REVIEW ARTICLE Department of Quality Assurance Techniques
Parixit et.al / IJIPSR / 4 (3), 2016, 269-286 ISSN (online) 2347-2154
International Journal of Innovative Pharmaceutical Sciences and Research www.ijipsr.com UTILITIES OF INFRARED SPECTROSCOPY IN QUANTITATIVE ANALYSIS OF PHARMACEUTICALS 1
Chandani Chandarana, 1 Vishalkumar Modi, 1 Tarashankar Basuri, 1 Parixit Prajapati* SSR College of Pharmacy, Silvassa, U.T. of Dadra & Nagar Haveli-396230, INDIA
Abstract In pharmaceutical science IR spectroscopy has emerged as a powerful analytical Technique. This paper delineates IR including both FTIR and NIR as a Quantitative tool used now-a-days and some Qualitative applications of IR spectroscopy. This paper involves how IR is used for quantification of different pharmaceutical dosage Form. Associated with chemometrics, FTIR becomes a powerful tool for the pharmaceutical industry. Keywords: Fourier Transform Infrared Spectroscopy (FTIR), Near Infrared spectroscopy (NIR), IR Spectroscopic Techniques, Quantitative Analysis, Qualitative analysis, Chemometrics.
Corresponding Author: Parixit Prajapati Department of Quality Assurance Techniques, SSR College of Pharmacy, Silvassa, U.T. of Dadra & Nagar Haveli-396230, INDIA Email:
[email protected] Phone: +91 9913093760
Available online : www. ijipsr.com
March Issue
269
REVIEW ARTICLE Department of Quality Assurance Techniques
Parixit et.al / IJIPSR / 4 (3), 2016, 269-286 ISSN (online) 2347-2154
INTRODUCTION IR spectroscopy used for the determination of organic and inorganic compounds [1]. Based on the nature of interaction of the IR radiation with the vibrational modes of molecules, the changes in vibrational energy, accompanied by changes in rotational energy [2]. It is fast, inexpensive technique used to determine the chemical functional groups in the sample as different functional groups absorb at different frequencies of IR radiation so it is used in structure elucidation [3,4]. Wide ranges of sample types like solid, liquid and gas can be scanned from the range of 4000-400 cm-1. This energy range is higher than necessary to promote molecules only to lower than typical values and their lowest excited vibrational states necessary for electron excitation in molecules. By use of modern instruments, IR spectra of materials at low picogram level can be obtained [5, 6].
PRINCIPLE For absorption of IR, molecule has fulfill two conditions like correct wavelength of radiation and electric dipole [1]. When natural frequency of vibration of molecule is same as the frequency of incident radiation it absorbs IR and when molecule can cause change in its electrical dipole it’s absorb the radiation. The molecule which cannot change dipole movement, it cannot absorb IR [2]. IR spectra are obtained by detecting changes in transmittance or absorption intensity as a function of frequency. Most commercial instruments measure and separate IR radiation using Fourier transform spectrometers or dispersive spectrometers [6]. Regions of Infrared radiation The frequency region of the spectrum between 12500 cm-1 and 10 cm-1 is known as IR region. It is subdivided into three regions as follows: [3] Table 1: Ranges of IR radiation Ranges
Far Infrared
Middle Infrared
Near Infrared
Wavelength range (μm)
50 – 100
2.5 – 50
0.78 – 2.5
Wavelength number (cm-1)
200 – 10
4000 – 200
12500 – 4000
Frequency (υ) Hz
6 × 1012 - 3 × 1011
1.2 × 1014 - 6 × 1012
× 1014 - 1.2 × 1014
Available online : www. ijipsr.com
March Issue
270
REVIEW ARTICLE Department of Quality Assurance Techniques
Parixit et.al / IJIPSR / 4 (3), 2016, 269-286 ISSN (online) 2347-2154
INSTRUMENTATION OF IR [1] IR radiation sources: IR instruments require a source of radiant energy which emits IR radiation which must be intense enough for detection, extend over the desired wavelength andsteady. Various sources of IR radiations are as follows: 1. Nernst glower 2. Incandescent lamp 3. Mercury arc lamp 4. Tungsten lamp 5. Glober source 6. Nichrome wire
Fig. 1: Instrumentation of IR spectroscopy [10] Monochromators: Monochromators are mainly of two types: a) Prism monochromator: Prism is generally made up of various metal halide salts which transmit in the IR. It is used as a dispersive element. Sodium chloride must be used as a prism salt. Generally single pass and double pass monochromators are used. b) Grating monochromator: by replacing the prism higher dispersion can be produced by grating monochromator. It is made up of the material like aluminum which is not attacked by moisture. It can be used over considerable ranges. Sample cells and sampling of substances: IR spectroscopy has been used to characterize solid, liquid or gas samples as follows: i. Solid: Various techniques are used for preparing solid samples such as pressed pellet technique, solid films, solid run in solution, solid films, mull technique etc. Available online : www. ijipsr.com
March Issue
271
REVIEW ARTICLE Department of Quality Assurance Techniques
Parixit et.al / IJIPSR / 4 (3), 2016, 269-286 ISSN (online) 2347-2154
ii. Liquid: samples can be held using a liquid sample cells which are made of alkali halides. Aqueous solvents will dissolve alkali halides so they cannot be used. Only chloroform as an organic solvent can be used. iii. Gas: sampling of gas is similar to the sampling of liquids. Detectors: For measurement of the intensity of unabsorbed infrared radiation Detectors are used. Detectors like thermocouples, Bolometer, thermistor, Golay cell, and pyro-electric detectors are used. DIFFERENT IR SPECTROSCOPIC TECHNIQUES Different techniques used to acquire IR spectra are described as follows like FTIR, ATR, specular reflectance, DRIFT and NIR [11]. Fourier Transform Infrared spectroscopy (FTIR): FTIR is a qualitative and quantitative tool for analyzing pharmaceutical Dosage form. The FTIR involves an Interferogram which is a complex signal contains all the frequencies that make the IR spectrum which is in a Time-domain spectrum which is converted into the frequency-domain spectrum. This mathematical operation is known as Fourier transforms (FT). So, this instrument is known as FTIR. When performing FT, a spectrum with a better signal-to-noise ratio can be plotted on the sum of accumulated interferograms. Here, two mirrors are used moving mirror and fixed mirror. The energy passes through a beam splitter, one mirror which is placed at a 45 angle to the radiation, which allows the incoming radiation pass through it but it separates into two perpendicular beams, one is undeflected and other one oriented at 90 0 angle. It goes to fixed mirror and return to beam splitter. Thus, the combined beam containing constructive and destructive interferences. Which is called the interferogram [9].
Fig. 2: FTIR spectrophotometer Available online : www. ijipsr.com
March Issue
272
REVIEW ARTICLE Department of Quality Assurance Techniques
Parixit et.al / IJIPSR / 4 (3), 2016, 269-286 ISSN (online) 2347-2154
Attenuated Total Reflectance (ATR technique): ATR spectroscopy mostly used for hard materials, flat surfaces and a piece of art which cannot be put into an IR cell because of non transparency of the material. The system consists of a thimble of material that is transparent to IR such as NaCl or KBr. ATR is mostly used in qualitative and quantitative IR analysis of opaque material. It is also used to monitor organic reactions. The samples which cannot be handled by IR methods like stains, glues, paints, varnishes are analyses by this method.ATR uses total internal reflection, so an evanescent wave is generated. A beam of IR light is passed through the ATR crystal as it reflects at the internal surface in contact with the sample. This reflection forms the evanescent wave which extends in the sample. The penetration depth in the sample is typically between 0.5 and 2 micrometers, with the exact value being determined by the angle of incidence, wavelength of light and the indices of refraction for the ATR crystal. By varying the angle of incidence the number of reflections may be varied. Then the beam is collected by a detector.
Fig. 3: multiple reflection of ATR system For liquid sample: pouring a shallow amount over the surface of the crystal is sufficient. For solid sample: solid samples are usually clamped against the ATR crystal because the evanescent wave into the solid sample is improved with a more intimate contact, so trapped air is not the medium through which the evanescent wave runs, so that would distort the results. The signal to noise ratio obtained depends on the number of reflections and on the length of the optical light path which dampens the intensity. So that a common claim that more reflections give better sensitivity cannot be made one advantage of ATR over transmission-IR, is the limited path length into the sample. This avoids the problem of strong attenuation of the IR signal in highly absorbing media like aqueous solutions. Available online : www. ijipsr.com
March Issue
273
REVIEW ARTICLE Department of Quality Assurance Techniques
Parixit et.al / IJIPSR / 4 (3), 2016, 269-286 ISSN (online) 2347-2154
Fig. 4: ATR spectrophotometer Specular Reflectance: This method is generally used to measure thin coatings. It consists of a mirror like reflection and it produces reflection measurements for a reflective material. The thin surface coatings having grazing angle and angle of incidence are analyses in the ranges from nm to µm.
Fig. 5: Specular Reflectance spectrophotometer Diffuse Reflectance (DRIFT spectra): This technique is generally used for measuring IR spectra of solids like paper, coal and powders. It is an alternative approach for pressed-pellet techniques. It consists of reflection accessories which are used to collect the diffusely scattered light by ellipsoidal mirrors, while eliminating the specular reflectance, which make complications in IR spectra. This technique is called as DRIFTS.
Fig. 6: DRIFT spectrophotometer Available online : www. ijipsr.com
March Issue
274
REVIEW ARTICLE Department of Quality Assurance Techniques
Parixit et.al / IJIPSR / 4 (3), 2016, 269-286 ISSN (online) 2347-2154
Specular vs. Diffuse Reflection: Specular reflection is defined as light reflected from a smooth surface like mirror, any irregularities in the surface are small compared to the wavelength at a definite angle, whereas diffuse reflection is diminished by rough surfaces so the light reflect in all directions. There are more occurrences of diffuse reflection than specular reflection in everyday environment. NIR spectroscopy NIR spectroscopy covers a broad range of Industrial Qualitative and Quantitative methods of Analysis Spectral region 12500-4000 cm-1 is known as NIR. NIR being derived from the first, second, and third overtones of the fundamental region and Combination bands, all attributed to information from the mid-IR.NIR spectroscopy is typically used for quantitative measurement of organic functional groups like O-H, N-H, and C=O. its applications include, polymer, pharmaceutical, clinical and agricultural analysis. It consists of a source, a detector, and a dispersive element like prism or Grating for recording the intensity at different wavelengths [12]. FT-NIR is non-destructive, it requires no sample preparation, making it reliable and quick for quantitative and qualitative analysis. FT-NIR is a powerful analysis tool capable of accurate multi-component quantitative analysis for identification of raw material rapidly. Its instruments are also used for wavelengths above 1000 nm. Silicon-based CCDs are used as a detector which are suitable for the shorter end of the NIR range, but are not sensitive over most of the range over 1000 nm [13].
Fig.7: Range NIR spectrophotometer QUALITATIVE APPLICATIONS OF IR SPECTROSCOPY IN PHARMACEUTICALS [1] IR spectroscopy is mainly used for chemical investigations. Some qualitative applications are discussed as follows: Identification of substances: IR spectroscopy is used for Identification of organic substance with another one. If two samples have identical spectra under same conditions of measurement. It must be the sample of similar substance. Conditions which involves are physical state of the samples, concentrations of Available online : www. ijipsr.com March Issue 275
REVIEW ARTICLE Department of Quality Assurance Techniques
Parixit et.al / IJIPSR / 4 (3), 2016, 269-286 ISSN (online) 2347-2154
solutions and the solvents used. The characteristic IR absorption region of some important bands is available like alkenes, aldehydes, ethers, aromatic compounds, ketenes, alkynes, alcohols and amines. Determination of molecular structure: IR spectroscopy is useful in determining molecular structure of unknown substances.By examining the positions of absorption bands in the spectra, the establishment of nature of groups present in the molecules is done. Determination of the progress of reaction: The progress of chemical reactions can be seen by small portions of reaction mixture withdrawn time to time which gives the rate of disappearance or increasing absorption bands. Interpretation of IR spectrum can be useful for determination of reaction which gives products or not. Detection of Impurity The impurities of sample can be determined by comparing the spectra with reference spectrum of pure compound. The spectrum of crude sample is not so sharp. So, it can be determine. In Pharmaceutical Industry: IR spectroscopy can be used to determine impurities in raw material. It is also used for the Identification of materials made by competitors. It can be useful for quality control for checking the composition and the percent present of the product. QUANTITATIVE APPLICATIONS OF IR IN PHARMACEUTICALS: Table 2: Quantitative determinations by FTIR spectroscopy: Sl. No.
Analyte
Sample form
Functional group
Absorptio n band 1242 cm
1
Atenolol
Tablet
C–O Stretch
2
Ampicillin Sodium
Powder for Injection
C=O
1700 cm-1
Ceftazidime
Powder for Injection
Aromatic ring
14751600 cm-1
3
Available online : www. ijipsr.com
−1
March Issue
Remarks The correlation coefficient value was 9989. The mean percentage recovery was 99.76 ±0.185. This validated method is able to quantify ampicillin sodium in powder for injection preparation and can be used as a routine analysis in quality control. Calibration curve was obtained at 0.5 to 7.0 mg and mean recovery percentage was 98.98 ± 0.70.
Ref. [14]
[15]
[16]
276
REVIEW ARTICLE Department of Quality Assurance Techniques
Parixit et.al / IJIPSR / 4 (3), 2016, 269-286 ISSN (online) 2347-2154
4
Ciprofloxacin Hydrochloride
Tablet
C=O
1707 cm
5
Cilnidipine
Tablet
C=O
1697 cm-1
6
Disulfiram
Tablet
-HC=N-
914 cm-1
Tablet
C=O
1717 cm-1 (dmp) 1656 cm-1 (par)
8
Domperidone and omeprazole
Tablet
C=O (dmp) And C=N ( omp)
9
Domperidone and Ranitidine
Tablet
-NH (ran) C=O (dmp)
7
Domperidone and Paracetamol
-1
1717 cm1 (dmp) 1627 cm1 ( omp) 1717 cm-1 (dmp) 1620 cm1 (ran)
10
Efavirenz
Tablet
C=O
1750 cm-1
11
Furosemide
Tablet
S=O
1390– 1290 cm-1
Available online : www. ijipsr.com
March Issue
The percent recovery of ciprofloxacin in three tablet dosage forms was found to be in the range of 98.76 ± 0.27. The %RSD was less than two with recovery levels 99.8102.5 and 99.8-101.4 as per absorbance and peak area respectively. The suggested methods of IR and HPLC were compared with each other and also with official method in BP 1999 for DSF. The results were compared with student’s t test and fisher F test statistically and indicated that they were statistically insignificant. The results obtained with FTIR showed good correlation with UV-Spectrophotometric method. The method was found to be highly precise with high recovery levels (>99%). The method was found to be highly precise with %RSD99.
The method was found to be precise with high recovery levels (>99%). The coefficient of determination, LOD and LOQ was found to be 0.993, 49.12 μg/mL and 148.84 μg/mL respectively. Results were compared with the results obtained with the existing UV method by using t-test, which indicated that there is no significant difference between the methods at P=0.05. The method fulfilled most validation requirements in the 2 mg/mL and 20 mg/mL range, with a 0.9998
[17]
[18]
[19]
[20]
[21]
[22]
[23]
[24]
277
REVIEW ARTICLE Department of Quality Assurance Techniques
Parixit et.al / IJIPSR / 4 (3), 2016, 269-286 ISSN (online) 2347-2154
12
Lorazepam
Tablet
C=O
1704 cm-1
13
Paracetamol
Tablet
C=O
1650 cm-1
14
Ibuprofen
Tablet
C=O
1721.5 cm−1
15
Roxithromycin
Tablet
C=O
1765 to 1705 cm−1
1261 cm−1
16
Simethicone
Suspension and Tablet
symmetric stretching of CH -Si and CH rocking
17
penicillamine
vapor samples
CO band
2170 cm−1
18
zidovudine
Tablet
azide
2086.8 cm−1
19
amisulpride
Tablet
S=O
1057 cm−1
Available online : www. ijipsr.com
March Issue
coefficient of results obtained by simple calibration model, and coefficient of variation
