Determination of sulfite description

The "Introduction"
Sulfites are a kind of early food additive is widely used around the world, can be used as food bleaches, preservatives, and enzymatic Browning inhibition of non-enzymatic Browning, breeding food Browning, Browning of fruit is not to, but to prevent fresh shrimp spots, in acidic medium, is also very effective antimicrobial agent.
When sulfite food additives used in excess, may cause serious damage to the nutrients in the food, reduce the nutritional value of food. If using an excessive amount of sulfites, there will be headaches, nausea, dizziness and adverse reactions such as asthma. If animals eat containing sulfites in kind for a long time, nerve inflammation, bone marrow atrophy and other adverse symptoms.
"Principle"
According to the GB/T5009.34-2003 of the determination of sulfites in foods, sulfites in foods after extraction and detection reagents react to form a colored compound, using detector for determination of absorbance at 550nm, absorbance is directly proportional to its content in a certain range.
"Detected"
Bamboo shoots, candied fruit, cookies, fans, sugar, starch, Lily, dried fruits, chocolates, wines, beers and malt beverages.
"Technical specification"
Detection limit: 2mg/kg
Linear range: 2-1200mg/kg
"Steps"
1. Select test mode: conventional testing
2. sample pretreatment methods
① Weigh approximately 1.0g uniform grinding samples, add pure water to 50mL scale;
② 1.0mL extract;
③ 40C ultrasonic 10min;
Black-out, cooling, filtration, filtrate aside.
3. control test
① 1.5ml g purified water, 4ml sample, shake;
② take 2.5ml control samples in the colorimetric;
③ cell into the specified to the first channel, press ' control measure.
4. sample test
① take the detection of fluid 1mL a, 0.5mL b shake detection liquid;
② 4mL sample, mix at room temperature (25 ± 5 ℃) color for 10 minutes;
③ take 2.5ml samples to be tested in the colorimetric;
④ will be fitted with a fluid cell into the specified channel, press the ' sample survey '.
Time:
(1) low level testing
① When the test result is less than 25mg/kg, enter ' low test ' test mode to obtain more accurate data.
② steps '2. ① ' changed to ' uniform weigh approximately 2.0g crushed samples, add pure water to 10mL scale ', the remaining steps do not change.
(2) high level test
① When the test result is greater than the 400mg/kg, go to ' test ' test mode to obtain more accurate data.
② steps '2. ① ' changed to ' uniform weigh approximately 0.3G crushed samples, add pure water to 45mL scale ', the remaining steps do not change.

Note: the maximum amount of use in terms of sulfur dioxide residue.
"Considerations"
① above room temperature of 25 ± 5 ℃, if the actual room temperature deviation can be adjusted through a bath of warm water or an ice bath, to achieve optimal results.
II used in the detection of fluid has a different level of damage to the skin, use protection. Carelessly filled with dry skin should immediately wash with plenty of water.
③ Save the test reagents need cool and dry place away from light, refrigerator 2~5℃ keeping the best.