X-ray Fluorescence Analysis: Investigation of Microdroplet Sample Preparation

Kawauchi, Akihiko; Ishida, Masahiro; Saitoh, Ikuko

doi:10.1080/00387019608007265

Cited by 1 publication

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“…Neither sulfate nor silicate precipitates upon the addition of calcium ions; both were present in the filtrate of the secondary filtration. These materials were determined by XRF using microdroplet sample preparation (9). Kawauchi (7) also investigated AS hydrolysis based on differences of acid concentration and hydrolysis time in an autoclave.…”

Section: Resultsmentioning

confidence: 99%

Nonsolvent quantitation of anionic surfactants and other inorganic ingredients in laundry detergent products by X‐ray fluorescence spectrometry

Kawauchi

1999

J Surfact & Detergents

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This paper reports the development of a method for measuring alkyl-benzene sulfonates, alkyl sulfates, and other inorganic ingredients in laundry detergent products without requiring the use of chlorinated organic solvents such as chloroform. Zeolite is first filtered as a residue on filter paper from an aqueous detergent solution. A calcium solution is then added to the filtrate. Alkyl-benzene sulfonates, alkyl sulfates, and phosphate are precipitated as calcium salts and recovered as residues via filtration. The filters are then subjected to X-ray fluorescence spectrometry (XRF) for measuring the levels of zeolite, phosphate, and total anionic surfactant. The remaining filtrate is also subjected to XRF by using the microdroplet preparation for measuring levels of sulfate and silicate. Separately, the level of alkyl-benzene sulfonates is measured following the same XRF procedure after alkyl sulfates are hydrolyzed using an autoclave. This sample preparation procedure was investigated using XRF and was confirmed to be applicable for simultaneous measurements of alkyl-benzene sulfonates, alkyl sulfates, zeolite, phosphate, silicate, and sulfate without using any organic solvents. In the method described in this paper, interelement effects between anionic surfactants and phosphate are not negligible. Fluorescent X-rays of sulfur or phosphorus are absorbed by calcium complexes of phosphate or anionic surfactants. The slope of calibration curves varies with the levels of coexistent elements; external calibration methods cannot be employed for unknown sample matrices. However, for quality assurance purposes, this method is ideal in terms of turnaround time and laboratory hygiene.Paper no. S1101 in JSD 2, 79-83 (January 1999). KEY WORDS:Alkyl sulfate, alkyl-benzene sulfonate, laundry detergent, phosphate, silicate, sulfate, X-ray fluorescence spectrometry, zeolite.Epton (1,2) developed a two-phase titration for anionic surfactant quantitation that has now become universally accepted methodology for anionic surfactants determination. Chloroform is dictated for two-phase titration in the official methods (3-5), but recently the use of potentially hazardous organic solvents such as chloroform in the working environment is restricted by law (6). Kawauchi (7) developed an inductively coupled plasma atomic emission spectrometry (ICP-AES) method where anionic surfactants and inorganic ingredients in laundry detergent products were determined without using any organic solvents. This ICP-AES method was designed to replace the two-phase titration methodology, providing one potential solution to the issue while also reducing turnaround time without compromising data quality. This time, X-ray fluorescence spectrometry (XRF) was applied for surfactant determination to eliminate the use of organic solvent. The XRF method uses the same sample preparation procedure as the ICP method and has achieved quicker determination for the materials listed above in laundry detergent products. In this paper, the advantages and disadvantages of th...

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Section: Resultsmentioning

confidence: 99%