**Human VDR ELISA Kit – For the Quantitative In Vitro Determination of Human Vitamin D Receptor Concentrations in Serum, Plasma, Cerebrospinal Fluid, Tissue Homogenate, and Other Biological Fluids**
**FOR LABORATORY RESEARCH USE ONLY. NOT FOR USE IN DIAGNOSTIC PROCEDURES**
Before using this product, please read this entire package insert carefully. This ELISA (Enzyme-Linked Immunosorbent Assay) is intended for research purposes only and should not be used for diagnostic or therapeutic applications.
The VDR ELISA Kit allows for the quantitative measurement of Human Vitamin D Receptor (VDR) levels in various biological samples. The assay is based on a competitive binding principle. A standard curve is generated using a set of calibration standards, and sample concentrations are determined by comparing their optical density (OD) values to this curve.
**INTENDED USE AND TEST PRINCIPLE**
This VDR ELISA Kit is designed for laboratory research use only and is not suitable for diagnostic procedures. The Stop Solution changes the color from blue to yellow, and the intensity of the color is proportional to the amount of VDR present in the sample. Calibration standards are included to ensure accurate quantification.
**SAMPLE COLLECTION AND STORAGE**
- **Serum**: Use a serum separator tube. Allow samples to clot for 2 hours at room temperature or overnight at 4°C before centrifugation at 2000×g for 20 minutes. Assay immediately or aliquot and store at -20°C. Avoid repeated freeze-thaw cycles.
- **Plasma**: Collect using heparin as an anticoagulant. Centrifuge within 30 minutes at 2000×g, 2–8°C. Store at -20°C. Avoid freeze-thaw.
- **Cell Culture Supernatants, Tissue Homogenates, and Other Fluids**: Remove particulates by centrifugation. Assay immediately or store at -20°C. Ensure no hemolysis or particulate matter is present.
**MATERIALS REQUIRED BUT NOT SUPPLIED**
1. 37°C incubator
2. Microplate reader capable of measuring absorbance at 450 nm
3. Pipettes, disposable tips, and absorbent paper
4. Distilled or deionized water
**REAGENTS PROVIDED**
All reagents should be stored at 2–8°C. Check the expiration date on the label.
- Microtiter Strip Plate: 12×8 strips / 12×4 strips
- Standard (6 vials): 0.5 ml/vial
- Sample Diluent: 6.0 ml / 3.0 ml
- HRP-Conjugate Reagent: 10.0 ml / 5.0 ml
- 20X Wash Solution: 25 ml / 15 ml
- Chromogen Solution A: 6.0 ml / 3.0 ml
- Chromogen Solution B: 6.0 ml / 3.0 ml
- Stop Solution: 6.0 ml / 3.0 ml
- Closure Plate Membrane: 2 / 2
- User Manual: 1 / 1
- Sealed Bags: 1 / 1
**NOTES**
- Standard concentrations: 40, 20, 10, 5, 2.5, 1.25 ng/ml
- If sample values exceed the highest standard, dilute with Sample Diluent and repeat the test.
**PRECAUTIONS**
1. Do not substitute reagents between kits. All components are matched for optimal performance.
2. Allow all reagents to reach room temperature (20–25°C) before use. Do not thaw using water baths.
3. Do not use beyond the expiration date.
4. Use only deionized or distilled water for dilutions.
5. Keep microtiter plates in sealed bags until needed. Unused strips should be stored at 2–8°C with desiccant.
6. Use fresh pipette tips for each transfer to avoid cross-contamination.
7. Wear gloves during the procedure. All biological materials should be treated as potentially infectious.
8. Dispose of all samples appropriately to inactivate viruses.
9. Liquid waste must be treated with sodium hypochlorite (final concentration 1.0%) for 30 minutes before disposal.
10. Substrate solution is sensitive to contamination. Do not use if it appears bluish.
11. Chromogen B contains 20% acetone; keep away from heat or flame.
12. Bring all reagents to room temperature before starting the assay.
**REAGENT PREPARATION AND STORAGE**
- **Wash Solution (1X)**: Dilute 1 volume of 20X Wash Solution with 19 volumes of deionized or distilled water. Store at 2–8°C for up to one month.
**ASSAY PROCEDURE**
1. Prepare all reagents before beginning.
2. Add 100 µl of standards, controls, and samples to the microtiter plate. Cover with adhesive strips and incubate for 60 minutes at 37°C.
3. Wash the plate 4 times (manual or automated).
- **Manual Washing**: Aspirate, fill with 1X Wash Solution, aspirate again. Repeat four times. Invert and blot dry.
- **Automated Washing**: Aspirate and wash four times. Set fill volume to 350 µL/well.
4. Add 50 µl of Chromogen A and 50 µl of Chromogen B to each well. Incubate for 15 minutes at 37°C, protected from light.
5. Add 50 µl of Stop Solution to each well. The color will change from blue to yellow. If uneven, gently tap the plate.
6. Read OD at 450 nm within 15 minutes. Subtract blank OD from all readings.
7. Plot the standard curve using average OD values vs. concentrations. Determine sample concentrations by interpolating from the curve.
**QUALITY CONTROL**
- Intra-assay CV < 15%, Inter-assay CV < 15%.
- Assay range: 1.25–40 ng/ml.
- Sensitivity: <1.0 ng/ml.
- Cross-reactivity: No significant interference with recombinant or natural Human VDR.
- Storage: 2–8°C (frequent use); 6 months at -20°C.
**QUOTES AND NOTES**
Please follow all instructions carefully. Always perform a standard curve for each run. Variations in technique, time, or temperature may affect results. Each user should generate their own standard curve for best accuracy.
Working Principle
The basic working principle is evaporation, condensation, and heat exchange. For example, in a typical hyperbolic natural draft cooling tower, the heat exchange in the tower is realized through the natural convection of air, which is driven by the density difference between the internal and external air. The internal air has a high temperature and low density, while the external ambient air has a low temperature and high density. Mechanical draft cooling towers, on the other hand, use fans to create air flow inside the tower.
Structure
It generally consists of parts such as the tower body, packing, water distribution system, ventilation equipment, air distribution device, water eliminator, and water collector. The packing is an important component for heat exchange, usually made of plastic, wood, or other materials, which can increase the contact area and time between water and air to promote heat exchange.
The basic working principle is evaporation, condensation, and heat exchange. For example, in a typical hyperbolic natural draft cooling tower, the heat exchange in the tower is realized through the natural convection of air, which is driven by the density difference between the internal and external air. The internal air has a high temperature and low density, while the external ambient air has a low temperature and high density. Mechanical draft cooling towers, on the other hand, use fans to create air flow inside the tower.
Structure
It generally consists of parts such as the tower body, packing, water distribution system, ventilation equipment, air distribution device, water eliminator, and water collector. The packing is an important component for heat exchange, usually made of plastic, wood, or other materials, which can increase the contact area and time between water and air to promote heat exchange.
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