Laboratory Robotics and Automation最新文献

This article presents a self-made device used for continuous determination of pH in hard-working industrial conditions: mining and sugar industries. The device consists of a pH detector and a specific pH meter. The tungsten (W) based pH electrode and the mechanical cleaner of the electrode surface are the main parts of the pH detector. The continuous cleaning of the electrode surface ensures the high accuracy (±0.15 pH) of the continuous pH measurements. © 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 147–150, 1999

A rapid and sensitive method is described for flow-injection spectrophotometric determination of trace chromium (VI) in natural water. Preconcentration and elution of the trace analyte are achieved through quantitative and rapid adsorption on the surface of nanometer-size TiO₂ (anatase) powders and followed by the quantitative and reproducible elution of Cr(VI) using 2.0 M HCl as an eluent. The eluted Cr(VI) reacts with 1,5-diphenylcarbazide (DPCB) in the reaction coil to form a color complex, which is then detected by a spectrophotometer at the wavelength of 540 nm. The preconcentration factor is 55 for the sample volume of 25 mL, and the detection limit is 0.8 ng/mL Cr(VI). Under the optimized conditions, the analysis of Cr(VI) can be achieved at the rate of 6 samples/h for 0.001 μg/mL Cr(VI) or 20 samples/h for 0.1 μg/mL Cr(VI). The relative standard deviations are in the range of 0.37–3.35% (n = 5). © 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 141–145, 1999

An on-line determination of chlorine dioxide (ClO₂) in potable water using chlorophenol red (CPR) by gas diffusion flow-injection analysis (FIA) was investigated in the presence of various chlorinated species that can occur under normal water-treatment conditions. A gas diffusion membrane is used to separate the donor (sample) stream from the acceptor (detecting) stream (the donor stream transports the sample stream to the membrane separate device, and the acceptor stream collects all of the penetrated analytes and transports quantitatively to the detector) and makes it possible for this method to eliminate interference from metal ions, as well as other oxychlorinated compounds such as chlorite and chlorate. The system is more selective for chlorine dioxide than chlorine. The linear range of ClO₂ concentration is 0–0.5 mg·mL⁻¹ with a detection limit of 0.02 μg·mL⁻¹ (S/N = 3) and a sampling frequency of 50 h⁻¹. © 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 157–161, 1999

The construction and analytical evaluation of a graphite-epoxy ion-selective electrode coated with an ion pair formed between [Fe(oxalate)₃]³⁻ and tricaprylylmethylammonium cation (Aliquat 336) in a poly(vinylchloride) (PVC) matrix was recently presented [14]. The same active material was used in a tubular electrode in a flow-injection system. The tubular electrodes were made using carbon rods with external diameter of 6 mm and internal holes of 1 mm with different lengths (2.0, 2.5, and 3.0 cm). A thin membrane film of [Aliquat 336]₃[Fe(oxalate)₃], dibutylphthalate (DBPh) in PVC was deposited 3–4 times directly in hole walls using a dropper. The effect of membrane composition and electrode length over the iron (III) electrode response [slope (mV/dec)] was initially evaluated in triplicate, at pH range from 4 to 8 and in 0.2 mol L⁻¹ of oxalate solution as carrier. The best response (−18.7 ± 0.3 mV/dec) was attained with the 5% m/m ion pair; 65% m/m DBPh and 30% m/m PVC and a 2.0 cm electrode length, in this pH range. The electrode shows a linear response to E (mV) vs. log [Fe(oxalate)³⁻₃] in the iron (III) concentration range from 3.2 × 10⁻⁵ to 1.0 × 10⁻² mol L⁻¹ and a useful lifetime of at least 700 determinations for each polymeric membrane used. The detection limit was 2.5 × 10⁻⁵ mol L⁻¹, and the relative standard deviation was less than 2% for a solution containing 5.0 × 10⁻⁴ mol L⁻¹ of iron (III) (n = 12). The sampling rate was 90 h⁻¹, and the results obtained with this procedure are in close agreement with those obtained using the AA spectrophotometry (r = 0.9999). © 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 163–168, 1999

In the food production industry, estimation of protein content in various forms of products is a continual process where the estimated values are required for documentation as well as testing purposes. Chromatographs and infrared spectrometers are used to physically obtain the protein spectra from the food samples. The spectra provides some measures of protein contents of the samples. The use of faster on-line estimation programs with sufficient accuracy is desirable. A recent study indicates that the use of neural networks for the task of protein estimation is highly feasible. We followed upon the idea and modeled a few type of neural networks. These network types include back-propagation networks (BPNs), genetic reinforcement networks (GRNs), and radial basis function networks (CRBFNs). We found that the tested models are usable for the estimation purposes. In this article, we present our modeling and test results. © 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 151–155, 1999

Flow-injection immunoanalysis (FIIA) is a novel and automatic technique combining flow-injection approach with specific antibodies to complement the step of an immunoassay in a flow-through column format. This short review focuses on new FIIA contributions for environmental analysis problems with special emphasis on the pesticide residue determinations. Several major strategies in development of such technique with respect to the preparation of the antibody, immunoreactor support selection, novel coupling procedures for antibody and antigen immobilization, immunobinding conditions and elution and regeneration protocols, as well as assay formats and trace and detection schemes are taken into account. Some novel applications of the FIIA that appeared in more recent years as related to the field of pesticide residue analysis in environmental waters are outlined. © 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 83–89, 1999

An automated flow-rate meter easy to construct and operate is described. This is controlled by a microcomputer connected to an analog/digital converter interface and by a control software. It uses two acrylic flow cells, each comprising a bicolor light-emitting diode and a phototransistor placed on opposite sides. The performance of this flow-rate meter was evaluated by applying it to three flow manifolds: one monosegmented flow titration system by binary sampling; one conventional monosegmented flow system, and one single-line FIA system. The FIA system flow rate was assessed by means of a Vanderslice's expression. The time range of measurement of the flow rates was of 3.5–19.5 seconds and relative errors of 0.2–2.6% as well as relative standard deviations from 0.4 to 3.1% were attained. The flow-rate meter allows one to optimize precision and velocity of measurements just by changing one of its parameters. Moreover, the flow-rate meter can be used with flow systems, therefore allowing one to perform on-line measurements, which facilitates a quick and effective control of the channels flow rate.© 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 97–104, 1999

The flow system with fully rotary valve (FRV) operated as a directive valve has been designed and applied for calibration purposes. The role of the FRV was to create the set of standard solutions of compositions desired by directing and merging the streams of a single initial standard solution inserted into a flow manifold. The idea is presented of how different numbers of standards with the analyte concentrations distributed variously along a calibration line are possible to be prepared. It has been experimentally revealed that the system developed allows one to perform the calibration procedure with low consumption of time, work, and reagents, providing accurate and precise analytical results. © 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 111–119, 1999