Trace and Ultratrace Analysis of Purified Water Samples and Hydrogen Peroxide Solutions for Phosphorus by Flow-Injection Method

Abstract

IntroductionNowadays, especially in semiconductor industries, large amounts of ultrapurified chemicals, such as water, hydrogen peroxide, acids, and bases, are required for manufacturing highquality semiconductors in microelectronic industries. 1 The use of ultrapurified chemicals can help to fulfill two main objectives, namely the production of high-quality products and the minimization of rejects.2 Consequently, there has been a growing demand for the sensitive and accurate determination of trace and ultratrace amounts of impurities, such as boron, phosphorus and silicon, in ultrapurified chemicals. In general, such nonmetallic elements/compounds are less sensitive to conventional atomic spectroscopic methods, such as AAS, ICP-AES and ICP-MS. For example, the limits of detection (LOD) of silicate and phosphate in ICP-MS, which is known to be one of the most sensitive instruments and is often used in semiconductor analysis, are about 1 ppb or larger. Therefore, its sensitivity is not sufficient for the determination of a sub-ppb or ppt level of such non-metallic substances.The determination of trace and ultratrace amounts of phosphorus has become more and more important in such fields as semiconductor industry, ultrapurified chemicals (UPC) and ultrapurified water (UPW) manufactures etc. 3 The phosphomolybdenum blue method, either with or without solidphase enrichment, has often been used for phosphorus and silicate determination, 4-8 though the procedures are sometimes troublesome and time-consuming, for improving the sensitivity they need filtration/collection procedures with membrane filters. Sensitive spectrophotometric and fluorometric methods based on ion-associate formation deserve much attention. Molybdophosphate forms ion-association complexes with bulky cationic or basic dyes, which are the basis of sensitive detection methods for determining phosphorus spectrophotometrically. Malachite Green has found the widest application.9-15 Motomizu et al. [16][17][18] have reported a highly sensitive spectrophotometric method for determining phosphorus at sub-ppb and ppt levels using relatively small volumes of the sample solutions, an organic solvent (methyl cellosolve: MC), and a tiny membrane filter for collecting the ion associate of molybdophosphate with Malachite Green. The absorbance of the collected ion associate dissolved in MC was measured by an off-line flow injection-spectrophotometric detection method, which is relatively simple and shows excellent sensitivity. However, the collection/concentration procedure with a tiny membrane filter and dissolution of the ion associate in MC is troublesome and time-consuming.Highly sensitive fluorescence quenching methods for the determination of phosphate coupled with a flow-injection technique were also reported. These methods are based on the formation of an ion associate of molybdophosphate with Rhodamine 6G. 19,20 They are very sensitive with a detection limit of 0.1 ppb, 19 though the prepared reagent solution was not stable. Later, a method with Rhodamine...

Trace and ultratrace analysis methods for the determination of phosphorus by flow-injection techniques

“…Only by coupling the flow-injection detection method with some enrichment procedures, which do not require any chemicals, the detection sensitivities can be improved, as is shown in the method with the evaporation enrichment/ion-associate collection method [65,80].…”

“…5) [30]: LOD was about 10 nM. Recently, the RB/fluorescence quenching method was brushed up by reexamining the experimental conditions; LOD was improved to be 5 nM [80]. This method was applied to the determination of phosphorus in ultrapurified waters by coupling with an off-line evaporation/enrichment procedure: 50 ml of sample waters was evaporated on a hot plate to 5 ml, and the enriched samples were injected into the carrier stream of the double-line flow system: LOD was about 15 ng/l of phosphorus [80].…”

A gas-diffusion flow injection method coupled with online solid–liquid extraction for the determination of ammonium in solid samples

“…Numerous methods for the determination of ammonia and the ammonium ion have been developed and they employ detection techniques such as spectrophotometry [3][4][5][6][7][8], spectrofluorometry [9][10][11], conductometry [12,13], chromatography [14,15], capillary electrophoresis [16][17][18], and potentiometry [19].…”

An online solid phase extraction method for the determination of ultratrace level phosphate in water with a high performance liquid chromatograph

“…Other methods for detecting trace phosphate are solvent extraction of PAMB; complex formation of PAMB with cationic dyes such as rhodamine (Frank et al, 2006;Nasu and Minami, 1989;Taniai et al, 2003), crystal violet (Fogg et al, 1977), or malachite green (Susanto et al, 1995a,;1995b); and flow-injection analysis (APHA, 1999;Dinz et al 2004;Estela and Cerdà, 2005;Mesquita et al, 2011;Ribeiro et al, 2013). Ultratrace levels of phosphate have also been detected by flow-injection analysis systems combined with PAMB-complex formation with a cationic dye (Li et al, 2005;Motomizu and Li, 2005;Susanto et al, 1995;Zhang and Chi, 2002;Yaqoob et al, 2004;). These systems required specially designed sophisticated instruments, and the reagent solutions were not stable (Li et al, 2005).…”

“…Ultratrace levels of phosphate have also been detected by flow-injection analysis systems combined with PAMB-complex formation with a cationic dye (Li et al, 2005;Motomizu and Li, 2005;Susanto et al, 1995;Zhang and Chi, 2002;Yaqoob et al, 2004;). These systems required specially designed sophisticated instruments, and the reagent solutions were not stable (Li et al, 2005).…”