Factors influencing level of hydrogen peroxide in exhaled breath condensate

Hydrogen peroxide (H₂O₂) in exhaled breath condensate (EBC) has been proposed as a marker for oxidative stress in the airways. The aim of the present study was to evaluate the measurement of H₂O₂ in EBC with or without use of a nose clip, and the influence of mouth rinsing, sampling time and storage.An elevated H₂O₂ level was seen during nasal breathing compared to mouth breathing with nose clip (3.4 pmol/s vs. 2.1 pmol/s, p = 0.02). Breathing through the mouth, using a nose clip, was therefore practiced in all experiments. The H₂O₂ levels were increased when mouth rinsing was performed using an acid buffer (1.4 pmol/s vs. 1.9 pmol/s, p = 0.03). 15 min sampling time decreased the H₂O₂ output by almost 50% compared with 2 min sampling time (1.2 vs. 0.6 pmol/s, p = 0.03). When samples were left unattended for 15 min no change in H₂O₂ concentration in the EBC was seen.We found no significant differences in H₂O₂ levels between samples stored for 4 weeks at − 80 °C and samples analysed directly; however, a significant decrease in the levels was seen for samples stored for 4 weeks at − 20 °C.In conclusion, the method of EBC collection and storage plays an important role in reducing variability within and between individuals.     

Pionic Kα X-ray energy and linewidth IN 20Ne and 22Ne

We have measured the energies and linewidths of the pionic K_α X-rays for ²⁰Ne and ²²Ne using a natural liquid-neon target. The results are

     

48.

The calibration of glass electrodes and cadmium and copper ion-selective electrodes     

Ingrid Aggeryd  Yi-Chang Liang  ůAke Olin 《Analytica chimica acta》1985

The glass electrode is calibrated on the concentration scale against the hydrogen electrode from measurements of the potentials of the two electrodes immersed in the same buffer. The p[H⁺] of the buffer is changed between 2 and 11 by addition of base. The difference in potential between the electrodes is used to correct the glass electrode potentials. Analogously, cadmium and copper ion-selective electrodes (i.s.e.) can be calibrated against the corresponding metal-amalgam electrodes in p[M²⁺] buffers. The response of the copper i.s.e. (Radiometer Selectrode) was always close to Nernstian, whereas the response of the cadmium i.s.e. was variable and larger than Nernstian. The method is independent of errors in equilibrium constants and composition of the buffers, but it assumes ideal behaviour of the hydrogen and amalgam electrodes.     

49.

Determination of total selenium in water by atomic-absorption spectrometry after hydride generation and preconcentration in a cold trap system     

Ornemark U  Pettersson J  Olin A 《Talanta》1992,39(9):1089-1096

A cold trap system for the determination of selenium by hydride generation-atomic absorption spectrometry (HG-AAS) is described. For a 30-ml sample the limit of detection is <2 ng/l. and the precision is better than 4% at the 30 ng/l. level. A number of digestion procedures for the destruction of organic matter prior to the determination of total dissolved selenium in water has been tested and compared. Concordant results were obtained except for oxidation by peroxodisulphate in strongly acidic solutions with a high content of organic material. The selenium concentrations found were in agreement with those obtained by HG-AAS after preconcentration by evaporation and dry ashing with the magnesium nitrate-nitric acid-hydrochloric acid method.     

50.

Measurement of the Ec.m. = 184 keV resonance strength in the 26gAl (p, gamma)27 Si reaction     

Ruiz C  Parikh A  José J  Buchmann L  Caggiano JA  Chen AA  Clark JA  Crawford H  Davids B  D'Auria JM  Davis C  Deibel C  Erikson L  Fogarty L  Frekers D  Greife U  Hussein A  Hutcheon DA  Huyse M  Jewett C  Laird AM  Lewis R  Mumby-Croft P  Olin A  Ottewell DF  Ouellet CV  Parker P  Pearson J  Ruprecht G  Trinczek M  Vockenhuber C  Wrede C 《Physical review letters》2006,96(25):252501

The strength of the Ec.m. = 184 keV resonance in the 26gAl(p, gamma)27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF's ISAC facility. We measure a value of omega gamma = 35 +/- 7 microeV and a resonance energy of Ec.m. = 184 +/- 1 keV, consistent with p-wave proton capture into the 7652(3) keV state in 27Si, and discuss the implications of these values for 26GAl nucleosynthesis in typical oxygen-neon white-dwarf novae.     

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20Ne	22Ne
Neenergy (keV)	239.12±0.14	230.49±0.88
width (keV)	15.43±0.41	12.65±3.51

The calibration of glass electrodes and cadmium and copper ion-selective electrodes

The glass electrode is calibrated on the concentration scale against the hydrogen electrode from measurements of the potentials of the two electrodes immersed in the same buffer. The p[H⁺] of the buffer is changed between 2 and 11 by addition of base. The difference in potential between the electrodes is used to correct the glass electrode potentials. Analogously, cadmium and copper ion-selective electrodes (i.s.e.) can be calibrated against the corresponding metal-amalgam electrodes in p[M²⁺] buffers. The response of the copper i.s.e. (Radiometer Selectrode) was always close to Nernstian, whereas the response of the cadmium i.s.e. was variable and larger than Nernstian. The method is independent of errors in equilibrium constants and composition of the buffers, but it assumes ideal behaviour of the hydrogen and amalgam electrodes.     

Determination of total selenium in water by atomic-absorption spectrometry after hydride generation and preconcentration in a cold trap system

A cold trap system for the determination of selenium by hydride generation-atomic absorption spectrometry (HG-AAS) is described. For a 30-ml sample the limit of detection is <2 ng/l. and the precision is better than 4% at the 30 ng/l. level. A number of digestion procedures for the destruction of organic matter prior to the determination of total dissolved selenium in water has been tested and compared. Concordant results were obtained except for oxidation by peroxodisulphate in strongly acidic solutions with a high content of organic material. The selenium concentrations found were in agreement with those obtained by HG-AAS after preconcentration by evaporation and dry ashing with the magnesium nitrate-nitric acid-hydrochloric acid method.     

Measurement of the Ec.m. = 184 keV resonance strength in the 26gAl (p, gamma)27 Si reaction

The strength of the Ec.m. = 184 keV resonance in the 26gAl(p, gamma)27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF's ISAC facility. We measure a value of omega gamma = 35 +/- 7 microeV and a resonance energy of Ec.m. = 184 +/- 1 keV, consistent with p-wave proton capture into the 7652(3) keV state in 27Si, and discuss the implications of these values for 26GAl nucleosynthesis in typical oxygen-neon white-dwarf novae.