Quantitative chromatographic method for the determination of low levels of nitrilotriacetic and ethylenediaminetetraacetic acids in diethylenetriaminepentaacetic acid

Monitoring EDTA process residuals in recombinant protein manufacturing using liquid chromatography

We have developed a chromatographic method for the high sensitivity quantitation of EDTA process residuals in recombinant protein manufacturing validation studies. The reversed-phase HPLC method is based upon the detection of Cu(2+)/EDTA complexes at 254 nm, and has been qualified for use on intermediates from a purification process for a recombinant protein expressed in E. coli. Quantitation of EDTA in recombinant protein process intermediates is linear in the range of 0.2 to 64 microM with LOD/LOQ values below 2.0 microM. The assay is suitable for use in process backgrounds containing Tris, HEPES, MES, NaCl, hexanediol, NH(4)SO(4), and PEG. EDTA spike recovery values in all process samples tested were greater than 90% at the 4.0 microM concentration. System suitability parameters for the chromatographic method were developed based upon peak area and retention time precision, column efficiency and USP tailing. Peak area precision and intermediate precision values across the linear range of the assay exhibited C.V. values less than 15% at any concentration tested in all sample backgrounds. The assay robustness was tested by transfer of the assay to a second laboratory and analyst with use of multiple process intermediate lots, reagent/column lots, and HPLC systems.

Determination of ethylenediamine tetraacetic acid in injection forms by ion-pair chromatography

A high performance liquid chromatographic method was developed for the determination of ethylenediamine tetraacetic acid (EDTA) in injection forms. The method consists of direct extraction of the samples with ethyl acetate; the organic layers were evaporated to dryness and further diluted to a 0.025% (w/v) copper nitrate in order to achive the formation of the EDTA-copper solution complex. The chromatographic separation was performed on a C8 Hypersil column. The mobile phase consisted of a mixture of acetonitrile-0.015 M tetrabutylammonium hydroxide (10:90, v/v), (pH* 7.0) pumped at a flow rate of 1.5 ml min(-1). The UV detector was operated at 300 nm. Correlation coefficients of the calibration graphs were better than 0.9995, relative standard deviation was less than 2.5%. Detection limit of EDTA was found to be 1.97 microg ml(-1).

Determination of EDTA in vancomycin by liquid chromatography with absorbance ratioing for peak identification

An LC method is described for the determination of EDTA in vancomycin formulations. EDTA is complexed with iron and the Fe(EDTA)- complex is separated from vancomycin components on a reversed-phase column using an ion pair mobile phase. Quantitation is achieved using UV detection, with absorbance ratioing employed to discriminate between the analyte and vancomycin-related compounds. The complexity of the sample matrix and the trace levels of EDTA that are of interest dictate unique development considerations. This method offers good specificity and precision over the range 20-300 ppm EDTA in vancomycin formulations, while maintaining a degree of simplicity. Wavelength selection is optimized to demonstrate the potential application of absorbance ratioing to trace determinations. This method has been effectively applied to vancomycin formulations containing a wide range of chemical impurities and is not affected by vancomycin degradation products.

Low-level determination of ethylenediaminetetraacetic acid in complex matrices

A method for the determination of ethylendiaminetetraacetic acid (EDTA) in foodstuffs by high performance liquid chromatography (HPLC) and gas chromatography (GC) is described. This method is applied to foodstuffs rich in sugars and polysaccharides for which aqueous extraction cannot be directly used in chromatographic analysis. EDTA, in its iron chelate form, is extracted with water from the defatted foodstuff. The extract is then purified by ion-exchange chromatography. At this stage of purification, the quantitative level of EDTA can be estimated by HPLC and the result can be confirmed by GC. The detection level of our samples of tinned beans was under 5 mg/kg.

Quantitative determination of disodium edetate in ophthalmic and contact lens care solutions by reversed-phase high-performance liquid chromatography

A specific and sensitive HPLC method has been developed for the quantitative determination of disodium edetate (1) in a variety of ophthalmic and contact lens care solutions. Using this method, a common contaminant, nitrilotriacetic acid (2), is easily separated from 1. Sample preparation involves a single dilution step prior to mixing with an aqueous cupric nitrate solution to form a copper:EDTA complex for analysis. An aliquot of the resulting mixture is analyzed by HPLC using either a 10-microns styrene divinyl benzene column or, for separations requiring greater selectivity and resolution because of interfering components in the sample matrix, a 5-microns octadecyl column with a mobile phase of acetonitrile:0.006 M aqueous tetrabutylammonium phosphate, pH 6.5 (20:80). The column effluent is monitored by UV detection at 254 nm. The method is linear, quantitative, and reproducible for a wide variety of formulations. Using this method, the average recovery of 1 from spiked samples was 100%, with a relative standard deviation of less than 2%. The minimal quantifiable level of 1 was approximately 2.8 ng (equivalent to an analytical concentration of 1.5 microgram/mL).

Determination of ethylenediaminetetra-acetic acid in aqueous rinses of detergent-washed rubber stoppers of pharmaceutical vials using solid-phase extraction and capillary gas chromatography

A fused silica capillary gas chromatographic method is presented for the determination of traces of ethylenediaminetetra-acetic acid (EDTA) in aqueous rinses of rubber stoppers of pharmaceutical vials after treatment with detergents containing EDTA. Isolation and enrichment of EDTA from the aqueous medium is achieved using a commercially available strong anion-exchange solid-phase extraction cartridge, transformed to the formate form. A 2.0-ml volume of methanolic HCl is used for both elution of EDTA from the extraction column and formation of the tetramethyl ester derivative. With the incorporation of a methanolic wash to eliminate interfering components prior to elution with methanolic HCl, a limit of detection of 25 ng EDTA per ml water with a non-selective flame ionization detector is possible.