Alizarin red powder (ARS), chemical formula C14H7NaO7S and CAS 142-71-2, orange or yellow brown powder, easily soluble in water, slightly soluble in ethanol, insoluble in benzene and chloroform; The pH of the 1% aqueous solution is 2.15, and its color is light yellow brown. After adding hydrochloric acid, it turns yellow, and after adding sodium hydroxide, it turns blue purple. As a dye based coordination agent, it has been widely used in spectrophotometric analysis. In recent years, many authors have used the adsorption catalytic wave of ARS and its metal complexes on mercury electrodes for electroanalysis, improving the sensitivity and selectivity of the determination. It is one of many dyes and belongs to anthraquinone compounds. It is widely used in dyes and acid-base indicators. It is one of the representative dyes with high toxicity, complex structure and high chemical oxygen demand (COD) value.
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Chemical Formula |
C14H8O4 |
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Exact Mass |
240 |
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Molecular Weight |
240 |
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m/z |
240 (100.0%), 241 (15.1%), 242 (1.1%) |
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Elemental Analysis |
C, 70.00; H, 3.36; O, 26.64 |
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Alizarin Red S (ARS) is an orange yellow to yellow brown anthraquinone derivative with the chemical formula C ₁₄ H ₇ NaO ₇ S and a molecular weight of 342.26. It is soluble in water, slightly soluble in ethanol, insoluble in benzene and chloroform, and has unique metal chelating ability, acid-base responsiveness, and color development characteristics. Since its synthesis in the 19th century, Alizarin Red S has demonstrated extensive value in scientific research and industrial applications, covering biomedical, analytical chemistry, materials science, geology, and art fields.
The core application of Alizarin Red S is focused on biomedical research related to calcification. It forms orange red complexes through specific chelation with calcium salts such as hydroxyapatite and calcium carbonate, becoming a classic tool for detecting calcium deposition.
1. Research on osteogenic differentiation and bone mineralization
During the differentiation of stem cells into osteoblasts, the extracellular matrix deposits calcium salts to form mineralized nodules. Alizarin red powder staining can visually display the distribution and quantity of these nodules, and is the gold standard for evaluating osteogenic differentiation efficiency. For example, after inducing differentiation of MC3T3-E1 mouse osteoblast precursor cells, treatment with Alizarin Red S staining solution (2%, pH 4.2) resulted in mineralized nodules appearing orange red, while undifferentiated cells showed no staining.
Quantitative analysis of staining intensity through colorimetric method can accurately calculate calcium deposition and provide key indicators for screening osteoporosis drugs.
2. Pathological diagnosis of bone tissue
Alizarin Red S is used to stain calcified areas in bone slices to assist in the diagnosis of pathological calcified diseases. For example, in pathological sections of tuberculous caseous necrosis, aortic atherosclerotic plaque and foreign body calcification, Alizarin Red S can specifically mark calcium salt deposition, and combined with HE staining can distinguish calcium phosphate (orange red) and calcium oxalate (colorless or light yellow), providing morphological evidence for disease mechanism research.
3. Research on vascular calcification
Vascular smooth muscle cells can differentiate into osteoblast like cells under pathological conditions such as atherosclerosis, resulting in calcification of vascular wall. Alizarin red S staining can quantitatively analyze calcium deposition in aortic explants or cultured vascular smooth muscle cells, and evaluate the efficacy of calcification inhibitors (such as bisphosphonates). For example, studies have shown that the sensitivity of the Alizarin Red S staining method for detecting aortic calcification in rats is 30% higher than that of the traditional von Kossa staining method.
4. Tumor calcification detection
Some tumors (such as breast cancer and thyroid cancer) can be calcified. Alizarin red S staining can be used to identify calcification in tumor tissue sections. For example, in the pathological section of breast cancer, alizarin red S can mark microcalcifications, combined with molybdenum target X-ray images, to improve the accuracy of early diagnosis.
Analytical Chemistry: A Versatile Tool for Metal Ion Detection
Alizarin Red S, as a coordinating agent and indicator, plays an important role in metal ion analysis. It can achieve multi-component detection through complexation reactions, adsorption catalysis, and acid-base color changes.
1. Determination of metal ions by spectrophotometry
Alizarin Red S can form stable colored complexes with metal ions such as aluminum, beryllium, germanium, indium, cobalt, etc., for quantitative analysis by spectrophotometry. For example, in a pH 5.0 acetate buffer, Alizarin Red S forms a 1:1 complex with aluminum ions, with a maximum absorption wavelength of 520nm and a detection limit of 0.01 μ g/mL. This method has been applied to monitor aluminum pollution in environmental water samples.
2. Polarography and electroanalytical chemistry
Alizarin red S and its metal complexes can generate adsorption catalytic waves on mercury electrodes, significantly improving detection sensitivity.
For example, in an ammonia medium, the catalytic wave height of Alizarin Red S-Thorium complex is 50 times that of conventional polarographic waves, with a detection limit as low as 0.001 μ g/mL. This technology has been used for trace analysis of thorium in nuclear waste.
3. Acid base indicators and titration analysis
The acid-base color change range of Alizarin Red S is pH 3.7 (yellow) to 5.2 (purple), which can be used as an endpoint indicator for strong acid titration of weak bases. For example, in the ammonia titration experiment of boric acid, the color change point of Alizarin Red S coincides with the stoichiometric point, with an error of less than 0.1%.
4. Fluoride determination
Alizarin Red S forms a colorless complex with fluoride ions in an acetate buffer at pH 4.1, causing the solution to change color from red to yellow. The fluoride concentration can be determined by colorimetric method. This method has high sensitivity and a detection limit of 0.05mg/L, and is suitable for monitoring fluoride content in drinking water.
Materials Science: "Structural Regulators" for the Synthesis of Functional Materials
The metal chelating ability and molecular structural characteristics of Alizarin Red S make it play a key role in material synthesis, covering areas such as pigments, ceramics, and mineral flotation.
1. Art pigments and industrial coatings
Alizarin Red S can be combined with alumina to produce Alizarin Deep Red Lake Pigment, which has excellent light and heat resistance and has been widely used in oil painting, watercolor painting, and architectural coatings. For example, in the 19th century, European painters created a large number of classic works using Alizarin Red S pigment, which was much more stable than natural cochineal pigments.
2. Ceramic glaze and glass coloring
Alizarin Red S is an important component of blue ceramic glaze, and its coloring mechanism is the formation of cuprous oxide (Cu ₂ O) crystals by copper ions at high temperatures. By adjusting the amount of Alizarin Red S added, the color tone of the glaze can be controlled from light blue to deep blue to meet the needs of different artistic styles.
3. Mineral flotation inhibitors
In the flotation process of carbonaceous shale, Alizarin Red S can inhibit the flotation of gangue minerals through chelation, thereby improving the recovery rate of target minerals such as calcite. For example, research has shown that adding 0.1mmol/L Alizarin Red S can increase the recovery rate of calcite from 75% to 92%.
Geology: The 'Chemical Microscope' for Mineral Identification
The mineral selective staining properties of Alizarin Red S make it a practical tool for geological research, especially for rapid identification of carbonate minerals.
1. Carbonate mineral staining
Alizarin Red S can selectively stain calcite (CaCO ∝) to a deep red color, while dolomite (CaMg (CO ∝) ₂) does not stain due to magnesium ion interference. This feature is used to distinguish between calcite veins and dolomite veins in sedimentary rocks and assist in determining paleoenvironmental conditions. For example, in the study of ancient marine carbonate rocks, Alizarin Red S staining can reveal changes in the magnesium calcium ratio of ancient sea water.
2. Rock thin section analysis
Combined with polarizing microscope, Alizarin red powder staining can identify calcareous cement in rocks and analyze the process of diagenesis. For example, in the study of sandstone diagenesis, Alizarin Red S staining shows that calcareous cement appears orange red, revealing the influence of groundwater chemical environment on rock porosity.
Alizarin Red S, as a mediator dye, has promoted the development of the textile industry. Its dyeing process combined with metal mordants can produce rich colors.
1. Natural fiber dyeing
Alizarin Red S can produce colors such as red, brown, and purple by treating cotton, wool, and silk fabrics with metal mordants such as aluminum, chromium, and iron. For example, in the 19th century, the British textile industry used the Alizarin Red S-Chromium mordant dyeing process to produce red woolen fabric, which had a color fastness of over level 4, far exceeding traditional plant dyes.
2. Research on staining mechanism
The binding of Alizarin Red S to fibers involves hydrogen bonding, van der Waals forces, and metal coordination interactions. For example, in cotton fiber dyeing, Alizarin Red S first adsorbs onto the fiber surface, then forms chelates with aluminum ions, and finally embeds into the amorphous region of the fiber to achieve high color fastness.
(1) Add 15% fuming sulfuric acid to alizarin, sulfonate at 105-110 ℃, hold for 3 hours, cool, pour into distilled water, salt out with sodium chloride at 60 ℃, heat to 70 ℃, leave overnight, and filter. After washing with a 10% sodium chloride solution, dissolve it in distilled water, place and filter. Soak the crystals in a solution of ethanol and hydrochloric acid (9:1), stir continuously, leave overnight, and dry the crystals below 80 ℃.
Purification: Dissolve the obtained alizarin red in hot water, add activated carbon for decolorization, filter, stir the filtrate while adding ammonia water until a small amount of crystal precipitates, stir for 20 minutes, let it sit overnight, filter, and dry the product at 70-80 ℃.
(2) Dissolve the crude alizarin red in heated water, add activated carbon for decolorization, slowly add filtered clear industrial ammonia water to the filtrate under stirring until a small amount of crystals precipitate, continue stirring for 20 minutes, let it crystallize, filter, and dry the crystals at 70-80 ℃ to obtain refined alizarin red.
In 1869, German chemists Karl Graber and Karl Lieberman extracted anthracene from coal tar, oxidized it to anthraquinone, and then fused it with alkali to produce alizarin red. In this way, alizarin red became the first natural dye to be artificially synthesized. Its appearance had a huge impact on traditional plant dyes. The cheap alizarin red powder, which can be produced on a large scale, suddenly met the growing commercial demand, The demand for natural alizarin red plummeted, and at that time, large areas of European madder fields in France could only be converted to other crops. Today, alizarin red is still used as a dye on fabrics by Chemicalbook, but its popularity has declined significantly under the influence of other artificial dyes. Alizarin red, extracted from the roots of European madder, was previously used as a food additive pigment, but was banned by Japan and European and American countries due to research showing a risk of cancer. Currently, commercial alizarin red is mostly used to dye fabrics, and is also made into "maderlake" paint. Of course, if you are a biological animal, you may be more familiar with the so-called "osteoblast alizarin red staining experiment".
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