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Sample Preparation Techniques to Isolate and Recover Organics and Inorganics
Published in Paul R. Loconto, Trace Environmental Quantitative Analysis, 2020
We now discuss the results of studies that show the strong dependence of D on the pH of the aqueous phase. However, we first introduce the experimental procedure used to generate the data. To about 50 mL of distilled deionized water (DDI) is added an aliquot of a 1% solution of oxine dissolved in methanol. An aliquot of a cadmium salt solution is then added. The pH is adjusted to the desired value with 1% ammonia. This spiked sample is passed through a conditioned C18-bonded SPE sorbent, and a brightly colored band is seen near the top of the column. The SPE cartridge is subsequently eluted with 5 mL MeOH directly into a 10 mL volumetric flask used as a receiver. The contents of the volumetric flask are brought to the calibration mark with 1% nitric acid in DDI. The source of nitric acid (HNO3) must be a high-purity acid deemed suitable for atomic absorption spectrophotometric analysis. The contents in the volumetric flask were aspirated into a Model 303 Flame AA (PerkinElmer). The metal, cadmium, is quantitated based on an external standard mode of instrument calibration in 50:50 MeOH:1% HNO3. Ten replicate SPEs were conducted at pH values 6.2 and 8.8. The absorbance (A) was measured and the data is shown in Table 3.33.145 It is evident that at a pH of 6.2, little to no cadmium was recovered, whereas at pH 8.8, almost 30 times as much cadmium was recovered! Two other studies on the isolation and recovery of Cd2+ by chelating the ion with oxine and isolating the complex on C18 and C8 chemically bonded silicas gave similar results.
Introductory Guidelines for the Use of This Manual
Published in V. Dean Adams, Water and Wastewater Examination Manual, 2017
Transfer the chemical quantitatively. In a pre-rinsed volumetric flask of the proper size, add some fresh DDW. Quantitatively transfer the chemical that was weighed into the flask, rinsing the paper if necessary. Add more fresh DDW, being sure to rinse any dry chemical into the bottom of the flask. Add DDW so that the flask is about three quarters full. Carefully swirl or stir the solution until the chemical is dissolved. Fill the volumetric flask with DDW so that the meniscus of the solution is at the calibration line. With a ground glass stopper in place, invert the solution several times to mix thoroughly.
Methods for Water Analysis
Published in Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus, Environmental Chemical Analysis, 2018
Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus
The electrothermal atomizer is recommended for aluminum, antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, selenium, silver, and tin. One hundred mL samples are digested as above, with 2 mL of 30% hydrogen peroxide added if arsenic or selenium are to be measured. A matrix modifier is added if needed. The samples are transferred to a 100 mL volumetric flask and brought to volume. A blank is done in the same way. Standards are prepared, and should be matched as closely as possible to samples, especially to the acid concentration.
Velocity Field and Scalar Field Measurements of Turbulent Buoyant Round Jets in a Two-Layer Stratified Environment
Published in Nuclear Science and Engineering, 2020
Sunming Qin, Victor Petrov, Annalisa Manera
Utilizing the idea of the ternary diagram, a combination of two aqueous solutions with a density difference of 3.16% are chosen to conduct the experiments in this work, which is the largest density difference that can be achieved by using the mixtures of water (H2O), glycerol, and sodium sulfate (Na2SO4), while keeping the refractive index constant during the mixing process. Measurements of refractive index and density are performed at the temperature of 293.35 K and atmospheric pressure over the whole composition diagram of the H2O–glycerol–Na2SO4 system. The refractive index nD is measured with a Sper Scientific 300037 digital refractometer with a range of 1.3330 < nD < 1.5318, which has an accuracy of 0.1% at a resolution of 0.0001. The density measurement is performed using a 50-mL volumetric flask, class A in combination with a Lianze I2000 digital multifunction scale, with an accuracy of 0.1 g, which overall results in uncertainty within 1% for the density measurements.