摘要：In this study a modified sealed method is developed for chemical oxygen demand (COD) determination. For time-saving and ease of operation, an oven and ultraviolet spectrophotometer were chosen as heating equipment and chromate detector, respectively. Organic compounds such as formic acid, acetic acid, oxalic acid, malonic acid, aniline, glycerol, glucose and potassium hydrogen phthalate were used as prematerials to modify a calibrated equation in the final detection at 348 nm in the ultraviolet spectrophotometer. A masking effect of mercury sulfate to chloride ion was also evaluated with the digestion agent. The results show that the masking agent, if necessary, must be used before addition of the digestion agent, and they demonstrate an excellent inhibition from 1 to 1000 mg/l of chloride ion existing in the water sample. During actual sample tests, the modified sealed oven-UV method performed very appropriately in environmental samples being accurate and with a low detection limit of 9.26 mg/l.
