Simultaneous Estimation of Cefixime and Ofloxacin in Bulk and ...

Asian J. Pharm. Ana. 2011; Vol. 1: Issue 2, Pg 36-38
A 2 ay 1 -A 1 ay 2
C Y = --------------------- ---------------------- (2)
ax 2 ay 1 -ax 1 ay 2
Where, A1 and A2 are absorbance of the sample at 290.4nm
and 297.4 nm respectively, ax 2, ax 1 = denote absorptivities
of X at 290.4 nm and 297.4nm respectively, ay 1 ,ay 2 =
denote absorptivities of Y at 290.4 nm and 297.4nm
respectively, CX = concentration of cefexime; CY =
concentration of ofloxacin.
Method B. Absorbance Ratio Method:
It depends on the property that, for a substance which obey
Beers law at all wavelengths is constant value independent
of concentration or path length.
From the following set of equations the concentration of
each component in sample can be alculated.
For Cefixime:
Qm – Qy
A1
Cx = -------------- X ----- ---------------------- (3)
Q x – Qy a
For Ofloxacin:
Qm – Qx A1
CY= ------------- X ------ ---------------------- (4)
Qy – Qx a
Where, Cx = Concentration of Cefixime, CY =
Concentration of Ofloxacin, A1 = Absobance of sample at
iso-absorptive wavelength 282.0 nm, a = Mean absorptivity
of CEFI and OFLO at iso-absorptive 282.0 nm,
Absorbance of sample solution at290.4nm
Qm = ____________________________________
Absorbance of sample solution at 282.0 nm
Absorptivity of Cefixime at290.4 nm
Qx = ____________________________________
Absorptivity of Cefixime at 282.0 nm
Absorptivity of Ofloxacin at 297.4 nm
Qy = ____________________________________
Absorptivity of Ofloxacin at 282.0 nm
Spectral characteristics of CEFI and OFLO:
Solutions of CEFI and OFLO (10 g/ml, each), were
prepared separately by appropriate dilution of standard
stock solution. Both the solutions were scanned in the
spectrum mode from 400 nm to 200 nm. Overlay absorption
spectra were recorded (Fig. 1).
Preparation of calibration curves
Appropriate dilutions of the standard stock solution were
done separately to get 5,10,15,20, and 25 g/ml of CEFI
and 2, 4, 6, 8, and 10g/ml of OFLO. The absorption
[AJPAna.]
spectra of all solutions were recorded between 200-400 nm.
The absorbances were measured at 290.4 nm (max of
CEFI) 297.4 nm (max of OFLO) and 282.0 nm (isoabsorptive
point).Beer’s lamberts range for CEFI and
OFLO were selected and working calibration curves of both
the drugs were plotted separately.
Determination of Absorptivity Value of CEFI and
OFLO:
Appropriate dilutions of the standard stock solution were
done to get 10 g/ml of each CEFI and OFLO, respectively.
The absorbances were measured for CEFI and OFLO at
290.4 nm (max of CEFI), 297.4 nm (max of OFLO) and
282.0 nm (iso-absorptive point). The absorptivity values of
the drugs were determined at the selected wavelengths.
Assay of tablet formulation:
Twenty tablets were weighed and average weight was
calculated. The tablets were crushed to obtain fine powder.
Tablet powder equivalent to 100 mg of CEFI was
transferred to 100.0 ml volumetric flask, ethanol added,
ultrasonicated for 10 minutes and volume was made-up to
the mark with ethanol. The solution was then filtered
through a Whatman filter paper (No. 41). The filtrate was
further diluted with ethanol to obtain 10 g/ml of CEFI and
10 g/ml of OFLO. The concentration of both CEFI and
OFLO were determined by measuring the absorbance of the
sample at 290.4 nm, 297.4 nm Calculated using (method A,
simultaneous equation method) and (method B, absorbance
ratio method). Concentration of sample solution was
determined by using above equations1, 2,3 and 4.The
results are reported in the Table 1.
RESULTS AND DISCUSSION:
The present method could be provided a convenient and
accurate method for simultaneous analysis of CEFI and
OFLO. In simultaneous equation method, wavelengths
selected for analysis were 290.4nm (max of Cefixime) and
297.4 nm (max of Ofloxacin). In both the methods
linearity for detector response was observed in the
concentration range of 5-25 g/ml for CEFI and 2-10 g/ml
for OFLO. Absorptivity coefficient were calculated for both
the drugs at selected wavelengths and substituted in
equations for determining concentration of CEFI and OFLO
in tablet sample solution. Percent label claim for CEF and
OFLO in tablet analysis, by both the method was found in
the range of 98.54 % to 100.5%. Standard deviation and
coefficient of variance for six determinations of tablet
sample, by both the methods, was found to be less than ±
2.0 indicating the precision of both the methods. Accuracy
of proposed methods was determined by recovery studies.
The percent recovery for CEFI and OFLO, the methods was
found in the range of 98.19 % – 100.45 %. The developed
method could be employed for routine analysis of Cefixime
and Ofloxacin in combined dose tablet formulation.
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