Laboratory measurement: Chlorophyll-a concentration measurement with acetone method using spectrophotometer

Chlorophyll-a is an important factor in photosynthesis of microalgae. The concentration of chlorophyll-a in microalgae can be used to analyse and investigate the density and biomass of microalgae in the ecosystem. This is because microalgae are primary producer in the food web in freshwater and ocean. Thus, an accurate estimate of chlorophyll-a concentration in microalgae is very significant. In this study, the samples of microalgae were collected from Tasik Harapan and Tasik Aman, USM Penang, Malaysia. The samples were tested using 90% acetone method by using spectrophotometer (model HITACHI U-1900) to record the absorbance values with selected wavelengths namely 750 nm, 664 nm, 647 nm, and 630 nm The results showed that the chlorophyll-a concentration in microalgae increased when the absorbance was increased. The chlorophyll-a concentration in microalgae depended on several factors such as amount of sunlight available, total phosphorus (TP), water flow, light, catchment area, water depth, weather, and other physical factors. This study determined the value of chlorophyll-a concentration in microalgae collected from Tasik Harapan and Tasik Aman, USM Penang. The highest and the lowest chlorophyll-a concentration were recorded in this study. The spectrophotometer with 90% acetone method successfully determined the maximum and minimum sensitivity of chlorophyll-a concentration within the wavelengths tested.