Nonsolvent quantitation of anionic surfactants and inorganic ingredients in laundry detergent products

Abstract

This paper reports the development of a method for measuring alkylbenzene sulfonates and alkyl sulfates (AS) without requiring the use of chlorinated organic solvents, such as chloroform. Alkylbenzene sulfonates and AS are precipitated with calcium and then isolated by filtration. Through this filtration process, they are separated from inorganic sulfur compounds. After the precipitate is prepared, the level of sulfur is measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) to determine the total anionic surfactant level. Separately, AS are hydrolyzed in an autoclave, and the level of alkylbenzene sulfonates is then measured in the same manner. By using the autoclave, a safe and rapid hydrolysis step has been achieved. In addition to alkylbenzene sulfonates and AS, phosphate, silicate, sulfate, and zeolite can be determined with this sample preparation. This sample preparation procedure was investigated by ICP-AES and was confirmed applicable for simultaneous measurements of alkylbenzene sulfonates, AS, phosphate, silicate, sulfate, and zeolite without using organic solvents. Relative standard deviation for the analysis is less than 1.7%, recovery is more than 99.0%, and the calibration curve gives a correlation coefficient of R = 1.000. The detection limit of this method for alkylbenzene sulfonates and AS is 0.6%, for zeolite, 0.04%, for phosphate, 0.4%, for silicate, 0.1%, and for sulfate, 0.2%, by weight in product. This method is applicable to various laundry detergent products that contain the materials mentioned above and is 10 times faster than the six wet chemical methods normally used to analyze these compounds. JAOCS 74, 787-792 (1997).

Electrocoagulative and Biological Treatment of Laundry Wastewater

“…GC-MS is less often used for analysis of LAS, as this method would require derivatization of LAS into a volatile compound [25]. Quantification of anionic surfactants and inorganic constituents' viz., phosphates, silicates and zeolite, has been analysed by Inductively coupled plasma-optical emission spectroscopy (ICP-OES) [26]. Specifically, alkylbenzene sulfonates and alkyl sulphates were determined due to their ability to precipitate upon addition of calcium ions [26].…”

“…Quantification of anionic surfactants and inorganic constituents' viz., phosphates, silicates and zeolite, has been analysed by Inductively coupled plasma-optical emission spectroscopy (ICP-OES) [26]. Specifically, alkylbenzene sulfonates and alkyl sulphates were determined due to their ability to precipitate upon addition of calcium ions [26]. Non-ionic surfactants that are used widely in domestic and industrial detergents [27] are represented by two major classes, which include alcohol ethoxylates (AE) and alkylphenol ethoxylates (APEOs) [28].…”

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

“…Chloroform is dictated for two-phase titration in the official methods (3)(4)(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.…”

“…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 this newly developed method will be discussed compared to the preceding work (7).…”

“…Calcium-surfactant complexes, calcium tripolyphosphate, and zeolite can be trapped on 0.2-m or narrower pore size filters (7). On the other hand, silicate and sulfate are water-soluble and do not precipitate upon addition of calcium ions.…”