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PHARMACEUTICAL CHEMISTRY > BASIC PHARMCHEM > Flashcards

BASIC PHARMCHEM Flashcards

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1
Q

What is the full name of EDTA?

A

Ethylenediaminetetraacetic acid

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2
Q

Define sequestering agent.

A

A sequestering agent is a substance that can form stable complexes with metal ions, effectively removing them from solution.

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3
Q

What are two properties of EDTA?

A
  1. It can bind to multiple metal ions. 2. It is highly soluble in water.
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4
Q

Define ‘Complex’.

A

A complex is a chemical species formed from the combination of a metal ion and one or more ligands.

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5
Q

Define ‘Ligand’.

A

A ligand is a molecule or ion that donates a pair of electrons to a metal ion to form a coordinate bond.

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6
Q

Define ‘Dative bond’.

A

A dative bond is a type of coordinate bond where one atom provides both electrons for the bond.

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7
Q

Define ‘Chelate’.

A

A chelate is a complex formed when a ligand binds to a metal ion at multiple points.

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8
Q

Define ‘Chelation’.

A

Chelation is the process of forming a chelate complex.

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9
Q

Explain the endpoint of titration based on the reaction: Xylenol range – Lead + EDTA → Lead – EDTA + Xylenol range.

A

The endpoint of titration is the point at which the amount of titrant added is stoichiometrically equivalent to the amount of substance in the sample.

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10
Q

What is spectroscopy?

A

Spectroscopy is a broad scientific technique that involves the study of the interaction between matter and electromagnetic radiation.

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11
Q

What is the wavelength range of the UV spectrum?

A

The wavelength range of the UV spectrum is 200 nm to 400 nm.

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12
Q

How does UV-VIS spectroscopy work?

A

UV VIS spectroscopy works by shining a beam of light through a sample and measuring the amount of light absorbed by the sample at different wavelengths.

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13
Q

What is the purpose of a blank or reference measurement in UV-Vis spectroscopy?

A

A blank measurement provides a reference spectrum in the absence of the analyte, allowing for the correction of background absorption due to the solvent or impurities.

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14
Q

What are two most common sources in UV-Vis Spectroscopy?

A

carbon arc and mercury arc

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15
Q

What does FTIR stand for?

A

FTIR stands for Fourier Transform Infrared spectroscopy.

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16
Q

What information does FTIR provide about a sample?

A

FTIR provides information about the functional groups and chemical composition of a sample based on its infrared absorption spectrum.

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17
Q

What is wavenumber in FTIR?

A

Wavenumber is the frequency of infrared radiation, measured in reciprocal centimeters (cm⁻¹), and is commonly used in FTIR spectroscopy.

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18
Q

How does FTIR contribute to pharmaceutical analysis?

A

FTIR is used in pharmaceutical analysis to identify active ingredients, assess purity, and monitor formulation stability.

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19
Q

What is the fingerprint region in an FTIR spectrum?

A

The fingerprint region (typically 1500-400 cm⁻¹) contains unique absorption patterns in an FTIR spectrum, aiding in material identification.

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20
Q

What is the purpose of a detector in FTIR spectroscopy?

A

The detector captures the modulated infrared signal and converts it into an electrical signal for further analysis.

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21
Q

How is FTIR used in environmental analysis?

A

FTIR is employed in environmental analysis to detect pollutants, monitor air quality, and study soil composition.

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22
Q

What functional group is present in the spectrum below?
( refer telegram )

A
  1. Hydroxyl, OH
  2. Carbonyl, C=O
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23
Q

What is atomic absorption spectroscopy (AAS), and how does it work?

A

Atomic absorption spectroscopy is a technique used for quantitative analysis of elements in a sample by measuring the absorption of characteristic wavelengths of light. It works based on the principle that atoms absorb light at specific wavelengths when they transition from lower to higher energy states.

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24
Q

Explain the components of an atomic absorption spectrometer and their functions.

A

An atomic absorption spectrometer consists of a light source (hollow cathode lamp), monochromator, sample introduction system (nebulizer and burner), atomizer (flame or furnace), and a detector. The light source emits light at the element’s characteristic wavelength, the monochromator selects the desired wavelength, the sample introduction system introduces the sample, and the atomizer converts the sample into atomic form. The detector measures the absorption of light by the atoms.

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25
How is the calibration curve constructed in atomic absorption spectroscopy, and why is it necessary?
Calibration curves are constructed by measuring the absorption of known concentrations of standard solutions. These curves relate the concentration of the analyte to the absorbance. Calibration is essential for quantifying unknown sample concentrations accurately.
26
What are the factors affecting the sensitivity and precision of atomic absorption spectroscopy?
Sensitivity is influenced by factors like the light source intensity, path length, and atomization efficiency. Precision depends on factors such as the stability of the light source, the quality of the monochromator, and the stability of the flame or furnace.
27
Discuss the role of the nebulizer in sample introduction in atomic absorption spectroscopy.
The nebulizer converts the liquid sample into an aerosol, which is then introduced into the flame or furnace. It plays a crucial role in ensuring a fine and consistent spray of the sample, thereby improving atomization efficiency and analytical precision.
28
Discuss the significance of the hollow cathode lamp as the light source in atomic absorption spectroscopy.
The hollow cathode lamp emits light at specific wavelengths. This monochromatic light is crucial for accurate measurements, as it matches the absorption lines of the element being analyzed, providing high specificity and sensitivity.
29
What is the major contribution of AAS in analytical chemistry?
AAS has significantly contributed to analytical chemistry by providing a reliable and accurate method for the quantitative determination of trace and ultra-trace elements in various samples.
30
How does AAS contribute to pharmaceutical analysis?
AAS is used to quantify/measure trace metals in pharmaceutical products, ensuring compliance with regulatory requirements.
31
What role does AAS play in food and beverage analysis?
AAS is used in food and beverage analysis to determine the concentration of essential trace elements and potential contaminants. It ensures the safety and quality of food products by detecting elements such as lead, cadmium, and arsenic at low concentrations.
32
What are the advantages of AAS in comparison to other analytical techniques?
AAS offers advantages such as high specificity, good sensitivity, and relatively simple instrumentation. It is cost-effective, easy to operate, and widely applicable across various sample matrices, making it a preferred choice for many analytical laboratories.
33
What is paper chromatography, and how does it work in separating mixtures?
Paper chromatography is a technique used for separating mixtures of substances into their individual components based on their differential migration through a stationary phase (paper) due to differences in their solubility and affinity for the mobile phase (solvent).
34
Why is water not used in paper chromatography as a mobile phase?
It is preferable to use a less polar solvent, such as ethanol, so that the non-polar compounds will travel up the paper while the polar compounds will stick to the paper, separating them.
35
What are the limitations of paper chromatography?
Paper chromatography cannot handle large amounts of sample, is ineffective in quantitative analysis, cannot separate complex mixtures, and is less accurate than HPLC.
36
What is the importance of paper chromatography in the food industry?
Paper chromatography has traditionally been used to analyse food colours in ice creams, sweets, drinks and beverages, jams, and jellies. Only edible colours are permitted for use to ensure that no non-permitted colouring agents are added to the foods.
37
Can you explain the principle behind the movement of substances in paper chromatography?
Substances move in paper chromatography due to a combination of capillary action and differential solubility. Components with higher solubility in the mobile phase move faster and travel a greater distance, leading to separation.
38
Can paper chromatography be used to identify unknown substances in a mixture? If yes, how?
Yes, it can be used. By comparing the Rf values of unknown substances with those of known standards under identical conditions.
39
What is Thin-Layer Chromatography (TLC)?
TLC is a chromatographic technique based on adsorption separation.
40
What is the role of the stationary phase in TLC?
The stationary phase, typically silica coated on a plate, interacts with the sample as the mobile phase passes over it.
41
How do compounds separate in TLC?
Compounds separate based on their affinity for the stationary phase and the mobile phase.
42
How is separation visualized in TLC?
Separation is visualized and analyzed by measuring the distance traveled by the compounds and the solvent front.
43
What are the components of a TLC system?
The components include the TLC plate (stationary phase), mobile phase, sample spot, developing chamber, and visualization methods.
44
What is the function of the mobile phase in TLC?
The mobile phase carries the sample along the plate.
45
What is the role of the developing chamber in TLC?
The developing chamber creates a controlled environment for separation.
46
What methods are used for visualization in TLC?
Visualization methods, such as UV light or chemical reagents, reveal the separated compounds.
47
What is the retention factor (Rf) in TLC?
The Rf value represents the relative migration of a compound.
48
How is the Rf value calculated?
Rf is calculated as the ratio of the distance traveled by the compound to the distance traveled by the solvent front.
49
What are the advantages of TLC?
Advantages of TLC include cost-effectiveness, quick analysis, and short development time.
50
What are the disadvantages of TLC?
Disadvantages include limitations in quantitative analysis, difficulty in identifying components, and shorter stationary phase.
51
How does a polar stationary phase affect TLC?
A polar stationary phase has a higher affinity for polar compounds, leading to reduced mobility and lower Rf values.
52
Name one common gas used as a GC carrier gas.
Helium
53
What is GC instrumentation?
Carrier gas, injection port, column, detector
54
Describe stationary phase in GC.
Liquid coated onto the surface of an inert solid.
55
What is the most common detector in GC and what is the function?
Flame ionization detectors (FID)
56
How does GC work?
1. The sample is injected into the injector, where it is vaporized. 2. The vaporized sample is carried by the flowing inert gas through the chromatographic column. 3. Components of the sample interact with the stationary phase and the mobile phase in column differently, leading to separation. 4. Detectors analyse the emerging compounds, producing signals that are recorded and used for analysis.
57
What type of molecule elute first in GC?
Molecule with low boiling point.
58
What would happen to the retention times of compounds A and B if the column temperature were raised?
Raising the column temperature usually reduces the retention time of compounds. This is because higher temperatures increase the vapor pressure of the analytes, leading to faster elution from the column.
59
What is HPLC, and how does it differ from other chromatographic techniques?
- High-Performance Liquid Chromatography (HPLC) is a separation technique used to separate, identify, and quantify components in a mixture. - It differs from other chromatographic techniques, such as gas chromatography, in that it uses a liquid mobile phase
60
State two main types of HPLC and differences between these two types.
- The two main types of HPLC are Normal Phase HPLC and Reverse Phase HPLC. - Normal phase HPLC is a type of HPLC where the stationary phase is polar, and the mobile phase is nonpolar while reverse phase HPLC is a type of HPLC where the stationary phase is nonpolar, and the mobile phase is polar.
61
What is the mobile and stationary phase in HPLC?
- The mobile phase is the liquid (solvent or a mixture of solvents) that carries the sample through the column. - The stationary phase in HPLC is a solid support material packed in the column that interacts with the sample components.
62
What are the key components of an HPLC system, and state the functions of each components.
- HPLC system comprises a pump, injector, column, detector, and data analysis system. - The pump delivers the mobile phase, the injector introduces the sample into the column, the column separates the components, the detector measures the concentration, and the data analysis system processes and displays the results.
63
What is retention time, and how is it used in HPLC?
- The time taken for a particular compound from injection point to travel through the column to the detector. - It can be used to identify analytes if the method conditions are constant.
64
What is a calibration curve?
A calibration curve is a graph that shows the relationship between known concentrations of a compound and the corresponding detector response.
65
How is the peak area related to the amount or concentration of a compound in a chromatogram?
The peak area is directly proportional to the amount or concentration of the corresponding compound.
66
How does the flow rate affect HPLC separation efficiency?
A higher flow rate can reduce the separation efficiency of HPLC by decreasing the time that the sample interacts with the stationary phase.
67
How does the choice of stationary phase impact HPLC separation? .
Different stationary phases interact differently with sample components based on factors like polarity, hydrophobicity, and size, affecting the overall resolution of peaks
68
Figure above shows the spectrum of normal phase HPLC. Match the compounds below with the corresponding peaks in the HPLC spectrum above. Justify your answer.
A = Propanoic acid B = Ethanoic acid C = Methanoic acid - Increasing the number of carbon chain will increase the non-polar characteristic of molecule. - In normal phase HPLC, the stationary phase is polar. - Thus, propanoic acid which have longest carbon chain eluted first due to its high non-polar characteristic and weak interactions with the polar stationary phase.
69
Which of these molecules best to correspond to IR below. Justify your answer.
Compound E. A broad peak at 3300 cm-1 and no dominant peak around 1700 cm-1 (too weak to be a C=O). That broad peak at 3300 means the compound have an alcohol (OH group). The only option that makes sense is E (cyclopentanol) since it has both an OH group and the number of carbon and hydrogen similar to C5H10O.
70
Which of these molecules best to correspond to IR below. Justify your answer
Compound B. A broad peak in the 3300-2600 cm-1 means the compound have alcohol (OH group) and a strong peak a little above 1700 cm-1 which is typical of a C=O.
71
A sample consisting of A, B, C and D which have boiling point 46 ℃, 74 ℃, 87 ℃ and 124 ℃, respectively. Identify which peaks correspond to A, B, C and D. Justify your answer.
Compound A has lowest boiling point makes it more volatile. This allows the compound to move through the column more quickly, elute first and resulting in a shorter retention time in gas chromatography. This followed by compound B, C and D as the boiling point increases.
72
State the range of wavelength of ultraviolet radiation.
200-400 nm
73
Describe the relationship between the wavelength and frequency of electromagnetic radiation.
As the wavelength of electromagnetic radiation increases, its frequency decreases, and vice versa.
74
Explain how does a UV-Visible Spectrophotometer work.
- A UV-Visible Spectrophotometer emits light in the UV or visible range through a sample. - When a sample exposed to UV vis light, electron in the molecule transit for lower energy level to higher energy level. - The absorbance spectrum is recorded.
75
Which of these molecules best to correspond to IR spectrum below. Justify your answer.
- Compound C - No broad peak at region range 3000-3300 cm-1 means the compound have no hydroxyl group. - Strong peak around 1700 cm-1 represents C=O. - The best option is compound C since it has strong C=O and no hydroxyl group.
76
Explain how can IR spectroscopy be used to verify the oxidation of a primary alcohol to an aldehyde.
The broad O–H stretch band disappears, indicating the loss of the hydroxyl group. A new, strong absorption band for the C=O stretch of the aldehyde appears around 1700–1740 cm⁻¹.
77
Figure below shows the IR spectrum. State the functional groups present in the spectrum and give your reasons.
- hydroxyl (OH) and carbonyl (C=O) group - broad peak in the 3300-2600 cm-1 means the compound have hydroxyl group (alcohol). - strong peak in the region 1700 cm-1 which is typical of a C=O.
78
Explain how does Thin Layer Chromatography (TLC) work.
- In TLC, a thin layer of adsorbent material, such as silica gel or alumina, is coated on a aluminium, glass or plastic plate. - The sample is applied as a spot near one end of the plate. - The plate is then placed in a developing chamber with a solvent, and capillary action causes the solvent to move up the plate, carrying the components of the sample with it. - As the solvent travels, different components separate based on their affinity for the adsorbent.
79
Find the Rf values for A, B and C. Based on retention factor of mixtures, identify the least polar mixture. Justify your answer.
- Compound B. - Least polar compounds tend to interact weakly with the polar stationary phase. - So, it tends to move faster in mobile phase, resulting in highest Rf values.
80
A GC chromatogram consisting of A, B, C and D peaks which have boiling point 32 ℃, 67 ℃, 84 ℃ and 131 ℃, respectively. Identify which peaks elute first and justify your answer.
- Compound A will elute first. - It has lowest boiling point, makes it more volatile. - This allows the compound to move through the column more quickly, elute first and resulting in a shorter retention time in gas chromatography.
81
If the molecules have same boiling point, which one elute first in GC?
If the boiling point of components is the same, then a low size molecule will elute first and high size molecule elutes later.
82
State the difference between normal and reverse phase HPLC.
In normal phase HPLC, stationary phase is polar and mobile phase is nonpolar while in reverse phase HPLC stationary phase is non polar and mobile phase is polar.
83
A mixture containing alcohol, ester, and carboxylic acid component. Identify which component corresponds to peaks A, B and C as shown in the chromatogram. Justify your answer.
A = carboxylic acid B = alcohol C = ester - Ester is the least polar, while carboxylic acid is the most polar component. - In reverse phase HPLC, the stationary phase is non polar. - Ester will be eluted last due to its low polarity and strong interactions with the nonpolar stationary phase. - Carboxylic acid will be eluted first due to its high polarity and weak interactions with the nonpolar stationary phase.

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