Calcium salt, a hydroxy analogue of methionine, appears as a light gray granular powder and is a feed with the same biological potency as methionine. In addition to being a precursor of methionine, it can also alleviate the effects of heat stress on animals and provide additional Ca+, thereby reducing the amount of calcium carbonate in the diet and providing extra space to increase the content of other nutrients in the feed formula. So it is very important to determine its content. This article refers to the methods in the national standard and conducts experiments using a potentiometric titrator, obtaining good data.

Feed grade potassium iodide, as a supplement of iodine in feed, is widely used in feed production. The silver electrode potentiometric titration method has good specificity, is not limited by sample color, and has no endpoint discrimination, making it increasingly favored by people. Potentiometric titration is convenient, fast, highly accurate, and has better precision.

Lignin is the second largest renewable resource in nature, second only to cellulose, and will be the main source of resources for humanity in the future. Using lignin as a raw material to prepare new materials and chemical raw materials, gradually replacing increasingly depleted resources such as fossils, is becoming a new development trend. Lignin is a three-dimensional network amorphous polymer mainly composed of phenylpropane units (C6-C3) connected and irregularly coupled through carbon carbon bonds and ether bonds.

Humic acid (HA), also known as humic acid, is a complex organic weak acid formed by the decomposition of natural plants. It is widely present in peat, weathered coal, and some marine sediments. Humic acid has pharmacological effects such as anti-inflammatory, hemostatic, promoting blood circulation and lowering blood pressure, promoting ulcer healing, and anti-tumor. We used potentiometric titration to determine the content of total acidic groups in humic acid as a quality control standard.

Copper is an essential trace element for animals. In animal bodies, it not only participates in processes such as heme synthesis and red blood cell maturation, but also functions as a component (or cofactor) of several important enzymes. Adding high copper to feed can improve the daily weight gain, feed intake, and feed conversion rate of livestock and poultry. In recent years, the use of basic copper chloride as a feed additive that meets the requirements of efficient copper sources, low-level growth promotion, weak damage to nutritional components, non hygroscopic clumping, safety, and economy has increasingly attracted people's attention. Therefore, determining its content will provide a basis for feed ratio.

Ferrous sulfate is a mineral feed additive widely used in the feed industry. Iron is an important component of hemoglobin, myoglobin, cytochrome, and various oxidases, and has detoxifying effects on the toxin gossypol contained in cottonseed cake from pigs, chickens, and other sources. Therefore, determining its content will provide necessary basis for feed ratio. This article improves the content determination method of ferrous sulfate by using potentiometric titration in accordance with national standards, avoiding errors caused by color judgment and resulting in more accurate and reliable results.

Methionine is an important essential amino acid for animals. Methionine hydroxy analogues can be converted into methionine in animal bodies and exert their nutritional effects. In addition, it can also function as a component of several important enzymes (or as a cofactor) in animal bodies. Used as a rumen protein source for ruminants and an acidifier for piglet diets, it can inhibit bacteria, reduce heat stress, and decrease nitrogen excretion, protecting the environment. In addition, methionine is an important amino acid in poultry feed, which can effectively improve egg production rate. We use potentiometric titration to measure the content of basic copper chloride in feed additives, which is more accurate and faster.

Whether eating out or ordering takeout at home, we always use disposable bamboo chopsticks for convenience and cleanliness. However, is this really safe and hygienic? According to survey data, many small workshops now use industrial sulfur to fumigate bamboo chopsticks in order to reduce costs.

Acid value is used as a mandatory indicator in China to measure the degree of spoilage of meat and meat products. Before determining the acid value of meat and meat products, it is necessary to extract the oil and fat with petroleum ether, and then use the extracted oil and fat to determine the acid value of the oil and fat according to the method for determining the acid value of oil and fat. The transportation of imported and exported pet feed takes a lot of time, so its shelf life can be estimated based on the acid value of the feed. Therefore, the determination of acid value has become very meaningful in this industry.

Lycopene is a natural pigment found in plants. It mainly exists in the mature fruit of tomato plants in the Solanaceae family. Acid value is a metric for the number of free carboxylic acid groups in a compound (such as fatty acids) or mixture. Under the conditions of fat production, acid value can be used as an indicator of hydrolysis degree, and under its storage conditions, it can be used as an indicator of rancidity. Due to the interference of lycopene's own color, it is difficult to determine the endpoint during manual titration. In this study, the potentiometric titration method was used to detect the acid value of lycopene, which has the advantages of simple operation and accurate results.

The fatty acid value of grains is a quantity used to measure the content of free fatty acids in grains. The test results are expressed in milligrams of potassium hydroxide required to neutralize free fatty acids in 100g of grain samples. The change in fatty acid value reflects the degree of quality deterioration commonly used in rice. In the national standard grain storage judgment rules, it is used as a suitable storage index for rice and wheat.

NCO， Isocyanate groups are important indicators for measuring the properties of polyurethane prepolymers. This experiment uses an automatic potentiometric titrator to determine the NCO content of the gel sample.