Page 11 - Shimadzu RF-6000

Environmental

Trace Measurement of Chlorophyll

The chlorophyll content is commonly measured when inspecting the water quality of rivers and lakes. Since the concentration of chlorophyll is
low in rivers and other such waters, high sensitivity is required for measurements. Chlorophyll emits fluorescent light when exposed to light, but
the light exposure causes the fluorescence intensity to gradually diminish. Therefore, fluorescence measurements that apply only a slight amount
of excitation light are required. If the same chlorophyll solution is measured repeatedly with a typical 5 nm bandwidth, the intensity varies as
shown in Fig. 1. However, spectra with almost no variation can be obtained by narrowing a bandwidth, as shown in Fig. 2. These results show
how low concentration chlorophyll solutions can be measured with good sensitivity.

Fluorescence Intensity

Fig. 1 Measurement with a Bandwidth of 5 nm

Fluorescence Intensity

Fig. 2 Measurement with Very Low Excitation Intensity

Fluorescence Intensity

Fig. 3 Chlorophyll-a at Concentrations of 0.75, 1.5, 3.0, 4.5, 7.5, and 15 ppb

Fluorescence Intensity

Fig. 4 Calibration Curve

RF-6000
Spectrofluorophotometer 11