) titration. The method is based on the consecutive titration first of ascorbic acid by a novel reagent and then of water by a conventional KF reagent (KFR) in the same sample and cell with the electrometric "dead-stop" location of the end point in both titrations. The new reagent consists of iodine, potassium iodide, and sodium acetate in nonaqueous medium.

Simultaneous determination of water and enediols or thiols in chemical products and drugs not amenable to direct Karl Fischer titration.

A method proposed for determining water and enediols or thiols is based on consecutive titration of the enediols or thiols by a novel reagent and of water by the conventional Karl Fischer reagent in the same cell. The time for both titrations is 8-20 min. The novel reagent consists of iodine, sodium acetate as a base, and potassium iodide in a nonaqueous solvent system.

pH-metric determination of the acid value of vegetable oils without titration.

The acid value (AV) of vegetable oils is determined without titration by using a new reagent consisting of triethanolamine in a solution of water and isopropyl alcohol. When the oil sample is mixed with the reagent in the pH-metric cell, free fatty acids from the sample are extracted into the reagent (3-4 min). The initial pH, called conditional pH'1, is measured, a standard acid (HCl) is added, and the final pH, pH'2, is measured.

Determination of water samples and ene-diols or thiols in samples inaccessible for direct K.Fischer titration.

Novel reagents and the rapid technique were developed for the simultaneous determination of water and ene-diols or thiols in chemical products, drugs and other materials which are inaccessible for direct K.Fischer titration. The reagents consist of iodine, tetramethylammonium iodide or potassium iodide, base (diethanolamine, triethanolamine, sodium acetate and/or urea) in methanol mixed with N,N-dimethylformamide, or with formamide, or with dimethyl sulfoxide and N,N-dimethylformamide mixture as a solvent.

Microcell for anodic stripping voltammetry of trace metals.

A microcell for batch injection stripping voltammetry of trace metals with the use of a rotating disk working electrode has been developed and tested for samples of 0.2-0.3 mL.

Alternative methods for titratable acidity determination.

Methods for determination of titratable acidity, other than traditional titration, i.e. methods without titration, are considered.

Organically-doped sol-gel based tube detectors: Determination of iron(II) in aqueous solutions.

A novel type of disposable sensor for the determination of iron(II) in aqueous solution is described. The iron sensor serves to exemplify a new class of disposable field tests for field analysis of water pollutants. The sensors are comprised of capillary glass tubes filled with porous sol-gel silica powder doped with o-phenanthroline.

Theory of intralaboratory validation of accuracy of an analytical technique by standard reference materials.

The theory is presented for intralaboratory accuracy validation of a sample analysis technique, employing standard reference materials. The validation criteria and the corresponding probabilities of erroneous conclusions concerning accuracy are given.