A nano-high performance liquid chromatography-inductively coupled plasma mass spectrometry (nano-HPLC-ICPMS) method is developed, using a demountable direct injection high efficiency nebulizer (d-DIHEN), to reduce sample and mobile phase consumption, minimize organic waste generation, decrease analysis time, and enhance separation efficiency. A HPLC column (50 mm  0.3 mm id), packed with 3.5 mm C 18 material, is explored for chromatographic separation of five arsenic species naturally present in the environment or introduced as a pollutant: sodium (meta)arsenite [As(III)], arsenic acid [As(V)], dimethylarsenic acid (DMA), disodium methylarsenate (MA), and p-arsanilic acid (p-ASA). A fast chromatographic separation of five arsenic species is achieved in less than 12 min at a solution flow rate of 0.9 mL min À1 using a 50 nL sample injection. The HPLC-ICPMS interface provides well defined flow injection profiles at various concentrations, giving a correlation coefficient of 0.999 for each individual arsenic species calibration curve. Precision values for peak height and area of five arsenic species range from 0.5 to 6.5% RSD and absolute detection limits are within 0.4 to 5.4 pg arsenic, which are comparable to previously reported data at higher solution uptake rates (20 mL min À1 to 1 mL min À1 ) and larger sample injection volumes (20-100 mL).

SPS ͑bis-͑3-sulfopropyl͒ disulfide͒ is an essential electrolyte additive used in the fabrication of copper interconnects by electrodeposition. In electroplating baths, the disulfide component of SPS may be cleaved to form the thiol analog, MPS ͑3-mercaptopropyl sulfonate͒, by either homogenous interactions with the Cu͑I͒ reaction intermediate or by dissociative adsorption onto the copper surface. However, mechanistic studies into the role of these additives in copper electrodeposition are presently constrained by limited knowledge of the purity of commercially available SPS and MPS. This report details the use of ion chromatography ͑IC͒ and electrospray ionization mass spectrometry to characterize aqueous solutions of commercial SPS and MPS source materials. Sulfate ͑2.0%͒ and propane disulfonic acid ͑0.9%͒ ͑PDS͒ were determined to be the principal impurities in SPS ͑96.3% estimated purity, mass fraction͒. IC fractionation was used to purify and isolate SPS for surface and electroanalytical studies. Stability of SPS, MPS, and PDS in the presence of O 2 and Cu͑II͒ was also examined. No degradation of SPS or PDS in aqueous solution was observed over a 3-month period. Solutions of MPS were metastable to O 2 saturation, but the addition of Cu͑II͒ resulted in formation of SPS by dimerization as well as parasitic PDS generation.State-of-the-art Cu wiring for microelectronic circuitry is fabricated by electrochemical deposition. 1,2 The electroplating process requires the use of a specific combination of additives in an acidic Cu͑II͒ plating bath to enable void-free filling of recessed surface features such as trenches and vias. Commercial additive packages comprised at least three species: Cl − , an accelerator such as bis-͑3-sulfopropyl͒ disulfide ͑SPS͒, and a polyether-based suppressor such as polyethylene glycol ͑PEG͒ or a related block or branched copolymer. 3,4 Chloride is a required coadsorbate for the formation of the inhibiting PEG layer as well as the subsequent formation of the SPS-derived accelerating surface phase. Feature filling involves a competition between SPS and the polyether for Cl − -saturated Cu surface sites. 2,3 As the local surface area decreases, such as within a filling trench, the more tightly bound SPS-derived adsorbates remain on the surface while the polyether suppressor is displaced into the electrolyte. This displacement results in an accelerated rate of Cu deposition on the SPS-enriched concave surface segments, leading to bottom-up superconformal filling. Several quantitative descriptions of feature filling based on the curvature enhanced accelerator coverage ͑CEAC͒ mechanism are available. 2-6 Nevertheless, much remains unknown about the physical and chemical nature of the SPS-derived accelerator surface phase.A recent scanning tunneling microscope ͑STM͒ study of SPS adsorption on a Cl − saturated Cu͑100͒ surface revealed a plurality of lattice gas species diffusing on top of, or within, the Cl − adlayer. 7 In addition to the dimer-like SPS species, smaller molecules suggestive of th...

An automated sample introduction system, utilizing a demountable direct injection high-efficiency nebulizer (d-DIHEN), is successfully incorporated for the first time with an inductively coupled plasma optical emission spectrometer (ICP-OES) for the measurement of the phosphorus content in acid-digested nucleotides and deoxyribonucleic acid (DNA). With this experimental setup, the solution uptake rate and volume are reduced from 170 to 30 microL min(-1) and from 10 to 2.4 mL, respectively, thereby reducing the required DNA sample mass for solutions containing 3 microg g(-1) P from 300 to 72 microg of DNA, in comparison to previous analyses in our laboratory using a glass concentric nebulizer with cyclonic spray chamber arrangement. The use of direct injection also improves P (I) 213.617 nm sensitivity by a factor of 4 on average. A high-performance (HP) methodology in combination with the previous sample introduction system and ICP-OES provides simultaneous, time-correlated internal standardization and drift correction resulting in relative expanded uncertainties (% U) for the P mass fractions in the range of 0.1-0.4 (95% confidence level) for most of the thymidine 5'-monophosphate (TMP), calf thymus DNA (CTDNA), and plasmid DNA (PLDNA) analyses. The d-DIHEN with HP-ICP-OES methodology allows for the quantification of DNA mass at P mass fractions as low as 0.5 microg g(-1), further reducing the required DNA mass to 12 microg, with small uncertainty (< or = 0.4%). This successful approach will aid in the development and certification of nucleic acid certified reference materials (CRMs), particularly for these samples that are typically limited in volume.

Size, velocity and evaporation rate of droplets in an Ar inductively coupled plasma (ICP) are simultaneously measured for the first time using a novel laser based imaging technique. In interferometric droplet imaging (IDI), an interference pattern created by the reflected and refracted rays from a droplet are collected in an out-of-focus image. The droplet diameter is determined by counting the number of fringes in the collected interference pattern. Combination of IDI and particle tracking velocimetry (PTV) provides the capability of monitoring droplet properties during the journey inside ICP. Using a demountable-direct injection high efficiency nebulizer, droplets in the range of 3-30 mm in diameter traveling at 15-70 m s À1 are observed in the analytical zone of the ICP. The upper velocity threshold for surviving droplets is determined by the nebulizer gas flow rate, whereas the lower threshold is mainly influenced by thermal expansion of the plasma gas. Droplet evaporation rates (0.26-0.36 mm 2 s À1 ) are in good agreement with other reports and theoretical simulations for droplets in a 3000 K Ar environment.