Department of Chemistry – R&D Center
Dr. C. Kavitha R&D Scientist has established an R&D (Chemistry) facility under the Research Project entitled “Graphene/Graphene Oxide – Nano particles hybrid Structures for SERS based optical Sensors.” Sponsored by DST-SERB at BMSIT.
The research lab is equipped with DST-SERB Sponsored Raman Spectrometer for Material/Nano material Characterization along with basic synthesis facilities. These Raman spectrometer facilities are open for characterization of samples from internal (BMSIT)/External institutions/Industry.
Usage of Raman Facility Norms
UV-Visible Spectrophotometer – Shimadzu UV-1800
A compact double beam UV-VIS spectrophotometer wrapped in a sleek form. The light source is Tungsten halogen lamp and Deutrium lamp. UV-1800 uses the Czerny-Turner mounting for its monochromator and boasts the highest resolution in its class, a bright optical system and a compact design available as either a standalone instrument or a PC controlled instrument. The UV-1800 is USB memory ready which enables users to save measurement data to highly versatile USB memory, and perform data analysis and printing using a PC.
Operation mode: Three Types of operation is available
- Spectrum mode
- DPhotometric mode
- Kinetic mode
Applications of UV-Visible Spectrophotometer
- Detection of Impurities
UV absorption spectroscopy is one of the best methods for determination of impurities in organic molecules. Additional peaks can be observed due to impurities in the sample and it can be compared with that of standard raw material. By also measuring the absorbance at specific wavelength, the impurities can be detected. Benzene appears as a common impurity in cyclohexane. Its presence can be easily detected by its absorption at 255 nm.
- Structure elucidation of organic compounds.
UV spectroscopy is useful in the structure elucidation of organic molecules, the presence or absence of unsaturation, the presence of hetero atoms. From the location of peaks and combination of peaks, it can be concluded that whether the compound is saturated or unsaturated, hetero atoms are present or not etc.
- Quantitative analysis
UV absorption spectroscopy can be used for the quantitative determination of compounds that absorb UV radiation. This determination is based on Beer’s law which is as follows.
A = log I 0 / I t = log 1/ T = – log T = abc = εbc
Where ε is extinction co-efficient, c is concentration, and b is the length of the cell that is used in UV spectrophotometer.
Other methods for quantitative analysis are as follows.
a. calibration curve method
b. simultaneous multicomponent method
c. difference spectrophotometric method
d. derivative spectrophotometric method
- Qualitative analysis
UV absorption spectroscopy can characterize those types of compounds which absorbs UV radiation. Identification is done by comparing the absorption spectrum with the spectra of known compounds. UV absorption spectroscopy is generally used for characterizing aromatic compounds and aromatic olefins.
- Dissociation constants of acids and bases
PH = PKa + log [A - ] / [HA]
From the above equation, the PKa value can be calculated if the ratio of [A - ] / [HA] is known at a particular PH. and the ratio of [A - ] / [HA] can be determined spectrophotometrically from the graph plotted between absorbance and wavelength at different PH values.
- Chemical kinetics
Kinetics of reaction can also be studied using UV spectroscopy. The UV radiation is passed through the reaction cell and the absorbance changes can be observed.
- Quantitative analysis of pharmaceutical substances
Many drugs are either in the form of raw material or in the form of formulation. They can be assayed by making a suitable solution of the drug in a solvent and measuring the absorbance at specific wavelength.
Diazepam tablet can be analyzed by 0.5% H2SO4 in methanol at the wavelength 284 nm.
- Molecular weight determination
Molecular weights of compounds can be measured spectrophotometrically by preparing the suitable derivatives of these compounds. For example, if we want to determine the molecular weight of amine then it is converted in to amine picrate. Then known concentration of amine picrate is dissolved in a litre of solution and its optical density is measured at λmax 380 nm. After this the concentration of the solution in gm moles per litre can be calculated by using the following formula:
"c" can be calculated using above equation, the weight "w" of amine picrate is known. From "c"and "w", molecular weight of amine picrate can be calculated. And the molecular weight of picrate can be calculated using the molecular weight of amine picrate.
Peak Seeker Raman Spectrometer
The Raman spectrum is recorded with PeakSeeker Pro TM Raman system. The sample has been excited with in built 785 nm wave length laser. The power of the laser is 5-300 mW. The size of the laser spot is 100 micron. It has TE-cooled, high efficiency CCD detector arrays. The detector array is cooled to -20 ºC. The sample has been kept in the vial holder. The instrument meets the stringent requirements of USP Monograph 1120 for resolution, sensitivity and stability. Deep blocking laser rejection filters obstruct Rayleigh scatter and isolate Raman scatter for valuable molecular analysis. The Raman spectra were recorded with RSIQ software. The resolution of the spectra is ∼ 6 cm-1. The accumulation time is 5 s.
Raman spectra applicable for:
- Characterisation of materials/Nanomaterials.
- Determination of composition and phase, Band gap determination, Material Quality, Impurity levels and defect detection.
Samples requirement for Raman spectrum: Solid diameter size > 100 micron, liqids > 2 ml, powders > 30 mg, Pellets dia > 100 micron. The sample should be filled approximately 2/3 of the below mentioned sample vials.
Examples of Raman spectra Recorded for known samples:
The Raman spectra have been calibrated and has good agreement with known samples found in the literature.
Procedure for recording Raman spectra:
Candidates interested in recording Raman spectra has to follow the below points
- First author/Corresponding Author should sent a request mail to email@example.com from their institute/Industry mail id. The mail should contain the following details.
Number of Samples:
Corresponding Author Official addres:
HOD/Corresponding author signature:
- BMSIT faculties are welcome to utilize our research facilities for their Ph.D work in a collaborative manner. Faculties are strictly adviced not to bring others sample for Raman characterization.
- For non BMSITans, the Raman Characterization is available for nominal payment basis
For an academic candidates - 5 samples/hour has to pay Rs. 1000
For an Industry candidates - 5 samples/hour has to pay Rs. 2000
- The payment will be in the mode of cheque/DD addressed to Principal, BMSIT, and Payable at Bengaluru. Further the candidates should acknowledge Raman facilitiy, R&D Chemistry, BMSIT in their publications.
- For non BMSITans, collaborative work will be considered only after brief discussion about their research work with first author/corresponding author.
- Chemistry Candidates who are interested in doing part time Ph.D under VTU can contact Dr. C. Kavitha, Scientist, Department of Chemistry R&D center, BMSIT, Bengaluru.
- Interested Out station candidates can courier their samples along with the DD to Dr. C. Kavitha’s Office address.
Raman Data: The Raman data has been mailed to first author/Corresponding authors mail id
Other research facilities available in R&D Chemistry Dept.
Dr. Ramakrishnappa T, HOD
Yelahanka, Bengaluru – 560 064.
Mail to : firstname.lastname@example.org
Dr. C. Kavitha, Scientist,
Yelahanka, Bengaluru – 560 064.
Phone: 080 28561576. Extn: 416
Mail to: email@example.com