A simple and rapid method for the determination of the methylene blue active substances assay based on in-syringe automation of magnetic stirring-assisted dispersive liquid-liquid microextraction was developed. The proposed method proved to be valid for the determination of anionic surfactant in waste, pond, well, tap, and drinking water samples. Sample mixing with reagents, extraction and phase separation were performed within the syringe of an automated syringe pump containing a magnetic stirring bar for homogenization and solvent dispersion. The syringe module was used upside-down to enable the use of chloroform as an extraction solvent of higher density than water. The calibration was found to be linear up to 0.3mg/L using only 200 µL of solvent and 4 mL of sample. The limits of detection (3σ) and quantification (10σ) were 7.0 µg/L and 22 µg/L, respectively. The relative standard deviation for 10 replicate determinations of 0.1mg/L SBDS was below 3%. Concentrations of anionic surfactants in natural water samples were in the range of 0.032-0.213 mg/L and no significant differences towards the standard method were found. Standard additions gave analyte recoveries between 95% and 106% proving the general applicability and adequateness of the system to MBSA index determination. Compared to the tedious standard method requiring up to 50 mL of chloroform, the entire procedure took only 345 s using 250-times less solvent.

• MeSH
• automatizace * MeSH
• biotest metody   MeSH
• chemické látky znečišťující vodu analýza   MeSH
• injekční stříkačky MeSH
• limita detekce MeSH
• magnetismus * MeSH
• methylenová modř analýza   MeSH
• mikroextrakce kapalné fáze metody   MeSH
• povrchově aktivní látky analýza   MeSH
• rozpouštědla chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Continuous magnetic stirring-assisted dispersive liquid-liquid extraction followed by dispersive backextraction as a novel pre-treatment technique for adaptable and milliliter volumes of environmental samples has been developed. The procedure was automated using the technique "Lab-In-Syringe". The void of the automated syringe pump was used as size-adaptable extraction chamber. By a flow channel in the syringe piston, continuous flow through the syringe void was enabled. 1-Octanol was used as an extractant and dispersed by the action of a magnetic stirring bar, which was placed inside the syringe and driven by an external rotating magnetic field. Extract washing and dispersive backextraction in an alkaline aqueous acceptor phase were carried out after the preceding extraction from the acidified water sample. Analyte determination was achieved using multivariate spectrum analysis. The method was applied to determine priority pollutants, mono-nitrophenols, in surface water and enabled to reach limits of detection for o-, m-, p-nitrophenol (λ = 418, 390, 400 nm, respectively) of 0.14, 0.26, and 0.02 μmol L-1 (19.5, 36.2, and 2.8 μg L-1), respectively. Under optimized conditions, relative standard deviations were generally less than 5% and enrichment factors of o-, m-, p-nitrophenol 19, 25, and 21, respectively, were achieved using sample volumes of up to 24 mL. Average recoveries of o-, m-, p-nitrophenol from spiked surface water were 94, 82, and 92%, respectively. The concentration of humic acid was found 6-times reduced with respect to the analyte. In addition, adding spectral background modeling allowed nitrophenol determination with precision adequate for routine analysis.

• Publikační typ
• časopisecké články MeSH