Please also tell me why you picked the answer. Show any sources used. When carry

Question

Please also tell me why you picked the answer. Show any sources used.

When carrying out the analysis of morphine and its metabolites in post-mortem blood, solid phase extraction (SPE) is often used in the sample preparation step prior to analysis. Which ONE of the following describes the mechanism of how this preparation step is used? The SPE cartridge allows the morphine and its metabolites to remain in a suitable solvent. Morphine and its metabolites are retained on the chromatographic media of the SPE cartridge before being washed out with an appropriate solvent. The SPE cartridge acts as a simple filter, removing large particles that would interfere with the HPLC column. Morphine and its metabolites are not in the correct ionic form, therefore the SPE cartridge will allow the chemistry of the analytes to be modified for analysis via HPLC. A volatile substance is usually used to dissolve a sample before spotting onto the TLC plate. Which ONE of the following is the reason why a volatile solvent is usually used? To enable the sample to be separated in order to evaporate across the TLC plate. The TLC plate would usually be in the dry state and requires a solvent to prepare the surface. To avoid excess spreading of the sample across the TLC plate. The TLC plate requires a volatile solvent that would allow the non-volatile sample to be in the correct state for analysis. Which ONE of the following statements about the molar absorptivity coefficient (epsilon) is incorrect? It has a higher magnitude for transitions from sigma orbitals than from piorbitals. Its magnitude is affected by the wavelength of radiation used to irradiate the sample. It can be obtained from the calibration curve that relates concentration with absorbance. The value of epsilon for a given compound is dependent upon the solvent used in the analysis. Which ONE of the following statements about the effect of pH on the spectrum of the following compound is correct? pH will not affect the UV-Vis absorption spectrum. Acidic pH will displace the absorption maximum towards shorter wave lengths. Basic pH will displace the absorption maximum towards longer wave lengths. Acidic pH will displace the absorption maximum towards longer wave lengths. A compound had a transmittance of 60% in its UV/Vis spectrum. Which ONE of the following values corresponds to the absorption value for the compound. 3.981 0.222 0.251 0.511

Explanation / Answer

10. Analysis of morphine, mechanism followed is,

C.

11. the use of voltaile solvent to spot the compound on tlc plate is,

B.

12. True statement about molar absorptivity coefficient,

C.

13. pH dependent spectum of given compound, true statement,

B.

14. Compound with transmittance = 60%

Absorbance = 2 - log(%T) = 2 - log(60) = 0.222

Answer : B. 0.222

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