Choline is a quaternary amine that is synthesized in the body or consumed through the diet. Choline is critical for cell membrane structure and function and in synthesis of the neurotransmitter acetylcholine. Although the human body produces this micronutrient, dietary supplementation of choline is necessary for good health. The major challenge in the analysis of choline in foods and dietary supplements is in the extraction and/or hydrolysis approach. In many products, choline is present as choline esters, which can be quantitated individually or treated with acid, base, or enzymes in order to release choline ions for analysis. A critical review of approaches based on extraction and quantitation of each choline ester as well as hydrolysis-based methods for determination of total choline in foods and dietary supplements is presented.

Nine organic acids (citric acid, galacturonic acid, glycolic acid, isocitric acid, malic acid, oxalic acid, quinic acid, shikimic acid, and tartaric acid) and two anions (phosphate and sulfate) were determined in a suite of Vaccinium berry-containing dietary supplement standard reference materials (SRMs). Following solvent extraction, three independent methods were utilized in the quantification of these compounds. The first method involved reversed-phase liquid chromatography with ultraviolet absorbance detection at 210 nm and isotope dilution mass spectrometry. The second method utilized ion chromatography with conductivity detection. Finally, gas chromatography with isotope dilution mass spectrometry detection was used following derivatization with N-methyl-N-trifluoroacetamide (MSTFA). The combined data from these methods was used for the assignment of organic acid levels in the seven candidate SRMs.

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...

Assessment of total vitamin D intake from foods and dietary supplements (DSs) may be incomplete if 25-hydroxyvitamin D [25(OH)D] intake is not included. However, 25(OH)D data for such intake assessments are lacking, no food or DS reference materials (RMs) are available, and comparison of laboratory performance has been needed. The primary goal of this study was to evaluate whether vitamin D3 and 25(OH)D3 concentrations in food and DS materials could be measured with acceptable reproducibility. Five experienced laboratories from the U.S. and other countries participated, all using liquid chromatography tandem-mass spectrometry but no common analytical protocol; however, various methods were used for determining vitamin D3 in the DS. Five animal-based materials (including three commercially available RMs) and one DS were analyzed. Reproducibility results for the materials were acceptable. Thus it is possible to obtain consistent results among experienced laboratories for vitamin D3 and 25(OH)D3 in foods and a DS.