Method, Development and Validation for the Estimation of Magnesium Content in Esomeprazole-magnesium by Atomic Absorption Spectrophotometer

Introduction

Esomeprazole Magnesium Trihydrate is an official drug in USP [1] belongs to a category of proton pump inhibitor and is used in treating various acid related disorders [2]. Esomeprazole (Fig 1), is a S‐isomer  of omeprazole which  is  the  first drug in its category developed as a single optical isomer [3]. The literature review revealed that various analytical methods in single and combined dosage form involving spectrophotometer [4-6], RP-HPLC [7-14], HPTLC [15], UPLC [16], LC-MS [17]. Form the literature review it is found that there is no reported method for the estimation of Magnesium in Esomeprazole Magnesium as Magnesium excess and lower levels in body will cause hyper magnesaemia and hypomagnesaemia. In the present study a validated method is developed by using AAS to determine Magnesium content in Esomeprazole Magnesium Trihydrate.

Figure 1: Structure of Esomeprazole Magnesium Trihydrate Click here to View figure

 

Materials and Methods

Reagents

Esomeprazole Magnesium is obtained as a gift sample from varun herbals. Magnesium Standard Used in the study was purchased from Merck. Lanthanum Chloride and Hydrochloric Acid of Sd fine chem were used .and the water used is Milli Q Water

Working Standards and Solutions Preparation

Preparation of Lanthanum solution (4%)

Transfer 4 g of lanthanum chloride in to a 100 mL volumetric flask and add 50mL of Milli Q water and dilute up to volume with Milli Q water.

 Magnesium Standard Stock Solution Preparation

Pure 1000 µg/mL of Magnesium standard was purchased from NIST Traceable Material which is considered as stock solution A.

Transfer 0.5 mL of above Magnesium standard stock solution (1000 µg/mL) into a 20 mL volumetric flask and add 4 mL of 1 N hydrochloric acid and make up the volume with Milli Q water which is used as stock solution B. Transfer 0.1 mL, 0.2 mL, 0.3 mL, 0.4 mL and 0.5 mL of above stock solution B (25 µg/mL) to a separate 25mL volumetric flask add 1 mL of Lanthanum Chloride to each flask and dilute up to volume with Milli Q water i.e., 0.1 µg/mL, 0.2 µg/mL, 0.3 µg/mL, 0.4 µg/mL and 0.5 µg/mL of Magnesium respectively. From this solution a linear graph is plotted.

Sample Preparation

Take 100 mg of sample (Esomeprazole Magnesium) to a clean and dry 100 ml volumetric flask and add 20 ml of 1 N hydrochloric acid and dilute up to volume with Milli Q water which is considered as a stock solution A. Allow the solution to stand for 30 min after that transfer 0.25 ml of this solution to a 25 ml volumetric flask and add 1 mL of Lanthanum Chloride to each flask and dilute up to volume with Milli Q water.

Preparation of Blank

Transfer 1 mL of lanthanum Chloride solution to a 25 mL volumetric flask dilute up to the mark with Milli Q water and mix.

Instrumental Conditions

An AA-6300 atomic absorption spectrometer equipped with fully integrated atomizers of Shimadzu make was used for the analysis. The system was operated from an interfaced computer running Wizard software. The following are the optimal operating conditions for flame atomization of Magnesium are presented in table 1

Table 1: Optimal operating conditions for flame atomization of Magnesium

Element	Magnesium
Wavelength	285.2 nm
Read Time	10 Sec
Lamp Current	12 MA
Recommended Flame	Air-Acetylene
Fuel gas Flow	2.0
Support gas  Flow	17.0
Slit Width	0.2 nm
Signal type	Atomic Absorption
Atomization site	Burner Head
Equation	Linear through Zero
Flame Type	Air-Acetylene
Pre Spray time	3 sec
Integration time	5 sec

 

Results and Discussion

System Suitability

System suitability is a measure to ensure the performance of the system. The results obtained for standard deviation of absorption values (n=6) for Magnesium working standards were presented in Table 2 and was within range of acceptance criteria (%RSD ≤ 5).

Table 2: System Suitability

S.No	Magnesium Concentration (µg/mL)	Absorbance
1	0.4	0.3390
2	0.4	0.3397
3	0.4	0.3428
4	0.4	0.3458
5	0.4	0.3475
6	0.4	0.3453
Average		0.3434
SD		0.0035
% RSD		1.01

 

Specificity

Specificity is the ability to assess the analyte in sample with presents of unexpected other elements which interfere the results of analyte in sample. The results presented in table 3

Table 3: Specificity

Magnesium Concentration (ppm)	Wavelength	Average Concentration (n=6)
Blank Solution	285.2	0.0020
Standard Solution	285.2	0.3532
Sample Solution	285.2	0.3582

 

LOD

LOD is the lowest amount of analyte that can be detected which is determined by aspirating various concentrations with their respective absorbance shown in the table 4. Flow the below table the LOD was found to be 0.01 µg/mL

Table 4: Limit of Detection

S.No	Concentration	Absorbance
1	0.05 µg/mL	0.0241
2	0.04 µg/mL	0.0213
3	0.03 µg/mL	0.0170
4	0.02 µg/mL	0.0088
5	0.01 µg/mL	0.0059
6	0.005 µg/mL	– 0.0466

 

LOQ

LOD is the lowest amount of analyte that can be quantitatively determined with suitable precision and accuracy

LOQ = LOD * 3.3

= 0.01 * 3.3

= 0.03 µg/mL

Precision at LOQ Level

Precision reported as percentage relative standard deviation (%RSD) by aspirating the 0.033 µg/ mL Magnesium standard for 6 times. The results were presented in table 5 and were within range of acceptance criteria (%RSD ≤ 5).

Table 5: Precision at LOQ Level

S.No	Concentration	Absorbance
1	0.033 µg/ mL standard	0.0166
2	0.033 µg/ mL standard	0.0164
3	0.033 µg/ mL standard	0.0165
4	0.033 µg/ mL standard	0.0173
5	0.033 µg/ mL standard	0.0177
6	0.033 µg/ mL standard	0.0169
Average		0.0169
SD		0.005
%RSD		3.02

 

Linearity and Range

The concentration of standard solution is directly related and proportional to absorption in their lower and upper limits. The calibration curve is shown in fig. 2 and regression equation presented in table 6.

The range was plotted between Magnesium standard solution 0.03 µg/ mL to 0.5 µg/ mL (The range plotted from LOQ level to 150% with respect to sample solution). The results were presented in table 6 and were within range of acceptance criteria (Correlation Coefficient ≤ 0.99).

Figure 2: Calibration Curve Click here to View figure

 

Table 6: Calibration Curve

Concentration (µg/ mL)	Absorbance
0.0300	0.0165
0.1	0.1253
0.2	0.1818
0.3	0.2892
0.4	0.3537
0.5	0.4309
Correlation Coefficient	0.9929

 

Accuracy/ Recovery

Accuracy is the closeness of the test results obtained by the method to the true value which was obtained by spiking 50%, 100% and 150% of Esomeprazole Magnesium working standard concentrations, in triplicates and accuracy/ recovery was shown in Table 7. The results were presented in table 7 and was within range of acceptance criteria (Accuracy/ %Recovery in between 80 % – 120% ) and the %RSD for 3 spiked sample preparation should be NMT 5%).

Table 7: Accuracy

S.No	Sample	% Recovery	%RSD
1	50 % Spiked	91.85	1.84
2	100 % Spiked	95.02	1.62
3	150 % Spiked	97.89	0.38

 

Sample Analysis

The sample was prepared and aspirated as per the above method and the Magnesium content (on anhydrous basis) found in the given sample is 3.48 % which is within acceptance criteria (USP NF 40).

Conclusion

In the present study a validated simple, accurate, and precise method is developed to determine the content of Magnesium in Esomeprazole Magnesium bulk drug. The allowed Magnesium content is present between 3.30 % to 3.55 % on anhydrous basis (USP NF 40). The sample which is analyzed by using the method developed is 3.48 % so the Magnesium content in the given sample is inacceptable range.

References

1. United States Pharmacopeia NF 40.
2. Andersson, T.; Hassan-Alin, M.; Hasselgren, G.; Rohss, K.; Weidolf, L. Clin Pharmacol .2001,  40, 411-426
   CrossRef
3. Lind, T.;  Rydberg,  L.;  Kyleback,  A.; Jonsson,  A.;  Andersson, T.;  Hasselgren,  G.;  Holmberg,  J.;  Rohss,  K. Aliment Pharmacol. Ther.  2000,14,861‐867
   CrossRef
4. Patil, S. S.; Dhabale, P. N.; Kuchekar, B. Asian Journal of Research in Chemistry,2009,2 , 154–156
5. Gawande, V. V.; Chandewar A. V.; International Journal of Pharmacy & Technology, 2010, 2, 617–622
6. Prabu, S.L.; Shirwaikar, A.; Shirwaikar, A.; Kumar, C.D.; Joseph, A.; Kumar, R. Indian J Pharm Sci,  2008, 70, 128-31.
   CrossRef
7. Dilip, G.; Maheshwari.; Trivedi, P. D. Int. J Appl Sci Eng, 2011, 9, 187-94.
8. Deepak Kumar, J.; Nitesh, J.; Rita, C.; Nilesh, J. Pharm Methods, 2011, 2, 167–72.
   CrossRef
9. Imran, A.; Jat R.K.; Rambir, S.; Srivastava, V.; Srivatsava S. Int Res J Pharm, 2012, 3,111-113.
10. Zarna, D.; Ronak, D.; Vaishali, K.; Vidya Sagar, G.; Meeta, B.; Sheth, N. R. Asian J Research Chem, 2009, 2,108-111.
11. Meyyanathan, S.N.; Nagasamy Venkatesh, D.; Krishnaveni, N.; Babu, B.; Jeyaprakash, MR.; Rajanikanth, B. R. Int J Health Allied Sci, 2012, 1, 129-32
    CrossRef
12. Onal, A.; Oztunç A. Journal of Food and Drug Analysis,2006, 14, 12–18
13. Sripal Reddy, P.; Sait, S.; Vasudev murthy, G.; Vishwanath, B.; Prasad, V.; Jayapal Reddy, S. Der Pharma Chemica, 2011, 3, 553–564
14. Shetty, R.; Subramanian, G.; Kumar, R.A.; Pandey, S.; Udupa, N. Indian Drugs, 2005, 42, 158-161.
15. Sharma, S.; Sharma, M. C. American—Eurasian Journal of Toxicological Science, 2011, 3,143–148.
16. Nalwade, S. U.; Reddy, V. R.; Rao, D.D.;  Morisetti, N.K. J. Pharm. and Biomed, 2012, 57, 109-114.
    CrossRef
17. Hultman, I.; Stenhoff, H.; Liljeblad, M. J Chromatography B, 2007, 848, 317-22.
    CrossRef

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This work is licensed under a Creative Commons Attribution 4.0 International License.