Development of an Optode Detector for Determination of Anionic Surfactants by Flow Injection Analysis

Abstract

A flow-injection analysis (FIA) method for assaying an anionic surfactant (AS) using AS optode detector was demonstrated. The optode membrane consists of 2-nitrophenyl octyl ether as a plasticizer, lactone form rhodamine B (L-RB) and poly(vinyl chloride). The linear response concentration range of the AS optode to AS was 20-100 μmol dm-3 in the FIA system. The sampling rate for an AS ion (40 μmol dm-3 sodium dodecylbenzenesulfonate) in the proposed FIA system was ca. 5 samples h-1. The AS level in commercially available laundry detergents by the proposed FIA system was determined.

Microfluidic paper-based analytical device with a preconcentration system for the measurement of anionic surfactants using an optode detector

“…The optode responds with the same sensitivity to anionic surfactants, such as LAS, dodecylsulfate and di-2-ethylhexylsulfosuccinate. 16,17…”

“…According to our previous method, 16,17 an optode membrane was prepared as follows: six milliliters of 7.5 × 10 −4 mol dm −3 rhodamine B solution containing 1.0 mol dm −3 NaOH, and 2.0 g of NPOE were added to a conical tube and le in a constant temperature water bath at 55 °C for 24 h. The solution in the conical tube was centrifuged at 3500 rpm for 10 min. Next, 2.0 g of the upper NPOE layer in the conical tube was added to a tetrahydrofuran (10 mL) in which 0.45 g of poly(vinyl chloride) (PVC) powder was dissolved and stirred to complete the optode membrane solution.…”

“…The response mechanism of the optode to LAS has already been reported in our previous papers. 16,17 The response mechanism of the optode to the LAS is the result of ion-pair co-extraction of the LAS and protons. The L-RB (lactone form rhodamine B) in the optode membrane forms an ion associate with the extracted LAS; simultaneously, the formed L-RB ion associate is accompanied by a spectral change.…”

“…14,15 We have already developed an optode for AS 16 and applied it to the ow injection analysis (FIA) method of AS using the optode as a detector. 17 This method has the advantages of being able to quantify AS in the concentration range of 20 to 100 mmol dm −3 and being easy to operate, but it may not be suitable for on-site AS determination because the FIA requires equipment such as a pump to ow a carrier solution. In addition, this AS determination method using FIA has the disadvantage of having a high lower concentration limit for AS determination.…”

Determination of Polyhexamethylene Biguanide Hydrochloride Using a Lactone-Rhodamine B-Based Fluorescence Optode

“…Recently, we have reported an AS-sensitive optode based on a lactone rhodamine B (L-RB) film [15][16][17]. From the results, PHMB is expected to be determined with an optode responding to a hydrophobic anion such as AS, because PHMB will form an ion associate with the hydrophobic anion, and the concentration of the free hydrophobic anion is detected by the AS optode.…”