The selection of aquatic products is very skillful. Especially bright, white, plump, and fat water products need attention. Many of these products are foamed with poisonous water and the health of consumers here. There are serious hazards, so the detection of formaldehyde in water products is imperative. At present, China's current detection method for residual formaldehyde in aquatic products uses the industry standard of NY5172-2002, but this method is not easy to control. For this reason, it is necessary to change the detection method, and more automatic determination of nitrogen is used.
The determination principle of the automatic nitrogen determination instrument is to add phosphoric acid to the sample in a closed distillation tube and heat distillation to release the formaldehyde. The formaldehyde gas passes through the condensation device and is absorbed by water and then reacted with acetylacetone to form a yellow solution. , Quantitative by color shade ratio. The lowest detected concentration of formaldehyde in the water product of this method is 10 mg/kg.
Weigh 10.00g uniform sample, placed in a distillation tube, the distillation tube is installed in automatic nitrogen fixed instrument, turn it completely sealed, press the acid pump switch, add 10mL phosphoric acid to the distillation tube and close, open the distillation switch, Heat distillation, with a pre-added 20mL distilled water in the flask to receive, when the receiving flask is about 80mL distillate, turn off the distillation switch, distillation is completed, the distillate in the flask transferred to a volume of 100mL volumetric flask . Follow the same steps to make a blank test.
Weigh 10.00g of the sample, and add 5Lg/mL formaldehyde standard solution 10mL, respectively, with the automatic determination of nitrogen distillation apparatus to determine the formaldehyde recovery rate was 99.2%, 101.0%, 98.8%, 101.4%, 100.4%, to achieve The recovery rate was verified to prove that no damage was caused to the recovery of formaldehyde using the Kjeldahl analyzer. The result of this method was accurate.
Through the analysis of the determination results of the automatic nitrogen determination instrument, it was found that the determination of formaldehyde in the water-producing product by the automatic determination of nitrogen is accurate and reliable, and it is more intelligent than the glass distiller, easy to operate, and reduces the error caused by intermediate links. Therefore, the result is more accurate.
The determination principle of the automatic nitrogen determination instrument is to add phosphoric acid to the sample in a closed distillation tube and heat distillation to release the formaldehyde. The formaldehyde gas passes through the condensation device and is absorbed by water and then reacted with acetylacetone to form a yellow solution. , Quantitative by color shade ratio. The lowest detected concentration of formaldehyde in the water product of this method is 10 mg/kg.
Weigh 10.00g uniform sample, placed in a distillation tube, the distillation tube is installed in automatic nitrogen fixed instrument, turn it completely sealed, press the acid pump switch, add 10mL phosphoric acid to the distillation tube and close, open the distillation switch, Heat distillation, with a pre-added 20mL distilled water in the flask to receive, when the receiving flask is about 80mL distillate, turn off the distillation switch, distillation is completed, the distillate in the flask transferred to a volume of 100mL volumetric flask . Follow the same steps to make a blank test.
Weigh 10.00g of the sample, and add 5Lg/mL formaldehyde standard solution 10mL, respectively, with the automatic determination of nitrogen distillation apparatus to determine the formaldehyde recovery rate was 99.2%, 101.0%, 98.8%, 101.4%, 100.4%, to achieve The recovery rate was verified to prove that no damage was caused to the recovery of formaldehyde using the Kjeldahl analyzer. The result of this method was accurate.
Through the analysis of the determination results of the automatic nitrogen determination instrument, it was found that the determination of formaldehyde in the water-producing product by the automatic determination of nitrogen is accurate and reliable, and it is more intelligent than the glass distiller, easy to operate, and reduces the error caused by intermediate links. Therefore, the result is more accurate.
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