All glassware and polyethylene bottles were soaked in 2M nitric acid for at least 1 week, washed three times with bidistilled water, and finally soaked in 0.1 M hydrochloric acid until being ready for use
All glassware and polyethylene bottles were soaked in 2M nitric acid for at least 1 week, washed three times withbidistilled water, and finally soaked in 0.1 M hydrochloric acid until being ready for use