高效液相色谱-串联质谱法检测鸡肉中9种化学合成类抗球虫药多残留

建立了鸡肉中氯羟吡啶、二硝托胺、4,4′-二硝基均二苯脲(尼卡巴嗪代谢物)、磺胺氯吡嗪、磺胺喹口恶啉、地克珠利、妥曲珠利、妥曲珠利砜和妥曲珠利亚砜9种化学合成类抗球虫药多残留的高效液相色谱-串联质谱分析方法。样品采用2%乙酸酸化的乙腈/二甲亚砜(4:1, v/v)提取,150 mg二甲基十八碳硅烷粉(octadecylsilyl, ODS)、100 mg石墨化炭黑(graphitized carbon black, GCB)和100 mg弗罗里硅土(Florisil)吸附剂分散固相萃取净化,经Hypersil GOLD C18色谱柱(150 mm×4.6 mm, 5 μm)分离,电喷雾串联四极杆质谱多反应离子监测方式测定。9种分析物在20～150 μg/kg范围内线性关系良好,相关系数均大于0.995。样品基质中9种分析物在20、50和150 μg/kg加标水平下,平均回收率为81.5%～103.6%,相对标准偏差为4.5%～14.5%。该方法稳定、可靠,可满足鸡肉中化学合成类抗球虫药多残留的检测与确证。     

Non-aqueous capillary electrophoresis of p-quinone anion radicals.

The electrophoretic detection of two kinds of p-quinone anion radicals arising from the electrolysis of benzoquinone and chloranil was achieved by employing an acetonitrile medium. Sufficient dehydration of a running solution was necessary for the detection of the benzoquinone anion radical. Oxygen in the running solution also caused a serious decrease in the amount of the benzoquinone anion radical during electrophoresis. The addition of methanol as a hydrogen-donor decreased the electrophoretic mobility of the benzoquinone anion radical significantly, while that of the chloranil anion radical was little changed. This result is interpreted in terms of hydrogen-bonding interaction between the p-quinone anion radicals and methanol, reflecting the magnitude of their proton-accepting ability (benzoquinone anion radical > chloranil anion radical).     

Highly Pure Synthesis,Spectral Assignments,and Two‐Photon Properties of Cruciform Porphyrin Pentamers Fused with Benzene Units

Tetrameric porphyrin formation of 2‐hydroxymethylpyrrole fused with porphyrins through a bicyclo[2.2.2]octadiene unit gave bicyclo[2.2.2]octadiene‐fused porphyrin pentamers. Thermal conversion of the pentamers gave fully π‐conjugated cruciform porphyrin pentamers fused with benzene units in quantitative yields. UV/Vis spectra of fully π‐conjugated porphyrin pentamers showed one very strong Q absorption and were quite different from those of usual porphyrins. From TD‐DFT calculations, the HOMO level is 0.49 eV higher than the HOMO?1 level. The LUMO and LUMO+1 levels are very close and are lower by more than 0.27 eV than those of other unoccupied MOs. The strong Q absorption was interpreted as two mutually orthogonal single‐electron transitions (683 nm: 86 %, HOMO→LUMO; 680 nm: 86 %, HOMO→LUMO+1). The two‐photon absorption (TPA) cross section value (σ⁽²⁾) of the benzene‐fused porphyrin pentamer was estimated to be 3900 GM at 1500 nm, which is strongly correlated with a cruciform molecular structure with multidirectional π‐conjugation pathways.     

1,21‐Henicosanediol

In the molecular structure of the title compound, C₂₁H₄₄O₂, the hydro­carbon skeleton has an all‐trans conformation. One of the terminal hydroxyl groups is also trans with respect to the skeleton, while the other is gauche. In the crystal structure, the mol­ecules lie parallel to the b axis, forming layers with a thickness of b/2. The packing is similar to that in the smectic A phase of liquid crystals. These features are similar to those of the homologues with an odd number of C atoms, but different from those with an even number.     

Prospective study to assess the clinical efficacy of bone scintigraphy--some analyses of clinical data

The value of preoperative bone scans in patients with primary breast and prostate cancer was evaluated prospectively. Of 414 patients with breast cancer, clinical stage I is 14, II is 219, IIIA is 59, IIIB is 39 and IV is 14. Of 88 patients with prostate cancer, clinical stage I is 14, II is 15, III is 18 and IV is 41. 11 percent of patients with breast cancer and 54 percent of patients with prostate cancer had bone metastases. Clavicle, ribs, thoracic spine, lumbar spine and pelvis metastasized most frequently. The incidences of bone metastases were 18.4% with Scirrhous carcinoma, 15.4% with Medullary tubular carcinoma and 3.8% with Papillotubular carcinoma. The methodology and results of ROC analysis were described in our other papers. Some results of data analysis were described in this paper.     

Electrocatalysis of oxygen reduction on glassy carbon electrodes modified with anthraquinone moieties

Anthraquinone groups were electrochemically grafted to glassy carbon (GC) electrodes via methylene linker to study the oxygen reduction reaction (ORR) in alkaline medium. Two different anthraquinone derivatives, 2-bromomethyl-anthraquinone or 2-chloromethyl-anthraquinone, were used to modify the GC electrode surface. Several modification conditions encompassing potential cycling and electrolysis at a fixed potential were employed in order to vary the surface concentration of MAQ groups (Γ _MAQ) and to study the dependence of the O₂ reduction behaviour on electrografting procedure. Cyclic voltammetry confirmed the presence of anthraquinone moieties attached to the GC electrode and Γ _MAQ varied in the range of (0.5–2.4)?×?10^?10 mol cm^?2. Oxygen reduction was studied on MAQ-modified GC electrodes of various surface coverage using the rotating disc electrode (RDE) and rotating ring-disc electrode (RRDE) methods. The RDE and RRDE results of O₂ reduction reveal that GC/MAQ electrodes show rather similar electrocatalytic behaviour towards the ORR yielding hydrogen peroxide as the final product.