Clinical laboratories estimating enzyme activity in serum are using commercial lyophilized sera for four major purposes. These uses-as a standard and for intermethod, intramethod, and precision control-are segregated, and specifications for each deployment are examined in terms of requirements for the enzyme material: freedom from interfering or indicator enzymes and chromogens; high specific a...

Sensors, IR beams and lasers used in many opto-mechanical systems have stringent alignment retention requirements for use over an extended temperature range. Thermal effects are the primary cause for alignment drift during operation. Thermal expansion and contraction of materials can result in dimensional instability of mirror surfaces. This paper focuses on the importance of dimensional stabil...

A project was undertaken to develop mussel reference materials that were certified for their mass fractions of saxitoxin and decarbamoyl-saxitoxin. Fifteen laboratories from various European countries participated. Three of these had major responsibility for substantial parts of the work and overall coordination of the project. The project involved 4 main activities: (1) procurement and charact...

This paper starts by surveying papers that have quantified the level of agreement between instruments. The results are consistent in that there is not as much agreement as we would like. “Standardization” has been suggested as a means for improving intra-model agreement. In standardization, measurements of a set of samples are taken with two instruments. The measurements are compared, and this ...

The number of different laboratories that perform genetic testing for cystic fibrosis is increasing. However, there are a limited number of quality control and other reference materials available, none of which cover all of the alleles included in commercially available reagents or platforms. The alleles in many publicly available cell lines that could serve as reference materials have neither ...

High-precision iron isotopic compositions for Fe-bearing geological reference materials and chondrites with a wide range of matrices (e.g., silicates, oxides, organic-bearing materials) are reported. This comprehensive data set should serve as a reference for iron isotopic studies across a range of geological and biological disciplines for both quality assurance and inter-laboratory calibration...

We propose bionanoparticles as a candidate reference material for determining the mobility of nanoparticles over the range of 6 × 10(-8)-5 × 10(-6) m(2)V(-1)s(-1). Using an electrospray differential mobility analyzer (ES-DMA), we measured the empirical distribution of several bionanoparticles. All of them show monomodal distributions that are more than two times narrower than the currently used...

Accurate knowledge of lightpath and parallelism of cuvettes used in spectrophotometry are indispensable parameters that must be determined when accurate transmittance measurements of liquid materials are considered. A description is given of the design and techniques developed at NBS for production of quartz cuvettes (SRM 932) having a nominal radiation pathlength of 10 mm ± 0.03 mm. For each c...

Accurate, reliable and reproducible quantification of nucleic acids (DNA/RNA) is important for many diagnostic applications and in routine laboratory testing, for example, for pathogen detection and detection of genetically modified organisms in food. To ensure reliable nucleic acid measurement, reference materials (RM) that are accurately characterised for quantity of target nucleic acid seque...

The main objective of the research carried out by the Textile Conservation Sector at the Opificio delle Pietre Dure in Florence, Italy, was to verify the actual potential of optical investigation as means for identifying dyes on ancient textiles, and thus, to avoid taking micro-samples. For this we used samples of new fabrics dyed following procedures described in a number of fifteenth-century ...