Significance
From diagnostic exams to security screening, a major concern in X-ray imaging is the potential damage from absorbed radiation energy. Phase contrast techniques are being developed to alleviate the concern by detecting the slight refractive bending of X-rays in an object, instead of relying on the attenuation of the beam. A front runner in the development is technologies that require mechanical scanning of a grating in the X-ray beam to attain high-resolution images. This paper reports a motionless, electromagnetic scanning method in place of mechanical scanning. It lifts the constraints on speed and flexibility and reduces the complexity and cost of the technologies, all of which help bring them closer to everyday applications.
Hard X-ray phase-contrast imaging characterizes the electron density distribution in an object without the need for radiation absorption. The power of phase contrast to resolve subtle changes, such as those in soft tissue structures, lies in its ability to detect minute refractive bending of X-rays. Here we report a far-field, two-arm interferometer based on the new nanometric phase gratings, which can detect X-ray refraction with subnanoradian sensitivity, and at the same time overcomes the fundamental limitation of ultra-narrow bandwidths (Δλ/λ~10−4) of the current, most sensitive methods based on crystal interferometers. On a 1.5% bandwidth synchrotron source, we demonstrate clear visualization of blood vessels in unstained mouse organs in simple projection views, with over an order-of-magnitude higher phase contrast than current near-field grating interferometers.
Omeprazole is widely prescribed in the form of enteric-coated formulations, due to the rapid degradation of the drug in the acidic condition of the stomach. In the current article, we are reporting the development and complete validation of a stability indicating chiral high-performance liquid chromatography (HPLC) method for the enantioselective analysis of omeprazole in the enteric-coated formulations. A precise and sensitive enantiomeric separation of omeprazole was obtained on Chiralcel OD-H analytical column (250mm × 4.6 mm, 5μm particle size) using normal phase chromatography. The analysis was performed under UV detection at 301nm wavelength. During method development, the addition of methanol to the mobile phase helped in getting the sharp peaks. The developed method showed linear response over a wide concentration range of 0.39-800μg/ml and the regression coefficients value (r2) was obtained more than 0.999 for (S)- and (R)-omeprazole. The lower limit of detection (LLOD) and lower limit of quantification (LLOQ) for (R)-omeprazole were found to be 0.39 and 0.78 μg/ml, respectively for 5 μl injection volume. The percentage recovery of (R)-omeprazole ranged from 93.5 to 104 in spiked formulation samples and omeprazole sample solution and mobile phase were found to be stable for at least 24 h at room temperature. The proposed method was found to be suitable and accurate for the quantitative determination of undesired enantiomer in the enteric-coated omeprazole formulations.
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