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We present the results of a study of percent composition for a mixture which has been separated by gas chromatography and analyzed using helium pulsed-discharge photoionization detection (He-PDPID) and flame ionization detection (FID). FID has long been the means by which the percent composition of a hydrocarbon mixture has been determined since it has been previously established as a "carbon counting device". However, in this study we present results which show that He-PDPID is more accurate in determining the percent composition of a hydrocarbon mixture and, because it is a universal detection method and can detect compounds that FID cannot, it is also more effective for determining the percent composition of mixtures containing organic compounds with a variety of other functional groups.

An evaluation of five commercial software systems used for immunoassay data analysis revealed numerous deficiencies. Often, the utility of statistical output was compromised by poor documentation. Several data sets were run through each system using a four-parameter calibration function, and the results were compared to those from an independent method. Comparable results between systems were obtained, but often several attempts at analysis were necessary. The evaluation process revealed that it is difficult to monitor the numerous options available on these types of programs, and that incorrect results could easily be obtained if comparison analyses were not used. Recommendations for improved software functionality and for using the four-parameter calibration model are presented.

A "stopped-flow" method for the kinetic Jaffé determination of creatinine was developed, with the use of a computer-controlled continuous-flow system. Simplex optimization was used to find conditions of hydroxide and picrate giving maximum sensitivity for creatinine. We used a modified central composite experimental design to evaluate creatinine sensitivity and albumin, glucose, and acetone interferences as functions of hydroxide and picrate concentrations. More importantly, this work illustrates that the automated development of clinical chemical methods offers an efficient means of obtaining optimized, well-understood analytical procedures for subsequent routine use in the clinical chemistry laboratory.

Atomic absorption (AA) methods of analysis are subject to the influence of many experimental factors such as fuel and oxidant flow rates, burner height, and lamp current. The optimization of these factors and the corresponding improvement of response are integral parts of the development of AA methods. The importance of the systematic improvement of response was recognized by Cellier and Stace, who used sequential factorial designs to increase analytical sensitivity. Parsons and Winefordner considered the theoretical significance of various experimental factors and also employed factorial designs to achieve improved response. Other researchers have used similar statistical approaches in the development of AA methods.

Chemometrics is broadly defined as the application of mathematical and statistical methods to chemistry. Because the mathematical and statistical aspects of chemistry require measured values, analytical chemists have been at the forefront of the "chemometric revolution." Using the analysis of variance as a paradigm, I present an overview of chemometrics as it is practiced today. Receiving special emphasis are: the design of experiments to acquire information from the relevant universe of possible measurements; the establishment of relationships among independent and dependent variables; the importance of minimizing purely experimental uncertainty; sequential simplex optimization; analysis of principal components; and cluster analysis.

Chemometrics is broadly defined as the application of mathematical and statistical methods to chemistry. Because the mathematical and statistical aspects of chemistry require measured values, analytical chemists have been at the forefront of the "chemometric revolution." Using the analysis of variance as a paradigm, I present an overview of chemometrics as it is practiced today. Receiving special emphasis are: the design of experiments to acquire information from the relevant universe of possible measurements; the establishment of relationships among independent and dependent variables; the importance of minimizing purely experimental uncertainty; sequential simplex optimization; analysis of principal components; and cluster analysis.

A "stopped-flow" method for the kinetic Jaffé determination of creatinine was developed, with the use of a computer-controlled continuous-flow system. Simplex optimization was used to find conditions of hydroxide and picrate giving maximum sensitivity for creatinine. We used a modified central composite experimental design to evaluate creatinine sensitivity and albumin, glucose, and acetone interferences as functions of hydroxide and picrate concentrations. More importantly, this work illustrates that the automated development of clinical chemical methods offers an efficient means of obtaining optimized, well-understood analytical procedures for subsequent routine use in the clinical chemistry laboratory.

Presents the rules of the simplex algorithm and a simple method for introducing the application of simplex optimization to chemical systems.