Referee Method Research Articles

Multivariate analysis of non-homogeneous peaks in liquid chromatography

The effects of concentration, separation and spectral similarity as factors influencing the accuracy of iterative target testing factor analysis (ITT-FA) are investigated for three component systems by the application of analysis of variance (ANOVAR). ANOVAR is applied over a range of peak separations to map the changing effects of the three factors with increasing overlap. Two error responses were measured and analysed, (a) Relative cluster error (RCE) a measure of the error over all peaks in a cluster and (b) Relative peak error (RPE) the error of an individual peak. Multicomponent analysis (MCA) a method requiringa priori spectral information, is used as a referee method for ITT-FA.

Rapid determination of molybdenum in ferromolybdenum and molybdenum additives, with oxine

A rapid method is presented for the gravimetric determination of molybdenum (as the oxinate) in ferromolybdenum and molybdenum additives. The sample is fused with a mixed flux of sodium peroxide and sodium carbonate in a zirconium crucible for complete decomposition. Leaching the cooled fusion cake with water provides instantaneous separation of molybdenum as sodium molybdate from iron(III) and other hydrous oxides. After filtration, the molybdenum is precipitated with oxine after addition of EDTA and oxalate to obviate interference from other metal oxinates, and determined gravimetrically. The precision and accuracy are comparable to those of referee methods.

Determination of chlorpromazine and its sulphoxide in pharmaceutical dosage forms by third-order derivative ultraviolet spectroscopy

In pharmaceutical dosage forms, interference in the UV spectra of analytes by other UV-absorbing solutes leads to a requirement for the development of procedures with greater specificity. One method used to address this problem is the technique of derivative spectroscopy, where the composite spectrum is transformed to the second or higher derivative in the wavelength domain. This paper reports the novel application of this technique to the determination of a phenothiazine (chlorpromazine) and its sulphoxide impurity in various pharmaceutical dosage forms.A systematic approach developed for optimisation of the derivative order, graphical measurement and instrumental conditions led to the adoption of third-order derivative spectroscopy as a method with suitable precision and selectivity for the determination of the phenothiazines. Both the parent compound and the sulphoxide impurity can be assayed in dosage forms by measurement of the amplitudes of, respectively, the positive peak at 259 nm with respect to the negative peak at 267 nm, and the positive peak at 350 nm with respect to the negative peak at 361 nm. A new notation for denoting these amplitude measures is proposed, viz., 3D259,267 and 3D350,361, respectively. By comparison with an independent referee method based on reversed-phase HPLC, the proposed method and the referee method gave statistically similar results for the determination of chlorpromazine and its sulphoxide in injectables, tablets and syrups. The figures of merit for the proposed assays are described in terms of response linearity, 95% confidence limits, relative standard deviation, recovery data and correlation coefficients. It is suggested that similar methodology should be applicable to the analysis of other members of the phenothiazine class of compounds.

Comparison of several instrumental methods for determining chlorine residuals in drinking water

The authors evaluated four methods for determining chlorine residuals in water. Two membrane electrodes, a potentiometric electrode, and a continuous total chlorine analyzer were used by analysts to measure free or total chlorine in quality assurance samples and in tap water samples. Amperometric titration was used as a referee method. The statistical analyses of the evaluations are presented in this paper. Average precision of all analysts and of individual analysts is considered for each method.

A New Procedure for Comparing Methods in Food Science

Food science requires the ability to measure the amounts of substances under study. As new methods are developed, it is necessary to compare these methods in terms of their precision and accuracy. In most cases, since in error-free or referee method is not available, there are no “exact” values with which these new method measurements can be compared. To overcome these difficulties, a procedure for comparing methods, which incorporates principal component analysis, is discussed. This procedure is illustrated with an example where methods for the determination of the cholesterol content of cod muscle are compared.

Atomic Absorption Spectrophotometric Method for Determination of Water-Soluble Copper in Water-Insoluble Copper Fungicides: CIPAC Collaborative Study. Comparison with Bathocuproine Method

Abstract An atomic absorption spectrophotometric (AAS) method was collaboratively studied by 8 laboratories from Africa, the United States, Australia, and Europe. The samples were dispersed in deionized water. After centrifuging and filtering, the water-soluble copper in the filtrate was acidified and measured by atomic absorption spectrophotometry, in an airacetylene flame, at 324.7 nm. The results from 7 laboratories were satisfactory and no unfavorable comments were received. Repeatability standard deviations ranged from 0.005 to 0.023, and reproducibility standard deviations ranged from 0.012 to 0.062. When compared with the bathocuproine method, the difference in bias between both methods is not significant. They were both adopted as full CIPAC methods, with the bathocuproine method as the referee method. Both methods have been adopted official first action.

Discussion of: Statistical Comparison of Multiple Analytic Procedures: Application to Clinical Chemistry

The paper by Lawton, Sylvestre, and Young addresses the important problem of the statistical comparison of several analytic methods (all for measuring the same thing) when no referee method is available. The authors propose a multivariate approach to the problem, which provides estimates of some of the components of variance for each method. The procedure is intended for situations in which fairly large data sets are available from more than two methods. We tried our hand at implementing the recommended procedure on the data set used in the paper by Carey, Wold, and Westgard [2], which was used for the illustrative example in the paper under discussion. We will call this the Carey data set. We also tried the procedure on a smaller set of constructed data. The calculations are easy to program, provided one already has programs to invert matrices and to compute eigenvalues and eigenvectors.

Evaluation of an Automated Blood Smear Analyzer

The performance of a diff3 System prototype instrument that does automated leukocyte differential counts, erythrocytic morphology determinations, and leukocyte count and platelet count estimates, was compared with performance by laboratory personnel for a five-week period in an active general hospital. Using experienced supervisors as the referee method, this instrument performed as well as the routine laboratory staff in all aspects of leukocyte differential counting. With respect to erythrocytic morphology, estimates of hypochromia were inferior to those of the routine laboratory staff; comparisons of estimates of macrocytosis and polychromasia were not significantly different. Leukocyte and platelet numerical estimate performance by the diff3 System was not as good as that of automated cell-counting instruments, but categorization of platelet concentration as normal or abnormal did compare favorably with estimation by laboratory personnel. The flagging of abnormal slides by the instrument was comparable in sensitivity to that by the routine laboratory staff; however, specificity was less, with a significantly greater number of false positives obtained by use of the instrument.

Complexometric determination of aluminium in iron ore, sinter, concentrates and agglomerates

A method for the complexometric determination of aluminium in iron ore, sinter, concentrates and agglomerates encountered in international trade is described. The sample is fused in a zirconium crucible with a mixed flux of sodium carbonate and sodium peroxide. The fused mass is completely soluble in hydrochloric acid. The R 2O 3 oxides are then precipitated with ammonia and redissolved in hydrochloric acid. Elements such as iron, titanium and zirconium are separated from aluminium by solvent extraction with cupferron and chloroform. After removal of traces of organic matter from the aqueous phase, the solution is treated with an excess of EDTA, which is then back-titrated with zinc solution (Xylenol Orange as indicator). Addition of ammonium fluoride then releases EDTA equivalent to the aluminium and this is titrated with zinc solution. The method is rapid. The precision and accuracy are excellent, and the results comparable with those obtained by the referee method.

Rapid sample dissolution and determination of total iron in iron ore, sinter, concentrates and agglomerates

A method is described for rapid and complete dissolution of iron ores with a wide range of composition in order to determine total iron. The sample is fused with a mixed flux of sodium carbonate and sodium peroxide in a vitreous carbon crucible and the melt is dissolved in hydrochloric acid. Iron is then determined by redox titration with dichromate. The wide range of composition of the samples for which the method can be used, as exemplified by results obtained for ISO, BCS and NBS reference standards, demonstrates its universal applicability. The method is rapid, free from tedious and timeconsuming manipulations, suitable for routine control and yields results comparable with those obtained by the referee method.

A Referee Method for the Determination of Total Calcium in Serum

Abstract The first referee method of analysis (a method of known accuracy) in clinical chemistry has been developed through the cooperation of scientists from the National Bureau of Standards and eight clinical chemistry laboratories. Subject to some limitations discussed in the text, calcium in serum can be determined by the referee method to within ±2% of the "true or absolute" value. The complete protocol, based on an atomic absorption spectrometric procedure, is described in detail.

Determination of lead in airborne particulates in Chicago and Cook County, Illinois, by atomic absorption spectroscopy

A simple precise procedure for determining the lead content of suspended particulate samples collected from the air uses atomic absorption spectroscopy. It is necessary to utilize the standard additions technique to overcome matrix effects. Analyses of 38 samples collected in the Chicago and Cook County area on March 31, 1966, as a part of the National Air Sampling Network, yielded values from 0.10 to 3,18 g. of Pb per cubic meter of air. Results obtained by the referee method of polarography showed substantial agreement with atomic absorption values. Possibilities of employing atomic absorption for the determination of other metals found in suspended particulates are currently being investigated. 12 references, 4 figures, 2 tables.

The microdetermination of dissolved oxygen in water. V. development of a self‐testing and fully compensating analytical method

AbstractAn ion‐exchange technique is shown to be effective for removing interference by ferrous ion in the Winkler reaction. A referee method for the determination of dissolved oxygen in water is described incorporating full allowance for interfering substances and tests for bias and precision. The precision of one estimate of dissolved oxygen by the method is ±0·0015 p.p.m.

THE ANALYSIS OF SODA‐LIME GLASS1

ABSTRACTIn a discussion of the analysis of soda‐lime glass two types of methods must be considered: (1) the accurate or so‐called umpire or referee methods for determining the true composition of the glass, and (2) the less accurate but more rapid routine methods used in factory control. This paper deals primarily with the former.