Chemiluminescent determination of EDTA and related compounds using tris(2,2′-bipyridyl)ruthenium(III) photogenerated on-line

A new spectrophotometric method for determination of EDTA in water using its complex with Mn(III)

EDTA is an important ligand used in many industrial products as well as in agriculture, where it is employed to assist in phytoextraction procedures and the absorption of nutrients by plants. Due to its intensive use and recalcitrance, it is now considered an emerging pollutant in water, so there is great interest in techniques suitable for its monitoring. This work proposes a method based on formation of the Mn(III)-EDTA complex after oxidation of the Mn(II)-EDTA complex by PbO2 immobilized on cyanoacrylate spheres. A design of experiments (DOE) based on the Doehlert matrix was used to determine the optimum conditions of the method, and the influence of the variables was evaluated using a multiple linear regression (MLR) model. The optimized method presented a linear response in the range from 0.77 to 100.0μmolL(-1), with analytical sensitivity of 7.7×10(3)Lmol(-1), a coefficient of determination of 0.999, and a limit of detection of 0.23μmolL(-1). The method was applied using samples fortified at different concentration levels, and the recoveries achieved were between 97.0 and 104.9%.

Exploitation of the size-exclusion effect of reversed-phase high performance liquid chromatography for the direct analysis of diethylene triamine pentaacetic acid in therapeutic monoclonal antibody formulations

Monoclonal antibodies (mAb) are being widely studied for the treatment of cancers and other diseases. The mAb is typically in a solution formulation and administered as an intravenous infusion. Ready-to-use solutions are favored for their clinical convenience but they can potentially suffer from a shorter shelf life due to accelerated rates of some forms of degradation such as oxidation, relative to lyophilized formulations. To improve stability, the chelating agent diethylene triamine pentaacetic acid (DTPA) is often used at very low concentrations in biologics formulations to prevent oxidation induced by metal ions. Because of its low concentration and susceptibility to changes in concentration during stability study or processing, the measurement of DTPA levels during formulation and process development is critical. In response to this need we developed a platform reversed-phase HPLC method that allows for the rapid and direct determination of DPTA concentrations which does not require the prior removal of mAbs in formulation samples. The method exploits the "size exclusion effect" of C18 columns with narrow pore sizes (90-120Å) to elute large mAb at the void volume, enabling direct injections of mAb samples for quantitation of DTPA. The method was found to be suitable for the analysis of DTPA in the range of 2-20μg/mL across multiple drug formulations containing different therapeutic mAb and antibody drug conjugates. The method was successfully validated for specificity, precision, accuracy, linearity, and robustness.

Spectrophotometric determination of EDTA in aqueous solution through ferroin formation using sodium sulfite as the reducer

This paper presents a simple, easy and reliable method for determination of EDTA (ethylenediaminetetraacetic acid) in aqueous system. Using EDTA chelating with ferric irons, an excessive amount of Fe(3+) was added to EDTA solution, and Fe(3+) in excess was reduced by addition of a Na2SO3 solution, the outcome ferrous ions were then reacted with 1,10-phenanthroline monohydrate (PTM) to form ferroin, a color developing reagent. The absorbance of the ferroin was determined using spectrophotometry, from which EDTA concentration was obtained. The method was tested for interferences and applied to determination of trace amount EDTA in its degradation by ozone oxidation, and the result compared with those from high-performance liquid chromatography. It was revealed that a low limit of 1.4μM for EDTA concentration detection was achieved with a high correlation coefficient of 0.999 combined with a low relative standard deviation of 0.6%. In contrast to all reported processes, where ferric ions in excess have to be separated from those chelated with EDTA prior to their reduction followed by interaction with PTM and spectrophotometric determination, the key merit of the present method is that EDTA concentration is determined without need of ferric separation, rendering the present process very easy. The method is also characterized by low cost, high precision and high reproducibility at the same time.