Rapid Sampling Procedure Research Articles

Identification of Rotenone and Five Rotenoids in CFT Legumine Piscicide Formulation via High Resolution Mass Spectrometry and a New High-Throughput Extraction Procedure.

The piscicide CFT Legumine is applied to freshwater systems around the world to control invasive fish species. Rotenone, a potent inhibitor of mitochondrial cellular respiration, is the active ingredient of the piscicide; however, other rotenoids of unknown persistence and toxicity account for an equivalent amount by weight. This work identified six distinct rotenoids in CFT Legumine using liquid chromatography coupled with high resolution orbitrap mass spectrometry and optimized a rapid surface water sampling procedure for their analysis. The rotenoids were identified as rotenone and its isomer deguelin, their 12α-hydroxylated products rotenolone and tephrosin, as well as 6α,12α-dehydrorotenone and 6α,12α-dehydrodeguelin. The optimized procedure, extraction with Spin-X nylon membrane microcentrifuge filters followed by elution with acetonitrile, achieved recoveries ranging from 101 - 107 % and 97 - 145 % for all six rotenoids at high (125 nM, ~50 ppb) and low (25 nM, ~10 ppb) concentrations of CFT Legumine, respectively. Overall, this method provides a rapid sampling procedure necessary for monitoring rotenoid persistence in surface water to ensure safe and efficacious application of the pesticide.

Rapid Collection of Floral Fragrance Volatiles using a Headspace Volatile Collection Technique for GC-MS Thermal Desorption Sampling.

Fragrances of many flower families have been sampled and the volatiles analyzed. Knowing the compounds that make up the fragrances can be an important step to conservation of flowers that are threatened or endangered. Because floral fragrance is critical for attracting pollinators, this method could be used to better understand or even enhance pollination. We present a protocol using a portable charcoal air filter and vacuum to collect floral fragrance volatiles, which are then analyzed by a GC-MS. By using this method, fragrance volatiles can be sampled using a non-destructive method with a machine that is easily transported. This methodology uses a rapid sampling procedure, cutting sampling time down from 2-3 hours to approximately 10 minutes. Using GC-MS, the fragrance compounds can be identified individually, based on authentic standards. The steps used for collecting fragrance and control data are presented, from material setup to collecting the data output.

Photobioreactor design for isotopic non‐stationary 13C‐metabolic flux analysis (INST 13C‐MFA) under photoautotrophic conditions

Adaptive metabolic behavior of photoautotrophic microorganisms toward genetic and environmental perturbations can be interpreted in a quantitative depiction of carbon flow through a biochemical reaction network using isotopic non-stationary (13) C-metabolic flux analysis (INST (13) C-MFA). To evaluate (13) C-metabolic flux maps for Chlamydomonas reinhardtii, an original experimental framework was designed allowing rapid, reliable collection of high-quality isotopomer data against time. It involved (i) a short-time (13) C labeling injection device based on mixing control in a torus-shaped photobioreactor with plug-flow hydrodynamics allowing a sudden step-change in the (13) C proportion in the substrate feed and (ii) a rapid sampling procedure using an automatic fast filtration method coupled to a manual rapid liquid nitrogen quenching step. (13) C-substrate labeling enrichment was controlled through the total dissolved inorganic carbon concentration in the pulsed solution. First results were obtained from steady-state continuous culture measurements allowing the characterization of the kinetics of label incorporation into light-limited growing cells cultivated in a photobioreactor operating at the maximal biomass productivity for an incident photon flux density of 200 µmol m(-2) s(-1). (13)C label incorporation was measured for 21 intracellular metabolites using IC-MS/MS in 58 samples collected across a labeling experiment duration of 7 min. The fastest labeling rate was observed for 2/3-phosphoglycerate with an apparent isotopic stationary state reached after 300 s. The labeling rate was consistent with the optimized mixing time of about 4.9 s inside the reactor and the shortest reliable sampling period assessed at 5 s.

Metabolic flux analysis in Escherichia coli by integrating isotopic dynamic and isotopic stationary 13C labeling data

The novel concept of isotopic dynamic 13C metabolic flux analysis (ID-13C MFA) enables integrated analysis of isotopomer data from isotopic transient and/or isotopic stationary phase of a 13C labeling experiment, short-time experiments, and an extended range of applications of 13C MFA. In the presented work, an experimental and computational framework consisting of short-time 13C labeling, an integrated rapid sampling procedure, a LC-MS analytical method, numerical integration of the system of isotopomer differential equations, and estimation of metabolic fluxes was developed and applied to determine intracellular fluxes in glycolysis, pentose phosphate pathway (PPP), and citric acid cycle (TCA) in Escherichia coli grown in aerobic, glucose-limited chemostat culture at a dilution rate of D = 0.10 h(-1). Intracellular steady state concentrations were quantified for 12 metabolic intermediates. A total of 90 LC-MS mass isotopomers were quantified at sampling times t = 0, 91, 226, 346, 589 s and at isotopic stationary conditions. Isotopic stationarity was reached within 10 min in glycolytic and PPP metabolites. Consistent flux solutions were obtained by ID-13C MFA using isotopic dynamic and isotopic stationary 13C labeling data and by isotopic stationary 13C MFA (IS-13C MFA) using solely isotopic stationary data. It is demonstrated that integration of dynamic 13C labeling data increases the sensitivity of flux estimation, particularly at the glucose-6-phosphate branch point. The identified split ratio between glycolysis and PPP was 55%:44%. These results were confirmed by IS-13C MFA additionally using labeling data in proteinogenic amino acids (GC-MS) obtained after 5 h from sampled biomass.

Sampling and analysis of light hydrocarbons in volcanic gases

Volcanic gas emissions are strictly related to a specific stage of volcanic activity. Complete knowledge of their chemical composition can be extremely useful for efficient geochemical surveillance of active volcanism sites. A new, effective and simple method for the evaluation of light hydrocarbons in volcanic gases is described. A rapid sampling procedure and GC-FID analysis are employed. Data from different volcanic areas are shown and a their possible correlation is also discussed.

Uridine transport in concanavalin A- and lipopolysaccharide-activated mouse lymphocytes

Uridine transport is an important factor in regulating uridine accumulation in lymphocytes. Differences in uridine transport rates between T- and B-lymphocytes have been suggested to result in preferential uptake of uridine into T-lymphocytes versus B-lymphocytes. In the present study, a rapid sampling procedure was used to measure within 20 sec the high affinity-low capacity transport of [ 3H]uridine into concanavalin A (Con A)- and lipopolysaccharide (LPS)-activated lymphocytes. Changes in uridine transport were correlated with the degree of B- or T-lymphocyte stimulation which was determined by monitoring changes in cell size and long-term (2 hr) [ 3H]uridine and [ 3H]thymidine accumulation. The results indicated that uridine transport increased with the general activation state of lymphocytes and no preferential uridine transport was observed between Con A or LPS cultures which were maximally activated. We concluded that differences in uridine accumulation into mouse lymphocytes should not be attributed solely to differences in transport between T- and B-lymphocyte since uridine transport is substantially influenced by lymphocyte metabolic activity or activation state.

The presence of NO 2 in premixed flames

Previous findings that a substantial proportion of the NO x in the gases withdrawn from a premixed CH 4 or H 2 flame by a suction probe may be present as NO 2 are confirmed. Strong evidence is provided, however, that this result is an artifact of the probe system and that the proportion of NO 2 actually present in the flame is quite small. The evidence is of two kinds: (1) A 50-reaction kinetic model of reactions of the flame radicals was used to calculate the concentrations of NO and NO 2 emerging from the probe. The results showed first, that the NO 2 /NO ratio calculated for the most rapid sampling procedure used experimentally is close to that measured but second, that the ratio is independent of the initial NO 2 /NO ratio assumed to be present in the flame. This indicates that the measured NO 2 concentration in the sample gas bears little relation to the NO 2 concentration in the flame. (2) A laser-resonance fluorescence technique was used to measure NO 2 in situ in the flame. The NO 2 was also measured simultaneously by the probe technique. The true concentration of NO 2 in the flame as indicated by fluorescence was considerably less than that recorded by the probe technique. It is concluded that the results of probe measurements as hitherto conducted do not reflect even approximately the true NO 2 /NO ratios in the flames; the true ratios are in fact much smaller than those indicated by the probe technique.