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.

Test Method for Rheological Properties of Wheat Flour Dough Wheat flour dough is a semi-solid mixture with elasticity, extensibility, and plasticity. It is formed by mixing wheat flour and water in a certain proportion and kneading so that proteins absorb water to form a gluten network. It serves as the basic raw material for making pasta products such as bread, steamed buns, noodles, etc. Experimental Purpose 1.Evaluate flour processing quality and classificationThe primary purpose of the experiment is to determine which pasta products the wheat flour is suitable for through rheological curves. Based on the stability time and softening degree measured by the farinograph, it is possible to clearly distinguish strong gluten flour (suitable for bread), medium gluten flour (suitable for steamed buns and noodles), and weak gluten flour (suitable for biscuits and cakes).The longer the stability time, the stronger the mixing resistance of the dough, making it more suitable for bread requiring longtime fermentation. This method can be used for special flour screening, as different pasta products have distinctly different requirements for dough properties. 2.Predict the final quality of pasta productsThere is a significant correlation between the rheological properties of dough and the quality of baked or steamed products, and the experimental data have strong predictability. 3.Guide the optimization of production process parametersThe experimental results can provide specific operational basis for actual production and avoid blind adjustment based on experience. 4.Monitor raw material stability and breeding selection Batch stability monitoring: For flour processing plants, regular testing of rheological properties can monitor quality fluctuations of different batches of wheat flour to ensure product standardization. Reference for wheat breeding: In agricultural research, rheological indicators are important criteria for screening highquality wheat varieties. By analyzing the alveograph properties (such as tenacity P, extensibility L, and strength W) of dough from different varieties, breeding experts can directionally cultivate new wheat varieties suitable for specific processing requirements. Experimental Apparatus Sample:Wheat flour dough Apparatus: ST139 Electric Farinograph，conforming to ISO 55302 Experimental Procedures Sample weighing and water addition calculation Based on 14% moisture basis, weigh 300 g of pretreated wheat flour sample, accurate to 0.1 g.Estimate the water absorption of the wheat flour and calculate the required water volume. Water absorption (%) = (Water addition + Wheat flour weight − 300) / 3(Taking the 300g flour mixing bowl as an example, water addition is in mL.) The final maximum consistency of the dough shall be 500 ± 20 BU.If the curve in the preliminary test exceeds 500 BU, the water addition is insufficient; otherwise, it is excessive. The water addition can be adjusted according to the relationship: 20 BU ≈ 0.6%–0.8% water absorption. Kneading and curve recording Pour the weighed wheat flour into the 300g mixing bowl of the farinograph. Start the mixing bowl at a speed of 63 ± 2 r/min.Complete water addition within 25 seconds to ensure rapid mixing of water and flour.Timing starts from the beginning of water addition. The instrument automatically records the change in resistance of the dough to the mixing arms during kneading and generates a farinogram curve. The conventional test lasts for 20 minutes. The test time can be appropriately extended for special analysis, but the integrity of data collection must be ensured.During the test, closely observe curve changes. If abnormal fluctuations occur, check the instrument status or sample condition. Parallel test setup Each batch of samples shall be tested in at least 2 parallel tests.The allowable error of parallel tests is no more than ±1.5%.If the relative deviation exceeds 5%, the test shall be repeated to ensure data reliability. Experimental Results and Analysis The five wheat flours show significant differences in rheological properties and can be classified into four categories: strong gluten, mediumstrong gluten, medium gluten, and weak gluten according to farinograph parameters.The experimental results meet the requirements of GB/T 146142019.They can provide a scientific basis for raw material acceptance, quality control, and product development in flour enterprises, as well as data support for raw material selection and process optimization in pasta production enterprises.  

  Overview   Liquid hydrocarbons are important chemical raw materials widely used in the production and processing of chemical products such as ethylene, propylene and liquefied petroleum gas. The trace water contained in them will directly affect product quality and the safe operation of production equipment, and may also lead to side reactions in subsequent chemical reactions and catalyst deactivation. Accurate determination of trace water in liquid hydrocarbons is a key link in quality control and safety management of chemical production, and flash vaporization sampling technology is the core pretreatment method to achieve accurate determination of trace water in liquid hydrocarbons.   Experimental Objective   By determining the trace water content in liquid hydrocarbons, we can accurately judge whether liquid hydrocarbon raw materials meet the purity requirements of the production process, and avoid production problems such as equipment corrosion and reaction inefficiency caused by excessive moisture content. This determination is carried out in accordance with GB/T3727-2003 Determination of Trace Water in Industrial Ethylene and Propylene. The SH201 Flash Vaporization Sampler is specially designed for the pretreatment of liquid hydrocarbon samples, which is perfectly compatible with this national standard method. It can convert liquid hydrocarbons into gaseous samples with isocomposition, constant temperature and constant pressure, providing accurate pretreatment guarantee for trace water determination.   Experimental Samples: Liquid hydrocarbons (ethylene/propylene/liquefied petroleum gas, etc.)     Experimental Instruments 1. SH201 Flash Vaporization Sampler 2. Auxiliary equipment: Karl Fischer Moisture Titrator/Dew Point Meter, sampling cylinder, stainless steel tube/polytetrafluoroethylene tube, analytical balance, etc.   Operating Procedures 1. Place the SH201 Flash Vaporization Sampler in a fume hood, connect the vent port and injection port, and connect the injection port to a Karl Fischer Moisture Titrator/Dew Point Meter with the pipelines as short as possible. 2. Connect the downward outlet of the sampling cylinder to the instrument port and tighten it, fully open the cylinder outlet valve to ensure that the liquid sample directly enters the instrument. At the same time, connect the instrument power supply and ensure good earthing of the ground wire. 3. Turn on the instrument, enter the preheating interface to set the vaporization temperature (≥60℃). After 15 minutes of preheating and temperature constant, adjust the flow rate (1.5-2 L/min for routine analysis) and injection volume (5-15 L, the lower the moisture content, the larger the injection volume) on the parameter setting interface. 4. After the Karl Fischer Moisture Titrator/Dew Point Meter reaches the end point, press the instrument's injection key to start the injection and determination. The instrument will automatically control the flow rate and record the cumulative injection volume. 5. When the set injection volume is reached, the instrument will automatically switch to the vent state. The Karl Fischer Moisture Titrator/Dew Point Meter will complete the determination and display the water content. Input the actual injection volume to calculate the final moisture concentration, and the test report can be printed directly. 6. After the completion of one set of determinations, the next set of parallel determinations can be started directly without turning off the instrument. 5 parallel results are required for routine determinations.   Data Analysis and Result Evaluation   The trace water content in standard liquid hydrocarbon samples was determined by pretreatment with the SH201 Flash Vaporization Sampler combined with determination by a Karl Fischer Moisture Titrator. The instrument achieves isocompositional vaporization during the vaporization process, without water adsorption, freezing or concentration deviation. The repeatability error of the determination results meets the requirements of the national standard, and the basic error is controlled within ±5%. The measured value of trace water content accurately reflects the actual moisture content of liquid hydrocarbons, which can provide reliable and accurate data support for the quality judgment of liquid hydrocarbon raw materials in chemical production.