A rapid readout for many single plasmonic nanoparticles using dark-field microscopy and digital color analysis.

The integration of plasmonic nanoparticles into biosensors has the potential to increase the sensitivity and dynamic range of detection, through the use of single nanoparticle assays. The analysis of the localized surface plasmon resonance (LSPR) of plasmonic nanoparticles has allowed the limit of detection of biosensors to move towards single molecules. However, due to complex equipment or slow analysis times, these technologies have not been implemented for point-of-care detection. Herein, we demonstrate an advancement in LSPR analysis by presenting a technique, which utilizes an inexpensive CMOS-equipped digital camera and a dark-field microscope, that can analyse the λmax of over several thousand gold nanospheres in less than a second, without the use of a spectrometer. This improves the throughput of single particle spectral analysis by enabling more nanoparticles to be probed and in a much shorter time. This technique has been demonstrated through the detection of interleukin-6 through a core-satellite binding assay. We anticipate that this technique will aid in the development of high-throughput, multiplexed and point-of-care single nanoparticle biosensors.

Conformity assessment of multicomponent materials or objects: Risk of false decisions due to measurement uncertainty - A case study of denatured alcohols.

Risk of a false decision on conformity of a multicomponent material or object due to measurement uncertainty is discussed. Even if conformity assessment for each component of a material sample is successful, the total probability of a false decision (total consumer's risk or producer's risk) concerning the sample as a whole might still be significant. A model of the total probability of such false decisions is formulated based on the law (theorem) of total probability. It is shown that the total risk can be evaluated as a combination of the particular risks of conformity assessment of sample components. For a more complicated task, i.e. for a larger number of components of a sample under control, the total risk is greater. As a case study, the total probability of false conforming (total consumer's risk) is evaluated for customs control of completely denatured alcohols, where conformity assessment is performed by comparison of chemical analytical test results with the regulatory limits.

The death of the Job plot, transparency, open science and online tools, uncertainty estimation methods and other developments in supramolecular chemistry data analysis.

Data analysis is central to understanding phenomena in host-guest chemistry. We describe here recent developments in this field starting with the revelation that the popular Job plot method is inappropriate for most problems in host-guest chemistry and that the focus should instead be on systematically fitting data and testing all reasonable binding models. We then discuss approaches for estimating uncertainties in binding studies using case studies and simulations to highlight key issues. Related to this is the need for ready access to data and transparency in the methodology or software used, and we demonstrate an example a webportal () that aims to address this issue. We conclude with a list of best-practice protocols for data analysis in supramolecular chemistry that could easily be translated to other related problems in chemistry including measuring rate constants or drug IC50 values.

Certification of steroid carbon isotope ratios in a freeze-dried human urine reference material.

An accurate method for the measurement of carbon isotope ratios of steroids in human urine has been developed at the National Measurement Institute, Australia (NMIA) for the certification of a freeze-dried human urine reference material (CRM NMIA MX005). The method measures δ(13)C values by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) analysis following hydrolysis, solvent extraction and high performance liquid chromatography (HPLC) purification. Reference δ(13)C values for testosterone metabolites etiocholanolone, androsterone, and endogenous reference compounds (ERCs) 11ß-hydroxyandrosterone and pregnanediol were determined, as well as information δ(13)C values for testosterone, epitestosterone, 11-oxoetiocholanolone, and a range of differences (Δ(13)C) between testosterone metabolites and ERCs. The measurement uncertainty was rigorously evaluated with expanded uncertainties for the reference δ(13)C values between 1.1 and 1.6 ‰ at the 95% coverage level.

Use of gas chromatograms of essential leaf oils to compare clones of Eucalyptus camaldulensis.

Using a gentle vacuum technique essential oils were distilled from the leaves of six clones (29 different trees) of Eucalyptus camaldulensis which had previously been propagated by CSIRO, from four seed lots collected from an area of southern Australia bounded approximately by latitude 26 degrees S and longitude 142 degrees E. Inspection of the analyses of the oils together with principal components analysis (PCA) of the gas chromatograms shows that corresponding profiles (for those clones studied in groups of two, three, four and 20), as indicated by the scores of the principal components, are almost independent of environmental and seasonal conditions.