Application of ESCA to analytical chemistry I. Electrochemical concentration of metals for trace quantitative analysis by ESCA

A technique employing electrochemical deposition followed by ESCA measurements is described. This combination can be used to obtain quantitative analytical information for metal ions present in solution at the part per billion level or lower. Results of such experiments for lead are reported.     

Uncertainties of method performance statistics based on a balanced completely randomized model interlaboratory study

Using exact and asymptotic distributions, formulas were developed to derive population variances and uncertainties, and their corresponding unbiased estimates, for the method performance statistics, i.e., the sample mean (y..), the repeatability variance and standard deviation and (s2r and sr), and the reproducibility variance and standard deviation (s2R and sR) and obtained from collaborative study of an analytical method.     

On determining a 1-tailed upper limit for future sample HorRat values

Two formulas were developed for use in computing 1-tailed upper limits for future HorRat values obtained from the collaborative study of materials. One formula is applicable when a future sample HorRat value H [formula: see text] is computed based on a known concentration (e.g., C = spike level and RSD(R) is the sample relative reproducibility standard deviation) and the other formula is applicable when the true concentration (C) is unknown and a future sample HorRat value [formula: see text] is computed using the sample mean (e.g., y, the collaborative study overall mean for an analyte). A Monte Carlo simulation procedure was developed using the Statistical Analysis System (SAS) software to assess the accuracy of the 2 developed formulas. Based on the degree of closeness between the simulated and calculated limits, the formulas for computing upper limits for future sample HorRat values will prove to be useful to Study Directors in determining worst case scenarios concerning a method's reproducibility precision relative to that predicted using the "Horwitz equation". We also define the current empirical HorRat limits as 1-tailed 100p% upper limits to assess the statistical consequence, in a probability sense, of their application as an analytical methods screening tool.     

Procedures for estimating confidence intervals for selected method performance parameters.

Procedures for estimating confidence intervals (CIs) for the repeatability variance (sigmar2), reproducibility variance (sigmaR2 = sigmaL2 + sigmar2), laboratory component (sigmaL2), and their corresponding standard deviations sigmar, sigmaR, and sigmaL, respectively, are presented. In addition, CIs for the ratio of the repeatability component to the reproducibility variance (sigmar2/sigmaR2) and the ratio of the laboratory component to the reproducibility variance (sigmaL2/sigmaR2) are also presented.     

Synthesis of Novel Bisphosphono-Pyrimidinediones Via Pentacovalent Organophosphorus Methodology

Abstract

The synthesis of bisphosphono-pyrimidinediones from the condensations of pentacovalent oxaphospholenes with isocyanates is discussed.     

Two-photon resonant photo-hall effect in n-InSb

Resonant two-photon structure is observed in the photo-Hall response of n-InSb at liquid helium temperatures. The number of two-phonon photo-excited carriers, directly determined from the photo-Hall effect, is seen to be proportional to the square of the incident laser intensity and to decay via a two-stage process. The low intensity and photo-excited carrier decay results are described using a three-level system involving the shallow donor impurity levels.     

Stability of a microwave heated fluid Layer

When a time harmonic electromagnetic wave impinges on a slaba certain portion of the wave creates heat within the slab throughdipolar and ohmic heating. The electrical and thermal propertiesof the material dictate the dynamical nature of the heatingprocess, as well as the steady-state temperature profile. Thematerial considered here is a slab of fluid. We consider thecase where the fluid is bounded by thin rigid layers of transparentmaterial. The steady-state heating profile governs the typesof convective motions that can occur and also affects the stabilitycharacteristics of temperature, pressure and velocity perturbationsintroduced in the slab. The main objective here is to examinesuch stability characteristics, initially in the linear regime.Both rigid-rigid and rigid-free configurations are considered.