in ac research
In AC Research contains brief introductions to the research articles appearing in the December 1 issue. A free updated table of contents is available on the Web (http://pubs.acs.org/ac).
Resistance measurements for studying SAMs.
SECM sees deadly Staphyloccoci. Scanning electrochemical microscopy (SECM) enzyme-linked immunosorbent assays (ELISAs) are alternatives to standard ELISAs. Tomokazu Matsue and colleagues at Tohoku University (Japan) describe the use of an SECM ELISA to detect leukocidin, a toxin released by the dangerous bacteria methicillin-resistant Staphyloccocus aureus. The researchers report detection limits as low as 5.25 pg/mL of leukocidin. (“Immunoassay of the MRSA-Related Toxic Protein, Leukocidin, with Scanning Electrochemical Microscopy”; 10.1021/ac000895y; p 5761)
To study the phase transitions and desorption of self-assembled monolayers (SAMs) on gold surfaces, T. Pradeep and M. Venkataramanan at the Indian Institute of Technology measure the change in resistance as a function of temperature. The order–disorder phase transition corresponds to an increase in the resistance slope versus temperature plot, whereas the desorption of monolayers corresponds to a decrease in the slope at higher temperatures. (“A Method To Study the Phase Transition and Desorption of Self-Assembled Monolayers from Planar Gold Surfaces”; 10.1021/ac000071g; p 5852)
Injecting colloids and biopolymers into liposomes. Owe Orwar and colleagues at Göteborg University (Sweden) describe a combined electroporation and pressuredriven microinjection method for loading biopolymers and colloid particles into single cell-sized unilamellar liposomes. (“Electroinjection of Colloid Particles and Biopolymers into Single Unilamellar Liposomes and Cells for Bioanalytical Applications”; 10.1021/ac0003246; p 5857)
LC method for cyanuric acid in water. Ricardo Cantú and colleagues at the U.S. Environmental Protection Agency describe an LC method with UV detection that simplifies and optimizes certain parameters of previous methodologies by controlling the pH of the eluent. The method measures cyanuric acid in the 0.5- to 125-mg/L linear concentration range, with a detection limit of 0.05 mg/L in water. (“HPLC Method with UV Detection, pH Control, and Reductive Ascorbic Acid for Cyanuric Acid Analysis in Water”; 10.1021/ac0005868; p 5820) Alcohol in the gas phase. Norimichi Takenaka and
Thiols’ film debut. Jon R. Kirchhoff and Takayo Inoue of the University of Toledo modify an electrode with the coenzyme pyrroloquinoline quinone in a polypyrrole film to detect thiols. Trials with cysteine, homocysteine, penicillamine, N-acetylcysteine, and glutathione yield detection limits that are sensitive to pH and the nature of the thiol. (“Electrochemical Detection of Thiols with a Coenzyme Pyrroloquinoline Quinone Modified Electrode”; 10.1021/ac000716c; p 5755)
colleagues at Osaka Prefecture University (Japan) present a flow determination method for measuring methanol and ethanol in the gas phase using the nitrite formation reaction. Detection limits are 0.7 ppbv for methanol and 0.5 ppbv for ethanol. (“Flow Analysis Method for Determining the Concentration of Methanol and Ethanol in the Gas Phase Using the Nitrite Formation Reaction”; 10.1021/ac000538n; p 5847)
Metalloporphyrin get-together. Mark E. Meyerhoff and colleagues at the University of Michigan reveal the origin of non-Nernstian anion response in metalloporphyrin-based liquid/polymer membrane electrodes. UV–vis spectrophotometry confirms the formation of the culprit—hydroxide ion-bridged dimers of metalloporphyrins. (“Origin of Non-Nernstian Anion Response Slopes of Metalloporphyrin-Based Liquid/Polymer Membrane Electrodes”; 10.1021/ac000643x; p 5766)
SDIFA your oligos. Baochuan Guo and colleagues at Cleveland State University describe an approach called separates desorption/ionization from acceleration (SDIFA) for oligonucleotide analysis, which allows the electrical isolation
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of the sample holder from ion extraction/acceleration and selectively samples part of the desorbed ions, thereby reducing the initial velocity distribution and improving resolution. Compared with delayed extraction, SDIFA is more stable and reproducible, and it is less dependent on the experimental conditions. (“Improving the Performance of MALDI-TOF in Oligonucleotide Analysis Using a New SDIFA Technology”; 10.1021/ac0007231; p 5792)
cm-long spiral-shaped separation channel on a 5 3 5-cm glass microchip. Electrophoretic separation efficiencies for dichlorofluoroscein exceed 1 million theoretical plates and are achieved in
