EXPRESS: Landmark Publications in Analytical Atomic Spectrometry: Fundamentals and Instrumentation Development.

The almost-two-centuries history of spectrochemical analysis has generated a body of literature so vast that it has become nearly intractable for experts, much less for those wishing to enter the field. Authoritative, focused reviews help to address this problem but become so granular that the overall directions of the field are lost. This broader perspective can be provided partially by general overviews but then the thinking, experimental details, theoretical underpinnings and instrumental innovations of the original work must be sacrificed. In the present compilation, this dilemma is overcome by assembling the most impactful publications in the area of analytical atomic spectrometry. Each entry was proposed by at least one current expert in the field and supported by a narrative that justifies its inclusion. The entries were then assembled into a coherent sequence and returned to contributors for a round-robin review.

Double-Viewing-Position Single-Particle Inductively Coupled Plasma-Atomic Emission Spectrometry for the Selection of ICP Sampling Position in SP-ICP Measurements.

Double-viewing-position single-particle inductively coupled plasma-atomic emission spectrometry (DVP-SP-ICP-AES) measures emission intensity at two ICP vertical positions simultaneously using a single photomultiplier tube. A particle travelling up the ICP gives two consecutive temporal emission peaks. The Yb II 328.937-nm emission intensity of the two peaks for single Yb2O3 particles of diameter of 200 - 2000 nm are plotted against each other in a correlation plot. The correlation is poor when the gas temperature at the lower observation position is approximately the boiling point of the particles. Poor particle vaporization at the center of the central channel occurs because the gas temperature is 400 K lower than the temperature at the rim. The correlation is improved by shifting the observation positions up or using helium-argon mixed carrier gas to increase the gas temperature. Gas temperature is an important parameter for precise single particle-ICP measurements. DVP-SP-ICP-AES can be used to identify poor particle vaporization without the need of temperature measurement.

Tracking bismuth antiulcer drug uptake in single Helicobacter pylori cells.

Bismuth-based drugs have long been used for the treatment of Helicobacter pylori infection. In this work, the metal content in H. pylori was monitored at the single-cell level by time-resolved inductively coupled plasma mass spectrometry, and ∼2.9 × 10(7) Mg atoms/cell was determined for the wild-type. Bacteria treated with a Bi antiulcer drug deposited nearly 1.0 × 10(6) Bi atoms/cell, whereas the uptake process took ∼3 h to reach the half-maximum. Interference of ferric ions on bismuth uptake was demonstrated, suggesting that the metallodrug can utilize certain iron-transport pathways in the pathogen. The approach provides a general strategy for monitoring metals in single cells, facilitating exploration of metal-relevant bioprocesses.

Purple acid phosphatase-like sequences in prokaryotic genomes and the characterization of an atypical purple alkaline phosphatase from Burkholderia cenocepacia J2315.

Purple acid phosphatases (PAP) are a group of dimetallic phosphohydrolase first identified in eukaryotes. Bioinformatics analysis revealed 57 prokaryotic PAP-like sequences in the genomes of 43 bacteria and 4 cyanobacteria species. A putative PAP gene (BcPAP) from the bacteria Burkholderia cenocepacia J2315 was chosen for further studies. Synteny analysis showed that this gene is present as an independent gene in most of the members of the genus Burkholderia. The predicted 561 a.a. polypeptide of BcPAP was found to harbour all the conserved motifs of the eukaryotic PAPs and an N-terminal twin-arginine translocation signal. Expression and biochemical characterization of BcPAP in Escherichia coli revealed that this enzyme has a relatively narrow substrate spectrum, preferably towards phosphotyrosine, phosphoserine and phosphoenolpyruvate. Interestingly, this enzyme was found to have a pH optimum at 8.5, rather than an acidic optima exhibited by eukaryotic PAPs. BcPAP contains a dimetallic ion centre composed of Fe and Zn, and site-directed mutagenesis confirmed that BcPAP utilizes the invariant residues for metal-ligation and catalysis. The enzyme is secreted by the wild type bacteria and its expression is regulated by the availability of orthophosphate. Our findings suggest that not all members in the PAP family have acidic pH optimum and broad substrate specificity.

Microwave plasma treatment of polymer surface for irreversible sealing of microfluidic devices.

Microwave plasma was generated in a glass bottle containing 2-3 Torr of oxygen for plasma treatment of a polymer surface. A "kitchen microwave oven" and a dedicated microwave digestion oven were used as the power source. Poly(dimethylsiloxane)(PDMS) slabs treated by a 30 W plasma for 30-60 s sealed irreversibly to form microfluidic devices that can sustain solution flow of an applied pressure of 42 psi without leaking. Experimental set up and conditions for the production of a homogeneous plasma to activate the PDMS surface for irreversible sealing are described in detail. The surface of a microwave plasma-treated PDMS slab was characterized using atomic force microscopy (AFM) and attenuated total reflection-Fourier Transform infrared spectroscopy (ATR-FTIR). The plasma-treated surface bears silica characteristics.

[Speciation of iron using capillary electrophoresis inductively coupled plasma atomic emission spectrometry].

The separation of iron species, e. g. Fe2+ -Fe3+, Fe2+ -Fe(phen)3(2+), and Fe2+ -Fe3+, by mixing with complexing reagents of o-phenanthroline and EDTA, and Fe2+ -Fe3+ with o-phenanthroline was developed by capillary electrophoresis inductively coupled plasma atomic emission spectronetry (CE-ICP-AES). The effects of electrophoresis conditions such as voltage, buffer solution pH, and complex concentration on iron species are discussed. Satisfactory separation conditions for iron speciation have been acquired. Cations and anions, containing complexing agents, do not interfere in the separation of iron species. The method has advantage to CE-UV.