Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) for quantification of piroxicam in tablet dosage from as a green analytical method

Cite this paper: Vietnam J. Chem., 2020, 58(5), 615-621 Article 
DOI: 10.1002/vjch.202000049 
615 Wiley Online Library © 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH 
Attenuated total reflection-Fourier transform infrared 
spectroscopy (ATR-FTIR) for quantification of piroxicam in tablet 
dosage from as a green analytical method 
Nguyen Quoc Thang1*, Nguyen Thi Mai Tho1, Ho Ngoc Nga1, Nguyen Thi Kim Phuong2,3* 
1Chemical Engineering Faculty, Industrial University of Ho Chi Minh City, 
12 Nguyen Van Bao, Go Vap district, Ho Chi Minh City 70000, Viet Nam 
 2Institute of Resources Geography, Vietnam Academy of Science and Technology, 
01 Mac Dinh Chi, district 1, Ho Chi Minh City 70000, Viet Nam 
3Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 
18 Hoang Quoc Viet, Cau Giay district, Hanoi 10000, Viet Nam 
Submitted March 30, 2020; Accepted May 20, 2020 
Abstract 
A simple, rapid, precise, accurate, reproducible, economic and eco-friendly analytical method for the quantification 
of piroxicam in tablet dosage form, using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-
FTIR), has been developed. The measurements were based on the ATR technique, wherein there is no sample 
preparation, except for pulverizing the tablet, thereby eliminating the use of toxic chemicals or solvents. The calibration 
curve of piroxicam was obtained by performing a linear regression analysis, using data from the direct ATR-FTIR 
measurement of percentage transmittance (%T), corresponding to the secondary peak at 1526.38 cm-1 in the 
concentration (C) range of 25.18-93.63 mg/g. The linear regression equation obtained from the present data was 
represented by %T = -0.2178 C + 99.208 and was associated with a coefficient of determination (r2) of 0.998. The 
proposed method was validated for piroxicam in tablet form. The relative standard deviation percentage (%RSD) was 
found to be less than five, with a recovery percentage in the range of 96.0-99.3 %. 
Keywords. Piroxicam, ATR-FTIR, tablet dosage. 
1. INTRODUCTION 
The chemical structure of piroxicam (IUPAC name: 
4-hydroxy-2-methyl-1,1-dioxo-N-pyridin-2-yl-1λ6, 
2-benzothiazine-3-carboxamide) is shown in figure 
1. Piroxicam is used to reduce pain, swelling, 
and joint stiffness due to arthritis. It is a nonsteroidal 
anti-inflammatory drug (NSAID). Piroxicam acts by 
blocking the production of certain natural substances 
that cause inflammation in the human body.[1,2] 
 Figure 1: Chemical structure of piroxicam 
Several methods have been used for the 
quantification of piroxicam in pharmaceutical 
formulations, such as spectrophotometry, high-
performance liquid chromatography, voltammetry, 
differential pulse voltammetry, and capillary 
electrophoresis.[3-10] The disadvantages of these 
techniques are the need for large quantities of 
organic solvents, long analysis times and complex 
sample preparation steps. Organic solvents such as 
methanol, acetonitrile, trifluoroacetic acid, and 
borate buffer are not only very expensive, but also 
cause environmental damage. It is imperative to find 
an analytical method that is not only fast and 
accurate, but also does not cause environmental 
pollution, in order to comply with the principles of 
green chemistry. 
Nowadays, vibrational spectroscopic techniques 
are routinely being used for the authentication of 
pharmaceutical products.[11-18] They have also been 
applied extensively in the characterization, 
identification and quantification of medicines.[19, 20] 
Conventional Fourier transform infrared 
spectroscopy (FTIR) is one of the most traditional 
Vietnam Journal of Chemistry Nguyen Quoc Thang et al. 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 616 
techniques for identifying pharmaceuticals.[16,17] The 
use of FTIR requires skilled personnel because 
preparing samples for a transmission measurement is 
a rather complex task. The solid samples typically 
must be pulverized, finely diluted with the IR-
inactive KBr and then pressed into KBr-pellets, 
before analysis. The drawback of this approach is 
that it is time-consuming, requires continuous drying 
of KBr, and a hydraulic press to produce uniform 
KBr pellets. The use of attenuated total reflection 
(ATR) in combination with the FTIR technique is 
recommended in order to overcome these 
limitations. When ATR is used in conjunction 
with FTIR, samples can be examined straightaway, 
without further modification. All types of samples, 
including solids, liquids, powders, pastes, tablets, 
and fibers can be directly placed on the ATR crystals 
for measurement. In addition, the ATR-FTIR 
technique not only measures samples within a few 
seconds, but also provides excellent data quality, 
combined with high reproducibility. For these 
reasons, ATR-FTIR has been widely used as a tool 
in pharmacological research, pharmaceutical 
analysis, as well as in other scientific fields in recent 
years.[21-23] 
The main objective of this study was to develop 
a simple, rapid, cost-effective and environment-
friendly analytical method for the determination of 
piroxicam in marketed tablet dosages for routine 
quality control analysis, based on ATR-FTIR, 
without using any solvents or toxic chemicals and 
without any sample handling process. 
2. MATERIALS AND METHODS 
2.1. Material 
Pharmaceutical grade piroxicam and placebo were 
supplied from GLOMED Pharmaceutical Co., Ltd. 
lactose monohydrate, Plasdone S-630, benzoic acid, 
magnesium stearate and sodium starch glycolate 
were purchased from Merck (Darmstadt, Germany). 
2.2. Apparatus 
All spectra were recorded on the Jasco FT/IR-4700 
type A spectrophotometer (Japan) equipped with the 
ATR platinum diamond sampling stage to provide 
robustness and durability. The FTIR spectra we ... 
coefficient (r2) 
0.9987 
Standard error of 
regression 
3.18% 
Thus, ATR-FTIR method is completely aligned with 
the principles of green chemistry. That is, the 
piroxicam content can be evaluated, without the use 
of any solvent, whatsoever. 
To assess the linearity of the calibration curve, 
piroxicam was thoroughly mixed with powdered 
excipients. The piroxicam concentration was then 
analyzed in the range of 25.18–93.63 mg/g in 
triplicates. The calibration curve in this range was 
found to be linear, with the regression equation 
given by y = -0.2178x + 99.208 and a correlation 
coefficient (r2) of 0.9987 (see Figure 3 and Table 1). 
This regression equation was later used to estimate 
the concentration of piroxicam in the real samples.
Figure 3: (a) Transmittance spectra and (b) calibration curve for the piroxicam concentration in the 
range of 25.18-93.63 mg/g 
The precision of the method was expressed as 
the percentage of the relative standard deviation 
(%RSD). Repeatability was checked with multiple 
measurements of the spectrum over three days of 
two distinct types of piroxicam samples (standard 
and tablet) at a concentration of 20 mg, with 
subsequent calculation of the % RSD. These intra-
day and inter-day experiments were performed 
under the same operating conditions, in the same 
laboratory, for the same time period. As can be seen 
in table 2, the % RSD values for the precision 
studies are in the range of 2.53-3.15 % on day 1, 
1.05-1.92 % on day 2 and 1.36-2.84 on day 3. Both 
the intra-day and inter-day precision results were 
within the accepted limits, in accordance with ICH 
guidelines. 
The most common way to evaluate the accuracy 
of a proposed technique is the spike recovery 
method. In the present study, a known quantity of 
piroxicam (10.0, 15.0 or 20.0 mg) was spiked into 
Vietnam Journal of Chemistry Attenuated total reflection-fourier transform 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 619 
excipients. By comparing the amount of piroxicam 
found and the amount of piroxicam spiked, the 
recovery efficiency of the present method was 
calculated. The statistics of piroxicam recovery 
studies are compiled in table 3. The results indicate a 
high recovery performance (96.0-99.3 %) with an 
excellent %RSD (1.78-4.63 %) of the proposed 
method, which are within acceptable limits as 
specified by ICH guidelines. Furthermore, the 
recovery percentage values obtained here indicate 
that there is no significant interference effect from 
any excipient present in the matrix. This also implies 
that the method proposed here can be used to 
estimate the content of piroxicam, without any need 
for without solvent extraction. 
Compare to the result of reversed-phase high-
performance liquid chromatographic (RP-HPLC) 
method for the determination of piroxicam in tablets. 
Table 2: Results for the evaluation of precision of piroxicam (n = 6) 
Sample 
Amount 
added 
(mg) 
Day 1 Day 2 Day 3 
Amount 
found (mg) 
% RSD 
Amount found 
(mg) 
% RSD 
Amount 
found (mg) 
% RSD 
Standard 20.0 19.80±0.62 3.15 19.67±0.38 1.92 19.37±0.55 2.84 
Tablet 20.0 19.87±0.50 2.53 19.73±0.21 1.05 19.50±0.26 1.36 
Table 3: Recovery results of piroxicam from spiked samples (n = 5) 
Excipient (mg) Added amount (mg) Found amount (mg) Recovery (%) % RSD 
387.8 10.0 9.63±0.25 96.3 2.61 
386.4 10.2 9.80±0.26 96.1 2.70 
387.5 10.2 9.90±0.46 97.1 4.63 
387.1 15.1 14.90±0.30 98.7 2.01 
386.7 15.2 15.00±0.30 98.7 2.00 
387.9 14.9 14.80±0.30 99.3 2.03 
387.2 20.0 19.73±0.35 98.5 1.78 
386.9 20.1 19.27±0.42 96.0 2.16 
387.8 20.2 19.53±0.40 96.5 2.07 
3.2. Quantification of piroxicam in marketed 
tablet dosage 
The ATR-FTIR method developed and validated in 
this study was used to determine the quantity of 
piroxicam present in two different marketed brands. 
The results are summarized in table 4. The 
persistence of the peak around 1526 cm-1 in the 
FTIR spectrum of the marketed tablet dosages (see 
figure 4) confirmed that there was no significant 
interference due to the presence of excipients. The 
average recoveries of piroxicam in the two marketed 
tablet dosages are in the range of 95.6-97.4 % of 
what was claimed on the labels, with %RSD values 
in the range of 3.2-4.1 %. The recovery percentage 
of piroxicam is within acceptable limits (95-105 % 
in The British Pharmacopoeia Commission 
Secretariat of the Medicines and Healthcare 
Products Regulatory Agency).[29] This study 
demonstrates that the simple ATR-FTIR approach 
employed has the capacity to rapidly identify, as 
well as estimate piroxicam content in the presence of 
excipients. The whole process of crushing, 
identifying and quantifying the piroxicam content of 
a tablet would take about three minutes per tablet 
sample. 
Figure 4: FTIR spectrum of piroxicam in 
marketed tablet dosage 
The piroxicam level in two different marketed 
brands were determined using HPLC and FTIR 
method and the results of the independent-samples t-
Vietnam Journal of Chemistry Nguyen Quoc Thang et al. 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 620 
test were shown in table 5. Two significance level 
(2-tailed) in the table 5 were greater than 0.05, this 
usually concluded that piroxicam level means in 
HPLC and FTIR method were equal. The 
concentration of piroxicam in two marketed tablets 
were not significantly different between FTIR 
method and HPLC method. 
Table 4: The concentrations of piroxicam in marketed tablet dosage (n = 6) 
Marketed tablet Label claim (mg) Observed (mg) % RSD Recovery (%) 
Brand-1 20 19.12±0.14 3.2 95.6 
Brand-2 20 19.49±0.12 4.1 97.4 
Table 5: The independent-samples t-test compares the means of piroxicam level 
From HPLC and 
FTIR results 
Marketed tablet 
 t-test for equality of means 
HPLC method 
(mg) 
FTIR method 
(mg) 
t value 
Significance level 
(2-tailed) 
Brand-1 19.20±0.11 19.12±0.14 1.019 0.338 
Brand-2 19.31±0.13 19.49±0.12 2.282 0.052 
The method developed and validated in the 
present study emphasizes the accuracy and 
effectiveness of using ATR-FTIR spectroscopy to 
identify and analyze drugs. The most outstanding 
advantages of this method are enumerated below: 
(i) it is a fast analysis technique, 
(ii) sample preparation is not necessary, 
(iii) conforms to green chemistry standards, 
since no solvent or toxic chemical need be used, and 
(iv) has a remarkably high recovery efficiency 
(96.0 % to 99.3 %). 
4. CONCLUSIONS 
The ATR-FTIR is a useful, economical and eco-
friendly method to estimate piroxicam content in 
tablet dosage forms since it is simple, rapid, precise, 
and accurate, with no necessity for sample 
preparation and does not involve the use of any 
hazardous chemicals or solvents. The proposed 
method results showed that the calibration curve in 
25.18-93.63 mg/g range was found y = -0.2178x + 
99.208 and a correlation coefficient (r2) of 0.9987, 
the recovery performance was 96.0-99.3 %, the 
relative standard deviation was 1.78-4.63 %, less 
than 5 %, both the intra-day and inter-day precision 
results were in the range of 1.05-3.15 % on three day 
which were within the accepted limits. This is a 
well-established green standard method, which can 
be effectively used in the pharmaceutical industry 
for good manufacturing practice, research on drug 
release in semi-solid formulations and in vivo 
research. 
REFERENCES 
1. J. Kirschbam, in: K. Florey (Ed.), Analytical Profile 
of Drug Substances, Vol. 15, Academic Press, INC, 
New York, 1986. 
2. R. S. Vartanyan. Sintez osnovnykh lekarstvennykh 
sredstv (Synthesis of Main Pharmaceuticals), 
Meditsinskoe informatsionnoe agentstvo, Moscow, 
2004. 
3. A. S. Amin. Spectrophotometric determination of 
piroxicam and tenoxicam in pharmaceutical 
formulations using alizarin, J. Pharm. Biomed. Anal., 
2002, 29(4), 729-736. 
4. M. Mândrescu, A. F. Spac, V. Dorneanu. 
Spectrophotometric determination of piroxicam using 
ferric ferricyanide as reagent, Rev. Med. Chir. Soc. 
Med. Nat. Iasi., 2009, 113(1), 268-273. 
5. A. Bavili-Tabrizi. A Simple spectrofluorimetric 
method for determination of piroxicam and 
propranolol in pharmaceutical preparations, J. Food 
Drug Anal., 2007, 15(3), 242-248. 
6. A. D. Panainte, M. Vieriu, G. Tântaru, M. Apostu, N. 
Bibire. Fast HPLC method for the determination of 
piroxicam and its application to stability study, Rev. 
Chim.–Bucharest, 2017, 68(4), 701-706. 
7. A. Madhukar, V. S. Kumar, P. Anand, C. H. Samrat, 
T. Hemlatha, Mohd. T. Baba. Rapid analytical 
method development and validation of piroxicam by 
RP-HPLC, J. Chem. Pharm. Res., 2011, 3(3), 464-
469. 
8. A. R. Paniagua, M. D. Vázquez, M. L. Tascón, P. 
Sánchez ‐Batanero. Voltammetric determination of 
piroxicam after incorporation within carbon pastes, 
Electroanalysis, 1994, 6(3), 265-268. 
9. I. Y. Lopes de Macedo, L. F. Garcia, A. R. de Souza, 
W. T. Pio dos Santos, E. de Souza Gil, L. M. 
Cubillana-Aguilera, J. M. Palacios-Santander. 
Differential pulse voltammetric determination of 
piroxicam on lanthanide ferric oxide nanoparticles-
carbon paste modified electrode, Curr. Pharm. Anal., 
Vietnam Journal of Chemistry Attenuated total reflection-fourier transform 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 621 
2018, 14(3), 271-276. 
10. A. Gül Dal, Z. Oktayer, D. Doğrukol-Ak. Validated 
method for the determination of piroxicam by 
capillary zone electrophoresis and its application to 
tablets, J. Anal. Methods Chem., 2014, 2014, Article 
ID 352698, 7 pages. 
11. H. Ouhaddouch, A. Cheikh, M. O. B. Idrissi, M. 
Draoui, M. Bouatia. FT-IR spectroscopy applied for 
identification of a mineral drug substance in drug 
products: Application to bentonite, J. Spectrosc., 
2019, 2019, Article ID 2960845, 6 pages. 
12. D. Kowalczuk, M. Pitucha. Application of FTIR 
method for the assessment of immobilization of 
active substances in the matrix of biomedical 
materials, Materials, 2019, 12, 2972 
13. C. Siregar, S. Martono, A. Rohman. Application of 
Fourier transform infrared (FTIR) spectroscopy 
coupled with multivariate calibration for quantitative 
analysis of curcuminoid in tablet dosage form, J. 
Appl. Pharm. Sci., 2018, 8, 151-156. 
14. L. Sriphong, T. Rojanarata, C. Gasser, B. Lendl. At-
line analysis of pharmaceutical nanofiber-products 
using ATR-FTIR spectroscopy, Thai J. Pharm. Sci., 
2018, 42, 124-127. 
15. L. Hoellein, E. Kaale, Y. H. Mwalwisi, M. H. 
Schulze, U. Holzgrabe. Routine quality control of 
medicines in developing countries: Analytical 
challenges, regulatory infrastructures and the 
prevalence of counterfeit medicines in Tanzania, 
TrAC. Trends. Anal. Chem., 2016, 76, 60-70. 
16. P. Y. Sacré, E. Deconinck, T. De Beer, P. Courselle, 
R. Vancauwenberghe, P. Chiap. Comparison and 
combination of spectroscopic techniques for the 
detection of counterfeit medicines, J. Pharm. Biomed. 
Anal., 2010, 53, 445-453. 
17. D. Custers, T. Cauwenbergh, J.L. Bothy, P. Courselle, 
J.O. De Beer, E. Apers. ATR-FTIR spectroscopy and 
chemometrics: An interesting tool to discriminate and 
characterize counterfeit medicines, J. Pharm. Biomed. 
Anal., 2015, 112, 181-189. 
18. R. S. Ortiz, Kde C. Mariotti, B. Fank, R. P. 
Limberger, M.J. Anzanello, P. Mayorga. Counterfeit
Cialis and Viagra fingerprinting by ATR-FTIR 
spectroscopy with chemometry: Can the same 
pharmaceutical powder mixture be used to falsify two 
medicines?, Forensic Sci. Int., 2013, 226, 282-289. 
19. E. Sukkar. Taking stock of counterfeit medicines, 
Pharm. J., 2014, 292, 570-572. 
20. K. Kwok, L. S. Taylor. Analysis of the packaging 
enclosing a counterfeit pharmaceutical tablet using 
Raman microscopy and two-dimensional correlation 
spectroscopy, Vib. Spectrosc., 2012, 61, 176-182. 
21. A. A. Bunaciu, H. Y. Aboul-Enein, S. Fleschin. 
Application of Fourier transform infrared 
spectrophotometry in pharmaceutical drugs analysis, 
Appl. Spectrosc. Rev., 2010, 45(3), 206-219. 
22. S. E. Glassfor, B. Byrne, S. G. Kazarian. Recent 
applications of ATR FTIR spectroscopy and imaging 
to proteins, Biochim. Biophys. Acta., 2013, 1834(12), 
2849-2858. 
23. K. L. Andrew Chan, S. G. Kazarian. Attenuated total 
reflection Fourier-transform infrared (ATR-FTIR) 
imaging of tissues and live cells, Chem. Soc. Rev., 
2016, 45(7), 1850-1864. 
24. R. C. Rowe, P. J. Sheskey, M. E. Quinn. Handbook 
of Pharmaceutical Excipients, 6th ed., The 
Pharmaceutical Press, UK, 2009. 
25. World Health Organization. Quality assurance of 
pharmaceuticals, Vol. 2, 2nd ed., 2007. 
26. International Harmonised Tripartite Guideline (ICH), 
(Q2B), Harmonized Tripartite Guideline, Validation 
of analytical procedures: Methodology. Geneva: 
Proceeding of the International conference on 
Harmonization, 1996. 
27. M. K. Trivedi, S. Patil, H. Shettigar, K. Bairwa, S. 
Jana. Effect of biofield treatment on spectral 
properties of paracetamol and piroxicam, Chem. Sci. 
J., 2015, 6(3), 1-6. 
28. H. M. Stevens. Clarke's Isolation and Identification 
of Drugs, 2nd ed., Pharmaceutical Press, London, 
1996. 
29. The British Pharmacopoeia Commission Secretariat 
of the Medicines and Healthcare Products Regulatory 
Agency (MHRA), 2019. 
Corresponding authors: Nguyen Quoc Thang 
Industrial University of Ho Chi Minh City 
Hochiminh City Institute of Resources Geography 
12, Nguyen Van Bao, Go Vap, Ho Chi Minh City 
E-mail: nguyenquocthang@iuh.edu.vn; Tel.: +84- 983177314. 
Nguyen Thi Kim Phuong 
Institute of Resources Geography, VAST 
01 Mac Dinh Chi, District 1, Ho Chi Minh City 70000, Viet Nam 
nguyenthikimp@yahoo.ca; Tel.: +84- 909792142.