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In this study, the amino-functionalized metal-organic framework (NH2-MOFs) was used as an adsorbent for the extraction of cadmium in rice samples based on the pipette tip solid phase extraction (PT-SPE) before determined by the flame absorption spectrometry (F-AAS). The pH of the sample solution, initial concentration of the cadmium, the volume of the sample, elution ‎conditions, and the amount of adsorbent on the recovery of the cadmium were investigated and ‎optimized. The results showed that the best extraction efficiency of cadmium was obtained at pH 5.0, 2500.0 µL of cadmium solution, and 20.0 ‎µL of HCl (10% V/V) ‎ as eluent solvent. First, the cooking rice was transferred to a beaker and hydrochloric acid/nitric acid was added to it as a digestion process before analysis by the PT-SPE procedure. The limit of detection of this method was found to be 0.03 µg L-1 with a relative standard deviation of ≤ 2.5 % (for seven replicate analyses of 50 µg L-1 of cadmium). The linear and dynamic ranges were achieved at 0.3 -14.5 µg L-1 and 0.3 -150 µg L-1, respectively. The adsorption capacity of sorbent and enrichment factor was 175 mg g-1 and 125 folds, respectively.

Integrated planar lenses are critical components for analog optical information processing that enable a wide range of applications including beam steering. Conventional planar lenses require gradient index control which makes their on-chip realization challenging. Here, we introduce a new approach for beam steering by designing an array of coupled waveguides with segmented tails that allow for simultaneously achieving planar lensing and off-chip radiation. The proposed arrayed waveguide lens is built on engineering the evanescent coupling between adjacent channels to realize a photonic lattice with an equi-distant ladder of propagation constants that emulates the continuous parabolic index profile. Through coupled-mode analysis and full-wave numerical simulations, we show that selective excitation of waveguide channels enables beam steering with large field-of-views of ∼60°. The proposed arrayed waveguide lens can serve as a compact component in integrated photonic circuits for applications in imaging, sensing, and metrology.