Tate & Lyle's profits slumped in the first half as sales were hurt by operational disruption and competition for its Splenda Sucralose product.The agribusiness reported a 40% drop in adjusted pre-tax profit to £104m as sales declined 21% to £1.38bn.The company said sales were dragged down by lower prices in corn and for Splenda.Results were also affected by the strength of sterling against the US dollar and other currencies."As we announced on 23 September, the group's performance in the first half has been significantly held back by operational and supply chain disruption and an increasingly competitive market for Splenda Sucralose," said Chief executive Javed Ahmed."Notwithstanding these factors, the fundamentals of our business are robust with particularly strong growth in the emerging markets for our speciality food ingredients business excluding Splenda Sucralose, a high quality innovation pipeline and a resilient, cash generative bulk ingredients business. We are firmly focused on taking the necessary steps to work through the issues we face and improve the group's performance."The dividend was raised 5.1% to 8.2p per share.