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Study Resources (Chemistry)

  1.If a sample is analyzed using TLC with two different solid phases and several solvent systems, would the results be considered conclusive?  What about inclusion of standards and several developing reagents? At what point does a string of presumptive and screening tests become conclusive? 2.Related to Question 1 above, comment on.
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  6.Devise a solvent extraction method that could be used to separate a mixture of powdered sugar, cornstarch, cocaine, and amphetamine. Justify each step and separation. Repeat using SPE to affect the separation. 7.A case sample from a suspected arson fire is submitted to the lab. The fire was suppressed with large.
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  8.Would a sample of heroin containing significantly more 3-MAM verses 6-MAM be noteworthy? Why?  What could this indicate? 9.For any given molecule of heroin, what % of the carbon originates from morphine and what percentage is traceable to acetic anhydride, assuming that is the reagent used in the conversion? 10.Caffeine is an.
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  4.Diazepam tablets are supplied in 2, 5, and 10 mg increments. Assume several tablets are received in a lab as evidence.  Using the Physicians’ Desk Reference, the analyst was able to tentatively identify them as Valium, 10 mg. You further learn that the tablets also contain anhydrous lactose, starches, dyes,.
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  2.a) Without resorting to calculations, comment on the relative solubility of the following compounds: Silver bromate Ksp = 5.5x10-5; silver sulfide 6x10-51; magnesium carbonate 3.5x10-8; Mn(OH)2 1.6x10-13. b)Give the solubility product constant in the form pKsp. c)Calculate the solubility of each. d)At what pH would manganese hydroxide precipitate out?   .
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  2.a) From the perspective of “fitness for purpose,” which of the following methods would be best suited to characterize a single bullet fragment recovered from a body: SEM imaging coupled with x-ray spectroscopy; bulk analysis using acid digestion and ICP-MS; or LA-ICP-MS? Create a table that lists the pros and.
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  6.Why are reagents based on formation of diazonium ions and salts used almost exclusively for alkaloids and bases? 7.What would happen if the Liebermann reagent was added to a sample of cocaine HCl? Why?  Give a defensible chemical explanation. 8.The nitroprusside reaction will not work (i.e., not produce colored products) with primary.
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  1.Suppose a sample of urine contains quinine, a molecule that can be excited by UV light and fluoresces strongly. How would the design of a simple colorimeter/spectrometer have to be modified to detect the fluorescence and not the transmitted light coming from the excitation source? 2.The development of the technology for.
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  11.Name the functional group(s) in THC. What presumptive color/crystal tests could be useful aside from the Duquenois-Levine test? Why are crystal tests of limited use with plant extracts? 12.Resorcinol gives a false positive with the Duquenois-Levine test. Why? 13.Name a presumptive test or test series that could distinguish between testosterone and estradiol.
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  5.When samples are extracted using SPE or related techniques, internal standards are added before the sample is placed on the column. Why? 6.According to the Merck Index, a 1% solution (wt/vol) of caffeine in water produces a pH of 6.9. Calculate the Ka and pKa of caffeine.   .
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  8.Discuss and explain why the intensity of the source in any type of spectroscopy fundamentally controls the instrument’s LOD and LOQ. Why does interferometry change this? 9.Spectroscopy in the UV/VIS range produces broad bands for reasons discussed above. In addition, rotational and vibrational modes contribute to band broadening even though these quantum.
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  1.Is caffeine an addictive substance? 2.A common scene in movies and TV programs shows the detective tasting a suspected drug powder to determine its identity. In addition to being poor laboratory practice, it is a really bad idea. Discuss and explain. 3.How important is it for a forensic chemist to understand why.
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  1.Why are the functional groups attached to carbon 3 in morphine more active than those attached to carbon 6? 2.Postulate a mechanism and explanation for the formation of the aziridines during the Emde method of methamphetamine synthesis. 3.What by-products would you expect if the Birch method is used to prepare methamphetamine from.
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  3.Using the preceding data, information in the chapter, and supplementary information as needed (i.e., references), answer/explain the following: a) A “one well” approach is a variation of the cobalt thiocyanate test. In it, the cobalt thiocyanate reagent is dissolved in 98 mL of water to which 2 mL of con HCl.
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1.Name the functional group(s) in THC. What presumptive color/crystal tests could be useful aside from the Duquenois-Levine test? Why are crystal tests of limited use with plant extracts? 2.Resorcinol gives a false positive with the Duquenois-Levine test. Why? 3.One test occasionally performed on aqueous solutions containing a mixture of GHB and GBL.
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1.Why is it increasingly difficult to classify drugs as natural, semi-synthetic, or synthetic? 2.From a regulatory and analytical perspective, why would immediate precursors be of more concern than distant precursors? 3.For over-the-counter preparations, inactive ingredients are called fillers. Are these the equivalent of diluents, adulterants, impurities, contaminants, or thinners?  Why or.
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  10.Estimate the Ksp of the following drug salts: a)Lidocaine•HCl, soluble 1 part in 0.7 parts water b)Codeine sulfate: (C18H21NO3)2•H2SO4•3H2O, soluble 1 in 30 parts water.  Note: hydrates are common in drug formulations.  Determine the solubility in terms of molarity and assume the density of water is 1.0g/mL and then apply the appropriate.
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  6.Explain what is meant by the term “undetectable” when referring to a designer steroid. Obviously it is a misnomer if taken literally since such compounds have been identified. This term implies that the substance or its metabolic products cannot be detected by current methods either due to their chemical natural.
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  4.Use the concepts of scattering and polarizability to draw links between atomic and molecular scattering, refractive index, and Raman spectroscopy. 5.Calibration of spectroscopic methods is based on Beer’s Law and the linear relationship of the form y = mx + b. Theoretically, b should be zero but usually it is not..
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  13.The following data is obtained from the PDR regarding an elixir: TYLENOL® WITH CODEINE (Ortho-McNeil) Elixir CIII (acetaminophen and codeine phosphate) Contains: Codeine Phosphate  ........................................  12 mg Acetaminophen ...............................................  120 mg a)Assuming that the elixir is a syrupy aqueous solution, suggest a method to isolate the two active ingredients from the syrup using SPE. b)Make the procedure.
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  15.The following colors are obtained in presumptive testing: Steroid Liebermann’s Mandelin’s Testosterone Light violet Orange-red Testosterone cypionate Orange-brown Dark brown Testosterone enanthate No reaction Orange-red Testosterone propionate Orange-brown Orange-brown Explain/justify these observations. Source: Chiong, D. M., et al. “The Analysis and Identification of Steroids.” Journal of Forensic Sciences, 37 1992, 488–502.   .
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