Laboratory Robotics and Automation最新文献

This presentation addresses an automated quantitative analysis designed for determination of chloroanilines (CA) in personal cleansing (PC) liquid products containing trichlorocarbonilide (TCC). These materials may be present as impurities in the germicides as used, or they may be formed from the germicides during processing. This is a fully automated analysis which covers everything from sample preparation to determination of CA at the parts per million level. The CA is diazotizated by addition of sodium nitrite. After a prescribed reaction time, the excess nitrous acid is destroyed with ammonium sulfamate. The diazotizated CA is derivatized with naphthylethylene diamine and the level determined by difference in the UV-VIS absorption at approximately on peak (555 nm) and background (660 nm). Linearity, accuracy, and precision ensure the validity of the robotics method. The method has a linearity working range from 0 to 100 ppm (correlation coefficient, R = 0.9995). The method gives acceptable recoveries: R = 102% for liquid soap. Relative standard deviation is 1.14%. These results demonstrate that the system can determine the concentration of CA in PC products. This automated CA analysis frees up analysts from routine laboratory work for more technically difficult projects. The robot is capable of managing 36 samples per day, which is more than three times higher capacity than the manual procedure. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:282–285, 2000

A simple, fast, and low-cost flow-injection system is proposed for the determination of orthophosphate in digested plant material. The determination is based on the precipitation reaction of orthophosphate with 0.05 mol L⁻¹ zinc solution in 0.05 mol L⁻¹ triethanolamine buffer (TEA/TEAH⁺, pH 6.0) solution containing 0.025% (w/v) poly-(vinylalcohol). The zinc orthophosphate suspension produced was directly measured at 410 nm. Under the best experimental conditions, orthophosphate was determinated in the concentration range from 5 to 60 mg P L⁻¹, and the relative standard deviations were less than 1.6% for 10 and 20 mg P L⁻¹ solutions (n = 9). The analytical frequency was 180 h⁻¹. The results obtained using the proposed FIA procedure and those obtained using a standard spectrophotometric procedure agree at the 95% confidence level. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:236–240, 2000

A flow injection system with online sample preparation is proposed for the determination of phosphite in liquid fertilizers by spectrophotometry. After loop-based injection, phosphite is oxidized by an acidic permanganate solution (1.0 10⁻² mol L⁻¹ KMnO₄ + 1.0 mol L⁻¹ H₂SO₄) in a heated reactor (50 °C). The phosphate generated is then determined by the molybdenum blue method. Influence of flow rates, temperature, and concentration and order of addition of reagents, sample volume, and reactor configuration for the blue complex formation on recorded signals were investigated. The flow system was applied to phosphite determination in commercial samples of liquid fertilizers. The proposed system handles about 80 samples per hour [0.05–0.40% (w/v) H₃PO₃; R = 0,9998), consuming about 80 μL sample, 1 mg KMnO₄, 25 mg (NH₄)₆Mo₇O₂₄, and 10 mg ascorbic acid per determination. Results are precise [relative standard deviation ≤ 3.5% for 0.1% (w/v) H₃PO₃, n = 12] and in agreement with those obtained by gravimetry at 95% confidence level. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:286–290, 2000

An overview is made of the research work carried out in the author's laboratory, which is aimed at developing thin ion-selective chalcogenide membrane by induced cathodic electrodeposition onto inert conducting substrate at controlled potential of the membrane's components. The most important analytical results from implementing them in flow-injection analysis are presented. The basic principle and the major advantages of the electrochemical approach are outlined, with an emphasis on its contribution to obtaining new optimized membrane formulations such as Cu_2-xSe, CuAgSe, and Ag_2+ō Se_1−xTe_x with improved dynamic and surface properties. Selected examples of the performance of the newly developed ion-selective flow-injection potentiometric (ISFIP) detectors for Cu(II), Hg(II), Ag(I), and CN⁻ ions are considered with regard to lower linearity limit, selectivity, long-term stability as well as unique FIP applications. A comparison with the dynamic behavior of the commercially available ion-selective electrodes or their second-kind electrode counterparts prepared by anodic dissolution helps to reveal the aspects of the competitiveness of the proposed ISFIP detectors. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:216–225, 2000

The redox indicator, ferroin, tris(1,10-phenanthroline)iron(II) was incorporated into the perfluorosulfonated cation-exchange membrane Nafion and, together with optical fibers, a photodiode, and a light-emitting diode, was used for the construction of a redox optical sensor (optode). The optode was incorporated in the flow-through cell of a computer-controlled sequential injection (SI) system and used for the determination of ascorbic acid (vitamin C). A linear relationship between the logarithm of the ascorbic acid concentration and the membrane absorbance was obtained for the concentration range from 2.50 × 10⁻³ to 1.00 × 10⁻¹ mol L⁻¹ and a sample frequency of 17 h⁻¹. The concentration of ascorbic acid determined in a number of commercial pharmaceutical products agreed well with iodometric titration results. This result shows that the SI system incorporating the ferroin/Nafion optode is suitable for the automated analysis of ascorbic acid in pharmaceutical products. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:200–204, 2000

Appropriate design of flow-injection (FI) manifold and selection of suitable detectors may provide additional changes in the selectivity of the FI response compared to conventional nonflow measurements. As an example of such systems, based on data from the literature and our own experimental data, the potentiometric detection with different ion-selective electrodes and two different amperometric systems are discussed. Selectivity changes in flow-injection analysis (FIA) systems for ion-selective membrane electrodes depend on relative response to interferences observed in batch measurements. Simultaneous detection of pesticides is shown as an example of an amperometric FIA system with a bilayer lipid membrane working electrode. Simultaneous detection of lactate and ascorbate is shown in an FIA system with amperometric biosensing detection. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:205–215, 2000

This article reviews new concepts for in situ environmental analysis based on novel electrochemical sensing strategies. Several new strategies are covered, including the use of remotely deployed sensors and submersible (“lab-on-cable”) analyzers. These devices offer a fast return of the chemical information in a safe and timely manner. The new concepts are discussed in connection to the in situ monitoring of priority organic and inorganic contaminants. Such devices should have an enormous impact upon pollution control and prevention, because they should lead to a substantially more effective and economic monitoring of priority pollutants. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:178–182, 2000

A field-deployable, flow-injection-based instrument for monitoring nitrate in rivers is described. It incorporates a miniature spectrometer that gives full spectral acquisition (200–700 nm) in real time. This allows the dynamic range to be adjusted in the field to meet local requirements by monitoring at different wavelengths. For pristine environments, a linear range of 0–1 mg L⁻¹ NO₃-N (r² = 0.9998, n = 6) and a detection limit of 0.007 mg L¹ NO₃-N (based on blank plus 3s) were achieved by monitoring at 597 nm. For impacted environments, a linear range of 0–9 mg L⁻¹ NO₃-N (r² = 0.9998, n = 6) was achieved at 510 nm. Conventional peristaltic pumps were replaced by solenoid-operated, self-priming micropumps, and injection of sample was achieved by a series of electronic switching valves. The pulsations of the micropumps were effectively removed by subtracting the response at a nonabsorbing wavelength (444 nm). Instrument control and data acquisition and processing were done within a graphical programming environment. The monitor was successfully deployed for 3 days at the River Frome in Dorset, United Kingdom. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:183–193, 2000

A commercial Hg chalcogenide glass ion-selective electrode (ISE) has been characterized using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, and the compositional data have been used in the fabrication of our own Hg ISE. It is shown that continuous flow analysis (CFA) is suitable for rapid determinations of ultratrace levels of mercury in saline media when used in conjunction with an extrapolation method that predicts the steady-state potential of the Hg ISE by using the initial data following a stepwise change in aHg²⁺. The CFA technique yields a near-Nernstian response of 28 mV per decade change in aHg²⁺ in Hg buffers in the range 10⁻¹⁸ to 10⁻¹² M Hg²⁺. It is shown that the repeatability of the CFA technique in seawater is ±0.03 pHg units, and a seawater matrix effect causes a significant offset and apparent error in the response of the Hg ISE relative to Hg buffer standards. Standard addition CFA may be used to compensate for the seawater matrix interference. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:194–199, 2000