A rapid method for determining chlorobenzenes in dam water systems

Abstract

A method using direct immersion solid phase microextraction (DI-SPME) coupled to gas chromatography equipped with a flame ionisation detector (GC-FID) was developed for the analysis of 7 chlorinated benzenes in dam water. The main parameters affecting the DI-SPME process were optimised. The optimised method comprises the use of a 100 µm polydimethylsiloxane (PDMS) fibre coating; 5 mℓ sample size; 700 r/min rate of agitation and an extraction time of 30 min. The calibration curve was linear with correlation coefficients ranging from 0.9957-0.9995 for a concentration range of 1-100 ng/mℓ. The limits of detection and quantification ranged from 0.020-0.265 ng/mℓ and 0.204-2.65 ng/mℓ, respectively. Recoveries ranged from 83.6-107.2% with relative standard deviation of less than 9.2%, indicating that the method has good precision. The method is reliable and is free of matrix interferences. Water samples collected from Grootdraai Dam were analysed using the optimised conditions to assess the potential of the method for trace level screening and quantification of chlorobenzenes. The method proved to be efficient, as 1,3 dichlorobenzene, 1,4-dichlorobenzene and pentachlorobenzene were detected at concentrations of 0.429 ng/mℓ, 1.685 ng/mℓ and 1.433 ng/mℓ, respectively.

Extraction of l-Tryptophan by Hydroxyl-Functionalized Ionic Liquids

“…To explain this phenomenon, the solubility of tryptophan in [C 1 C 6 ­OHim]­NTf 2 was measured, and a value of 68.8 g L –1 was obtained (the solubility of tryptophan in water is listed in Table S2 in the Supporting Information). Therefore, the observed influence of the tryptophan concentration on the extraction efficiency may be interpreted from two perspectives: (I) under the conditions of V w : V IL = 15:1 and high tryptophan concentration (5.0 or 10 g L –1 ), the amount of tryptophan exceeds its solubility in [C 1 C 6 ­OHim]­NTf 2 ; (II) with increasing tryptophan concentration, the ionic strength in the aqueous phase increases, which makes the electrostatic interaction between tryptophan cation and chloride anion (existing as a counterion for the tryptophan cation in the water phase) increase, thereby decreasing the electrostatic interaction between tryptophan and [C 1 C 6 ­OHim]­NTf 2 and thus reducing the movement of tryptophan to the IL phase. − …”

Comparative study of ferrate and thermally activated persulfate treatments for removal of mono- and dichlorobenzenes from groundwater

“…Depending on the applied analytical procedure, detection limits of the four chlorobenzene compounds change in the range of 0.007-3.0 µg/L [3][4][5][6][7][8].…”