Banking giant Barclays saw adjusted profit before tax rise 10% in the first quarter of 2011, despite a 15% slide in top-line income at Barclays Capital, its high profile investment banking arm.Adjusted profit before tax grew to £2,004m from £1,822m in the first quarter of 2010. Net operating income dipped 1% to £6,478m from £6,557m a year earlier.Basic earnings per share slid 9% to 8.5p from 9.3p a year earlier. The quarterly dividend has been held at 1.0p.The Core Tier 1 ratio, the ratio of a bank's core equity capital to its risk weighted assets (RWA) and a key measure of a bank's capital strength, improved to 11.0% from 10.8% a year earlier.The loan to deposit percentage declined to 119% from 124%."We are making good progress on execution in line with our strategic priorities, with costs and risks carefully managed in the quarter, and our returns on equity and tangible equity (excluding own credit) above 10% and 12%, respectively," said group chief executive, Bob Diamond.Barclays Capital's top-line income of £3,278m was down 15% on 2010's £3,845m, reflecting a decline of 22% in Fixed Income, Currency and Commodities and increases of 11% in Equities and Prime Services and 10% in Investment Banking.Retail and Business Banking profit before tax rose 21% to £692m (2010: £570m). This included profit before tax in banking brand Absa of £135m (2010: £167m) now reported in Retail and Business Banking. Excluding Absa, profit before tax increased 38% to £557m (2010: £403m). Income was flat at £3,251m (2010: £3,248m) as new business growth was offset by higher levels of customer repayments. Impairment charges decreased by 29% to £659m (2010: £927m)."In the month of April to date, performance [of the whole group] has been in line with the trends of the first quarter and we remain content with the current market consensus for 2011. The improvement in impairment in the first quarter included a release of £190m on the loan to Protium and we do not therefore expect the same pace of improvement for the group for the whole year," the company said. ---jh