Give the rationale behind major steps in the analysis such as blending, filtration, heating of the sample or standard with DNS (dinitrosalicyclic acid), dilution, and absorbance measurement.
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Give the rationale behind major steps in the analysis such as blending, filtration, heating of the sample or standard with DNS (dinitrosalicyclic acid), dilution, and absorbance measurement.
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- Give the rationale behind major steps in the analysis such as blending, filtration, heating of the sample or standard with DNS, dilution, and absorbance measurement.You are an aquatic scientist and tasked to sample water that contains chlorophenols for gas chromatographic analysis from your local waste water treatment plant (WWTP). Using knowledge of sample preparation and chromatograph, how would you sample, preserve and prepare these samples for GC analysis and why GC is the best detection technique?For each of the following statements, answer True or False and explain your answer briefly. It is preferred to apply colour tests, as a screening test, over microcrystalline tests in drug analysis.
- give two examples of internal standards for menthol and thc analysis.With the knowledge on analytical separation and analyses, outline a suitable analytical separation protocol that can be employed to recover polluted river bodies and make them wholesome for drinkingWould column chromatography have worked in the separation of a fluorenone and benzoic acid mixture? Explain your answer 3. For the following statements, indicate if they are true or false a. Dichloromethane is less dense than water. b. Compounds with a charge are soluble in the organic layer. c. The solid precipitate that was formed after acidification of the aqueous layer was the acid impurity. d. The larger the melting point range, the purer the solid. e. A solution of 70% hexane/30% acetone is more polar than 100% hexane. f. A compound with impurities will have a higher melting point than the same compound without impurities.
- Briefly explain four importance of conducting sample preparation prior to instrumental analysis. Consider the following situations: If you were to analyse traces of petroleum from a piece of burned carpet, which sample preparation method is more suitable, solid phase microextraction (SPME) or pressurized liquid extraction (PLE)? Explain the choice of method chosen and why the other method is not suitable. If you were to analyse caffeine in a coffee drink, which sample preparation method is more suitable, solid phase microextraction (SPME) or solid phase extraction (SPE)? Discuss the reason for your choice and the reason for not choosing the other method.Pesticide residues were found in a lot of oranges; the compound identified was the epoxide of heptachlor (EH). To quantify the amount of this pesticide in oranges, 20 grams were taken from fruit peels and mixed with methylene chloride to extract it. The concentration of heptachlor epoxide in the sample was determined by gas chromatography coupled to a detector mass (GC-MS); and calibration was performed using anthracene (A) as internal standard. For In this analysis, the anthracene had a concentration of 350 ppm and the same volume was added to each standard. The table below shows the concentrations of the standard and the ratio of the areas.and the sample is: 0.1080.Determine the concentration of heptachlor epoxide in the sample.with your knowledge on analytical separation and analysis, outline a suitable analytical separation protocol that can be employed to recover polluted river bodies and make them wholesome for drinking.
- Of Aspirin, ethanol, acetaminophen, ethyl acetate, hexane, and water which could go undetected during HPLC analysis, but could result in a lower than expected melting point, why are they not detected by HPLC analysis?The compounds biphenyl and naphthalene are presented in a mixture. Can hexane be used as a solvent to separate the compounds by column chromatography with silica gel as the stationary phase? Why or why not.To determine the soil distribution coefficient (Kd), 10 g of dry soil is spiked with 100 mg of ring-labeled 14C-atrazine, 10 mL of deionized water is added, and the system is shaken for 24 hours. The aqueous and solid phases are separated, and the solid phase is extracted with 50 mL of methylene chloride while the aqueous phase is extracted with three successive 5 mL portions of methylene chloride. The atrazine concentration in the 50 mL of soil extract is 10 mg/L, and the concentration in the combined 15 mL from the aqueous extractions is 0.4 mg/L. Based on this information, calculate Kd.