Research Article

Austin J Anal Pharm Chem. 2018; 5(2): 1102.

# Application of Different Spectrophotometric Methods for Determination of Aspirin and Omeprazole in Pharmaceutical Preparation

Nassar MWI^{1}, Attia KAM^{1}, Mohamed AA^{1},
Morshedy S^{2} and Shahin M^{2}*

¹Analytical Chemistry Department, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt

²Pharmaceutical Analysis Department, Faculty of Pharmacy, Damanhour University, Damanhour, Egypt

***Corresponding author: **Mohamed Shahin,
Pharmaceutical Analysis Department, Faculty of
Pharmacy, Damanhour University, Damanhour, Egypt

**Received: **June 29, 2018; **Accepted: **September 12, 2018; **Published: **September 19, 2018

## Abstract

Three spectrophotometric methods have been developed for determination of aspirin and omeprazole in their new pharmaceutical dosage form. The zero order absorption spectra of aspirin and omeprazole show severe overlap. Second derivative, simultaneous equation and area under the curve spectrophotometric methods have been applied to resolve this overlapping through using different mathematical manipulations. The described methods has been validated with respect to linearity, limits of detection and quantification, accuracy, precision and specificity. Also, they have been applied for the determination of aspirin and omeprazole in their new pharmaceutical preparation.

**Keywords:** Aspirin; Omeprazole; Quantitative analysis

## Introduction

Yosprala tablet, a new combination of Aspirin (ASP), Figure 1 and Omeprazole (OPZ), Figure 2 was recently approved to protect high risk patient of developing aspirin-associated gastric ulcers [1].

**Figure 1:**Structure formula of ASP.

Figure 1:Structure formula of ASP.

**Figure 2:**Structure formula of OPZ.

Figure 2:Structure formula of OPZ.

In this work three validated simple spectrophotometric methods
have been developed for determination of ASP and OPZ in their pure
and pharmaceutical dosage form. The described methods namely
second derivative (^{2}D), simultaneous equation (SE) and area under
the curve (AUC) [2-4].

## Experimental

## Materials and reagents

Pure ASP (99.25%), OPZ (99.75%) and Yosprala® tablets nominally containing 81mg of ASP/40mg of OPZ per tablet were kindly supplied by National Organization for Drug Control and Research, Giza, Egypt. Ethyl acetate, methanol, and toluene, HPLC grade (Sigma-Aldrich, Germany).

## Apparatus

Shimadzu UV-Visible 1650 Spectrophotometer, (Tokyo, Japan), equipped with 10mm matched quartz cells.

## Standard solutions

A standard solution of 100μg/mL of ASP and OPZ was prepared by dissolving 10mg of the drug powder in 50mL of methanol using a two separated 100-mL volumetric flask and completing to volume with methanol.

## Procedures

**General procedures:** Different aliquots of ASP and OPZ standard
solutions (100μg/mL) were transferred to 10 ml volumetric flasks
ranging from (20–140) μg for ASP and (4–20) μg for OPZ then
volume completed with methanol. The absorption spectra (from
200 to 400 nm) of these solutions were recorded using methanol as a blank.

For ^{2}D method, the second derivative corresponding to each
absorption spectrum of each drug was recorded, using Δλ = 8nm and
scaling factor 70. The amplitude values were measured at 242nm for
ASP and 318nm for OPZ.

For SE method, the absorbance values at 275nm (Λ_{max} of ASP) and
302nm (Λ_{max} of OPZ) were recorded. Absorbance and absorptivity
coefficient values were used for calculating the concentration of ASP
and OPZ in their mixture using these equations:

where: A_{1} and A_{2} are absorbance of samples at 275 and 302 nm
respectively, a_{x1} and a_{x2} are absorptivity values` of ASP at 275nm
and 302nm respectively, a_{Y1} and a_{Y2} are absorptivity values of OPZ at
275nm and 302nm respectively, C_{x} is the concentration of ASPC_{y} is
the concentration of OPZ.

For AUC method: areas under curve [for the selected wavelength ranges 260-270 nm and 280-290 nm] were recorded. Areas under curve and area absorptivity values were used for calculating the concentration of ASP and OPZ in their mixture using equations these equations:

where AUC^{X} _{λ1- λ2} and AUC^{X} _{λ3- λ4} are area under curve for ASP at the wavelength range 260- 270 and 270-280, respectively. AUC^{Y} _{λ1- λ2} and AUC^{Y} _{λ3- λ4} are area under curve for OPZ at the wavelength range 260- 270 and 270-280, respectively. AUC^{X} _{λ1- λ2} and AUC^{X} _{λ3- λ4} are absorptivity values for ASP at the wavelength range 260- 270 and 270-280, respectively. AUC^{Y} _{λ1- λ2} and AUC^{Y} _{λ3- λ4} are absorptivity values for OPZ at the wavelength range 260- 270 and 270-280, respectively.

**Analysis of laboratory prepared mixtures:** Into serious of 10ml
volumetric flasks an accurate aliquots equivalent (20–140) μg and
(4–20) μg for ASP and OPZ respectively were added together and
volumes were completed with methanol. These laboratory mixtures
were analyzed using the general procedures of each method.

**Analysis of pharmaceutical formulation:** Five Yosprala® tablets
(81mg of ASP/40mg of OPZ per tablet) were weighed and powdered.
Appropriate weight of powder equivalent to one tablet was accurately
weighed, transferred to 100ml volumetric flask and the volume was
made up to 50ml with methanol. The solution was shaken vigorously
for 20min then sonicated for 30 min and filtered. The volume was
completed to 100ml with methanol to produce a stock solution
labeled to contain 0.81 and 0.4mg/ml of ASP and OPZ respectively.
Necessary dilutions of the stock solution were made with methanol
to obtain different concentrations of ASP and OPZ covering the
linearity range.

## Result and Discussion

The zero order absorption spectra of ASP and OPZ, Figure
3 show severe overlap which hindered the application of direct
spectophotonetric methods. ^{2}D, SE and AUC spectrophotometric
methods have been developed to severe overlapping of the absorption
spectra of ASP and OPZ without previous separation.

**Figure 3:**Zero-order absorption spectra of ASP (100μg/mL) OPZ (10μg/mL) in methanol.

Figure 3:Zero-order absorption spectra of ASP (100μg/mL) OPZ (10μg/mL) in methanol.

## Methods development and optimization

**Second derivative method:** The second derivative method
enabled determination of ASP and OPZ in their binary mixture. Two
factors have been checked to give the most accurate results. Several
delta lambda and scaling factor values were examined and it was
found that delta lambda= 8 and scaling factor= 70 were the best values
factors to give the most derivative spectra enabled the estimation of
the two compounds. A to f 242nm, ASP was determined without
any contribution of OPZ which cross zero line at this wavelength, as
shown in Figure 4. On the other hand, ASP cross zero line at 308nm
as shown in Figure 5, so the amplitudes at 308nm was proportional to
the concentrations of OPZ without any interference from ASP. The
measured amplitude values versus the final drug concentrations in
μg/mL were plotted to get the calibration graph and the regression
equation was derived for each one as shown in Table 1.

**Table 1:**Characterization and validation data for determination of ASP and OPZ by the proposed spectrophotometric methods.

Parameters

Second derivative

Simultaneous equation

Area under the curveASP

OPZ

ASP

OPZ

ASP

OPZ

Wavelength (nm)

242

308

276 and 302

260-270 and 280-290

Linearity

range (μg/mL)

20-140

4-20

20-140

4-20

20-140

4-20

Accuracy (%R)

^{a}100.093

99.04

99.78

99.69

98.77

100.23

Precision

(%RSD)

^{a}Repeatability

0.934

0.87

0.87

0.721

0.658

0.524

Intermediate

precision

1.043

0.987

0.987

1.023

0.871

0.742

^{a}Values for 3 determinations of 3 different concentrations.

Table 1:Characterization and validation data for determination of ASP and OPZ by the proposed spectrophotometric methods.

**Figure 4:**Second derivative of absorption spectra of ASP (20- -140μg/ml) and OPZ (20μg/ml) in methanol.

Figure 4:Second derivative of absorption spectra of ASP (20- -140μg/ml) and OPZ (20μg/ml) in methanol.

**Figure 5:**Second derivative of absorption spectra of OPZ (4- 20μg/mL) and ASP (20μg/mL) in methanol.

Figure 5:Second derivative of absorption spectra of OPZ (4- 20μg/mL) and ASP (20μg/mL) in methanol.

**Simultaneous equation method:** For quantitative estimation
of ASP and OPZ, absorbance values were recorded at 275nm and
302nm. The absorptivity coefficient values of each component at both
wavelengths were determined. Then the absorbance and absorptivity
coefficient values were used for calculating the concentration of ASP and OPZ in their mixture using equations 1&2 mentioned under the
general procedure. The characterization and validation of the method
were presented as shown in Table 1.

**Area under the curve method:** The area under the curve for
ASP and OPZ were recorded over wavelength ranges of 260–270
nm and 270–280 nm. The absorptivity values of ASP and OPZ were
determined at each wavelength range. The concentrations of ASP and
OPZ in their mixture using the equations 3&4 mentioned under the
general procedure. The characterization and validation of the method
were presented as shown in Table 1.

## Methods validation

The proposed methods were validated in compliance with the ICH guidelines. Table1 shows the LOD, LOQ, linearity and range also accuracy and precision of the proposed methods.

The validity of the proposed procedures is further assessed by applying the standard addition technique and the results indicated that no excipients interference. The results obtained were shown in Table 2. Table 3 shows the specificity; recovery of the laboratory prepared mixtures of the studied drugs.

**Table 2:**Recovery study of ASP and OPZ by adopting standard addition technique via the proposed spectrophotometric methods.

Drug

Pharmaceutical

Taken (&mug/mL)

Pharmaceutical found (&mug/mL)

Pure

added

(μg/mL)

Pure

found

(&mug/mL)

% RecoverySecond derivative

ASP

24.3

24.20

^{a}20

20.18

100.9

40

40.33

100.82

60

60.14

100.23

Mean± %RSD

100.65±0.366

OPZ

8

7.97

^{a}15

15.12

100.8

20

20.13

100.65

30

30.41

101.36

Mean± %RSD

100.93±0.374

Simultaneous equation

ASP

24.3

24.19

^{a}20

20.12

100.6

40

40.22

100.55

60

60.81

101.35

Mean± %RSD

100.83±0.448

OPZ

8

7.94

^{a}15

15.12

100.8

20

20.08

100.4

30

30.14

100.46

Mean± %RSD

100.55±0.216

Area under the curve

ASP

24.3

24.26

^{a}20

20.12

100.6

40

40.27

100.67

60

59.73

99.55

Mean± %RSD

100.27±0.627

OPZ

8

7.89

^{a}15

14.96

99.73

20

20.09

100.45

30

29.61

98.7

Mean± %RSD

99.63±0.879

^{a}Average of five determinations.

Table 2:Recovery study of ASP and OPZ by adopting standard addition technique via the proposed spectrophotometric methods.

**Table 3:**Determination of aspirin and omeprazole in laboratory mixtures by the proposed spectrophotometric methods.

Method

ASP (μg/mL)

ASP (μg/mL)

% Recovery of ASP

OPZ (μg/mL)

OPZ found (μg/mL)

% Recovery of OPZSecond derivative

8.1

7.99

98.64

4

3.95

98.75

16.2

16.45

101.54

8

7.9

98.75

24.3

24.23

99.71

12

12.1

100.83

32.4

32.68

100.86

16

16.04

100.25

Mean± %RSD

100.19±1.279

Mean± %RSD

9.65±1.061

Simultaneous equation

8.1

8.12

100.24

4

3.99

99.75

16.2

16.32

100.74

8

7.94

99.25

24.3

24.36

100.24

12

12.12

101

32.4

32.53

100.4

16

16.19

101.18

Mean± %RSD

100.41±0.233

Mean± %RSD

100.29±0.946

Area under the curve

8.1

8.13

100.37

4

3.97

99.25

16.2

16.41

101.29

8

7.98

99.75

24.3

24.19

99.54

12

12.21

101.75

32.4

32.48

100.24

16

16.11

100.68

Mean± %RSD

100.37±0.719

Mean± %RSD

100.35±1.102

Table 3:Determination of aspirin and omeprazole in laboratory mixtures by the proposed spectrophotometric methods.

## Application to pharmaceutical formulation

The quantitative analysis of ASP and OPZ in Yosprala® tablets was determined by the proposed methods. Satisfactory results were obtained in good agreement with the label claim, indicating no interference from excipients and additives as shown in Table 4.

**Table 4:**Determination of ASP and OPZ in Yosperala® tablets by the proposed spectrophotometric methods.

Parameters

Second derivative

Simultaneous equation

Area under the curve

ASP

OPZ

ASP

OPZ

ASP

OPZn

^{a}5

5

5

5

5

5

Average (%Recovery)

100.36

100.77

98.25

99.58

100.25

98.78

%RSD

0.75

0.51

0.98

0.87

0.62

0.52

Table 4:Determination of ASP and OPZ in Yosperala® tablets by the proposed spectrophotometric methods.

## Conclusion

In this work, three different spectrophotometric methods provide a simple, accurate and precise ways for quantitative analysis of aspirin and omeprazole in their pure and pharmaceutical dosage form. The suggested methods found sensitive and could be applied for routine analysis of studied drugs in the pure form or in the pharmaceutical formulation.

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