方法检出限三个评估方法标准解读与比较

文献中有多项方法检出限评估标准,如何正确理解和运用这些标准得到可比较的参数对基层实验室具有指导意义。对目前国内外方法检出限评估方法标准进行了系统总结和梳理,介绍了不同方法的特点、适用范围和注意事项。利用实验室实例和文献数据,比较了三种代表性方法计算结果。基于科学性和可操作性的原则,针对不同需求,提出了检出限评估改进建议及实施方案。     

An immobilized immuno-stirrer for the determination of creatine kinase-mb isoenzyme in blood serum

An immobilized immuno-stirrer is described for the determination of creatine kinase-MB isoenzyme in blood serum. The IgG antibodies are immobilized on alkylamine glass beads using glutaraldehyde as cross-linking reagent, and the beads are packed into a rotating porous cell. After incubation with stirring, the CK-M isoenzymes in the blood serum sample are inhibited and are bound to the antibodies inside the stirrer. The residual CK-B isoenzyme activity is then determined spectrophotometrically or electrochemically. The binding capacity of the immuno-stirrer to CK-M isoenzyme was estimated to be 800 Ul^-1 with an average inhibitory efficiency of 97.8%. The within-day and day-to-day coefficients of variation were 5% and 4%, respectively, over a period of 52 days. An immuno-stirrer loaded with antibodies attached to cyanogen bromide-activated cellulose beads was also characterized, but the antibodies were not as stable as on glass beads.     

A novel class of tunable zinc reagents (RXZnCH2Y) for efficient cyclopropanation of olefins

A class of zinc reagents (RXZnCH(2)Y) generated with an appropriate organozinc is very effective for the cyclopropanation of olefins. The reactivity and selectivity of these reagents can be regulated by tuning the electronic and steric nature of the RX group on Zn. A reasonable level of enantioselectivity was obtained for the cyclopropanation of unfunctionalized olefins when a chiral (iodomethyl)zinc species was used, providing a valuable approach for the asymmetric cyclopropanation of unfunctionalized olefins.     

Syntheses and properties of superabsorbent composites based on natural guar gum and attapulgite

Utilization of raw materials available in nature and their application to derive other useful products without any adverse impact on the environment has long been a desired goal. In this work, guar gum (GG) and attapulgite (APT) clay were used as raw materials for preparing guar gum‐g‐poly(acrylic acid)/attapulgite (GG‐g‐PAA/APT) superabsorbent composites through the graft copolymerization of GG, partially neutralized acrylic acid (AA) and APT in aqueous solution. The effects of reaction conditions such as concentrations of the initiator and crosslinker, APT content, etc. on water absorbency were investigated. The composite prepared under optimal conditions gave the best absorption of 529 g/g sample in distilled water and 61 g/g sample in 0.9 wt% NaCl solution. Swelling behaviors revealed that the superabsorbent composites retained a high water absorbency over a wide pH range of 4–11, and the developed composites also exhibited improved reswelling and water‐retention capabilities. The superabsorbent composites can be utilized as eco‐friendly water‐manageable materials for agricultural and horticultural applications. Copyright © 2008 John Wiley & Sons, Ltd.     

Combinatorial approach to study enzyme/surface interactions

A fast combinatorial approach to access information about the immobilization behavior and kinetics of enzymes on a variation of surfaces is presented. As a test system, Candida Antarctica Lipase B was immobilized on a self-assembled monolayer bearing a gradient of surface energy. The respective immobilization behavior was monitored by Fourier transform infrared micro-spectroscopy. In addition, the activity of the immobilized enzyme was monitored over the entire film in real time with a specially developed fluorescence activity assay embedded into a siloxane gel. It was found that the highest amount of active protein was immobilized on the hydrophilic end of the gradient surface. This effect is associated with a higher surface roughness of this area resulting in hydrophobic micro-environments in which the enzyme gets immobilized.     

The effect of benzyl amine on the efficiency of the base-catalyzed transamination of α-keto esters

This paper describes the effect of benzyl amine on the base-catalyzed transamination of α-keto esters. Among various benzyl amines examined, o-HOC₆H₄CH₂NH₂ was found to be highly effective for the reaction, affording a wide variety of α-amino esters in good yields. The o-OH group of the benzyl amine facilitates the transamination process likely via H-bond. Moderate enantiomeric excess was obtained for α-amino ester when a quinine derived catalyst was used.     

Recent advances in transition metal-catalyzed sp3 C-H amination adjacent to double bonds and carbonyl groups

Transition metal-catalyzed C-H amination at positions adjacent to double bonds and carbonyl groups is discussed in this critical review. While the focus will center on the recent developments of α-oxidative amination, some historical developments and mutually beneficial reports in the broader field of C-H amination will be discussed. C-H amination has become a viable method for the efficient installation of nitrogen atoms en route to target molecules (89 references).