scholarly journals Reverse flow injection analysis of trace amounts of anionic surfactants in seawater without liquid–liquid extraction

2011 ◽  
Vol 6 (No. 4) ◽  
pp. 198-204 ◽  
Author(s):  
L. Yu ◽  
M. Wu ◽  
W. Dong ◽  
J. Jin ◽  
X. Zhang

  In order to control the pollution by anionic surfactants in seawater, a simple, accurate and sensitive reverse flow injection (rFIA) spectrophotometric method for the determination of anionic surfactants in seawater is suggested in this paper. Sodium dodecylbenzenesulfonate (LAS) was selected as the reference anionic surfactant. The method is based on the ion associate formed between LAS and Ethyl Violet. The absorbance of the complex is measured by optical detector at 585 nm. Chemical factors and rFIA variables affecting the system are also discussed. Under the optimal conditions, the linear range of this method was 25.0–400.0 μg/l; the detection limit was 2.4 μg/l; the relative standard deviation was 0.38%. This method is suitable for automatic and continuous analysis, and was successfully applied to determine the content of anionic surfactants in seawater.

Author(s):  
Mariam Jamal ◽  
Hind Hadi

Objective: A simple and fast reverse flow injection system including a solid-phase reactor containing PbO2 with spectrophotometric detection was suggested for the determination of nitrazepam (NIT) in pharmaceutical tablets.Methods: The method was based on oxidation of the reagent (phloroglucinol) with PbO2 immobilized in a polymeric matrix which was then coupled with reduced NIT in aqueous medium. The pink-colored product was measured at 530 nm.Results: The calibration graph was linear over the range of 50–400 μg/mL with a relative standard deviation of <2% (n=29) and a sample throughput of 48 samples per hour. The variables of the solid-phase reactor such as composition, particle size, and length of the reactor were studied. The chemical and physical parameters, which affect the reverse flow method, were also studied.Conclusion: The oxidation reactor engaged with a flow system was successfully applied for the determination of NIT with good sensitivity and precision.


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