Determination of free cyanide and zinc cyanide complex by capillary electrophoresis.

A capillary electrophoretic (CE) protocol was developed for the separation and quantification of free cyanide and zinc cyanide complex, two key species in gold cyanidation of zinc-bearing sulfidic ores. Several common carrier electrolytes were implemented in an indirect UV detection method. The effect of electric field strength, injection volume, concentration of electro-osmotic flow (EOF) modifier and UV-absorbing agent in background electrolyte (BGE) was examined while peak height, peak area and noise were considered for optimization. The best results were obtained using a BGE that contained 35 mM sodium chromate, 12 mM free cyanide and 0.45 mM hexamethonium bromide at pH 10.5. Free cyanide concentration was compared to that measured with the conventional silver nitrate titration method in solutions containing free cyanides and weak cyano-complexes. The developed CE protocol proved very robust in capturing the concentration of free cyanides (4% error) unlike the titration method which exhibited substantial sensitivity to the interfering weak cyano-complexes (38% error).

Fluticasone inhalation in moderate cases of bronchopulmonary dysplasia.

OBJECTIVE: This randomized, controlled trial was designed to determine the efficacy of inhaled fluticasone propionate on oxygen therapy weaning in a population of preterm infants who were born at <32 weeks of gestation and experienced moderate bronchopulmonary dysplasia (BPD). METHODS: Thirty-two infants who were < or =32 weeks of gestation, had moderate BPD that required supplemental oxygen (fraction of inspired oxygen > or =0.25), and were aged between 28 and 60 days were randomized. Fluticasone propionate 125 microg twice daily for 3 weeks and once daily for a fourth week was delivered to infants who weighed between 500 and 1200 g. The dosage was doubled for infants who weighed > or =1200 g. RESULTS: Compared with placebo, treatment had no effect on either duration of supplemental O2 therapy or ventilatory support as assessed by survival analysis. At 28 days, a trend toward a lower cortisol/creatinine ratio in the treatment group was noted compared with placebo (25.1 +/- 18.9 vs 43 +/- 14.4). In the fluticasone group at 28 days, the systolic arterial pressure (78 +/- 3 vs 68 +/- 3 mm Hg) and diastolic arterial pressure (43 +/- 3.4 mm Hg vs 38 +/- 2.0 mm Hg) were higher compared with baseline fluticasone values. The chest radiograph score was lower than baseline (2.8 +/- 1.4 vs 3.7 +/- 2.2) in the fluticasone group at 28 days. This study has a statistical power of 1.0 to detect a significant difference in the duration of oxygen supplementation of >21 days between the study groups. CONCLUSION: We conclude that fluticasone propionate reduces neither supplemental O2 use nor the need for ventilatory support in this patient population. However, fluticasone does have a positive radiologic effect in lowering chest radiograph scores. In addition, our data point to a possible association among inhaled fluticasone treatment and higher arterial blood pressure. Thus, the results of this investigation do not support the use of inhaled corticosteroids in the treatment of oxygen-dependent infants who have established moderate BPD.

Shooting slurries with laser-induced breakdown spectroscopy: sampling is the name of the game.

Analyses of iron ore slurries in industrial and laboratory environments showed that many physical and geometric parameters affect the stability and reproducibility of the response to laser-induced breakdown spectroscopy. A thorough reexamination of the sampling strategy led to a revised sampling layout that ensures a true representative sampling of the slurry and significantly improves the sensitivity and repeatability of the sampling method. An examination of the characteristics of slurries revealed that the mean particulate size and the concentration of solids in a slurry influence the measurement of silica, whereas the magnetite content is responsible for a matrix effect. On-line monitoring of iron ore slurries should be practicable, provided that these variables are controlled within a few percent or that some means of correction is implemented.