Liquid Chromatographic Analysis of Phthalate Esters in Dutch River Water

Abstract

Analysis of the phthalate esters di-(2-ethylhexyl) and di-n-butyl phthalate--DEHP and DBP. respectively-has been carried out by means of (a) high-performance liquid chromatography (HPLC) in the system silica gel/hexane-dichloromethane (1 : 2, v/v) containing 0.1-0.2 yo of ethanol, and (b) gas chromatography (GC) on 4 % OV-101 on Chromosorb W (HP) at a temperature of 240°C. Detection was done by U.V. absorption spectrometry at 233nm and flame ionization, respectively.The procedure has been used to analyse series of water samples of the Dutch rivers Rhine, IJssel and Meuse. Since the phthalate levels of the samples rapidly decrease with time, extraction invariably was performed without delay at the sampling station. The DEHP values on an average are approx. 1 ppb for all three rivers; for DBP, values of 0.3-0.5 ppb are found for the rivers Rhine and Meuse, while a somewhat high value of 2ppb is reported for the river IJssel. The results obtained by HPLC and GC show good agreement; the former technique is less time-consuming.

Phthalic Acid Esters

“…Similarly, Schouten and coworkers [208] found rapid loss of DEHP and DBP from river water samples which could not be attributed to adsorption. They observed a 50% loss of DEHP within 5 days and a 90% loss of DBP within 3 days.…”

“…As mentioned, the avoidance of contamination in the analytical laboratory requires control even over the maintenance and clean-ing procedures followed by outside personnel. Other workers have also described procedures for reducing the contamination problem [115,208,209,264]. In our experience phthalate contamination is the most difficult analytical problem to overcome in obtaining reliable, reproducible results at very low concentrations.…”

“…Mathur [153] described the contamination problem in some detail and provided some representative data on phthalates in laboratory materials. Schwartz and coworkers [209] have discussed the problems which they had with extraction thimbles, filter paper and Florisil, and Schouten and coworkers [208] state that the lower limit on their HPLC analysis of phthalates in water (10 ng) is set by the contamination level of the hexane used for extraction. Table 6 (adapted from [86]) provides a glimpse of the magnitude of the problem; it is a tabulation of the phthalate levels found in our laboratory for a variety of common substances.…”

“…However, variable ultraviolet detectors now provide easy access to the nm range where PAEs have a large absorption band suitable for sensitive detection. Schouten [208] and Schwartz [209] and their collaborators used both GC and HPLC methods in their studies of the water and sediments for a series of Dutch rivers. They report that they had an HPLC detection limit of 5-10 ng (comparable to GCjFID) and that they could reduce their solvent and procedural blanks to very low levels.…”

“…To this we should add 4) biological and chemical degradation following sample collection [169,201,208,209,213]. As mentioned above, estimation of the appropriate sample size depends on information which is contained in later sections.…”