Residual corrosion inhibitor monitoring

A method for determining corrosion inhibitor residual concentration of dry crude oil, the method comprising:

• mixing the dry crude oil with a standard solution to form a first mixture, the standard solution comprising a corrosion inhibitor in a known concentration;
• mixing the first mixture with an aqueous saline solution to form a second mixture, the aqueous saline solution comprising about 1% salt concentration or greater;
• agitating the second mixture for about 1 hour or longer and at a temperature of about 50 degrees Celsius (° C.) or greater;
• after agitation, allowing a hydrocarbon phase and an aqueous phase of the second mixture to separate;
• obtaining a portion of the aqueous phase;
• and
• analyzing the portion of the aqueous phase with reversed phase liquid chromatography using a mobile phase having a mixture of methanol to phosphate buffer at a 1:1 ratio and a pH of about 2.5 to determine a corrosion inhibitor residual concentration of the dry crude oil.