Instrumental Analysis Methods PDF

Chapter One Part 1: Introduction to Instrumental Methods of Analysis What is Analysis? A detailed examination of anything complex in order to understand its nature or to determine its essential features Classification of analytical methods...

Chapter One Part 1: Introduction to Instrumental Methods of Analysis What is Analysis? A detailed examination of anything complex in order to understand its nature or to determine its essential features Classification of analytical methods (1) Classical methods or Chemical analysis: rely on chemical reactions to perform an analysis. And Do not require highly advanced techniques– Carried out using ordinary lab glassware and equipment  Titration (2) Instrumental analysis: is a field of analytical chemistry that investigates analyte (Quantitative and Qualitative) using scientific instruments depending on physical property. Chemical vs. Instrumental analysis Chemical Instrumental Questions answered by analytical chemistry Two major types of questions: (1) Does the sample contain substance X? or What is the identity of the substance in the sample?  Qualitative analysis (2) How much of substance X is in the sample (in numerical terms)?  Quantitative analysis Pharmaceutical analysis The application of analytical methods in order to identify a drug (single or combined) in its bulk or pharmaceutical dosage form What is an analytical Sample? An analytical sample comprises both (1) The analyte, which is the specific substance of interest (2) The matrix, which is the broader composition of the sample containing the analyte along with other components. Unknown sample Analytical samples For example, in analyzing the amount of hemoglobin in blood, hemoglobin is the analyte, and all other blood constituents apart from hemoglobin is the matrix. Samples: representative of the population SELECTIVITY!!!! Pharmaceutical Product Composition Any pharmaceutical product formulation is based on raw materials Natural products (leaves, flower, fruits …) Raw materials Synthetic materials – manufactured in the lab  Pharmaceutical Product Composition Pharmaceutical Products Active pharmaceutical ingredient (API) Excipients Additives The active pharmaceutical Building blocks of the API Added to give special qualities of ingredient is the part of any drug the formulation. that produces the intended effects Pharmacologically No therapeutic value, but Therapeutic Effect inactive substances necessary for the manufacturing of different dosage form We need to separate the component of interest Why we moved from chemical analysis to Instrumental analysis? More sensitive in certain types of samples More selective in certain types of samples Example: Analyzing aspirin in raw material vs. blood (using titration)??? Classification of Instrumental methods of analysis 1) Spectrophotometric methods 2) Chromatographic methods 3) Thermal methods 4) Other Miscellaneous methods Classification of Instrumental methods of analysis Spectroscopy: is a general term for the science of the interactions of radiation (electromagnetic radiation) with matter. Chromatography comprises a group of powerful separation methods Chapter One Part 2: Instruments for Analysis Basic principle: An instrument for chemical analysis converts information about the physical or chemical characteristics of the analyte to information that can be manipulated and interpreted by a human. To retrieve the desired information from the analyte, it is necessary to provide a stimulus, The stimulus results in an interaction between the stimulus and the analyte. Then a response from the system under study results whose nature and magnitude are measurable. Components: Generally, instruments for chemical analysis comprise just a few basic components: 1. Signal generator 2. An input transducer (Detector) 3. A signal processor 4. An output transducer or readout device The flow of information through the instrument 1 1- Signal generator In spectroscopic methods:  Signal generators play a vital role in generating the input signals or light sources that interact with the sample being analyzed.  Source of energy that interacts with analyte.  1) There are light sources that emit non-specific wavelengths (a broad range of wavelengths across the electromagnetic spectrum). Example: Tungsten and Xenon Lamps: These are common light sources for UV-Vis and UV-Vis-NIR spectrophotometers.  2) There are light sources that emit specific wavelengths of light. 1- Signal generator  Monochromators: are optical devices used to select and isolate a narrow range of wavelengths from a broader spectrum of light.  Monochromators consist of several key components, including:  An entrance slit (Adjustable)  Dispersive element (usually a prism)  And an exit slit. 1 2 Interaction between matter and EMR 2- Types of interaction: Matter can interact with electromagnetic radiation in various ways, and these interactions are fundamental to the field of spectroscopy: Absorption Emission Transmission Scattering 3- Analytical signals: 1 3 2 Interaction between matter and EMR 3- Analytical signals: Interactions between matter (samples or substances under study) and electromagnetic radiation  lead to changes in the intensity, frequency, or wavelength of the radiation, which are detected as analytical signals. Example: absorption spectra(attenuated light beam), emission spectra Analytical signals provide information about the sample 4- Input transducer (Detector) 1 3 4 2 Interaction between matter and EMR 4- Input transducer (Detector) A transducer is a device that converts one kind of signal to another. Detectors: convert analytical signals to an electric current Examples: Examples of Detectors 1. Photocell and Photomultiplier Tube (PMT)  Convert light (photons) to electrons  When exposed to light, they produce an electrical current proportional to the intensity of the light. 2. Electrode  Convert chemical potential to electrical potential 5- Signal processor 1 3 4 5 2 Interaction between matter and EMR 5- Signal processor The signal processor modifies the transduced signal from the detector in such a way as to make it more convenient for the operation, it analyze, interpret and manipulate electrical signals come from the detector The most common modifications are: Amplification Attenuation Filtered to reduce noise Mathematical Conversion Conversion from current into voltage 6- Output Transducer (Readout device) 1 3 4 5 6 2 Interaction between matter and EMR 6- Output Transducer (Readout device)  A readout device is a transducer that converts a processed signal (electrical signal) to a signal that is understandable by a human observer.  Provide processed electrical output that gives accurate quantitative data about the analyte  Provide processed electrical output that gives accurate quantitative/qualitative data about the analyte