The present LC-MS/MS method for estimation of Nitecapone in human plasma using Tolcapone as an internal standard is established and validated as per FDA guidelines.A good response was obtained with ZORBAX Eclipse plus C18 column (150 mm × 4.6 mm ID, 5 μm) and mobile phase with a mixture of 0.01 M Ammonium phosphate buffer with pH adjusted to 5.0 with OPA and Acetonitrile (70:30, v/v) at a flow rate of 0.8 mL/min by positive ion mode (API 4000) with an injection volume of 20 µL and a run time of 3.0 min.Detection is performed by atmospheric pressure electrospray ionization (ESI) tandem mass spectrometry in positive ion mode.The precursor to product ion transitions is m/z 266.20 to 156.20 for Nitecapone and m/z 274.20 to 183.10 for Tolcapone (Internal standard) were used for quantization.The retention time of Nitecapone and Tolcapone (Internal standard) were found to be 2.12 min and 2.58 min, respectively.Linearity established for Nitecapone in the range of 50 ng/mL to 2000 ng/mL with correlation coefficient (r = 0.9997), and the overall percentage recovery was 90.39 % for Nitecapone and 92.34 % for Tolcapone (Internal standard) respectively.The CV % values of accuracy and precision for Nitecapone were found to be ≤ 15%, which indicates the accuracy and precision of the proposed method.This method is suitable for routine therapeutic drug monitoring of Nitecapone. INTRODUCTION:The literature review reveals that very few LC methods were reported for the estimation of Nitecapone individually and combined with other drugs at the time of commencement of work.However, there are very few LC-MS/MS methods were reported for the estimation of Nitecapone in human plasma, and the HPLC methods available are with long runtime, hence time-consuming.
We have made the PL measurements on ruby at room temperature and 4.2 K. The characteristic R 1 and R 2 lines of chromium in ruby are found to be absent in the spectra recorded at 4.2 K. Instead of these characteristic lines a band centered on 1.6 eV is observed. A possible explanation has been discussed in terms of co-existence of the two electronic states due to presence of Cr 3+ and Cr 4+ ions in the ruby lattice.
The magnetic, anisotropy, and the magneto-optic properties of (Co/V)n multilayers prepared by e-beam evaporation under ultrahigh vacuum are presented. The magnetization at 5 K suggests one atomic layer of Co to be nonmagnetic. The overall magnetization is found to have a linear temperature dependence, which indicates a lowered dimensionality in these (Co/V)n multilayers. The surface and bulk anisotropies constant are determined to be at room temperature, Ks = 0.5 erg.cm-2 and Kv = 9.4 106 erg.cm-3, respectively. Polar Kerr rotation (PKR) dependence on t(Co) and t(V) are also presented. It is found that PKR decreases monotonicaly with increasing V thickness for the samples with t(Co) = 22.5 Å.
We have investigated the low-field M-H minor loop of a sintered YBa2Cu3O7−δ disk (Tc=87 K at R=0) at liquid nitrogen temperatures both in the zero-field and field-cooled states. It is found that the M-H minor loop is of the Rayleigh type with only odd harmonics of the Fourier series as is well known in ferromagnetic materials. The third harmonic component shows a dc-bias field dependence with symmetric and asymmetric hysteresis in the respective zero-field and low field-cooled states. These results are qualitatively explained in terms of the vortex dynamics and the associated losses in an external bias field.
X-ray absorption near edge structure (XANES) measurements on LII edge of Sm are employed to study the intermediate valence in SmSe1-x Asx (0.0 ⩽ x ⩽ 1.0) solid solutions in which the substitution of trivalent anion As for Se2− drives Sm to a higher valence from divalent towards trivalent in the SmSe lattice. Two absorption peaks corresponding to two different valent states of Sm provide direct evidence for mixed valence of Sm in these alloys. The split white line at the LII edge of Sm is used to determine the Sm mean valence in the alloys. Average valence data deduced from Sm LII edge XANES shows a continuous valence transition with increasing As concentration upto 80 at.% of As. At 90 at.% of As the Sm is fully converted into trivalent state. Mean valence data for Sm shows fair agreement with those measured employing other techniques.
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