Chlorophyll content determination method
Chlorophyll is a necessary substance for photosynthesis. Without chlorophyll, photosynthesis can not be performed normally, and light energy can be converted into chemical energy. Chlorophyll can be found in green plants, blue-green algae and other organisms, and is divided into chlorophyll a, chlorophyll b, chlorophyll c, and chlorophyll d. Chlorophyll is present in the chloroplast vesicles.
Three Methods for Determination of Chlorophyll Content
Chlorophyll content is closely related to the photosynthetic rate and plant nutrition status. Usually, we will know the growth status of plants by measuring the chlorophyll content. In general, there are three kinds of plant chlorophyll content determination: spectrophotometry, living chlorophyll meter method and photoacoustic spectroscopy. Spectrophotometry is the most widely used method for determining chlorophyll content.
Absorption Spectrum of Leaf Chlorophyll in Different Extracts of Coral Tree
1-95% acetone 2 ethanol 2-95% ethanol
3-80% acetone 4-95% acetone 2 ethanol (homogenate)
Calculation of chlorophyll content
The determination of chlorophyll content firstly extracts the chloroplast pigment. The chloroplast pigment contains chloroplast a, chloroplast b, carotene and lutein. When extracting chloroplast pigments, we use different reagents such as acetone, ethanol and other organic substances. When the reagents are different, the results obtained will be different. In the picture above we use four different solvents for the extraction of chloroplast pigments. In the figure, the chlorophyll content was calculated by comparing the absorbance of the four solvents at wavelengths between 600 nm and 700 nm. From the figure, we can roughly conclude that the light absorption properties of the four chlorophyll extracts are basically the same.
The determination of chlorophyll content by spectrophotometry is based on the Lambert-Beer law and the mathematical expression is A=Kbc. Among them, A is the absorbance; K is the absorption coefficient; b is the thickness of the solution; c is the concentration of the solution.
The maximum absorption peaks of the chlorophyll a, b solution in acetone in the visible range were at 663 nm and 645 nm, respectively. The absorbance coefficients of chlorophyll a and b at 663 nm were 82.04 and 9.27, respectively; the absorbance coefficients at 645 nm were 16.67 and 45.60, respectively. According to the Lambert-Beer law, we can list the equations:
D663 = 82.04Ca+9.27Cb
D645 = 16.67Ca+45.60Cb
According to the above equations, you can find:
Ca = 12.72D663 C 2.59D645
Cb = 22.88D645 C 4.67D663
Then we can find the total amount of chlorophyll CT = (D652 × 1000) / 34.5
The above figure shows the progress of different chlorophyll extracts in the extraction of chlorophyll. It can be seen that the difference is still quite large. We can compare ourselves. From the figure, we can find that 95% acetone 2 ethanol (homogeneous) has the best extraction effect. Therefore, when we carry out chlorophyll content determination, we can consider using 95% acetone 2 ethanol (homogenized) as the extract.
So, we have now invented a relatively convenient instrument for measuring chlorophyll content—the chlorophyll content measuring instrument. It measures the performance index of soil and the nitro requirement of plants by measuring the relative chlorophyll content of plants, and understands the Growth Status.
Graph Chlorophyll Content Tester
Chlorophyll content measuring instrument technical parameters
Measuring object
Plant leaves
measurement method
2-wavelength optical density difference method
Measuring area
2mm×3mm
sensor
Silicon Semiconductor Photodiode
Display method
Measured value: 3-digit LCD display
Measurement times: 2 digit LCD display
Measuring range
0.0 to 99.9 SPAD
Memory capacity
30 data, automatically calculate and display the average
power supply
2 AA batteries (1.5V)
Battery Life
More than 20000 measurements
Measurement interval
Less than 2 seconds
Accuracy
Within ±1.0 SPAD units (SPAD values ​​range from 0-50 at room temperature)
Repeatability
Within ±0.3 SPAD units (SPAD values ​​between 0-50)
Reproducibility
Within ±0.5 SPAD units (SPAD values ​​between 0-50)
Volume (length×width×height)
164×78×49mm
weight
225 grams (excluding batteries)
Operating environment
0 to 50°C
Storage environment
-20 to 55°C
Other functions
Alarm function; calibration function
Standard configuration
Host, Calibration Card, Host Cover, Battery
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