Acid Esters In Water Research Articles

Determination of Phthalic and Phosphoric Acid Esters in Water with Used of Solid Phase Extraction

Solid-phase microextraction (SPME) with six different non-polar and polar fibres was used to extract seven phthalate esters from water samples for analysis by gas chromatography–mass spectrometry. With regard to extraction efficiency and repeatability of the extractions, the 70-μm Carbowax–divinylbenzene fibre was especially suitable for the selected phthalates with water solubilities between 4200 mg l−1 (dimethyl phthalate) and 0.0003 mg l−1 (di-n-octyl phthalate). Linearity was controlled in the range between 0.02 and 10 μg l−1. In analysed drinking water samples from Leipzig (Germany) and Katowice (Poland) four of the investigated phthalates [diethyl phthalate, di-n-butyl phthalate, butylbenzyl phthalate and di(2-ethylhexyl) phthalate] were found to be present in concentrations between 0.02 and 0.6 μg l−1.

Determination of phthalic and phosphoric acid esters in water with used of solid phase extraction

Determination of phthalic and phosphoric acid esters in water with used of solid phase extraction

A Comparison of Different Ways of Sample Preparation for the Determination of Phthalic Acid Esters in Water and Plant Matrices

Abstract Different methods for the isolation of phthalates from water were tested and compared with the aim of evaluating the risk of secondary contamination of sample and to reach good values of recovery for six tested esters (i.e. dimethyl-, diethyl-, di-n-butyl-, benzylbutyl-, bis(2-ethylhexyl)- and di-n-octyl phthalates). Classic liquid-liquid extraction with hexane gave good recoveries for all six esters (70 - 100%, spiking level 20 μg/1), but the increased relative standard deviations document problems with cross contamination. Micro extraction with iso-octane is suitable for the determination of benzylbutyl-, bis(2-ethylhexyl)- and di-n-octyl phthalates even at low levels of contamination (1 μg/1) and also for di-n-butyl phthalate at higher levels (tens of μg/1). The detection limits for these esters ranged from 0.01 to 0.05 μg/1. The recovery of more polar phthalates (dimethyl-, diethyl phthalate) is very low. Solid phase extraction on octadecyl reverse phase with ethyl acetate as elution solvent ...

Base catalyzed cyclization of substituted esters of hydantoic and thiohydantoic acids

Base catalyzed cyclization rates have been measured of 22 derivatives of hydantoic and thiohydantoic acid esters in water and methanol. The cyclization of methyl and ethyl esters of hydantoic and 5-methylhydantoic acids is accompanied by hydrolysis of the ester group, whereas with the other derivatives the hydrolysis does not take place. Hydrolysis of the cyclization products (hydantoin and thiohydantoin derivatives) is not significant under the kinetic conditions. The cyclization of methyl ester of 5-phenylhydantoic acid in methanol is reversible; the equilibrium mixture contains 30% of the starting ester. In all the cases the cyclization is subject to specific base catalysis; exceptions are esters of 5-phenylthiohydantoic and 5-phenyl-2-methylthiohydantoic acids whose cyclizations are subject to general base catalysis. Substituents always accelerate the cyclization. The 3-substituents have the greatest effects, the cyclization rate being considerably increased with bulk of the substituents; similarly large effect of 5-phenyl group consists mainly in its polar effects on the pre-equilibrium. The cyclization are slower in methanol at the same concentration of the lyate ion: the greatest difference (up to 3 orders of magnitude) is observed with the 5-phenyl derivatives.

Studies of micro high-performance liquid chromatography : III. Development of a “micro-pre-column method” for pre-treatment of samples

A sample pre-treatment method is described in which components are adsorbed on a micro pre-column, and an investigation of the method (with phthalic acid esters in water as sample components) is reported. The esters could be concentrated in the pre-column simply and rapidly, and were separated in a micro separation column. Concentrations of diethyl phthalate in the ppb-range were rapidly determined by pre-treatment of 10 ml or less of the aqueous solution. The method was suitable for use in micro-performance liquid chromatography.

Phthalic acid esters in water

Two phthalic acid esters, di(n-butyl)phthalate and di (2-ethylhexyl)phthalate, were surveyed in the river water, well water and city water of Tokyo metropolice area. In the river water these esters were found in the range of 0·4–6·8 μ gl−1. The concentration was low in the upper reaches of the stream but increased downstream, giving no seasonal variation. The esters were not found in the well water examined. In the household tap water they were contained in the range of 1·2–3·3 μg l−1 while in the raw water of water supply they were contained in the range of 1·9–8·2 μg l−1. Results of jar test revealed that these esters were efficiently removed from water by using activated carbon or aluminium sulphate.