FlashPack: Fast and simple preparation of ultra-high performance capillary columns for LC-MS

Capillary ultra-high-pressure liquid chromatography (cUHPLC) is essential for in-depth characterization of complex biomolecule mixtures by LC-MS. We developed a simple and fast method called FlashPack for custom packing of capillary columns of 50-100 cm length with sub-2-μm sorbent particles. FlashPack uses high sorbent concentrations of 500-1000 mg/ml for packing at relatively low pressure of 100 bar. Column blocking by sorbent aggregation is avoided during the packing of sorbent particles by gentle mechanical tapping of the capillary proximal end by a slowly rotating magnet bar. Utilizing a standard 100 bar pressure bomb, Flashpack allows for production of 15-25 cm cUHPLC columns within a few minutes and of 50 cm cUHPLC columns in less than an hour. Columns exhibit excellent reproducibility of back-pressure, retention time and resolution (CV 8,7 %). FlashPack cUHPLC columns are inexpensive, robust and deliver performance comparable to commercially available cUHPLC columns. The FlashPack method is versatile and enables production of cUHPLC columns using a variety of sorbent materials.

Microclimatology and ecophysiology of the urban vegetation of a city with tropical climate modified by altitude in Mexico

Background. The urban area continues growing, and in most cases, the planning of green areas does not include in the species selection their physiological characteristics, which determine plant survival.Question/Hypothesis. Stomatal conductance (gS) is a key variable that provides information on how the environment affects a plant physiology. Therefore it is important to inquire how gS is affected in an urban site.Studied species/Data description. Data of environmental variables (photosynthetically active radiation, PAR; air temperature, TA; vapor pressure deficit, VPD), leaf water potential, ?; and gS were collected in four species Ficus retusa, Fraxinus uhdei, Ligustrum lucidum and Quercus rugosa.Study site and years of study. Two sites, in the center and in the rural area, were selected in Puebla, Mexico, during the wet and dry seasons (2012-2013).Methods. Environmental variables, gS and ? were measured with a diffusion porometer and a pressure bomb through the day every two hours in apparently healthy leaves. Also an experiment under greenhouse conditions was performed.Results. Maximum values of PAR, TA and VPD were registered in the city center in the dry season, whereas maximum gS and ? were found in the rural area in the wet season. ? and gS were significantly higher in F. retusa followed by F. uhdei, whereas the lower values were observed in L. lucidum and Q. rugosa. All variables affected gS for all species.Conclusions. The results demonstrate that it is possible to recommend Ficus retusa and Fraxinus uhdei as suitable species to ameliorate the urban environment.