Atomic fluorescence spectroscopy determines arsenic elements in food additives.

GB 5009.76-2014 National Standard for Food Safety Arsenic determination in food additives instead of GB/T 5009.76-2003 Arsenic determination in food additives will be officially implemented on March 1, 2016. Atomic fluorescence spectroscopy is used as one of the methods of arsenic determination in food additives. Atomic fluorescence as a test of arsenic, mercury, lead and other heavy metals of conventional analytical instruments with high sensitivity, easy to operate and so on, and as the source of China's hydrogenation atomic fluorescence technology in Beijing Jinsokun launched a new generation of atomic fluorescence photometer is "many, fast, good, provincial" four characteristics. Here's how to test arsenic in food additives using atomic fluorescence photons for your laboratory testing peers.In accordance with the new standard, the application of atomic fluorescence photometrics to test arsenic elements in food additives requires the preparation of the following reagents: sodium hydroxide (NaOH) (excellent purity), sodium boron hydrochloride or potassium boron hydrogenation (NaBH4 or KBH4), thioly (CH4N2S), nitric acid (HNO3) (excellent purity) ), sulphuric acid (H2SO4) (excellent pure), perchloric acid (HCIO4) (excellent pure), hydrochloric acid (HCl) (excellent pure), magnesium nitrate (Mg (N03) 2.6H2O), magnesium oxide (MgO), hydrogen peroxide (H2O2).. Preparation of reagents 1, sodium hydroxide solution (2 g/L): 2.0 g sodium hydroxide, dissolved in 1,000 mL water, mixed.2, sodium boron hydride solution (10 g/L): 10.0 g sodium boron hydrogenation, dissolved in 1,000 mL sodium hydroxide solution, mixed well. Ready-to-use (also known as 14 g potassium boron hydrocarbon instead of sodium boron hydrocarbon).3, thioly solution (50 g/L): 50 g thiophene, dissolved in 1,000 mL water, mixed.4, sulphuric acid solution (1 plus 9): take 100 mL sulphuric acid, carefully poured into the water 900 ml. Medium, mix well.5, sodium hydroxide solution (100 g/L): 1.0 g sodium hydroxide, dissolved in 10 mL water.6, hydrochloric acid solution (1 plus 1): take 100 mL hydrochloric acid slowly poured into 100 mL water, mixed well, cooled for use.7, magnesium nitrate solution (150 g/L): 150 g magnesium nitrate, dissolved in 1,000 mL water, mixed well.. Standard solution preparation 1, arsenic standard reserve solution (0.1 mg/mL). ): Accurately named from 100 degrees C drying more than 2h arsenic trioxide 0.1320 g, plus 100 g/L sodium hydroxide solution 10 mL dissolved, water quantitatively transferred to 1,000 mL capacity bottle, sulfuric acid solution (1 plus 9) 25 mL fixed capacity to scale.2, arsenic standard use liquid (1/g/mL): absorb 1.00 mL arsenic reserve standard liquid in a 100 mL capacity bottle, dilute with water to the scale.. Analysis stepTaking wet solution as an examplecalled taking solid sample 1 g to 2.5 g (accurate to 0.001 g), liquid sample 5 g to 10 g (accurate to 0.001 g), placed in 100 mL conical bottle, add nitric acid 20 mL to 40 mL, sulfuric acid 1.25 mL, placed overnight. The next day, heat and dissolve on an electric plate (220 degrees C). If the solution treatment to about 10 mL still has uncomposed substances or color darkening, remove cooling, add nitric acid 5 mL to 10 mL, and then dissolve to about 10 mL observation, so repeated two or three times, pay attention to avoid carbonization. If it is still not completely dissolved, then add perchloric acid 1 mL to 2 mL, continue to heat until the solution is complete, and then continue to heat until the white smoke perchloric acid dissipates, the white smoke of sulfuric acid begins to rise. Remove the cooling, add 25 mL of water, and heat until white smoke sulfate is produced. Remove the cooling, use water to transfer the digestive fluid into a 25 mL capacity bottle or color tube, add thioly solution (50 g/L) 2.5 mL, and finally use water to scale and mix well for testing. Do blank tests at the same time.. Standard series solution preparationin the 25 mL capacity bottle in order to accurately add 1 sg / mL arsenic standard use liquid 0 mL, 0.05 mL, 0.20 mL, 0.50 mL, 1.00 mL, 2.00 mL, sulfuric acid solution (1 plus 9)9) 12.5 mL, 50 g/L thioion 2.5 mL, plus water to scale, equivalent to arsenic concentration 0 ng/mL, 2 ng/mL, 8 ng/mL, 20 ng/mL, 40 ng/mL, 80 ng/mL, mixed and measured.. Instrument reference conditions (the following conditions to
SK-Le analysis atomic fluorescence photonometer
as an example) light source: air core cathode lamp, lamp current 60 to 80mA negative high voltage: -300 to -350V main gas flow: fixed value, 500mL/min about Flow: 800 to 1000mL/min pump speed: 70 to 80 rpm check-out limit (reference value): 0.01ng/mL Note: (1) in hydrochloric acid generally have a certain content of As, so the use of excellent pure HCL can reduce the gap. However, there are also individual cases of analysis of pure As content is lower than the excellent level of pure, as well as different production plants or different production lot number As content is also very different, so it is recommended to use a small amount of HCl to make 10% (V/V) conditions for comparative inspection. (2) all the utensils before use must be soaked for 24 hours with HNO3 (1-1) and then carefully cleaned to prevent as contamination. (3) The arsenic standard storage fluid prepared in this note is in a tricolor state, in order to prevent arsenic from being oxidized during preservation, it is still recommended to add thiophenidate and asseptic acid, potassium iodide pre-reduced As (V.) to As (III.), the reduction speed is affected by temperature, room temperature is below or less than 15 degrees C, should be placed for at least 30 minutes, the sample must also be pre-reduced. (4) the capacity of the standard solution must be fixed for a long time and cannot be changed arbitrarily. (5) standard solution should be made with a fixed 5mL scale pipe, which can be used directly for the preparation of all standard series. (6) the concentration of potassium boron hydrocarbon solution had a great influence on As assay.
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