Use of Chlorophyll-a in Extract of Microcystics Aeruginosa as Primary Standard in Fluorophotometric Determination of Chlorophyll

Chlorophyll-a (CHL-a) was extracted from Microcystis aeruginosa with ethanol, and mass concentration of CHL-a in the extract amounted to 1 902.5 μg·L-1 as determined by spectrophotometry. The CHL-a was used instead of the chlorophyll standard substance in fluorophotometric determination of chlorophyll. Linear rrelationship was kept between values of fluorescence intensity and mass concentration of CHL-a in the range of 30-1 800 μg·L-1. Five samples of water were analyzed, and consistent results were obtained by using standard solutions prepared with either the CHL-a extract or the chlorophyll standard as shown by the results of t-test. As shown by ehe testing results, ① the effect of time of preservation within 5 h under 4 ℃, ② effect of acidity in the pH range of 3 to 9, and ③ effect of working temperatures in the range of 5 ℃ to 30 ℃, on the stability of the extract. As shown by the values of emission fluorescence intensity measured, relative errors of within ±5.0% were obtained, which was satisfactory for the analytical operation. It was concluded that the CHL-a extract was feasible to be used as a substitute for chlorophyll standard substance.