Tandem measurements of iron and creatinine by cross injection analysis with application to urine from thalassemic patients

• It has been demonstrated that ‘cross injection analysis’ is suitable for simultaneous analysis of two analytes.
• We developed a new and simultaneous method for determination of deferiprone-bound iron and creatinine in human urine
• The ratio of concentrations of excreted iron and creatinine can be used to evaluate the efficacy of the chelating therapy using spot urine sample.

This work presents development of a method for the dual determination of Fe(III) and creatinine using cross injection analysis (CIA). Two CIA platforms connected in series accommodated sample and reagents plugs aspirated via y-direction channels while water was pumped through the x-direction channel toward a flow-through cell of a diode array UV–vis. detector. Iron was detected from the colorimetric reaction between Fe(II) and 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-(3-sulfopropyl)amino) aniline (5-Br-PSAA), with prior reduction of Fe(III) to Fe(II) by ascorbic acid. The Jaffe׳s reaction was employed for the detection of creatinine. Under the optimal conditions, good linearity ranges were achieved for iron in the range 0.5 to 7 mg L−1 and creatinine in the range 50 to 800 mg L−1. The CIA system was applied to spot urine samples from thalassemic patients undergoing iron chelation therapy, and was successfully validated with ICP-OES and batchwise Jaffe׳s method. Normalization of urinary iron excretion with creatinine is useful for correcting the iron concentration between urine samples due to variation of the collected urine volume.

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