Ion-chromatographic determination of seven common anions in electronic-grade, water-miscible solvents.
An ion-chromatographic method has been developed to determine seven common anions in electronic-grade acetone, isopropyl alcohol, methanol, and N-methyl-2-pyrrolidone (NMP), solvents whose cleanliness is vital to the manufacturing of semiconductor devices. The system requires only a pump, conductivity detector, and switching valve as hardware. A calibration study was conducted first, by preparing and analyzing 11 concentrations (between 0.3 and 6.0 ng/g) in deionized (DI) water. Subsequently, a spiking study was performed by spiking each solvent at each of nine concentrations (between 50 and 500 ng/g). Dilutions of 1-100 (w/w) were prepared and analyzed. For each anion, recovered concentrations were estimated using the appropriate calibration curve. For each recovery curve, uncertainties in predicted concentrations were between +/-20 and +/-150 ng/g (except for phosphate in acetone), at 95% confidence. Recoveries were between 82% and 112% for all anions in all solvents, except for nitrite and nitrate in acetone, nitrite in methanol, and fluoride in N-methyl-2-pyrrolidone.
Air Liquide-Balazs Analytical Services, 13546 North Central Expressway, Dallas, TX 75243, USA. lynn.vanatta@airliquide.com
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D000096:Acetone / Q000737:chemistry; D000838:Anions / Q000032:analysis* / Q000737:chemistry; D001555:Benzene Derivatives / Q000737:chemistry; D002852:Chromatography, Ion Exchange / Q000379:methods*; D000432:Methanol / Q000737:chemistry; D011760:Pyrrolidinones / Q000737:chemistry; D012680:Sensitivity and Specificity; D012997:Solvents / Q000737:chemistry*
D000838:Anions; D001555:Benzene Derivatives; D011760:Pyrrolidinones; D012997:Solvents; D000096:Acetone; C038678:N-methylpyrrolidone; C007164:cumene hydroperoxide; D000432:Methanol