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Determination of Phenols in the Atmosphere (Gas Chromatographic Method)
Published in James P. Lodge, Methods of Air Sampling and Analysis, 2017
While neither phenol nor the stock 0.1 % solution degrade rapidly, lots of Reagent phenol differ in water content; this also changes with time. Blotting the crystals of phenol largely removes this problem. However, for highest accuracy, it may be desirable to assay the material periodically, both in the reagent bottle and in the stock solution (which should be stored in the refrigerator for no more than one month). Pipet 50.0 mL of 0.1% solution into a 500-mL iodine flask. Add 100 mL of water. Pipet in 10.0 mL of bromate-bromide solution, then add 0.5 mL of concentrated hydrochloric acid. Mix. If the brown color of bromine does not persist in the solution (as it should not), add successive 10.0-mL portions of bromate-bromide solution by volumetric pipet until the bromine color persists. (This usually requires a total of four such additions.) Stopper the flask after each addition. After the final addition, allow the flask to stand, stoppered, for 10 min, then quickly add 1 g of potassium iodide, stopper, and swirl to dissolve. Titrate the liberated iodine with 0.025 N sodium thiosulfate solution in the usual way, adding starch indicator when the iodine color is nearly discharged. Carry 50.0 mL of a blank (water) through the same procedure; it will require only a single 10.0-mL portion of bromide-bromate solution. Calculate the concentration of phenol in the stock solution as follows:
Introduction
Published in Jamie Bartram, Richard Ballance, Water Quality Monitoring, 1996
Jamie Bartram, Richard Ballance
✓ Starch indicator solution. Make a smooth paste by blending 1g of soluble starch with a little cold distilled water in a beaker of capacity at least 200ml. Add 200ml of boiling distilled water while stirring constantly. Boil for 1 minute and allow to cool. Store in a refrigerator or at a cool temperature. Alternatively, thiodene powder may be used as an indicator.
Differences between constant and intermittent drying in surf clam: Dynamics of water mobility and distribution study
Published in Drying Technology, 2018
Siqi Wang, Yao Li, Zhuyi Lin, Mingqian Tan
To analyze the peroxide value of clam, 12 g of rehydrated clam sample was extracted with triploid petroleum ether at 25°C for 12 h, and the resulting solution was added by 30 mL mixture of acetic acid and chloroform (2:3, v/v). After adding 1.0 mL of saturated potassium iodide solution, the testing solution was then microwaved for 30 s and placed in the dark for 3 min, and then titrated with sodium thiosulfate (0.002 mol L−1) solution to yellow color. The titration end point was determined when the color changed to blue upon adding 1 mL of starch indicator. The peroxide value X (mmol kg−1) can be calculated by equation: where V and V0 are the volumes of the sodium thiosulfate for the clam sample and blank control, respectively. m is the weight of rehydrated clam.
Recovery of phosphorous from industrial waste water by oxidation and precipitation
Published in Environmental Technology, 2018
Rikard Ylmén, Anna M. K. Gustafsson, Caterina Camerani-Pinzani, Britt-Marie Steenari
Determination of the phosphite fraction of the total phosphorous in the waste water was made by thiosulfate titration [10]. Iodine was used in excess to oxidize phosphite to phosphate. A sodium bicarbonate solution was also added to make sure the water was alkaline to facilitate the oxidation of phosphite. After the reaction, the remaining iodine was titrated using thiosulfate with starch as the indicator. The difference in the amount of iodine was then used to calculate the amount of phosphite in the sample. The procedure used was as follows: exactly 1.0 cm3 of the sample, 10 cm3 of de-ionized water (, Millipore Milli-Q Advantage A10), 10 cm3 of 5 wt% sodium bicarbonate (99.7–100.3%, Sigma-Aldrich) in de-ionized water and 25 cm3 of 0.05 mol/dm3 iodine solution (Reag. Ph. Eur., Fluka) was added to a titration flask. The flask was stoppered and placed in a dark place for 30 min to oxidize the phosphite. Then 10 cm3 of 10 vol% acetic acid (≥ 99.7%, Sigma-Aldrich) in de-ionized water was added and the solution was titrated with 0.1 mol/dm3 sodium thiosulfate solution (Reag. Ph. Eur., Fluka). When the solution became light yellow, a few drops of starch indicator (1% in HO, Fluka) was added and the titration was continued until all colour had disappeared. The phosphate concentration in the sample was calculated as the difference between the total phosphorous concentration and the phosphite concentration in the sample.
Ozonated Olive Oil with a High Peroxide Value for Topical Applications: In-Vitro Cytotoxicity Analysis with L929 Cells
Published in Ozone: Science & Engineering, 2018
Yasemin Günaydın, Handan Sevim, Deniz Tanyolaç, Özer A. Gürpınar
The PV is generally determined by the quantity of the peroxides in the sample measured as milliequivalents of active oxygen in 1000 g of oil sample (Martinez Tellez, Ledea Lozano, and Díaz Gómez 2006) In our study, the PV was determined with slight modifications from the standard method. In particular, 1 g of OZ was weighed in a 250-mL conical flask and mixed with 20 mL of chloroform/glacial acetic acid (2/3 v/v). After complete dissolution of the sample, 0.5 mL of a saturated solution of potassium iodide was added to the flask. The mixture was shaken well and stored for 24 h at 25 °C in the dark (Martinez Tellez, Ledea Lozano, and Díaz Gómez 2006). Subsequently, 1 mL of a 1% (mg/mL) starch indicator solution was added and mixed with 30 mL of water. Finally, titration was carried out with a 0.01 M sodium thiosulfate solution until disappearance of the deep blue color. The PV was calculated by Equation [1]: