Chlorophyll is a vital pigment essential for the process of photosynthesis. It plays a crucial role in capturing light energy and converting it into chemical energy, which plants use to grow and thrive. Without chlorophyll, plants would be unable to perform photosynthesis effectively. This green pigment is found not only in green plants but also in blue-green algae and other photosynthetic organisms. There are several types of chlorophyll, including chlorophyll a, b, c, and d, each with slightly different absorption properties.
To understand plant health and growth conditions, scientists often measure chlorophyll content. There are three common methods used: spectrophotometry, the use of a living chlorophyll meter, and photoacoustic spectroscopy. Among these, spectrophotometry is the most widely applied technique due to its accuracy and reliability.
The determination of chlorophyll content typically begins with the extraction of chloroplast pigments from plant tissues. These pigments include chlorophyll a, chlorophyll b, carotenoids, and xanthophylls. The choice of solvent—such as acetone or ethanol—can significantly affect the results. In one experiment, four different solvents were used, and their absorption spectra were compared between 600 nm and 700 nm. The results showed that while there were minor differences, the overall absorption patterns were similar across all solvents.
Spectrophotometric analysis relies on the Lambert-Beer law, expressed as A = Kbc, where A is absorbance, K is the molar absorptivity, b is the path length, and c is the concentration of the solution. For chlorophyll a and b, the maximum absorption peaks occur at 663 nm and 645 nm, respectively. Using this data, equations can be derived to calculate the concentrations of chlorophyll a and b:
- D663 = 82.04Ca + 9.27Cb
- D645 = 16.67Ca + 45.60Cb
From these, we can solve for Ca and Cb:
- Ca = 12.72D663 – 2.59D645
- Cb = 22.88D645 – 4.67D663
Finally, the total chlorophyll content (CT) can be calculated using the formula CT = (D652 × 1000) / 34.5.
In practice, the choice of solvent greatly influences the efficiency of chlorophyll extraction. Based on experimental results, 95% acetone mixed with ethanol (homogenized) was found to yield the best extraction performance. This method is often preferred when conducting chlorophyll content analysis.
To make the process more efficient and accessible, specialized instruments like the chlorophyll content meter have been developed. These devices measure the relative chlorophyll content in plant leaves by analyzing optical density at two wavelengths. They provide quick, non-destructive readings and help assess plant health, nutrient status, and growth conditions.
A typical chlorophyll meter features a sensor made of silicon semiconductor photodiodes and displays results on an LCD screen. It has a measuring area of 2mm×3mm and operates within a range of 0.0 to 99.9 SPAD units. The device can store up to 30 measurements and automatically calculates the average. It uses two AA batteries and offers high accuracy, repeatability, and reproducibility, making it ideal for fieldwork and agricultural applications.
With its compact design (164×78×49 mm) and lightweight (225 grams), the instrument is easy to handle and suitable for both laboratory and on-site use. It functions well in a wide temperature range, from 0°C to 50°C, and can be stored between -20°C and 55°C. Additional features include alarm alerts, calibration options, and a user-friendly interface.
This technology provides farmers, researchers, and horticulturists with a reliable tool to monitor plant health and optimize crop management strategies. By understanding chlorophyll levels, they can make informed decisions about fertilization, irrigation, and overall plant care.
Polyacrylamide
Polyacrylamide (PAM) is a water-soluble polymer, which is insoluble in most organic solvents, has good flocculating properties, can reduce frictional resistance between liquids, Can be divided into non-ionic, anionic, cationic and amphoteric four types.
When PAM is used for flocculation, it is related to the surface properties of the species being flocculated, especially the potential, viscosity, turbidity, and pH of the suspension. The kinetic potential of the particle surface is the reason for particle inhibition. Can reduce the potential and condense.
Granular polyacrylamide flocculant cannot be directly added to sewage. It must be dissolved in water before use, and its aqueous solution are used to treat sewage.The water in which the particulate polymer is dissolved should be clean. Generally tap water is suitable for formulating polymer solutions. Strong ACID, strong alkali, high salt water is not suitable for preparation. Water at room temperature is ok, no necessary to heat. Dissolution is slow when the water temperature is below 5 ° C. Increasing the water temperature will accelerate the dissolution rate, but above 40 ° C will accelerate the degradation of the polymer and affect the use effect. The solution concentration is recommended to be 0.1% -0.3%.
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