The role of proficiency testing in the detection and resolution of calibration bias in the LeadCare® blood lead analyzer; limitations of peer-group assessment

Following implementation of the CLIA ‘88 laboratory regulations, the primary role of proficiency testing (external quality assessment, PT) in the U.S. has been widely viewed as one of assuring regulatory compliance. PT can also be an effective tool for detecting widespread analytical problems, subject to limitations based on the method of PT assigned value determination. A recent case study describes the role of two PT programs in detecting and resolving a calibration bias in the LeadCare blood lead analyzer, and illustrates the limitations of peer-group target determination in fulfilling that PT role.     

Long term confidentiality: a survey

Sensitive electronic data may be required to remain confidential for long periods of time. Yet encryption under a computationally secure cryptosystem cannot provide a guarantee of long term confidentiality, due to potential advances in computing power or cryptanalysis. Long term confidentiality is ensured by information theoretically secure ciphers, but at the expense of impractical key agreement and key management. We overview known methods to alleviate these problems, whilst retaining some form of information theoretic security relevant for long term confidentiality.     

Tandem Chemoselective Suzuki–Miyaura Cross‐Coupling Enabled by Nucleophile Speciation Control

Control of boronic acid speciation is presented as a strategy to achieve nucleophile chemoselectivity in the Suzuki–Miyaura reaction. Combined with simultaneous control of oxidative addition and transmetalation, this enables chemoselective formation of two C? C bonds in a single operation, providing a method for the rapid preparation of highly functionalized carbogenic frameworks.     

Development of candidate reference materials for the measurement of lead in bone

The production of modest quantities of candidate bone lead (Pb) reference materials is described, and an optimized production procedure is presented. The reference materials were developed to enable an assessment of the interlaboratory agreement of laboratories measuring Pb in bone; method validation; and for calibration of solid sampling techniques such as laser ablation ICP-MS. Long bones obtained from Pb-dosed and undosed animals were selected to produce four different pools of a candidate powdered bone reference material. The Pb concentrations of these pools reflect both environmental and occupational exposure levels in humans. The animal bones were harvested post mortem, cleaned, defatted, and broken into pieces using the brittle fracture technique at liquid nitrogen temperature. The bone pieces were then ground in a knife mill to produce fragments of 2-mm size. These were further ground in an ultra-centrifugal mill, resulting in finely powdered bone material that was homogenized and then sampled-scooped into vials. Testing for contamination and homogeneity was performed via instrumental methods of analysis.

Negative Temperature Sensitive Hydrogels in Controlled Drug Delivery

Summary: PVP/PNIPAAm copolymers exhibit a temperature sensitive nature that makes them an attractive candidate for controlled drug delivery devices. Diclofenac sodium was added to the monomeric mixture, which included an initiator and crosslinking agent (where appropriate), prior to UV photopolymerisation. It was found that the xerogels retained similar properties as the original samples (not containing drug) at lower levels of drug integration. In all cases, drug dissolution analysis showed that the active agent was released at a slower rate at temperatures above the Lower Critical Solution Temperature (LCST). Interestingly, the drug release trends were almost identical for both the physically and chemically crosslinked hydrogels, when the decrease in transition temperature caused by the incorporated crosslinking agent is taken into consideration. It is believed that both types of copolymers reached a constant maximum swollen weight at a set of temperatures above their transition temperatures. When this swollen plateau is attained, the hydrophilic-hydrophobic interactions are balanced, thus the gel does not swell or shrink further and the drug diffuses out at a constant rate.     

Ultrasound-assisted synthesis of C-glycosides

A significant rate enhancement was observed in the preparation of allyl and allenyl-C-glycosides from glycosyl acetate or methyl O-glycoside precursors when ultrasound irradiation was employed as an energy source. The C-glycosides were obtained in 77-96% yields in <20 min using TMSOTf as promoter. These results show that sonication provides rapid and efficient access to useful C-glycoside-based building blocks.