Quetiapine fumarate (QTF) is a selective monoaminergic antagonist with high
affinity for the serotonin Type 2 (5HT2), and dopamine type 2 (D2) receptors.
Titrimetric and spectrophotometric assay of quetiapine fumarate (QTF) using
perchloric acid and acetic acid as reagents are described. The first method
(method A) is a non-aqueous titrimetric method and is based on the titration
of QTF in glacial acetic acid with 0.01M acetous perchloric acid using
crystal violet as indicator. In the second method (method B), QTF has been
measured in 0.1M acetic acid spectrophotometrically at a wavelength of 222
nm. The titrimetric method was applicable over the range of 2.0 - 20.0 mg of
QTF. The reaction stoichiometry of 1:3 is obtained which served as the basis
for calculation. In spectrophotometry, Beer?s law was obeyed over the
concentration range of 1.25 - 15.0 ?g mL-1. The linear regression equation of
the calibration graph was A = 0.0115 + 0.0673 C with a regression coefficient
(r) of 0.9986 (n=7). The apparent molar absorptivity was calculated to be
4.25 ? 104 L mol-1cm-1 and the Sandell sensitivity was 0.0145 ?g cm-2. The
limits of detection (LOD) and quantification (LOQ) calculated as per the ICH
guidelines were 0.07 and 0.21 ?g mL-1, respectively. Accuracy and precision
of the assays were determined by computing the intra-day and inter-day
variations at three different levels of QTF. The intra-day and inter-day
relative standard deviation (%RSD) were in the range of 0.99 - 2.88 and 1.65
- 2.32%, for method A and method B, respectively, with an acceptable
percentage relative error (%RE) < 2%. The methods were successfully applied
in the determination of QTF in two different brands of tablets with good
accuracy and precision and without detectable interference by excipients. The
methods have demonstrated to be simple and easy to apply in routine usage and
do not need any costly instrumentation. Therefore, the reported procedures
are advantageous and can be adopted in routine quality control laboratories
in the developing or under developed countries.
The magnetic, Raman, ferroelectric, and in-field 57Fe Mössbauer studies of polycrystalline multiferroic Sr3Co2Fe24O41 are reported in this paper. From the magnetization studies, it is observed that the sample is soft magnetic in nature with low temperature magnetic spin transitions like longitudinal to transverse conical structure around 130 K and change in magnetic crystalline anisotropy from conical to planar structure at 250 K. Ferroelectric studies of the sample exhibit the spontaneous polarization at low temperature. Strong spin phonon and spin lattice coupling is observed through low temperature Raman spectroscopy. From the in-field 57Fe Mössbauer spectroscopy, spin up and spin down site occupations of Fe ions are calculated in the unit cell.
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