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Determination of disulfide hydrazone Improvement of lead in food

Main measures are strictly controlled {I4 lead content in food. We passed several tests. Hydrazone colorimetry in the disulfide on the basis of the original to make some changes, not only save time and easy operation, and the results are satisfactory, the method now described as follows: 1 Materials and methods 1.1 principles defecate GB/T5009.12- 19961.2 Instruments 721 spectrophotometer, 25m1 with plug cuvette. Water vacuum suction on the basis of 13 reagents in GB/T5009.12-1996 make some changes to strong ammonia ammonia 1 +1. Standard use of lead per ml of diluted rather lug lead. 1.4 sample handling with the GB-T5009.12-19961.5 analysis step lessons 10.0mr, constant volume after digestion solution and the same amount of reagent blank solution. 25m1 colorimetric tube were placed in the standard use of drawing 0.1.00,2.00,3.00.4.00,5.00 mL of lead solution (rather 0,1,2.3,4,5 ug lead) . Were placed 25m | colorimetric tube, and add 1-99 sample digestion in nitric acid to 10.0ml. Reagent blank solution and standard solution of lead in the Canadian 2m] ammonium citrate solution (200g /) lm [hydroxyl ammonium hydrochloride solution (200g / L), mix, add 2 drops of phenol red indicator solution, adjusted to the red with concentrated ammonia , then the 2ml potassium solution (100g / L), mix. Use the plus 5.0ml disulfide hydrazone solution. Stopper than the color of each arm will be in the ratio of pipe rack Later Zhou Dynasty, while shaking lmin still stratified, with the unsolicited order of the upper net absorption of negative pressure suction,ralph lauren outlet, methane, ozone layer will be poured 1cm cuvette to chloroform-zero, the absorbance is measured at the wavelength of 510mm, and then calculated the regression equation using a calculator, to compare the sample with the standard 5. Calculation results and discussion 2.1 with GB/T5O09.12-19962 standard curve method, using this method. Lead in 0r5g linear range. The experimental standard series of 10 batches of concentration on the absorbance of the regression equation y = 0.0609x-b0.1738r = 0.99982.2 accuracy of the test sample was added in 0.5rag / Pb reference material to do the recovery test, a total of of 25 times,polo outlet online, the method improved the recovery of 95.3 to 102.3% range. The average recovery 96.22.3 precision of the original law and the law with the same sample (0.5mg/kg) were given for 10 Desert I,tory burch outlet, the relative standard deviation were 9.88 and 4.922.4 Comparison experiment, two different samples of the results determined in Table 1. Determined by the t test results of t = 1.63, t 0.05. Determined with the original law was no significant difference between the two methods in Table 1 the results of this measurement compared (mg / kg) 3 1 Summary of the original disulfide Hydrazone colorimetry standard concentration of dissolved pacing improved, making the broadcast way suction. Not only shorten the time,uggs online, but also ensure the consistent extraction of the pipe to take to reduce the error standard solutions, standard curve better, so I of the desert. 4. Regression using the calculator more convenient and accurate. Given more accurate results. 2. With a 25mL colorimetric tube instead of separating filter bucket, through the improved accuracy. Precision better. Recovery test is not only convenient place. And simple operation. 3. Vibration while using cuvette also satisfied by t test no significant difference =
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