Test Method for Fat Content in Feed Feed refers to industrially processed products for animal consumption, which are digestible by livestock and poultry, non-toxic to their organisms, and provide essential nutrients, promote growth and development, maintain health, and improve the quality of animal products. Such products include not only single feed ingredients but also compound feeds formulated with scientific ratios of various raw materials, such as compound feed, concentrated feed, and additive premix feed. According to different purposes and compositions, feed can meet the nutritional needs of various animal species, growth stages, and production objectives. Experimental Objectives 1.Evaluate Nutritional Value and Energy SupplyFat is one of the most efficient energy sources in feed, providing approximately 2.25 times more energy per unit mass than carbohydrates or proteins. By determining the crude fat content, the metabolizable energy level of feed can be accurately calculated to judge whether it meets the energy requirements of different animals (such as livestock, poultry, aquatic animals, and pets) at specific growth stages. 2.Optimize Feed Formulation DesignDifferent animals have varying fat requirements. For instance, young animals need high levels of essential fatty acids to support nervous system development, while high-yield dairy cows require moderate fat to enhance energy for milk production. Testing fat content facilitates the scientific proportioning of raw materials (e.g., soybean oil, fish meal, extruded soybeans), avoiding indigestion caused by excessive fat or energy deficiency due to insufficient fat, achieving precise nutrient supply. 3.Ensure Feed Quality and FreshnessFat is prone to oxidative deterioration and rancidity, impairing palatability and animal health. By detecting crude fat content combined with indicators such as acid value, peroxide value, and free fatty acids, the freshness and storage stability of fat can be evaluated, preventing the use of inferior raw materials and extending product shelf life. 4.Support Quality Control and Standardized ProductionRegular testing of fat content is a critical part of quality control during feed processing. It monitors batch fluctuations of raw materials, mixing uniformity, and processing losses, ensuring each batch complies with enterprise standards or national specifications (e.g., GB/T 6433), improving product consistency and market competitiveness. 5.Meet Scientific Research and Regulatory RequirementsFat content is fundamental data required for agricultural research, new feed development, and new product registration. Meanwhile, specific products such as infant formula food and pet food must comply with mandatory national standards for fat content (e.g., GB 10765-2021), and testing is a prerequisite for compliance. Experimental Samples and Instruments Experimental Sample: Feed Experimental Instrument: ST-06D Fat Analyzer, compliant with GB 6433 Experimental Procedures 1. Sample Preparation Take a representative feed sample and grind it to pass completely through a 40-mesh sieve (0.45 mm) to ensure uniformity and extraction efficiency. For extruded pelleted feed, pre-extraction is required: soak in petroleum and dry to eliminate interference from surface grease before formal testing. High-moisture samples (e.g., silage) should be pre-dried to constant weight at 60℃±5℃ to prevent fat oxidation. Weigh 2.0000 g to 5.0000 g of the sample (accurate to 0.0001 g), place it into a constant-weight filter cartridge, and seal for later use. 2. Instrument and Reagent Preparation Use a Soxhlet extractor (250 mL or 500 mL). Clean the receiving flask, dry it in an oven at 105±2℃ for 1 hour, weigh it after cooling (recorded as m0​). Anhydrous diethyl  or petroleum  (boiling range 30-60℃) is selected as the solvent, with purity ≥99.5% and peroxide content ≤0.005% to avoid potential safety hazards. The electronic balance used has a precision of no less than 0.1 mg and is calibrated at least twice a year. 3. Extraction Process Place the filter cartridge into the extraction tube, add 150-200 mL of solvent to the receiving flask, and assemble the device. Perform reflux extraction on a constant-temperature water bath at 60-80℃, controlling the reflux rate to 8-10 cycles per hour (updated from the old version), with a total duration of about 6-8 hours until the extract is colorless or no oil stains remain on the filter paper. For the filter bag method, encapsulate the sample in a special filter bag and place it directly into an automatic extractor, simplifying operations for batch testing. 4.Solvent Recovery and Weighing After extraction, recover most of the solvent by distillation, and let the remaining small amount volatilize naturally in a fume hood. Dry the receiving flask in an oven at 105±2℃ for 1 hour, weigh it after cooling in a desiccator (recorded as m1​), and repeat drying until constant weight (difference between two weighings < 0.0008 g). Experimental Results The crude fat content of this feed sample is 6.7%, in strict accordance with the requirements of GB/T 6433-2025.

Eggshell Strength Test Method The eggshell is the outer casing of eggs laid by oviparous animals. It is thin yet sturdy, serving to prevent water evaporation, resist mechanical damage, and supply calcium required for skeletal development. It is mainly composed of calcium carbonate (accounting for 91%–95%), magnesium carbonate, calcium phosphate, and organic substances (such as proteins and mucopolysaccharides). Among these, calcium carbonate exists in the form of calcite, which binds with the protein fiber matrix during calcium deposition to form a rigid structure. Microscopically, the eggshell consists of a mammillary layer, a spongy layer, and a cuticle layer, forming a hierarchically ordered mineralized structure that is lightweight and pressure-resistant. Due to its properties, eggshells are commonly used in ceramic production as a raw material substitute for calcite. They are also applied in preparing bone repair nanomaterials, and serve as dietary calcium fortifiers, feed additives, and components of eco-friendly plastic substitutes. Experimental Purpose Eggshell strength refers to the ability of an eggshell to resist fracture and withstand maximum pressure when subjected to external force. It is a key indicator for evaluating the external quality of eggs, covering the entire industrial chain from breeding, processing, logistics to consumption, and is of great significance for improving industrial efficiency and ensuring food safety. The main functions are as follows: ①Reduce transportation and storage loss: Insufficient eggshell strength easily leads to cracking caused by collision or stacking pressure, resulting in direct economic losses and potential contamination risks. Testing allows the selection of high-strength eggs for long-distance transportation to reduce breakage rates. ②Ensure food safety and consumption experience: Damaged eggshells are prone to microbial invasion, accelerating spoilage and posing food safety hazards. ③Optimize breeding management and feed formulation: Eggshell strength is affected by nutrients such as calcium, phosphorus, and vitamin D₃. Regular testing can guide the adjustment of feed ratios to improve eggshell quality. ④Poultry breeding: By breeding individuals with excellent eggshell strength, superior breeds with higher breakage resistance can be gradually developed. ⑤ Monitor flock health: An abnormal drop in eggshell strength may be an early sign of diseases such as Newcastle disease and infectious bronchitis, facilitating timely intervention. ⑥Promote scientific research and standardization: Provide reliable data for universities and research institutions to study eggshell formation mechanisms, nutritional physiology, and environmental impacts; meanwhile, support quality inspection departments in market supervision. Experimental Equipment ①ST120H Eggshell Strength Tester ‌ Experimental Procedures ①Inspect the instrument and test samples to ensure they are clean, dry, and free from contamination. ② Connect the power supply, turn on the instrument, and preheat for 5–10 minutes to stabilize the sensor. ③ Select fresh, crack-free eggs of uniform size. Equilibrate the samples in a standard environment (temperature 20±2℃, humidity 50±5% RH) for 2 hours to eliminate environmental effects on eggshell performance. Place the egg with the large end upward steadily on the egg holder or positioning slot of the instrument base, ensuring the egg is vertical. ④ Press the "Start" button to initiate the testing program. The probe slowly presses down on the top of the eggshell at a constant speed. At the moment the eggshell fractures, the instrument automatically records the maximum pressure value and stops loading. ⑤ Read and record the value. Repeat the measurement 1–3 times and calculate the average value for better representativeness. ⑥ Clean up residual egg liquid. Experimental Analysis Based on multiple tests, the average eggshell strength of the randomly selected samples in this experiment is 3.5 kg/cm², approximately 34.3 N, meeting the standard for commercial eggshell strength.    

  Determination of Acid Value of Petroleum Products Petroleum products are a general term for various commodities directly produced from petroleum or its components, mainly including six categories: fuels, chemical raw materials, lubricating oils, paraffin wax, asphalt, etc. Among them, fuels such as gasoline, diesel oil and aviation kerosene account for the vast majority of refined oil products, with about 85% of crude oil eventually converted into various fuels for transportation and industrial use. In addition, petroleum also provides basic raw materials for chemical products such as plastics, chemical fibers and rubbers, and about 15% of a barrel of crude oil is used to produce high value-added products such as light chemical oil and ethylene. Petroleum products are essentially mixtures of various hydrocarbons, mainly composed of organic compounds, so they fall into the category of organic compounds in chemical classification. Although it is a mixture, since all components contain carbon elements, which meets the definition of organic matter, it is usually classified as an organic compound in examination and industrial contexts. Experimental Purpose 1.Assess the risk of corrosion to metals: The higher the acid value, the more acidic substances (such as organic acids, naphthenic acids, etc.) contained in the oil. In the presence of moisture, these acidic components will significantly corrode metal equipment and affect the service life of refining units, engines or lubrication systems. By measuring the acid value, it can be judged in advance whether the oil will cause corrosion damage to storage, transportation and operating equipment. 2.Judge the refining degree and quality of oil products: The acid value of new oil can reflect its refining degree. The more thorough the refining, the fewer acidic impurities and the lower the acid value. Therefore, acid value is one of the important indicators to measure the purity of oil products in factory inspection. 3.Monitor the oxidative deterioration of oil products during use: Lubricating oil, transformer oil and other products will produce acidic products due to oxidation during long-term operation, leading to an increase in acid value. When the acid value exceeds a certain limit (e.g., a change of > +0.01 mgKOH/g), it indicates that the oil has begun to deteriorate, which may produce sludge or affect insulation performance, requiring timely replacement. 4.Guide the processing and utilization of high-acid crude oil: Crude oil with an acid value greater than 0.5 mgKOH/g is called "acidic crude oil", which is prone to cause corrosion of refining equipment and difficult to process. Accurate determination of acid value helps to optimize deacidification processes, adjust blending ratios, and select appropriate corrosion inhibition measures. 5.Guarantee the service performance of fuels and lubricating oils: High-acid diesel oil may cause nozzle coking and piston wear; an increase in the acid value of lubricating oil means a decline in lubrication function. Regular testing can ensure that oil products operate within a safe range and avoid mechanical failures. Experimental Sample and Instruments Experimental Sample: Petroleum products Experimental Instrument:SH108C Potentiometer titration TAN/TBN Tester ，in compliance with ASTM D664 Experimental Procedure 1.Electrode CalibrationTurn on the power of the potentiometric titrator and preheat for 30 minutes. Calibrate the electrode with pH = 7.00, 4.00 and 10.00 buffer solutions in sequence to ensure the potential measurement error ≤ ±2 mV. 2.Sample Determination Weighing: Weigh the sample according to the estimated acid value, accurate to 0.001 g, and place it in a 250 mL beaker. Dissolution: Add 100 mL of titration solvent and start the magnetic stirrer to fully dissolve the sample (if stratification occurs, the proportion of toluene may be increased appropriately). Titration Operation: Immerse the electrode tip into the solution, avoiding contact with the bottom of the beaker. Parameter Setting: Set the titration speed to 0.5 mL/min, and the endpoint identification mode to "potential jump" (jump range ≥ 50 mV). Titration: Titrate with standard potassium hydroxide isopropanol solution, record the titration volume (V₁) and endpoint potential. Blank Test: Perform a blank titration with only 100 mL of titration solvent under the same conditions, and record the blank volume (V₀). 3.Duplicate TestConduct at least two parallel determinations on the same sample. The difference between the two results shall meet the precision requirements (repeatability of new oil ≤ 0.044(X+1), where X is the average of the two results). Experimental Results The measured acid value of the lubricating oil is 0.084 mgKOH/g, which meets the factory standard. This indicates that the oil has sufficient refining depth, low content of acidic impurities, and low corrosion risk to equipment. The relative deviation of duplicate determinations is ≤ 2.1%, which meets the repeatability requirement in ASTM D664-24 (RSD ≤ 2%), proving that the experimental data is accurate and reliable.  

Test Method for Gel Strength Gelatin is a protein extracted from connective tissues such as animal skin, bones and tendons. Its main component is a partial hydrolyzate of collagen. At room temperature, it is colorless to pale yellow, translucent flakes or powder, with good gelling properties, hydrophilicity and biocompatibility. As an important natural polymer material, it is widely used in food, medicine, cosmetics, industry and other fields. According to different applications, gelatin can be classified into edible gelatin, pharmaceutical gelatin, industrial gelatin and photographic gelatin. Experimental Purpose The main purpose of determining gelatin strength is to quantify the gelling ability of gelatin and ensure its texture, stability and safety meet standard requirements in food, pharmaceutical and other applications. By accurately measuring the gel strength (Bloom value), this experiment provides a scientific basis for product quality control, production process optimization and regulatory compliance: 1.Evaluate product performanceThe Bloom value directly reflects the hardness and elasticity of gelatin, which determines its actual performance in products such as jellies, gummy candies and capsule shells. For example, high-Bloom gelatin is suitable for hard pharmaceutical capsules, while low-Bloom gelatin is ideal for soft-textured desserts. 2.Ensure quality consistencyThrough standardized testing, manufacturers can select qualified raw materials, avoid problems such as collapse, syneresis or disintegration failure caused by batch differences, and improve product stability and market competitiveness. Experimental Apparatus Sample: Gelatin Instrument: Model ST-16C Gel Strength Tester, compliant with QB/T 2354 Experimental Procedures Instrument preparationTurn on the gel strength tester in advance. Set the probe descending speed to 0.5 mm/s and the pressing depth to 4 mm. Let the instrument stabilize before use. Sample placementQuickly take the gel bottle from the constant temperature water bath, dry the water droplets on the outer wall, remove the rubber stopper, and place the bottle on the test platform of the gel strength tester. Ensure the center of the bottle is aligned directly below the probe. Start measurementStart the tester. The probe descends at the set speed. When the probe is pressed 4 mm below the gel surface, record the force value displayed by the instrument (Bloom g). Parallel testPerform the measurement on another sample following the same steps. Take the average of the two results as the final test result. Experimental Results and Analysis Sample A is Type A skin gelatin, Grade 200.The standard requires gel strength ≥ 200 g Bloom.The measured average value is 206.5 g Bloom, which meets the standard requirement. The difference between the two parallel samples is 3 g Bloom ≤ 10 g Bloom, so the result is valid.  

DSC Measurement Method for Sulfapyridine Sulfapyridine is a sulfonamide antibiotic with a molecular weight of 249.29, molecular formula C₁₁H₁₁N₃O₂S, and CAS No. 144-83-2.It appears as a white to off-white solid at room temperature, stable in properties, flammable, and light-sensitive.It is slightly soluble in water, soluble in a little DMSO and a little methanol. Experimental Purpose Differential Scanning Calorimetry (DSC) is widely used to study the thermal behavior and physicochemical properties of drugs, and plays an important role in pharmaceutical R&D and quality control. For sulfapyridine, a sulfonamide antibacterial drug: DSC can be used to determine its purity. The melting point of pure sulfapyridine is 191–193 °C. DSC accurately measures its melting peak, which indirectly reflects sample purity. Sulfonamides often exhibit polymorphism. Different crystal forms show different thermodynamic stability, solubility, and bioavailability. DSC can identify and distinguish crystal form transitions. It can also be used for drug-excipient compatibility studies by monitoring the thermal behavior of sulfapyridine mixed with excipients to detect possible interactions. Experimental Apparatus ① ST146 Crystalline Thermal Analyzer ② Sampler, crucible, desiccator, high-precision balance and other auxiliary equipment Experimental Procedures ①Inspect the instrument and auxiliary equipment to ensure they are clean, dry, and free of contamination. Calibrate the instrument for temperature, heat flow, and specific heat capacity using standard materials such as indium, zinc, and sapphire. Dry the sample. Weigh a sample mass of typically 5 ± 2 mg, then seal it in a dedicated crucible. After calibration, set parameters according to measurement requirements. The instrument will automatically measure and display results. Repeat the test 1–3 times. Experimental Results and Analysis In the standard heating program (10 K/min, 30–400 °C): The measured melting enthalpy (ΔH) of the sample was approximately 145 J/g. Melting occurred at about 190 °C. Crystallization was observed during cooling at approximately 140–160 °C. Melting occurred again at about 190 °C in the second heating, consistent with the initial melting point. Decomposition was observed at 250 °C. Based on comprehensive evaluation, the sample complies with pharmacopoeia requirements: it is pure and well-preserved.  

Determination Method for Relative Density of Undecylenic Acid Undecylenic acid, also known as 10undecylenoic acid, is an organic compound with the molecular formula C₁₁H₂₀O₂. It is a pale yellow to yellow liquid at room temperature and atmospheric pressure. When cooled, it forms milky white crystalline masses with a characteristic odor. It is miscible with ethanol, chloroform, fatty oils, or volatile oils in all proportions, and insoluble in water. It is widely used in the synthesis of perfumes, pharmaceutical antifungal agents, and other products. Experimental Purpose As a physical constant, relative density can objectively reflect the intrinsic quality of undecylenic acid and is one of the important indicators for evaluating its efficacy and safety. Reflect purity and consistency: According to the Relative Density Test (Method 0601) in the Chinese Pharmacopoeia, the relative density of undecylenic acid is 0.910–0.913 g/cm³ at 25 °C. By measuring its relative density, it can be determined whether the undecylenic acid sample is adulterated. ③ Assist in authenticity identification: Combined with other physical constants such as refractive index and iodine value, relative density helps to verify whether the sample is genuine undecylenic acid. ④ Ensure compliance in industrial applications: In perfumes, pharmaceuticals (e.g., antifungal preparations), and cosmetics, the concentration and purity of undecylenic acid directly affect product safety and efficacy. Relative density is a key parameter for raw material acceptance. The experiment is performed according to Method 3 (Oscillating Density Meter Method) for the Relative Density Test (0601) in the Chinese Pharmacopoeia 2020.The ST217A Automatic Pharmaceutical Relative Density Meter (Shengtai Instrument) complies with this method and is therefore used for the test. Experimental Apparatus ①ST217B Automatic Touchscreen Pharmaceutical Relative Density Meter ② Auxiliary items: purified water, stirring rod, beaker, etc. Experimental Procedures ① Inspect the instrument: Verify that the power supply, sensor, temperature control system (e.g., Peltier thermostat), Ushaped oscillating tube, and other components are functioning normally. ② Clean the measuring cell: Wash the Ushaped tube or sample cell with anhydrous ethanol or distilled water, then dry it to avoid interference from residues. ③ Calibrate the instrument: Inject pure water at 25 °C (density = 0.997043 g/mL) into the measuring cell, remove air bubbles, press the “Calibrate” key, and allow the instrument to complete calibration automatically. Then take out the measuring cell and clean it. ④ Sample introduction: Filter to remove bubbles and impurities. Start the automatic program; the builtin sampling pump completes sampling, cleaning, and drying automatically. Results are output within 2–10 minutes. ⑤ Read the results and repeat the test 1–3 times. Experimental Results and Analysis According to the requirement of the Chinese Pharmacopoeia 0601 Relative Density Test, the relative density of undecylenic acid at 25 °C shall be 0.910–0.913 g/cm³.The values obtained in three replicate tests all fall within the specified range, meeting the standard requirements.