PubMed · 4084164
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J H Apted. 1985. Case report: trouser dermatitis.. https://doi.org/10.1111/j.1440-0960.1985.tb01822.x
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High-performance liquid (HPLC) and thin-layer (TLC) chromatographic methods for the detection and quantification of diazeniumdiolates are described. The HPLC determinations were made using a Rocket Platinum NH2 column (7 x 53 mm, 100-A pore size, 3-microm particle size), under isocratic conditions with mixtures of acetonitrile, methanol, and water containing 0.1% diethylamine (v/v), at a flow rate of 2.5 ml/min, a column temperature of 22 degrees C, and UV detection at 250 nm. The TLC determinations were similarly made using Merck NH2 F254S precoated glass plates (approximately 2 x 5 cm, 5-microm particle size, 0.2-mm layer thickness) with mixtures of acetonitrile, methanol, and water containing 0.1% diethylamine (v/v). Preexisting traces of carcinogenic nitrosamines were detected in some samples of diazeniumdiolates. The methods provide a more efficient means of characterizing the purity of diazeniumdiolate samples prepared for use in biomedical applications than older procedures which rely on differential absorbance measurements at 250 and 350 nm, respectively.
The treatment of Direct Yellow 86 dye wastewater by the UV/H(2)O(2) process in continuous annular photoreactors was studied under various UV light intensities, influx concentrations of dye, dosages of H(2)O(2) and dimensions of photoreactor. A photoreactor design equation combined the UV light distribution profile in the reactor and the empirical rate expressions for the decomposition of dye and H(2)O(2) was used to predict the destruction of dye within photoreactors of different geometries at various operating conditions. Experimentally observed removal of the dye pollutant in the plug flow annular reactor agreed well with the theoretical solutions modeled by the developed photoreactor design equation.
Derivatives of the azoalkane 2,3-diazabicyclo[2,2,2]oct-2-ene (1a) with bridgehead 1,4-dialkyl (1b), 1,4-dichloro (1c), 1-hydroxymethyl (1d), 1-aminomethyl (1e), and 1-ammoniummethyl (1f) substituents form host-guest inclusion complexes with beta-cyclodextrin. They were employed as probes to assess substituent effects on the kinetics and thermodynamics of this complexation by using time-resolved and steady-state fluorimetry, UV spectrophotometry, induced circular dichroism (ICD) measurements, and (1)H NMR spectroscopy. The kinetic analysis based on quenching of the long-lived fluorescence of the azoalkanes by addition of host provided excited-state association rate constants between 2.6 x 10(8) and 7.0 x 10(8) M(-)(1) s(-)(1). The binding constants for 1a (1100 M(-1)), 1b (900 M(-1)), 1c (1900 M(-1)), 1d (180 M(-1)), 1e (250 M(-1)), and 1f (ca. 20 M(-1)) were obtained by UV, NMR, and ICD titrations. A positive ICD signal of the azo absorption around 370 nm was observed for the beta-cyclodextrin complexes of 1a, 1d, and 1f with the intensity order 1a >> 1d approximately 1f, and a negative signal was measured for those of 1b, 1c, and 1e with the intensity order 1c < 1b approximately 1e. The ICD was employed for the assignment of the solution structures of the complexes, in particular the relative orientation of the guest in the host (co-conformation).