Amperometric and spectrophotometric methods were developed for measuring iodide tracer concentration in water produced from offshore oil reservoirs. The amperometric method exhibited a linear response from 1 to 10 mg L-1 with limits of detection and of quantification of 0.2 and 0.6 mg L-1, respectively. The spectrophotometric method also exhibited a linear response from 1 to 10 mg L-1 with limits of detection and of quantification of 1 and 3 mg L-1, respectively. Both methods showed to be accurate, linear, homoscedastic and their recoveries were 101 ± 2 and 100 ± 3%, respectively, while the recoveries for produced reservoir water samples (fortified with iodide) were 97 ± 7 and 100 ± 3%, respectively. High amounts of sulfate interfere in the spectrophotometric method. Both methods are promising, simple and inexpensive alternatives to ion chromatography for the detection of iodide tracer in produced water reservoir samples.
iodide; reservoir tracer; amperometry; ultramicroelectrode; spectrophotometry; produced water
