Liquid Phase Micro-Extraction of Linear Alkylbenzene Sulfonate Anionic Surfactants in Aqueous Samples

Abstract

Hollow fiber liquid phase micro-extraction (LPME) of linear alkylbenzene sulfonates (LAS) from aqueous samples was studied. Ion pair extraction of C10, C11, C12 and C13 homologues was facilitated with trihexylamine as ion-pairing agent, using di-n-hexylether as solvent for the supported liquid membrane (SLM). Effects of extraction time, acceptor buffer concentration, stirring speed, sample volume, NaCl and humic acids were studied. At 10–50 μg L−1 linear R2-coefficients were 0.99 for C10 and C11 and 0.96 for C12. RSD was typically ∼15%. Three observations were especially made. Firstly, LPME for these analytes was unusually slow with maximum enrichment observed after 15–24 h (depending on sample volume). Secondly, the enrichment depended on LAS sample concentration with 35–150 times enrichment below ∼150 μg L−1 and 1850–4400 times enrichment at 1 mg L−1. Thirdly, lower homologues were enriched more than higher homologues at low sample concentrations, with reversed conditions at higher concentrations. These observations may be due to the fact that LAS and the amine counter ion themselves influence the mass transfer at the water-SLM interface. The observations on LPME of LAS may aid in LPME application to other compounds with surfactant properties or in surfactant enhanced membrane extraction of other compounds.

An on-line push/pull perfusion-based hollow-fiber liquid-phase microextraction system for high-performance liquid chromatographic determination of alkylphenols in water samples

“…While enrichment, clean-up, low solvent consumption, and the absence of cross contamination and carry-over are the major advantages 14 of off-line HF-LPME, its major disadvantages 21 are relatively long extraction times, increased labor, and increased risk of loss of acceptor solvent (which could occur when the syringe is manually removed, when the support rod is inserted or removed, or when the syringe is connected to collect the extract), due to passive diffusion being the transport mechanism and the tedious manual operation process. In this study, we used a push/pull syringe pump as the driving source for perfusion of the acceptor phase and employed a heating mantle and an ultrasonic probe to accelerate the mass transfer, allowing the present PPP-HF-LPME device to be coupled on-line to a conventional HPLC system and resulting in a sampling time of just 2 min.…”

Electropolymerized polyaniline on electrospun silica nanofibers to prepare a SPME fiber for the sampling of linear alkyl benzenes

“…The inter-ber RSDs (reproducibility) for three randomly selected bers were in the range of 9.2-12.4%. For further evaluation of the reliability and applicability, the analytical performances of the developed method were compared with some similar the previous studies [23,29,30], reported on separation and determination of LABs (Table 5). The results clearly showed that the proposed method has a wider LDRs and lower LODs and a compared to the mentioned methods.…”

A novel in situ method for linear alkylbenzene sulfonate quantification in environmental samples using a digital image-based method

“…12 HPLC has also been coupled with different detectors for LAS determination; these combinations have included the following: HPLC-UV spectrophotometry, HPLC with spectro-uorimetry (HPLC-FL), and HPLC with a mass detector (HPLC-MS). 11,12,15,16 Although the HPLC-UV technique has become the most widely employed method for LAS identication and quantication, a simple UV-Vis spectrophotometric technique is relatively quicker and easier to apply and can be used for the analysis of simple samples with low interference and without the need for chromatography. The UV-Vis spectrophotometric method is applied based on the reaction of blue methylene with LAS, which generates an ion-pair compound, followed by liquid-liquid extraction.…”

“…12 HPLC has also been coupled with different detectors for LAS determination; these combinations have included the following: HPLC-UV spectrophotometry, HPLC with spectrofluorimetry (HPLC-FL), and HPLC with a mass detector (HPLC-MS). 11,12,15,16…”