Attenuated total reflectance spectroscopy

attenuated total reflectance

1. ATTENUATED TOTAL REFLECTANCE SPECTROSCOPY Presented by : Kolli Chaitanyalakshmi M.Pharmacy 1 st semister under the guidance of Dr. K. Shanta kumari , H.O.D Department of pharmaceutical analysis Nirmala college of pharmacy

2. contents Introduction instrumentation Sample analysis Applications Conclusion References

3. INTRODUCTION Attenuated total reflectance (ATR) spectroscopy is a versatile and powerful technique for infrared spectroscopy which enables samples to be examined directly in the solid or liquid state with out further preparation Inkanti madam

4. Instrumentation of atr Internal reflection spectroscopy passes infrared radiation through an infrared transmitting crystal of high refractive index greater than the sample, allowing radiation to reflect in the crystal one or more times Provided the refractive index of the prism, is greater than that of the sample medium, and if the angle ø is greater than the critical angle, the infrared light beam will suffers the total internal reflectance Attenuated total reflection accessory measures the totally reflected infrared beam when the beam comes and contact with a sample

5. In this way, an evanescent wave penetrates into the sample in contact with crystal, producing a spectrum of sample EVANESCENT WAVES : The infrared radiation interacts with the sample through a series of standing waves, called as evanescent waves. An evanescent wave is a penetrating electromagnetic field whose intensity quickly decays as it moves a way from its source

6. Atr data collection When collecting ATR data, samples are run as %reflectance or log (1/R). % reflectance equivalent to absorbance

7. Crystal materials and cleaning CRYSTAL COMPOSITION: Crystals are typically made of Germanium ( Ge ) Zinc sulfide (Zs) Silicon Diamond AMTIR: germanium, arsenic, selenium ( GeAsSe ) Zinc selenide ( znse ) or mixed thbr and thl

8. There are a number of crystal materials available for ATR. Zinc Selenide ( ZnSe ) and Germanium are most commonly used ZnSe scratches quite easily and so care must be taken when cleaning the crystal. It is recommended that lint free tissue is used.

9. Sample analysis ANALYSING LIQUIDS: After the crystal has been cleaned and an infrared background has been collected, the liquid is simply poured on to the crystal. The whole crystal must be covered if performing a qualitative or quantitative analysis.

10. ATR is an ideal technique for analysing liquids. Sample preparation is minimal. Cleanup is easy and fast. ATR can be used to analyse non-aqueous solutions such as oils, lubricants, paints, glues, solvents, inks, dyes, gels and pastes.

11. ANALYSING SOLIDS : It is an excellent technique for measuring the composition of solids. Some examples of solids are films, fabrics, paper, hard polymer sheets, glass, rubber. ATR is an ideal technique for measuring dark coloured which often absorb too much energy to be measured by IR transmission.

12. Powder analysis : Powders are easier to run by ATR than by IR transmission, because little or no preparation is required. This category includes pure samples and mixtures that are available in powdered form. Some examples of pure samples and mixtures pharmaceuticals and pigments.

13. applications Biological industries Pharmaceutical industries Medicinal industries Chemical industries includes measurement of drugs during manufactured by fermentation of methods, following the kinetics of metabolism of dietary constituents, investigation of detergents and cosmetics, or identification of contaminants in waste water, etc. Using ATR combined with spectral summation the infrared spectra of solutes, Very dilute aqueous solutions can be measured.

14. Future applications Forensic investigation Biomedical applications

15. conclusion ATR is an easy to use, fast and versatile technique for IR sampling. Solids , pastes, gels, powders, liquid can be analysed with little or no preparation.

16. references Organic spectroscopy by william kemp http://www.slideserve.com/glenda/attenuated-total-reflection-spectroscopy http://www.utsc.utoronto.ca/~traceslab/ATR_FTIR.pdf https://en.wikipedia.org/wiki/Attenuated_total_reflectance