Accurate Quantification of Pure Thiacloprid with Mass Balance and Quantitative H-NMR

Thiacloprid is the first-generation neonicotinoid insecticide,which is widely used in modern agriculture.Reference materials are essential for sound measurement and traceability of results in chemical analysis.Pure thiacloprid was comprehensively assessed by two orthonormal methods:mass balance(MB) and quantitative nuclear magnetic resonance spectroscopy(qNMR).From MB,its mass fraction value was 998.4 mg/g with the subtraction of structurally related impurities(99.87%),inorganic impurities(0.006 mg/g),water(0.33 mg/g),and volatile organic solvent(0 mg/g).To guarantee sufficient separation of structurally related purity,peak purity of thiacloprid was evaluated by five points of UV spectra.From the qNMR of hydrogen,its mass fraction value was 995.7 mg/g which was traced to the internal standard(methyl sulfone).Finally,the certified value was assigned to 997 mg/g,together with an expanded uncertainty of 3 mg/g(k=2).This high-purity thiacloprid can be applied to routine monitoring in agriculture and the food fields.

Single capillary oximetry and tissue ultrastructural sensing by dual-band dual-scan inverse spectroscopic optical coherence tomography

Measuring capillary oxygenation and the surrounding ultrastructure can allow one to monitor a microvascular niche and better understand crucial biological mechanisms.However,capillary oximetry and pericapillary ultrastructure are challenging to measure in vivo.Here we demonstrate a novel optical imaging system,dual-band dual-scan inverse spectroscopic optical coherence tomography(D2-ISOCT),that,for the first time,can simultaneously obtain the following metrics in vivo using endogenous contrast:(1)capillary-level oxygen saturation and arteriolar-level blood flow rates,oxygen delivery rates,and oxygen metabolic rates;(2)spatial characteristics of tissue structures at length scales down to 30 nm;and(3)morphological images up to 2mm in depth.To illustrate the capabilities of D2-ISOCT,we monitored alterations to capillaries and the surrounding pericapillary tissue(tissue between the capillaries)in the healing response of a mouse ear wound model.The obtained microvascular and ultrastructural metrics corroborated well with each other,showing the promise of D2-ISOCT for becoming a powerful new non-invasive imaging tool.