For preparation of dried samples (Sample 2 and 4), water hya-cinth samples of 2–3 cm length were placed properly on drying pans (not stacking nor closely packed) before being oven dried at 60 ± 3C for two to three days. Samples were consecutively weighed until constant weight is attained. The dried samples were either straightly used for experiments or transferred into airtight containers until further use