In recent years, with the rapid development of China's feed industry, the demand for calcium hydrogen phosphate as a calcium and phosphorus supplement in feed processing has soared, and counterfeit and fake products have also flooded into the market, bringing a lot to the aquaculture industry. Economic losses.
Common calcium hydrogen phosphate adulterants are: stone powder, bone meal, agricultural superphosphate, tricalcium phosphate, talcum powder, mixtures of phosphorite powder plus phosphoric acid, and mixtures of stone powder and phosphoric acid. Some of these adulterated products contain high levels of calcium and phosphorus, but the utilization rate of livestock and poultry is very low; some contain a large amount of fluorine and seriously endanger the health of livestock and poultry. The following describes the differential calcium phosphate assay and is for reference only.
1. The appearance of feed-grade calcium hydrogen phosphate is a white powder with uniform fineness. The calcium hydrogen phosphate incorporated into bone powder has a dark grayish or brownish color and bone powder smell.
2. Examination of phosphate ions A small amount of the sample was wetted with a 5% silver nitrate solution, showing that there was a phosphate ion, otherwise the sample was not a calcium hydrogen phosphate.
3. Calcium ion test Weigh 0.1g sample, add 5ml glacial acetic acid, boiled and filtered after cooling. The filtrate is added with 5ml of 3% ammonium oxalate solution. If a white precipitate is formed, calcium ion exists.
4. Dissolution test to take a little sample, add salt to dissolve, such as severe bubbling will produce gas pass 0.3% calcium hydroxide solution (upper supernatant), if a white precipitate, the sample is mixed with stone powder and other calcium raw materials; If completely insoluble, the sample may be phosphate ore powder, talcum powder, etc.; if a small portion is dissolved, the sample may be agricultural superphosphate and the like.
5. Determination of Phosphorus Content In the acid medium, phosphate and quinoline molybdate formed quinoline precipitated phosphomolybdic acid in the sample solution. The precipitate was filtered, washed, weighed after drying at 180° C., and the phosphorus content was calculated. According to the National Feed Standard, phosphorus content (P) ≥ 16.0% and normal content range from 16.00% to 18.0%, if not in this range, it is an adulterated product.
6. Determination of calcium content Add excess EDTA solution to the sample solution and complex with calcium ions. Use chrome black T as indicator and titrate excess ethylenediaminetetraacetic acid with zinc standard solution. Sodium, calculate calcium content. According to the National Feed Standard, calcium content is ≥21.0%-23.3%. If it is not in this range, it is a fake product.
7. Determination of fluorine content Fluorine is an essential trace element in animal normal physiological activities, but it is also a toxic element. Long-term intake of livestock and poultry containing excessive amounts of fluorine in the feed will cause chronic fluorosis, severely affect the normal growth of livestock and poultry, so the fluorine in the calcium phosphate must be detected. Fluorine is generally measured using a fluoride ion selective electrode method. According to the National Feed Standard, the fluorine content of feed-grade calcium hydrogen phosphate should not exceed 1800 mg/kg. If the measured result exceeds the standard, adulterated or non-toxic products must not be used.
Common calcium hydrogen phosphate adulterants are: stone powder, bone meal, agricultural superphosphate, tricalcium phosphate, talcum powder, mixtures of phosphorite powder plus phosphoric acid, and mixtures of stone powder and phosphoric acid. Some of these adulterated products contain high levels of calcium and phosphorus, but the utilization rate of livestock and poultry is very low; some contain a large amount of fluorine and seriously endanger the health of livestock and poultry. The following describes the differential calcium phosphate assay and is for reference only.
1. The appearance of feed-grade calcium hydrogen phosphate is a white powder with uniform fineness. The calcium hydrogen phosphate incorporated into bone powder has a dark grayish or brownish color and bone powder smell.
2. Examination of phosphate ions A small amount of the sample was wetted with a 5% silver nitrate solution, showing that there was a phosphate ion, otherwise the sample was not a calcium hydrogen phosphate.
3. Calcium ion test Weigh 0.1g sample, add 5ml glacial acetic acid, boiled and filtered after cooling. The filtrate is added with 5ml of 3% ammonium oxalate solution. If a white precipitate is formed, calcium ion exists.
4. Dissolution test to take a little sample, add salt to dissolve, such as severe bubbling will produce gas pass 0.3% calcium hydroxide solution (upper supernatant), if a white precipitate, the sample is mixed with stone powder and other calcium raw materials; If completely insoluble, the sample may be phosphate ore powder, talcum powder, etc.; if a small portion is dissolved, the sample may be agricultural superphosphate and the like.
5. Determination of Phosphorus Content In the acid medium, phosphate and quinoline molybdate formed quinoline precipitated phosphomolybdic acid in the sample solution. The precipitate was filtered, washed, weighed after drying at 180° C., and the phosphorus content was calculated. According to the National Feed Standard, phosphorus content (P) ≥ 16.0% and normal content range from 16.00% to 18.0%, if not in this range, it is an adulterated product.
6. Determination of calcium content Add excess EDTA solution to the sample solution and complex with calcium ions. Use chrome black T as indicator and titrate excess ethylenediaminetetraacetic acid with zinc standard solution. Sodium, calculate calcium content. According to the National Feed Standard, calcium content is ≥21.0%-23.3%. If it is not in this range, it is a fake product.
7. Determination of fluorine content Fluorine is an essential trace element in animal normal physiological activities, but it is also a toxic element. Long-term intake of livestock and poultry containing excessive amounts of fluorine in the feed will cause chronic fluorosis, severely affect the normal growth of livestock and poultry, so the fluorine in the calcium phosphate must be detected. Fluorine is generally measured using a fluoride ion selective electrode method. According to the National Feed Standard, the fluorine content of feed-grade calcium hydrogen phosphate should not exceed 1800 mg/kg. If the measured result exceeds the standard, adulterated or non-toxic products must not be used.
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