Protein is a principal component in commonly used dietary supplements and health food products. The analysis of these products, within the consumer package form, is of critical importance for the purpose of ensuring quality and supporting label claims. A rapid test method was developed using near-infrared (NIR) spectroscopy as a compliment to current protein determination by the Dumas combustion method. The NIR method was found to be a rapid, low-cost, and green (no use of chemicals and reagents) complimentary technique. The protein powder samples analyzed in this study were in the range of 22-90% protein. The samples were prepared as mixtures of soy protein, whey protein, and silicon dioxide ingredients, which are common in commercially sold protein powder drink-mix products in the market. A NIR regression model was developed with 17 samples within the constituent range and was validated with 20 independent samples of known protein levels (85-88%). The results show that the NIR method is capable of predicting the protein content with a bias of ±2% and a maximum bias of 3% between NIR and the external Dumas method.

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The visible absorption bands of the phenylperoxy radical in the gas phase have been investigated using cavity ring-down spectroscopy. Jet-cooling was used to reduce the spectral congestion. Structured spectra spanning the range from 17 500 to 19 000 cm–1 are reported for the first time. Analyses of these data have been guided by the results from time-dependent density functional calculations. The observed spectrum was found to be dominated by the bands of the B̃2A″–X̃2A″ transition. An analysis of the rotational contour for the origin band yielded a homogeneous line width of 2.2 cm–1, corresponding to a decay rate of 4.1 × 1011 s–1. The results provide a rationale for the lack of structure in room temperature spectra that have been previously attributed to phenylperoxy. They also indicate that the lower energy region of the spectrum may show resolvable structure at room temperature. If so, this would provide a more definitive signature for monitoring phenylperoxy in kinetic measurements.

Electron attachment to chlorine azide (ClN3) was studied using a flowing-afterglow Langmuir-probe apparatus. Electron attachment rates were measured to be 3.5×10−8 and 4.5×10−8 cm3 s−1 at 298 and 400 K, respectively, with an estimated 35% absolute accuracy. Cl− was the sole ion product of the attachment reaction; weak ion signals were observed for other anions and attributed to impurities and secondary ion-molecule reactions. Assuming a relative uncertainty of ±10% for these data, an activation energy for the attachment reaction may be given as 24±10 meV.

The reactivity of ClN(3) with 17 negative ions has been investigated at 300 K. The electron affinity (EA) of ClN(3) was bracketed to be between that of NO(2) and N(3), giving EA(ClN(3)) = 2.48 +/- 0.20 eV, in agreement with an electronic structure calculation. Reaction rate constants and product ion branching ratios were measured. In nearly all cases the major product of the reaction was chloride ions. Charge transfer, N(3)(-) production, and O atom incorporation is also observed. DFT calculations of stable complexes and transition states are presented for two typical ions. Mechanistic details are discussed in terms of reaction coordinate diagrams.