Acta Pharm. 57 (2007) 211-220
Short communication
Use of ceric ammonium sulphate and two
dyes, methyl orange and indigo carmine, in the determination of lansoprazole in pharmaceuticals
KANAKAPURA BASAVAIAH1*,
VEERAIAH RAMAKRISHNA2 and URDIGERE RANGACHAR ANIL KUMAR1
basavaiahk@yahoo.com
1Department of Chemistry, University of Mysore,
Manasagangotri, Mysore-570 006, India
2Department
of Drugs Control, Govt. College of Pharmacy, Bangalore-560027, India
Two spectrophotometric methods are proposed
for the assay of lansoprazole (LPZ) in bulk drug and
in dosage forms using ceric ammonium sulphate (CAS)
and two dyes, methyl orange and indigo carmine, as reagents. The methods involve
addition of a known excess of CAS to LPZ in acid medium, followed by
determination of residual CAS by reacting with a fixed amount of either methyl
orange, measuring the absorbance at 520 nm (method A), or indigo carmine,
measuring the absorbance at 610 nm (method B). In both methods, the amount of
CAS reacted corresponds to the amount of LPZ and the measured absorbance was
found to increase linearly with the concentration of LPZ, which is corroborated
by the correlation coefficients of 0.9979 and 0.9954 for methods A and B,
respectively. The systems obey Beer’s law for 0.5–7.0 mg mL-1 and
0.25–3.0 mg mL-1
for methods A and B, respectively. The apparent molar absorptivities were
calculated to be 3.0 ´ 104 and
4.4 ´ 104 L
mol-1 cm-1 for methods A and B, respectively. The limits
of detection (LOD) and quantification
(LOQ) are calculated to be 0.08 and
0.25 mg mL-1
for method A, and 0.09 and 0.27 mg mL-1
for method B, respectively. The intra-day and inter-day precision and accuracy
of the methods were evaluated according to the current ICH guidelines. Both
methods were of comparable accuracy (er
≤ 2%). Also, both methods are equally precise as shown by the relative
standard deviation values < 1.5%. No interference was observed from common
pharmaceutical adjuvants. The accuracy of the methods was further ascertained
by performing recovery studies using the standard addition method. The methods
were successfully applied to the assay of LPZ in capsule preparations and the
results were statistically compared with those of the literature
UV-spectrophotometric method by applying Student’s t-test and F-test.
Ključne riječi: lansoprazole, determination,
spectrophotometry, ceric ammonium sulphate, methyl orange, indigo carmine,
pharmaceuticals