Podcast
Questions and Answers
What is the range of high sensitivity in molarity?
What is the range of high sensitivity in molarity?
Which of the following methods is NOT used to confirm the identity of a compound in UV/VIS spectroscopy?
Which of the following methods is NOT used to confirm the identity of a compound in UV/VIS spectroscopy?
What type of species does quantitative determination using UV/VIS primarily analyze?
What type of species does quantitative determination using UV/VIS primarily analyze?
What must be supplemented with qualitative spectrophotometric data for proper identification?
What must be supplemented with qualitative spectrophotometric data for proper identification?
Signup and view all the answers
What is the definition of molar absorptivity (ε)?
What is the definition of molar absorptivity (ε)?
Signup and view all the answers
What are applications of spectrophotometry in qualitative analysis?
What are applications of spectrophotometry in qualitative analysis?
Signup and view all the answers
Which type of compounds commonly absorbs ultraviolet and visible radiation?
Which type of compounds commonly absorbs ultraviolet and visible radiation?
Signup and view all the answers
What effect does conjugation have on the absorption of organic compounds?
What effect does conjugation have on the absorption of organic compounds?
Signup and view all the answers
Which of the following is an example of a chromophore that absorbs UV radiation?
Which of the following is an example of a chromophore that absorbs UV radiation?
Signup and view all the answers
How does the presence of multiple chromophores affect absorption?
How does the presence of multiple chromophores affect absorption?
Signup and view all the answers
What does UV-VIS spectrophotometry primarily analyze?
What does UV-VIS spectrophotometry primarily analyze?
Signup and view all the answers
Which is NOT a characteristic of compounds that absorb UV-VIS radiation?
Which is NOT a characteristic of compounds that absorb UV-VIS radiation?
Signup and view all the answers
What factor influences the position of absorption maxima in spectrophotometry?
What factor influences the position of absorption maxima in spectrophotometry?
Signup and view all the answers
What factors influence absorption by inorganic species?
What factors influence absorption by inorganic species?
Signup and view all the answers
What characterizes a charge-transfer complex?
What characterizes a charge-transfer complex?
Signup and view all the answers
Which of the following is an example of a charge-transfer complex?
Which of the following is an example of a charge-transfer complex?
Signup and view all the answers
What is one of the main advantages of UV-VIS molecular absorption spectrophotometry?
What is one of the main advantages of UV-VIS molecular absorption spectrophotometry?
Signup and view all the answers
Which characteristic is NOT associated with spectrophotometric methods?
Which characteristic is NOT associated with spectrophotometric methods?
Signup and view all the answers
Why are absorption spectra of inorganic compounds often similar to organic compounds?
Why are absorption spectra of inorganic compounds often similar to organic compounds?
Signup and view all the answers
Which factor does NOT affect light absorption by inorganic species?
Which factor does NOT affect light absorption by inorganic species?
Signup and view all the answers
What is the typical range of relative errors encountered in UV-VIS spectrophotometric methods?
What is the typical range of relative errors encountered in UV-VIS spectrophotometric methods?
Signup and view all the answers
What is a requirement for a colored product used in spectrophotometric determinations?
What is a requirement for a colored product used in spectrophotometric determinations?
Signup and view all the answers
What principle does a colored product need to follow for spectrophotometric measurements?
What principle does a colored product need to follow for spectrophotometric measurements?
Signup and view all the answers
Which of the following is a derivatizing reagent used for spectrophotometric determination of pharmaceutical compounds?
Which of the following is a derivatizing reagent used for spectrophotometric determination of pharmaceutical compounds?
Signup and view all the answers
What characteristic of a colored product increases the sensitivity of spectrophotometric measurements?
What characteristic of a colored product increases the sensitivity of spectrophotometric measurements?
Signup and view all the answers
How should the formation reaction of a colored product behave for effective use?
How should the formation reaction of a colored product behave for effective use?
Signup and view all the answers
Which types of amines can be derivatized using NBD-Cl?
Which types of amines can be derivatized using NBD-Cl?
Signup and view all the answers
What must be adjusted to ensure a colored product is unaffected by environmental changes?
What must be adjusted to ensure a colored product is unaffected by environmental changes?
Signup and view all the answers
Which is not a requirement for a colored product in spectrophotometric determination?
Which is not a requirement for a colored product in spectrophotometric determination?
Signup and view all the answers
What type of reagent is 2,4 dinitrofluorobenzene (DNFB)?
What type of reagent is 2,4 dinitrofluorobenzene (DNFB)?
Signup and view all the answers
What is the purpose of using DNFB in pharmaceutical analysis?
What is the purpose of using DNFB in pharmaceutical analysis?
Signup and view all the answers
Which drug is determined using NBD-Cl?
Which drug is determined using NBD-Cl?
Signup and view all the answers
What type of drugs can NQS help determine?
What type of drugs can NQS help determine?
Signup and view all the answers
Which of the following is a property of NQS?
Which of the following is a property of NQS?
Signup and view all the answers
What type of amines does DNFB react with?
What type of amines does DNFB react with?
Signup and view all the answers
For which drug is DNFB specifically mentioned as being applied?
For which drug is DNFB specifically mentioned as being applied?
Signup and view all the answers
Which of the following describes the primary use of NBD-Cl?
Which of the following describes the primary use of NBD-Cl?
Signup and view all the answers
What role can gatifloxacin play in an oxidation-reduction reaction?
What role can gatifloxacin play in an oxidation-reduction reaction?
Signup and view all the answers
Which of the following ions is involved in the formation of Prussian Blue?
Which of the following ions is involved in the formation of Prussian Blue?
Signup and view all the answers
What is one application of spectrophotometry mentioned in the content?
What is one application of spectrophotometry mentioned in the content?
Signup and view all the answers
How is the determination of ferrous ions achieved in colorimetric methods?
How is the determination of ferrous ions achieved in colorimetric methods?
Signup and view all the answers
Which metal ion is NOT mentioned in relation to spectrophotometric analysis of gatifloxacin?
Which metal ion is NOT mentioned in relation to spectrophotometric analysis of gatifloxacin?
Signup and view all the answers
What is produced when ferricyanide is reduced during the oxidation of paracetamol?
What is produced when ferricyanide is reduced during the oxidation of paracetamol?
Signup and view all the answers
Which statement about the applications of spectrophotometry is accurate?
Which statement about the applications of spectrophotometry is accurate?
Signup and view all the answers
What is the primary requirement for a substance to be used in colorimetric determination?
What is the primary requirement for a substance to be used in colorimetric determination?
Signup and view all the answers
Study Notes
Instrumental Analysis (PMC 205) - Spectrophotometry (Lecture 4)
-
Lecture Objectives:
- Understand applications of spectrophotometry in qualitative analysis
- Understand applications of spectrophotometry in quantitative analysis of organic and inorganic compounds
- Learn selected examples for determination of pharmaceutical compounds by spectrophotometry
Applications of UV-VIS Spectrophotometry
- UV-VIS spectrophotometry is widely used in chemical and clinical labs. It has many advantages, including versatile application to many organic and inorganic compounds and various biochemical species.
- It's also easy, simple, and rapid, compared to other sophisticated techniques.
- Spectrophotometry has high accuracy (1% to 3% relative error).
- Selectivity is moderate to high, depending on the wavelength.
- Spectrophotometry is highly sensitive, ranging from 10-6 to 10-4 M.
Absorption by Organic Species
- Organic compounds with chromophores (carbonyl, azo, nitro, conjugated diene, and aromatic rings) have characteristic absorption bands in the UV or visible range.
- Conjugation between chromophores shifts absorption maxima to longer wavelengths and increases absorption intensity.
Absorption by Inorganic Species
- Absorption spectra of most inorganic ions or molecules resemble organic compounds.
- Absorption by inorganic species depends on:
- Oxidation state of the element
- Position in the periodic table
- Type of ligand bonded to the ions.
- Many inorganic compounds are colored and absorb light in the visible region.
Absorption by Charge-Transfer Complexes
- Charge-transfer absorption occurs in many inorganic and organic complexes.
- A charge-transfer complex has an electron-donor group attached to an electron-acceptor.
- Upon light absorption, an electron transfers from the donor to an orbital in the acceptor.
- Example: Ferric-thiocyanate complex.
Qualitative Analysis
- Molar absorptivity (ɛ) or specific absorbance (A) (1%-1cm) and the UV/VIS absorption spectrum help identify compounds.
- UV spectra alone are not sufficient to confirm identity; additional data like IR, NMR, MS, solubility, melting/boiling points are needed.
Absorption Characteristics of Common Organic Chromophores
- A table displays different chromophores, their examples, absorption maxima (λmax), and molar absorptivity.
Physical Constants and Spectra Data
- The absorption spectrum is a physical constant and, along with other data (melting & boiling points, refractive index, IR, NMR, and MS), helps characterize compounds.
- Absorption bands with specific shapes can indicate the presence of specific structural features.
Quantitative Analysis
- UV-visible molecular absorption spectrophotometry is a crucial quantitative analysis tool in pharmaceutical and biological fields.
- Methods are used for both direct measurements on absorbing compounds and derivatization of non-absorbing compounds to generate absorbing products.
- Methods also exist using various metal complex formations.
- Determination of drug concentrations using specific wavelengths is common.
Quantitative Determination of Inorganic Species
- Copper is determined via ammine complex formation.
- Determination of ferric is possible using thiocyanate charge-transfer complexes.
- Ferrous ions can be determined via 1,10-phenanthroline complex.
Determination of Ferrous
- Ferrous ions are determined after reacting with 1,10-phenanthroline, forming a complex with distinctive color.
- Calibration standards are used for finding the corresponding concentration.
Determination of Ferrous (using 2,2'-Bipyridyl)
- Ferrous ions react with 2,2'-bipyridyl to produce a red-colored complex, enabling quantitative determination.
Quantitative Determination of Organic Compounds
- Spectrophotometry determines quantities of organic substances (e.g., drugs).
- Pharmaceuticals (tablets, capsules, ampoules, vials) and biological fluids (plasma, urine) are common analyte types.
Requirements for Colored Products
- Strong color for high sensitivity is required.
- Stable products, unaffected by pH changes.
- Rapid, quantitative reaction and must obey Beer-Lambert's law.
Derivatizing Reagents and Examples
- Derivatizing reagents react with the analyte to produce a colored product, improving measurements of weakly absorbing compounds.
- 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-CI), for primary and secondary amines.
- 2,4-dinitrofluorobenzene (DNFB), for primary and secondary amines.
- 1,2-Naphthoquinone-4-Sulphonic Acid Sodium Salt (NQS) for primary and secondary amines.
Spectrophotometric Methods After Derivatization
- Methods help detect weakly absorbing compounds by generating colored products
- These techniques depend heavily on drug structure and functional groups.
Diazotization and Coupling for Aromatic Amines
- This two-step method analyzes drugs containing aromatic amines.
- Aromatic amines first react with a diazotization reagent. This creates diazonium salts and then coupling happens with a separate reagent to form visible Azo dye.
- Techniques are used for certain drugs.
Metal Complex Formation
- Metal complexation changes the color of some drugs.
- Such effects can aid in spectrophotometric analysis using metal ions.
Oxidation-Reduction Reactions
- Oxidation or reduction reactions between drugs and reagents create colored reaction products.
- The absorbance of these colored products is measurable by spectrophotometry to measure drug concentrations.
- Example: Paracetamol oxidation using Ferricyanide, creating Prussian blue.
Summary of Today's Learning
- Applications of spectrophotometry in qualitative and quantitative analysis were covered.
- Various examples on pharmaceuticals/inorganic species were discussed.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers Lecture 4 of PMC 205, focusing on the applications of UV-VIS spectrophotometry in both qualitative and quantitative analysis. Gain insights into how spectrophotometry is utilized for the determination of pharmaceutical compounds and understand its advantages in lab settings.
