Peter B. Stockwell

Introduction

Commentary: Automation comes of age

P. B. Stockwell

&#x2018;Journal of Automatic Chemistry&#x2019;-the first 10 years

Commentary: From the Editor&#x27;s desk

A multicommutated flow system for simultaneous determination of iron and chromium in steel alloys by photometry is described. The flow network consisted of an automatic injector and four solenoid valves assembled to form two independent analytical pathways, each one comprising reaction coils and a flow cell. The light source (LED) and detector (photodiode) were attached to the flow cells to form a compact unit. The flow system was microcomputer controlled by Quick BASIC 4.5 software, which carried out all steps of the analytical procedure. The feasibility of the system was proved by the determination of iron and chromium in steel alloys and its accuracy was accessed by comparing results with those obtained by plasma atomic emission spectrometry (ICP-AES). No significant difference at the 95% confidence level was observed. Other profitable features such as low reagent consumption (0.33 mg 1,10-phenantroline and 0.03 mg 1,5-diphenylcarbazide per determination); relative standard deviations (<mml:math alttext="$n = 5$" id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>5</mml:mn></mml:mrow></mml:math>) of 0.4% for iron and 1.2% for chromium; and an analytical throughput of 160 determinations per h were also achieved.

Ridvan N. Fernandes

Boaventura F. Reis

Luís Fernando P. Campos

Automatic flow system for simultaneous determination of iron and chromium in steel alloys employing photometers based on LEDs as radiation source

Electrophoretic techniques have been developed and refined over
decades, and are now widely used in clinical laboratories. For
example, electrophoresis is routinely used to separate many different
components, including proteins, lipoproteins, and isoenzymes. More
recently, the applications of molecular biology in diagnosis have
increased the use of electrophoresis to separate DNA components in
the clinical laboratory. Various kinds of quantities are used for the
description of separation procedures. It is the purpose of this
document to provide manufacturers and users of electrophoretic
techniques with a list of relevant quantities and units consistent
with the International System of Units (SI) and standards of the
International Organization for Standardization (ISO).

G. F&#xE9;rard

Quantities and units for electrophoresis in
the clinical laboratory

This paper describes the results of analytical applications of electrochemical biosensors based on bilayer lipid membranes (BLMs) for the automated rapid and sensitive flow monitoring of substrates of hydrolytic enzymes, antigens and triazine herbicides. BLMs, composed of mixtures of egg phosphatidylcholine (egg PC) and dipalmitoylphosphatidic acid (DPPA), were supported on ultrafiltration membranes (glass microfibre or polycarbonate filters) which were found to enhance their stability for flow experiments. The proteins (enzymes, antibodies) were incorporated into a floating lipid matrix at an air-electrolyte interface, and then a casting procedure was used to deliver the lipid onto the filter supports for BLM formation. Injections of the analyte were made into flowing streams of the carrier electrolyte solution and a current transient signal was obtained with a magnitude related to the analyte concentration. Substrates of hydrolytic enzyme reactions (acetylcholine, urea and penicillin) could be determined at the micromolar level with a maximum rate of 220 samples/h, whereas antigens (thyroxin) and triazine herbicides (simazine, atrazine and propazine) could be monitored at the nanomolar level in less than 2 min. The time of appearance of the transient response obtained for herbicides was increased to the order of simazine, atrazine and propazine which has permitted analysis of these triazines in mixtures.

Dimitrios  P. Nikolelis

Christina G. Siontorou

Stabilized filter-supported bilayer lipid membranes (BLMs) for automated flow monitoring of compounds of clinical, pharmaceutical, environmental and industrial interest

A flow-injection system is proposed for the determination of metal-based additives in lubricating oils. The system, operating under computer control uses a motorised syringe for measuring and injecting the oil sample (200 <mml:math alttext="$\mu$" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>&#956;</mml:mi></mml:math>L) in a kerosene stream, where it is dispersed by means of a packed mixing reactor and carried to an atomic absorption spectrometer which is used as detector. Zinc was used as model analyte. Two different systems were evaluated, one for low concentrations (range 0&#8211;10 ppm) and the second capable of providing higher dilution rates for high concentrations (range 0.02%&#8211;0.2% w/w). The sampling frequency was about 30 samples/h. Calibration curves fitted a second-degree regression model (<mml:math alttext="$r^{2}$" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>r</mml:mi><mml:mn>2</mml:mn></mml:msup></mml:math> = 0.996). Commercial samples with high and low zinc levels were analysed by the proposed method and the results were compared with those obtained with the standard ASTM method. The <mml:math alttext="$t$" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>t</mml:mi></mml:math> test for mean values showed no significant differences at the 95% confidence level. Precision (RSD%) was better than 5% (2% typical) for the high concentrations system. The carryover between successive injections was found to be
negligible.

Gustavo  Pignalosa

Mois&#233;s  Knochen

Noel  Cabrera

Determination of Zinc-Based Additives in Lubricating Oils by Flow-Injection Analysis with Flame-AAS Detection Exploiting Injection with a Computer-Controlled Syringe

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Journal of Analytical Methods in Chemistry publishes research into the methods and instrumentation used in chemical analysis, including spectroscopic, spectrometric and wet chemistry techniques, and their applications in real-world problems.

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Chief Editor, Dr. María José Trujillo-Rodríguez, is based in the Chemistry Department (Analytical Chemistry Division) at Universidad de La Laguna, Spain.

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Journal of Analytical Methods in Chemistry publishes research into the methods and instrumentation used in chemical analysis, including spectroscopic, spectrometric and wet chemistry techniques, and their applications in real-world problems.

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Journal of Analytical Methods in Chemistry

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Journal of Analytical Methods in Chemistry