Patent ID: 6329206
Filing Date: 2001-12-11
Classification: G01N,Y10T

Abstract:
A process for determining the concentration of an amine inhibitor component that includes hexamethylenetetramine in a liquid aqueous pickling solution that has a pH value not more than 6.0, the process comprising the following operations:(I) separating a testing sample from the pickling solution in which the concentration of inhibitor is to be determined, the testing sample having a quantitatively known volume, mass, or both, and optionally preheated at at least 65.degree. C. for at least 30 min to form formaldehyde;(II) alkalinizing the testing sample, the testing sample being preheated at at least 65.degree. C. for at least 30 min to form formaldehyde, by adding a sufficient amount of an alkalinizing agent to form formaldehyde and to define a mixture and, optionally, adding water, wherein the pH of the mixture of the testing sample and the alkalinizing agent is raised to a value of at least 10.8 to accurately determine the formation of formaldehyde, whereby an iron content of the mixture is caused to precipitate as a solid from the mixture;(III) separating an alkanized sample of the liquid portion of the mixture of the sample and the alkalinizing agent from all of the solid portions of the mixture of the testing sample and the alkalinizing agent;(IV) determining the concentration of formaldehyde in the alkanized sample; and(V) calculating the concentration of hexamethylenetetramine in the pickling solution from the value of the concentration of formaldehyde found in the alkanized sample, wherein each mole of hexamethylenetetramine in the testing sample produces six moles of formaldehyde in the alkalinized mixture of the testing sample and the alkalinizing agent and all such produced formaldehyde remains dissolved in the liquid part of the alkalinized mixture.