Corresponding author: Md. Hossain Sohrab ( mhsohrab@bcsir.gov.bd ) Academic editor: Plamen Peikov
© 2020 Suriya Sharmin, Md. Hossain Sohrab, Fatema Moni, Farhana Afroz, Satyajit Roy Rony, Shammi Akhter.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Sharmin S, Sohrab MH, Moni F, Afroz F, Rony SR, Akhter S (2020) Simple RP-HPLC method for Aceclofenac quantitative analysis in pharmaceutical tablets. Pharmacia 67(4): 383-391. https://doi.org/10.3897/pharmacia.67.e57981
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A reverse phase liquid chromatographic method for estimation of Aceclofenac in bulk drug and tablet dosage form was developed and validated. The chromatographic conditions to achieve the highest performance parameters using octylsilyl column with guard filter were optimized. The separation was carried out using a mobile phase containing 10 mM Phosphate Buffer, pH 2.1 and methanol (30:70% v/v) pumped at a flow rate of 1.0 mL/min with detection at 272 nm. The method was shown to be linear in 19.8–148.5 μg/mL concentration range (regression coefficient of 0.999). The limit of detection (LOD) and limit of quantification (LOQ) was found to be 0.0692 μg/mL and 0.2076 μg/mL, respectively. The accuracy of the method was assessed by adding fixed amount of pre-analyzed sample to different standard solutions (80%, 100%, and 120% of the tested concentration) in triplicate. The percentage mean recoveries were 97.91% to 100.39% with %RSD values of 0.64–0.79. The method was found to be precise with %RSD value of 1.13 and 1.60 for intraday and interday precision study, respectively. The method specificity and robustness were also established. New and sensitive HPLC method for estimation of Aceclofenac has been developed, in respect to the reviewed analytical methods.
Aceclofenac, Octylsilyl column, 10 mM Phosphate Buffer, Method validation, Robustness
Aceclofenac (2-[(2,6-dichlorophenyl)amino]phenylacetoxyacetic acid) is a nonsteroidal anti-inflammatory drug (NSAID) of the phenylacetic acid group. Aceclofenac (ACF) [Fig.
Several methods utilized techniques like HPLC, UV-VIS Spectroscopy, GC, TLC etc. for quantification of ACF have been published as shown in Table
Sl No | Analytical Method | Method Condition/Mobile Phase/ Stationary Phase/Retention Time (Approximately) | Wavelength/Detector | Linearity Range | Reference |
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1 | HPLC | Methanol and 0.02% of orthophosphoric acid in the ratio of 70:30 (%, v/v); C18; 10 min | 275 nm | 1–100 µg/mL |
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2 | UV spectroscopy | Phosphate buffer saline of pH 7.4 as diluent | 273 nm | 0–20 µg/mL |
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3 | HPLC | Acetonitrile, methanol and water in the ratio of 60:28:12 (%, v/v) and pH of 7.0 adjusted with either glacial acetic acid and sodium hydroxide; C18; 6 min | 274 nm | 0.0138–0.370 µg/mL |
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4 | HPLC | Acetonitrile, methanol and phosphate buffer of pH 7.0 in the ratio 30:17:53 (%, v/v); C18; 13.8 min | 280 nm | 2–10 μg/mL |
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5 | GC | Injector temperature: 260 °C; Detector temperature: 300 °C; N2 flow rate: 5.0 mL/min; Make up flow: 30 mL/min; Split ratio: 10:1. Caffeine was used as internal standard (IS) | FID Detector (30 m X 0.53 mm; 1.5 µm) | 10–110 μg/mL |
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6 | Spectrophotometric method | Aceclofenac was reacted with 0.25% w/v solution of p-dimethyl-aminocinnamaldehyde (PDAC) in 1% v/v perchloric acid solution at 75 °C for 20 min and then diluted with methanol. | 665.5 nm | 20–100 μg/mL |
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HPLC | Methanol, acetonitrile and acetic acid (2% solution in deionized water) in the ratio of 100:150:250 (%, v/v/v) containing 0.3 ml triethylamine; C18; 8.8 min | 275 nm | 20–70 μg/mL | ||
Densitometric method | Chloroform, ethyl acetate and acetic acid in the ratio of 75:25:5, (% v/v/v). Calibration curve is obtained from area under the peak against the concentrations. | 254 nm and 275 nm | 1–10 μg/spot | ||
7 | Spectrophotometric method | Aceclofenac was reacted with p-dimethylamino-cinnamaldehyde and 1% perchloric acid at 90 °C for 10 min and then diluted with methanol. | 658 nm | 1–200 μg/mL |
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Aceclofenac was reacted with 3-Methyl-2-benzothiazolinone hydrazine hydrochloride and 0.1% ferric chloride for 20 min and then diluted with water. | 592 nm | 1–100 μg/mL | |||
8 | HPLC | Sodium phosphate buffer pH 5.0 and Acetonitrile in the ratio of 60:40 (%, v/v); C18; IS: Etoricoxib (ETC); 8 min | 275 nm. | 25–125 μg/mL |
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9 | HPLC | Mixed phosphate buffer pH 6.8 and acetonitrile in the ratio of 50:50 (%, v/v); C18; 8.5 min | 278 nm | 2–10 µg/mL |
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10 | UV spectrophotometry | Diluent: Methanol | 276 nm | 0–120 μg/mL |
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11 | Third-derivative spectrophotometry (D3) | Calibration curve was constructed from peak amplitude (height) against corresponding concentration for the linearity range of Aceclofenac solution in methanol. | 283 nm | 4–24 μg/mL |
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Ratio-spectra first-derivative (RSD1) spectrophotometry | The absorption spectra of Aceclofenac in the linearity range were divided by that of diclofenac sodium (25 mg/mL), and the ratio spectra were differentiated with respect to wavelength. Calibration curve was obtained by plotting the first-derivative values at 252 nm against the corresponding concentration. | 252 nm | 4–32 μg/mL | ||
Spectrodensitometric method of Thin-layer chromatogram | Chloroform, methanol and ammonia in the ratio of 48:11.5:0.5 (%, v/v/v) were used for TLC development. Calibration curve was constructed by plotting the area under the peak against the corresponding concentrations to develop the regression equation. | 274 nm | 2–10 µg/spot | ||
12 | Third derivative spectrophotometry | UV-spectrum of Aceclofenac solution was measured against absolute ethanol as a blank. The peak height at 242 nm was measured. The calibration curve was constructed with the measured peak height against the corresponding concentration. | 242 nm | 5–40 μg/mL |
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Ratio-spectra first-derivative (RSD1) spectrophotometry | Absorption spectra of Aceclofenac solutions were divided by the absorption spectrum of 5 mg/ml of the degradate. The ratio spectra thus obtained were smoothed and differentiated to determine first derivatives of the ratio spectra. The calibration curve was constructed between the measured first derivative values at 245 nm against the corresponding concentration. | 245 nm | 10–40 μg/mL | ||
pH-induced difference (ΔA) spectrophotometry | The difference in absorbance was observed between 0.1 N sodium hydroxide and 0.1 N hydrochloric acid solution of Aceclofenac. Calibration curve was constructed by plotting the difference in absorbance against respective concentration. | 273 nm | 15–50 μg/mL | ||
Quantitative densitometric evaluation of thin layer chromatogram | Tetrahydrofuran and methanol (90:10, % v/v) was used for TLC development. Calibration curve was constructed by plotting the area under the peak against the corresponding concentrations. | 275 nm | 50–200 μg/mL | ||
HPLC | Methanol and water in the ratio of 60:40 (%, v/v); C18; 8 min | 230 nm | 1–50 μg/mL | ||
13 | HPLC | 0.01 M ammonium acetate buffer with 2 ml (%, v/v) triethylamine and acetonitrile in the ratio of 68:32 (%, v/v) and pH was adjusted to 6.5 with glacial acetic acid; C8; 6.5 min | 270 nm | 8–16 µg/mL |
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14 | HPLC | 0.07% of orthophosphoric acid and acetonitrile in the ratio of 68:32 (%, v/v) at pH 7.0 ± 0.05; C18; 6 min | 275 nm | 160–240 µg/mL |
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15 | Microwave assisted spectrophotometry | Aceclofenac was reacted with ammonium molybdate in presence of sulfuric acid under microwave irradiation for 5 min. | 740 nm | 50–250 µg/mL |
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All weighing were done on Electronic balance (A & D Company Ltd, Japan). Digital pH meter (SENSION+, Spain), bath sonicator (Wisd Laboratory Instrument, Germany) were also used in this study. UV-Vis spectra were recorded on a Specord 250 plus PC double beam spectrophotometer using 1.0 cm quartz cells. High purity deionized water was obtained from Millipore, Milli-Q (Merck KGaA, Darmstadt, Germany) water purification system. Assay test was performed with a HPLC (Hitachi High – Tech Science Corporation, Tokyo, Japan) machine with pump (Hitachi chromaster 5110), autosampler (Hitachi chromaster 5210) and PDA Detector (Hitachi chromaster 5430). LC separations were performed on a C8 column (250 × 4.6 mm i.d., 5 μm particle size), LaChrom, Hitachi, Japan with C8 guard column (23 mm X 4 mm; 3 µm), LaChrom, Hitachi, Japan. Data was integrated using Agilent open lab control panel CDS software. The mobile phase consisted of 10 mM Phosphate Buffer, pH 2.1 and methanol in 40:60%, v/v. The flow rate was set to 1.0 mL/min and UV detection was carried out at 272 nm at 25 °C.
The 0.25-µm PTFE filters were obtained from Chromafil Xtra (Macherey Nagel GmbH & Co. AG., Germany). Working standards of pharmaceutical grade ACF (batch no. 28296) was supplied as a gift sample by Beximco Pharmaceutical Ltd (Dhaka, Bangladesh). Marketed ACF 100 mg tablets (Square Pharmaceuticals Ltd.) were purchased from local drug store. All chemicals and reagents of analytical grade were purchased from Active Fine Chemicals, Dhaka, Bangladesh.
10 mM phosphate buffer was prepared by dissolving 0.64 gm potassium dihydrogen phosphate and 0.4 mL phosphoric acid to 900 mL deionized water. pH of the solution was adjusted to 2.1 with dilute phosphoric acid solution if necessary. The final volume was then adjusted to 1000 mL with deionized water.
Commonly used excipients were mixed at appropriate amount to obtain the placebo mixture as Table
Stock solution of ACF was prepared in methanol (≈50 µg/mL) and the UV spectrum was taken in the range of 200–400 nm to obtain the wavelength for maximum absorbance (λmax) of Aceclofenac. As Aceclofenac (pKa≈3.4) is a strongly acidic drug, pH 2.1 was chosen as the buffer pH for mobile phase preparation. Mobile phase was taken as 10 mM phosphate buffer of pH 2.1 and methanol in the ratio of 30:70 (%, v/v). Solvent stability was checked at approximately 100 µg/mL concentration for consecutive five days in the mobile phase by determining the relative standard deviation (%RSD) of response and peak purity of the drug. The described method has been validated for response function, accuracy, repeatability and intermediate precision.
Standard stock solution at 1 mg/mL concentration was prepared in mobile phase by dissolving it first on not more than 5% of methanol. Sample stock solution was prepared by crushing randomly selected 10 tablets. Average weight equivalent sample was taken in volumetric flask to obtain concentration of approximately 1 mg/mL. Sample was also first dissolved in not more than 5% of methanol. The final volume was adjusted with mobile phase. The concentration for assay preparation was approximately 100 µg/mL. Drug content was determined using Equation 1.
(Eq. 1)
The linearity of the method was established by determining linear regression equation from the calibration curve of ACF. The calibration curve was prepared using six different concentration levels in triplicate ranging from 20% to 150% of the assay preparation of analyte. For this, a stock solution (1 mg/mL) of the drug was prepared in mobile phase using not more than 5% of methanol initially. A range of concentrations (19.8–148.5 µg/mL) were then prepared after suitable dilution of the prepared stock with mobile phase.
LOD and LOQ were separately determined based on the signal to noise ratio as per ICH guidelines (ICH Q2 R1. 2005).
Accuracy of the method was determined by performing the recovery experiment of standard addition method at three concentration levels in triplicate (
The precision of the instrument (RSD) was checked by repeated scanning of samples (n = 6) for ACF standard without changing the parameter of the proposed method.
To determine the intra-day and inter-day precision of the method, the drug solution at assay concentration (100 µg/mL) was prepared (n = 6) in one laboratory on the same day (1st, 3rd, and 6th hour) and also on five different days from the same standard stock solution. The concentration was calculated from the areas obtained and the results were expressed as relative standard deviation (%RSD).
Specificity was determined by checking the chromatograms of blank, placebo, standard and sample solution for interference with analyte peak, as well as through determination of peak purity for the drug in the presence of degradation products.
At first different placebo concentration were spiked with nominal concentration of drug substance and then different concentration level of drug were spiked with fixed placebo concentration to determine the peak response (
Robustness was determined by changing the different method parameters like mobile phase composition, pH of buffer, column temperature, mobile phase flow rate and detector wavelength.
Six replicate injection of ACF standard solution at assay concentration was checked for tailing factor, theoretical plate, retention time, capacity factor and relative standard deviation of response to establish suitability of the method in the instrument.
The wavelength for maximum absorbance of ACF was found to be at approximately 275 nm (Fig.
Marketed tablets were analyzed through the developed method which showed 101.78% of ACF with 0.186 of %RSD. The proposed method was found to be linear with a correlation coefficient of 0.999 (Table
Evaluation of linearity, Limit of Detection (LOD) and Limit of Quantitation (LOQ).
λmax. (nm) | Regression equation (y = mx + c) | Linearity range (µg/mL) | Residual sum of squares | Correlation coefficient | Baseline Noise in rms | S/N for LOD | S/N for LOQ |
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275 | 74894x + 94097 | 19.8 to 148.5 | 2.213 | 0.999 | 218.7 | 3.005 | 9.36 |
The baseline noise value was obtained from the software (Table
The mean recoveries were 97.91% to 100.39% substantiated the method as accurate (Table
Level | Theoretical Conc. (µg/mL) | Peak area | Actual Conc. (µg/mL) | % Recovery | % RSD |
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80% | 101.16 | 7553140 | 100.64 | 99.48 | 0.64 |
101.16 | 7618998 | 101.52 | 100.36 | ||
101.16 | 7525643 | 100.28 | 99.13 | ||
100% | 121.36 | 8984771 | 119.72 | 98.65 | 0.66 |
121.36 | 8917608 | 118.83 | 97.91 | ||
121.36 | 9034943 | 120.39 | 99.2 | ||
120% | 141.55 | 10664687 | 142.11 | 100.39 | 0.79 |
141.55 | 10737296 | 143.07 | 98.94 | ||
141.55 | 10644064 | 141.83 | 100.2 |
Sample No. | Repeatability | Intermediate Precision | |||
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Intra – day | Inter – day | ||||
1 | 102.83 | 1st hour | 102.57 | 1st day | 103.70 |
2 | 99.86 | 3rd hour | 101.40 | 2nd day | 101.22 |
3 | 101.73 | 8th hour | 102.68 | 3rd day | 102.53 |
4 | 102.48 | – | – | 4th day | 99.86 |
5 | 101.73 | – | – | 5th day | 103.59 |
6 | 101.69 | – | – | – | – |
Mean | 101.721 | 102.216 | 102.181 | ||
SD | 1.025 | 0.579 | 1.464 | ||
%RSD | 1.007 | 0.567 | 1.432 |
The developed analytical method should be specific for ACF assay in presence of all the potential matrix components which was checked by evaluating the peak responses and peak purity of the standard, sample, excipient and mobile phase (blank) solutions in assay concentration (Fig.
Concentration (%) | |||||
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Initial | 8 hour (80 °C) | 24 hour (80 °C) | 48 hour (80 °C) | ||
Standard | : | 100.16 | 100.72 | 103.28 | 103.13 |
Sample | : | 96.18 | 100.49 | 97.81 | 97.48 |
Fixed drug substance spiked with different concentration of excipient | Fixed excipient spiked with different concentration of drug substance | ||||
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Nominal drug substance concentration (µg/mL) | Excipient concentration (µg/mL) | Absorbance | Nominal excipient concentration (µg/mL) | Drug substance concentration (µg/mL) | Absorbance |
87.693 | 128.72 | 6705872 | 160.9 | 70.154 | 5428265 |
144.81 | 6664433 | 78.923 | 5898186 | ||
160.9 | 6707371 | 87.693 | 6873075 | ||
176.99 | 6784787 | 96.462 | 7506926 | ||
193.08 | 6805847 | 105.231 | 8074567 | ||
RSD = 0.881% | Regression equation, y = 78699x - 145122 | ||||
R² = 0.9892 |
The change in organic solvent of ±2% [Buffer/68–72(%, v/v) Methanol] significantly changed the peak retention time from 22.40–12.41 min, although the %RSD of the peak response was found to be 0.83. The method was found to be robust for pH variation of the buffer solution from 1.7 to 2.5 (%RSD of 0.45 for the peak response), although the retention time (Rt) changed from 11.09 to 12.52 min. For the change in column temperature from 20–25 °C the retention time changed from 14.23–12.27 min with acceptable %RSD (0.63) of the peak response. Flow rate of mobile phase was changed from 0.8 to 1.2 mL/min. The Rt and peak response of ACF both changed significantly for change of flow rate from 0.9 to 1.1 mL/min. Robustness of the method was checked for change in wavelength from 270–280 nm. The method was found to be robust for 272–278 nm with %RSD of 1.39 for peak response. The method conditions at which response were most stable was shown in Fig.
Robustness Study (a) Variance of peak area for change in different method parameters with %RSD; (b) Variance of Retention time for change in different method parameters with %RSD. *Method was robust for change in pH of mobile phase (±0.5), wavelength (±3 nm) and column temperature (±3 °C).
In this study a simple RP-HPLC-DAD method for use in routine estimation of ACF in bulk drug and tablet dosage form has been developed and validated. The accuracy, precision and specificity of the method have been established, with determination of the method parameters up to which the method was found to be stable.