Determination of ethylenediaminetetraacetic acid in sea water by solid-phase extraction and high-performance liquid chromatography.

The chelating agent EDTA is widely used, and as a result is showing up widely in the aquatic environment. Here we describe a preconcentration procedure for measuring EDTA concentration in sea water samples by HPLC. The procedure consists of forming an Fe(III) complex followed by solid-phase extraction using an activated carbon cartridge. After the preconcentration, EDTA was quantified by HPLC with ultraviolet detection (260 nm). The enrichment permitted the determination of EDTA at concentrations as low as 1 nM. Good recoveries were obtained for both brackish and full-strength sea water with high repeatability (RSD<6%). The method was applied to sea water samples taken from near the mouth of the Oyabe River in Japan.

Study of solid-phase extraction for the determination of sequestering agents in river water by high-performance liquid chromatography.

Anion-exchange solid-phase extraction accompanied with high-performance liquid chromatography has been developed for the determination of six kinds of aminopolycarboxylic acids (APCAs) in river water [N-(2-hydroxyethyl)ethylenediaminetriacetate (HEDTA), ethylenediaminetetraacetate (EDTA), 1,3-propanediaminetetraacetate (PDTA), diethylenetriaminepentaacetate (DTPA), 1,2-propanediaminetetraacetate (MeEDTA), and O,O'-bis(2-aminoethyl)ethyleneglycoltetraacetate (GEDTA)]. The enrichment of APCAs using an anion-exchange cartridge was successfully done by the removal of anions, which competed with APCAs in anion-exchange processes. Barium chloride solution was added to river water and the mixture was passed through On Guard II Ag and H cartridges and then a Bond Elut Jr.SAX cartridge to enrich APCAs. After elution, APCAs were analyzed on two reversed phase C30 columns connected in series and detected with ultraviolet detection. The enrichment using solid-phase extraction permitted the determination of APCAs in river water at concentrations as low as 1nM. Good recoveries (83-111%) were obtained for each APCA by the standard addition method on three river water samples with high accuracy (RSD 1.8-9.5%). Applying this method, two kinds of APCAs, EDTA and DTPA, were determined in samples from the Oyabe and Senbo Rivers in Japan.

Simple synthesis of diastereomerically pure phosphatidylglycerols by phospholipase D-catalyzed transphosphatidylation.

A simple method for synthesizing diastereomerically pure phosphatidylglycerols (PtdGro), namely, 1,2-diacyl-sn-glycero-3-phospho-3'-sn-glycerol (R,R configuration) and 1,2-diacyl-sn-glycero-3-phospho-1'-sn-glycerol (R,S configuration), was established. For this purpose, diastereomeric 1,2-O-isopropylidene PtdGro were prepared from 1,2-diacyl-sn-glycero-3-phosphocholine (PtdCho) and enantiomeric 1,2-O-isopropylideneglycerols by transphosphatidylation with phospholipase D (PLD) from Actinomadura sp. This species was selected because of its higher transphosphatidylation activity and lower phosphatidic acid (PtdOH) formation than PLD from some Streptomyces species tested. The reaction proceeded well, giving almost no hydrolysis of PtdCho to PtdOH in a biphasic system consisting of diethyl ether and acetate buffer at 30 degrees C. The isopropylidene protective group was removed by heating the diastereomeric isopropylidene PtdGro at 100 degrees C in trimethyl borate in the presence of boric acid to obtain the desired PtdGro diastereomers. The purities of the products, which were determined by chiral-phase HPLC, were exclusively dependent on the optical purities of the original isopropylidene-glycerols used. The present method is simple and can be utilized for the synthesis of pure PtdGro diastereomers having saturated and unsaturated acyl chains.