nyenaceyg
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 Wysłany: Pią 23:12, 25 Lut 2011 Temat postu: Proteus with food poisoning caused _9974 |
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With food poisoning caused by Proteus
UV spectrophotometer and reagents, water, steam distillation unit. Acetyl acetone: acetic acid in 100ml of distilled water in the ammonium 25g, glacial acetic acid and acetyl acetone 3IIIl 0.40ml, shaking Dissolution of reserves in the brown bottle. Preparation of standard stock solution of formaldehyde: lessons 7IIll formaldehyde (formaldehyde 38% to 40%) adding 0.5mot / L, sulfuric acid 0.5ml diluted with water to 250ml. Formaldehyde calibration: Take l0IIIl formaldehyde diluted to 100ml, and mix. Learn l0ml into 250ml conical flask, add water 90ml, adding 20ml0.1mol / L solution of iodine standard solution and l5ml1mol/LNaOH place 15min after mixing, add 20ml10.5mol / L of H2so4 placed 15min, with 0.1mol / L droplets of sodium thiosulfate standard set to light yellow, add 3ml starch indicator,[link widoczny dla zalogowanych], continue titration to the end of the blue to colorless and transparent, while doing the blank test,[link widoczny dla zalogowanych], according to the amount of consumption of sodium thiosulfate standard solution of formaldehyde concentration calculation. Standard use of formaldehyde solution: after the calibration standard stock solution of formaldehyde progressively diluted with water to 5 ~, e, / ml, when the temporary use of the existing service. 1.3 methods (qualitative analysis method) 1.3.1 obtain 5.0g of sulfur dioxide qualitative test sample plus 50ml water mixing, into conical flask, add 1:1 hydrochloric acid to the bottle, plus 2g of zinc tablets, rapidly in a bottle of lead acetate test paper bag, placed 1h observed at the same time as controls. Black lead acetate test strip, and the deep black than the control, the sample of sulfur dioxide qualitative test is positive, otherwise negative. 1.3.2 Formaldehyde qualitative test specimen processing: the qualitative test was positive in samples of sulfur dioxide by steam distillation, the collection of distillate use. Distillate take 5ml, add 5ml acetyl acetone, mix, placed in a boiling water bath heated 10rain, then the solution was yellow; In another 5ml of water at the same time as the blank test. Who showed a yellow sample tube (blank control depth), indicating that the formaldehyde test was positive, otherwise negative. 1.3.3 Quantitative analysis of formaldehyde sample processing: the qualitative test positive for formaldehyde, weighed crushing, mixing (if necessary, sieved) samples 5g, placed in distillation flask, add 20ml of water, 2.5IIll liquid paraffin, l0ml10 % phosphoric acid, and immediately with water steam distillation. Condenser tube inserted into the bottom of pre-filled with water and placed in ice bath l0ml the receiver. Accurate collection of distillate 100ml, while doing a blank distillation. Specimens learned distillate l0IIll, adding acetyl acetone mix 1ml,[link widoczny dla zalogowanych], placed in boiling water bath for 5min, remove to cool. And then distilled water to zero at the wavelength 435nm to 1em cuvette for colorimetric, record absorbance, check the calibration curve results. Preparation of calibration curve: lessons use formaldehyde standard solution 0.00,[link widoczny dla zalogowanych],0.50. 1.00,3.0 o, 5.0o, 7.0oml, add distilled water to l0.0oml, add the following above the same operation from acetyl acetone , after subtracting the absorbance of zero tube to draw the calibration curve. 2 Results and discussion l2, 28 samples were in formaldehyde, sulfur dioxide, also characterized as positive; a l6 were characterized as positive for sulfur dioxide, formaldehyde was negative. The l6 were characterized as positive for quantitative analysis of sulfur dioxide, of which 4 were exceeded. That the increase of the excessive sulfite bleach. L2 other samples, we were crushed with the shell of its Weigh 5g,[link widoczny dla zalogowanych], the highest measured value of formaldehyde 480mg/kg, the minimum value reached l9.5mg/kg, and measured the background level of formaldehyde in seeds in the 0.6- 7.2mg/kg of the question, which judgments were given l2 seeds, 8 were white (greater than the background value) all joined the formaldehyde bisulfite. Measured with The appearance of strange white melon seeds, fine smell, there was a smell (as opposed to five flavors), and if As the special nature of the white edible seeds (nibbling bite when the shell), we consider in the determination, the sample treatment should not be shelled. The seeds used for determination of the end of the country from the seeds of an acquaintance at the order processing, taking into account the added spice white spiced seeds are more likely to lead to inconsistent levels of formaldehyde in the background factors. Therefore, if the measured formaldehyde content of about 10mg/kg, preferably combined with measurements of sulfur dioxide content, which determine whether to join Sulfoxylate. 3
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