Dispersive liquid-liquid microextraction and spectrofluorimetric determination of aluminum in fish

$0 Background: Aluminum(Al) is a non-essential and toxic metal which human can be frequently exposed toby consuming Al containing medicines, inhalation of atmospheric dust, food,drinks, etc. There are some events showing that, Al can be involved as acausative factor in some diseases like Alzheimer’s disease, Parkinson’sdisease, cancer and diabetes.  Therefore,there is a great demand to introduce simple and accurate analytical methods fordetermination of trace amounts of Al in different samples specially foodstuffs.In this work a dispersive liquid-liquid microextraction technique has beendeveloped and optimized for spectrofluorimetric determination of Al in fish. $0$0 Methods: Approximately 1 g of homogenized fish sample was digestedby adding 10 ml of nitric acid 50%. After 30 minutes, 100 µl of digested samplewas transferred into another tube and mixed with 10 ml distilled water, 1 ml of8-hydroxyquinoline 1 ´ 10 -4 M and 1 ml of sodium chloride 4%(w/v). After that, pH of the mixture was adjusted to 7.00 by adding diluted hydrochloricacid. Then the mixed solution of 600 µl of acetonitrile (dispersive solvent)and 150 µl of chloroform (extracting solvent) was quickly injected into thetube and a cloudy mixture was obtained. After centrifugation of the obtained mixture,the collected organic phase at the bottom of the tube was analyzed by a spectrofluorimeterat excitation/emission wavelengths of 400/550 nm. $0$0 Results: All variables affecting the extractionstep, such as extracting and dispersive solvents, pH, time of complexformation, sample volume and speed of centrifugation were optimized. Then underthe optimum conditions, the method was validated in terms of linearity, LOD,LOQ, accuracy and precision, according to the ICH guideline. Obtained resultsindicated that, complex formation was completed after 30 minutes and theoptimized mixture of extracting and dispersive solvents was consisted of 150 mlchloroform and 600 ml acetonitrile, respectively. Under the optimum conditions,the method was linear in the concentration range of 20 – 500 ng/ml withcorrelation coefficient of more than 0.999. $0$0 Conclusion: Inpresent study a DLLME technique has been successfully applied for theextraction of trace amounts of Al from fish samples as a prior step todetermination of Al by spectrofluorimetry. $0