Analytical Compatibility between Various Techniques for Determining Dissolved Manganese in Produced Water

Petroleum-produced water is the primary effluent generated during the oil extraction process, presenting high flow rates, and containing a series of chemical components that are harmful to the environment, such as dissolved manganese. The proof of metrological compatibility between laboratories and different test methods or techniques is an analytical challenge when complying with environmental laws and regulations, which is the aim of this study. The first step of this study was to compare the results of manganese content in real test samples of produced water between some laboratories that used different test methods, that is, flame atomic absorption spectrophotometry, inductively coupled plasma optical emission spectroscopy, and inductively coupled plasma mass spectrometry. Based on one-way analysis of variance, systematic errors were found. The following step was to visit a specific lab, where one could confirm the relevance of the wavelength parameters, operating conditions for the view configuration, and effects of the saline matrices. Finally, a compatibility assessment between the reference laboratory and a new laboratory, which implemented and validated its analytical methodology based on these analytical adjustments, and the experiences and lessons learned in the previous step, was undertaken by a paired t-test.