Improved ruggedness for membrane-based amperometric sensors using a pulsed amperometric method.

This paper introduces a new approach to the use of membrane-based amperometric sensors which is expected to improve the ruggedness of these sensors significantly relative to the steady-state method in common use. In this new method, the fixed-voltage source used with the conventional steady-state method is replaced by a pulsed-voltage source. Unlike the fixed-source approach, which yields steady-state currents corresponding to large differences between analyte concentrations inside and outside the isolating membrane, the pulsed-source approach permits measurement of currents corresponding to near-equilibrium conditions between solutions inside and outside the membrane.

The inseparable triad: analytical sensitivity, measurement uncertainty, and quantitative resolution.

The formal definition of sensitivity associates the term with the change in the response of a system for a small change of the stimulus causing the response, i.e., the ratio of the response of a system to the stimulus causing it.

Measurement/data-processing method to improve the ruggedness of membrane-based sensors: Application to amperometric oxygen sensor.

This paper describes alternative measurement and data-processing approaches that can reduce effects of experimental variables on results obtained with a membrane-based sensor for oxygen. In the new approaches, the membrane-based sensor is first equilibrated with the sample solution, after which a polarizing voltage is applied and current vs. time data are recorded as the response decays toward a steady-state condition.

Unified view of kinetic-based analytical methods with emphasis on ruggedness. A review.

All analytical determinations can be grouped into two general categories, namely equilibrium-based and transient-based methods. This is an important grouping because most conventional approaches to transient-based methods are much less rugged than their equilibrium-based counterparts. As a result it is necessary to control variables within much narrower tolerances for transient-based methods than equilibrium-based methods to obtain similar degrees of reliability.

Use of artificial intelligence in analytical systems for the clinical laboratory.

Objective: To consider the role of software in system operation, control and automation, and attempts to define intelligence.

Methods And Results: Artificial intelligence (Al) is characterized by its ability to deal with incomplete and imprecise information and to accumulate knowledge. Expert systems, building on standard computing techniques, depend heavily on the domain experts and knowledge engineers that have programmed them to represent the real world.

Use of artificial intelligence in analytical systems for the clinical laboratory.

The incorporation of information-processing technology into analytical systems in the form of standard computing software has recently been advanced by the introduction of artificial intelligence (AI), both as expert systems and as neural networks.This paper considers the role of software in system operation, control and automation, and attempts to define intelligence. AI is characterized by its ability to deal with incomplete and imprecise information and to accumulate knowledge.

International Federation of Clinical Chemistry. Use of artificial intelligence in analytical systems for the clinical laboratory. IFCC Committee on Analytical Systems.

The incorporation of information-processing technology into analytical systems in the form of standard computing software has recently been advanced by the introduction of artificial intelligence (AI) both as expert systems and as neural networks. This paper considers the role of software in system operation, control and automation and attempts to define intelligence. AI is characterized by its ability to deal with incomplete and imprecise information and to accumulate knowledge.

Predictive steady-state chromatography. 1. Algorithms for leading and trailing edges of resolved and unresolved peaks in liquid chromatography.

This paper describes mathematical models and curve-fitting procedures that permit steady-state saturation signals to be computed accurately from data along leading and trailing edges of liquid chromatograms. This new approach to quantitative chromatography is called predictive steady-state chromatography (PSSC). It is shown that the computed saturation signals are virtually the same when determined from data along leading and trailing edges and they vary linearly with analyte concentration.

Kinetic method for the quantitative resolution of structural isomers based on the catalytic properties of beta-cyclodextrin.

This paper describes a new approach for the quantitative resolution of mixtures of structural isomers. The method is based on the observation that rate constants for the cyclodextrin-catalyzed hydrolysis of selected structural isomers are significantly different. By using cure-fitting methods, it is possible to use these differences in rate constants to resolve kinetic responses for mixtures into the responses for the individual components.

Systematic top-down approach to clinical chemistry.

This paper introduces a systematic approach to organizing the discipline of clinical chemistry. The approach is called a top-down systems approach because it starts at the top with the most general concepts and works down through less general concepts to the most specific details and techniques. The hypothesis is that the discipline can be organized into hierarchical levels of functional processes and operational approaches to those processes.

Increasing the biosafety of analytical systems in the clinical laboratory.

Biosafety is an important part of the know-how of all clinical laboratory professionals. Biosafely must have high priority in the design and use of analytical systems. Attention should be focused on reducing the handling of biological specimens, reducing biohazards to laboratory personnel, and on improving the labelling and containment of biohazardous materials.

International Federation of Clinical Chemistry (IFCC): systematic top-down approach to clinical chemistry.

This paper introduces a systematic approach to organizing the discipline of clinical chemistry. The approach is called a top-down, systems approach because it starts at the top with the most general concepts and works down through less general concepts to the most specific details and techniques. The hypothesis is that the discipline can be organized into hierarchical levels of functional processes and operational approaches to those processes.

Analytical applications of catalytic properties of modified cyclodextrins.

This paper describes the evaluation of the catalytic properties of modified cyclodextrins for analytical applications. The beta-dimethylcyclodextrin was modified by adding one and two imidazolyl groups at carbon three positions. The modifications produced enhancements of catalytic activity for the hydrolysis of p-nitrophenyl acetate at neutral pH by factors of 1000 or more relative to the unmodified cyclodextrins.

Initial studies of a new approach to the design and use of enzyme-based reactor/sensor systems: amperometric system for glucose.

This paper describes the development and evaluation of a new approach to the design and use of enzyme-based reactor/sensor systems (so-called "enzyme electrodes"). In the new approach, the reactor/sensor design is such that the measured response corresponds to reaction of all substrate in a fixed volume of solution. The result is that equilibrium-based measurements can be made, which in turn should result in advantages such as extended linear ranges and reduced dependencies on experimental variables such as enzyme activity, temperature, activators, inhibitors, etc.

Error-compensating kinetic method for enzymatic determination of DNAs.

We describe the adaptation and evaluation of an error-compensating method for kinetic determinations of deoxyribonucleic acids (DNAs). The DNA is first reacted with ethidium bromide to produce a fluorescent intercalation complex. Subsequent treatment of the complex with DNase catalyzes hydrolysis of the DNA, causing a time-dependent decrease in fluorescence, which is monitored.

Development and evaluation of an error-compensating predictive data-processing method for liquid chromatography.

This paper describes an alternative data-processing approach for liquid chromatographic responses. Transient data from the leading edges of chromatographic peaks for nonsaturating amounts of sample are used with a suitable mathematical model and curve-fitting program to predict the steady-state response that would be measured if sufficient sample were used to saturate the system. Results obtained by this approach are compared with peak-height and peak-area options by using aspirin as an analyte.

Kinetic study of the reaction of acetoacetate with glycine and sodium nitroprusside.

This paper describes an extensive kinetic study of the reactions involved in the determination of acetoacetate in body fluids. It is concluded that acetoacetate reacts with glycine to produce an imine intermediate that tautomerizes to an enamine. It is also concluded that nitroprusside reacts with the imine intermediate to produce an unstable product with an absorption maximum near 540 nm.

Improved data-processing method for atomic absorption spectroscopy with electrothermal atomization.

A new approach is described for processing transient data from electrothermal atomizers used in atomic absorption spectroscopy. The transient responses are first integrated and then a pseudo-first-order model is fit to the time-dependent integrals in order to predict the response that would be measured if the atomization process were monitored to completion. The principal advantage expected and observed for the new approach is its ability to reduce effects of variables such as atomization temperature.

Systematic top-down approach to clinical chemistry.

This paper introduces a systematic approach to organizing the discipline of clinical chemistry. The approach is called a top-down, systems approach because it starts at the top with the most general concepts and works down through less general concepts to the most specific details and techniques. The hypothesis is that the discipline can be organized into hierarchical levels of functional processes and operational approaches to those processes.

Data-processing method to reduce error coefficients for membrane-based analytical systems. 1. Amperometric-based sensor evaluated for quantification of oxygen.

This paper describes the use of a predictive, curve-fitting method to reduce the effects of experimental variables on results obtained with membrane-based devices. Multipoint data from the transient regions of responses are used with suitable models and curve-fitting methods to predict the signal that would be measured for the system at equilibrium. The resulting equilibrium response usually is much less dependent on experimental variables than the transient responses used to predict it.

Evaluation of transient responses of ammonia-selective potentiometric electrodes for quantitative applications.

An error-compensating, predictive kinetic method is adapted and evaluated for quantitative applications based on transient responses from an ammonia-selective electrode. Transient data collected during the early part of the electrode response are used with a curve-fitting method and appropriate mathematical models to predict the signal that would be measured if the response were monitored to equilibrium. Several different theoretical and empirical models were evaluated, and all but one of the models tested permitted reliable prediction of equilibrium potentials for most responses.

Simultaneous determinations of liver- and bone-type alkaline phosphatase by curve-fitting of inhibition kinetic data. II. Development and evaluation of a fluorescence-based method.

We describe a kinetic method for the determination of alkaline phosphatase (ALP) isoenzymes, based on fluorescence detection of 4-methylumbelliferone. Several different buffer-inhibitor combinations and substrate concentrations were evaluated. Best results were obtained for inhibition with 2.