Make-up Flow Research Articles

Evolution of the CO2 carrying capacity of CaO particles in a large calcium looping pilot plant

Post-combustion calcium looping is an emerging capture technology that uses CaO particles as CO2 sorbent. This work analyses the average maximum CO2 carrying capacity of the sorbent (Xave) in a continuous large-scale calcium looping (CaL) pilot plant, which is believed to adequately represent the lifetime of CaO particles in larger CaL systems based on the regeneration of CaO by oxyfuel combustion in the calciner. The CO2 carrying capacity is a key variable in designing the CO2 capture carbonator reactor and for optimizing the performance of the system. Several experimental campaigns have been carried out in La Pereda 1.7MWth pilot plant both under oxy-fired and air-fired combustion conditions, in which the evolution of Xave with time has been measured under a wide range of conditions in the calciner. A methodology based on a closure of mass and particle population balances has been used to estimate Xave. Closure of the sulphur balance was found to be very accurate as an internal calibration tool to quantify the make-up flow of limestone that effectively participates in the CO2 capture process in any given set of conditions. When the calciner reactor was operated in conditions far from the equilibrium of CO2 on CaO, a good agreement was found between the experimental Xave values and those calculated from population mass balances which account for the number of carbonation-calcination cycles of each particle. However, a CO2 carrying capacity lower than expected was observed in some tests in oxy-combustion mode when the calciner was operating close to equilibrium. Departure from ideal sorbent behavior and more intense deactivation was found to increase with longer residence times in the calciner (∼3min). This deactivating effect may be due to the effective increase in the number of carbonation-calcination cycles of the particles, caused by switching between carbonating and calcining conditions inside the calciner when the reactor operates close to equilibrium. The results obtained in this study indicate that optimum operation of the calciner for sorbent activity is achieved in conditions sufficiently far from equilibrium and with low bed inventories (short particle residence time in the calciner).

CO2 Capture by Calcium Looping at Relevant Conditions for Cement Plants: Experimental Testing in a 30 kWth Pilot Plant

Calcium looping technology has a high potential for capturing CO2 in cement plants as the CaO-rich purge from the calciner can be used to replace a sizable fraction of the CaCO3 used as feedstock. Integrating the CaL process into the cement plant requires the carbonator reactor to operate under new conditions (i.e., a higher carbonator CO2 load, a more active sorbent, smaller particle sizes). This work analyzes the impact of some of the new CaL operating conditions on the performance of the carbonator in a retrofitted 30 kWth testing facility as there is little experimental information available nowadays. A wide range of sorbent activities has been tested, including those corresponding to very large makeup flows of limestone that would be characteristic of CaL applications in cement plants. The results have been interpreted using a basic reactor carbonator model that required little modification of previous versions developed for power plants.

Coupling and optimisation of online nuclear magnetic resonance spectroscopy and mass spectrometry for process monitoring to cover the broad range of process concentration.

Real time online monitoring of chemical processes can be carried out by a number of analytical techniques, including optical and vibrational spectroscopies, nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). As each technique has unique advantages and challenges, combinations are an attractive option. The combination of a 500-MHz 1 H NMR and a small footprint mass spectrometer to monitor a batch reaction at process concentration was investigated. The mass spectrometer was coupled into the flow path of an online reaction monitoring NMR. Reaction mixture was pumped from a 100-ml vessel to an NMR flow tube before returning to the vessel. Small aliquots were diverted into a sampling make-up flow using an active flow splitter and passed to the mass spectrometer. Advantages of the combination were observed. 1 H NMR was ideal for quantitation of high level components, whereas MS showed a greater capability for detecting those at low level. In preliminary experiments MS produced a limited linear relationship with concentration (0.02% to 2% relative concentration, 0.01 mg/ml-1.25 mg/ml), because of signal saturation at the higher concentrations. NMR was unable to detect components below 0.1% relative to concentration maximum. Optimisation of sample transfer to the MS extended the linearity to 10% relative to the concentration maximum. Therefore, the combination of online NMR and MS allows both qualitative and quantitative analysis of reaction components over the full process range. The application of the combination was demonstrated by monitoring a batch chemical reaction and this is described. Copyright © 2016 John Wiley & Sons, Ltd.

Hyphenation of supercritical fluid chromatography with tandem mass spectrometry for fast determination of four aflatoxins in edible oil

Aflatoxins (AFTs) are of great concern all over the world. Supercritical fluid chromatography (SFC) has the advantage of fast, high resolution and excellent compatibility with a broad range of organic solvents and samples, thus hyphenating SFC with tandem mass spectrometry (MS/MS) can be used for the easy and fast determination of AFTs in edible oils. Edible oil was spiked with isotope-labeled aflatoxin standards, diluted with hexane and extracted with acetonitrile. The extraction was directly loaded to an SFC apparatus and separated on a UPC(2) 2-EP column with CO2 -methanol gradient elution. A post-column make-up flow was introduced to facilitate mass spectrometry performance, and the mixture was analyzed by MS/MS with an electrospray ionization (ESI) source. The SFC conditions including separation column, modifier and sample solvent were optimized, and the four target aflatoxins were baseline separated. The ESI interface parameters were also investigated, implicating the make-up flow as a critical factor for sensitive determination by SFC-MS/MS. The LOQs for the AFTs were 0.05-0.12μgL(-1) , while the RSDs were lower than 8.5%. Supercritical fluid chromatography was successfully coupled to tandem mass spectrometry to establish a simple, fast and sensitive method for the analysis of four aflatoxins in edible oil. This shows the combination of SFC-MS/MS has great potential in determination of trace contaminants in food. Copyright © 2016 John Wiley & Sons, Ltd.

Chiral analysis of poor UV absorbing pharmaceuticals by supercritical fluid chromatography-charged aerosol detection

Fast and efficient chiral analysis of drugs and synthetic intermediates with weak UV absorption is one of the most challenging analytical tasks in modern pharmaceutical research and development. In this study, the use of supercritical fluid chromatography-charged aerosol detection (SFC-CAD) for chiral analysis of poor UV absorbing analytes commonly encountered during pharmaceutical process research was investigated. Investigation of makeup flow rate showed that CAD responses remained largely steady from 1 to 1.5mL/min for different mobile phase compositions. The effect of the additives in the mobile phase and the makeup flow on the background noise of CAD detection was also studied. Accurate measurement of the enantiopurity of pharmaceuticals from −100% to 100% enantiomeric excess (ee) was achieved under isocratic conditions. The SFC-CAD system was used as a chromatographic screening system for method development and successfully applied to high-throughput chiral analysis of reaction mixtures in microtiter plates.

Multi-objective optimization of operating parameters of a MSF-BR desalination plant using solver optimization tool of Matlab software

Multi-Stage Flash (MSF) desalination process is energy intensive and it is, therefore, essential to search for operating the plant at its optimum parameters which lead to reduction of energy consumption and consequently lower water production cost.In this study, we used a solver optimization tool of Matlab software, for optimization of operating parameters of recirculation multi-stage flash (MSF-BR) desalting plant, taking in consideration the change of brine heater fouling factor and seasonal variation of seawater temperature. The solver uses genetic algorithms for solving multi-objective optimization problems. The operating variables over which optimization was carried out are the make-up flow rate, the cooling seawater flow rate, the brine recycle flow rate and the steam temperature. The optimization method and results analysis are based on actual plant data that includes 10 desalting units, each of 16 flashing stages and a nominal capacity of 26 700m3/d.Three objectives were considered in this optimization approach. The first is to maximize the fresh water capacity of the installation. The second is to minimize the heating steam flow rate in order to reduce the thermal energy consumption, and the third is to minimize the sum of flow rates of main pumps of the unit production in order to reduce the electric energy consumption. The expressions of the first two objective functions are obtained using response surface methodology (RSM). Solving the optimization problem has led to obtaining a set of Pareto optimal solutions, which defining various combinations of the optimal operating parameters of each MSF-BR desalination plant unit, and thus leading to optimal plant operation policy for the whole year.

Flow Confinement Enhancement of Heterogeneous Immunoassays in Microfluidics

This paper aims to enhance the analyte transport toward the sensing area and to enhance biosensors performances. A microchannel-based flow confinement method for rapid delivery of small sample volumes to sensor surface is described. To confine the flow, a sample flow is joined with a perpendicular makeup flow and is confined into a thin layer above the reaction surface. The numerical simulation of the confinement effect on the binding reaction is performed using the finite-element method. The influence of several parameters on the binding reaction is provided, such as the average flow velocity at the inlet of the microchannel and the velocity of the confinement flow, the characteristics of the flow confinement. The numerical results reveal that the flow confinement enhances mass transport of analytes and increase its velocity. The obtained results could be exploited in flow injection experiments for low volume.

Rapid chiral separation of racemic cetirizine in human plasma using subcritical fluid chromatography-tandem mass spectrometry

A method for fast chiral separation of cetirizine and quantitation of levocetirizine in human plasma using subcritical fluid chromatography with tandem mass spectrometry was developed and validated. The chromatographic separation was performed using a Chiralpak IE column (2.1mm×150mm, 5μm) with an isocratic elution of CO2/organic modifier (55/45, v/v) at a flow rate of 0.85mL/min. The organic modifier was composed of water/methanol (5/95, v/v). The makeup flow was optimized at water/methanol (10/90, v/v) and 0.2mL/min. The most influential parameters on the separation of cetirizine affecting resolution, retention time and sensitivity were selected by fractional factorial design. The 3 selected factors were optimized by response surface methodology. Tandem mass spectrometry was used at electrospray ionization, positive ion mode, and multiple-reaction monitoring mode. Isotope-labeled cetirizine-d4 was used as the internal standard. The sample preparation of human plasma was conducted by solid phase extraction of hydrophilic-lipophilic balance (HLB) type. The developed method was validated for selectivity, linearity, precision, accuracy, recovery, limit of quantitation (LOQ), and limit of detection (LOD). The real human plasma samples were analyzed and the pharmacokinetic results were compared with results of previous research. The developed method was found to be reliable based on the similarity between the results of the current and previous methods. The chiral separation for cetirizine and economic feasibility were compared with those of previous studies using normal phase-HPLC or reversed phase-HPLC. The established analytical method could be successfully applied to pharmacokinetic study with reduction in the analysis time and costs.

Capillary ion chromatography-mass spectrometry for simultaneous determination of glucosylglycerol and sucrose in intracellular extracts of cyanobacteria.

A capillary ion chromatography-mass spectrometry (MS) method was proposed to determine glucosylglycerol (GG), sucrose, and five other carbohydrates. MS conditions and make-up flow parameters were optimized. This method is accurate and sensitive for simultaneous analysis of carbohydrates, with mean correlation coefficients of determination greater than 0.99, relative standard deviation of 0.91-2.81% for eight replicates, and average spiked recoveries of 97.3-104.9%. Limits of detection of sodium adduct were obtained with MS detection in selected ion mode for GG (0.006mg/L), sucrose (0.02mg/L), and other carbohydrates (0.03mg/L). This method was successfully applied to determine GG and sucrose in intracellular extracts of salt-stressed cyanobacteria.

Rapid chiral separation of atenolol, metoprolol, propranolol and the zwitterionic metoprolol acid using supercritical fluid chromatography–tandem mass spectrometry – Application to wetland microcosms

A method for enantiomeric separation of the three β-blocking agents atenolol, metoprolol, propranolol and the zwitterionic metoprolol acid, a major metabolite of both metoprolol and in environmental matrices also atenolol, has been developed. By use of supercritical fluid chromatography and the polysaccharide-based Chiralpak® IB-3, all four compounds were simultaneously enantiomerically separated (Rs>1.5) within 8min. Detection was performed using tandem mass spectrometry, and to avoid isobaric interference between the co-eluting metoprolol and metoprolol acid, the achiral column Acquity® UPC2 BEH 2-EP was attached ahead of to the chiral column. Carbon dioxide with 18% methanol containing 0.5% (v/v) of the additives trifluoroacetic acid and ammonia in a 2:1 molar ratio were used as mobile phase. A post column make-up flow (0.3mL/min) of methanol containing 0.1% (v/v) formic acid was used to enhance the positive electrospray ionization. Detection was carried out using a triple quadrupole mass spectrometer operating in the selected reaction monitoring mode, using one transition per analyte and internal standard. The method was successfully applied for monitoring the enantiomeric fraction change over time in a laboratory scale wetland degradation study. It showed good precision, recovery, sensitivity and low effect of the sample matrix.

Determining the suitability of mass spectrometry for understanding the dissolution processes involved with pharmaceutical tablets.

A current challenge for analytical chemists is the development of the measurement systems and approaches required to understand dynamic processes such as tablet dissolution. The design and development of oral tablets could be improved by the availability of detailed information about the rates of release of the individual tablet components. Small footprint mass spectrometry (MS) systems are gaining use for on-line reaction monitoring because of their ability to rapidly determine multiple reactant, intermediate, and product species. We have therefore assessed the utility of such MS systems to the study of dissolution processes. Aqueous dissolution media containing phosphate and other non-volatile buffer salts were pumped from a standard USPII dissolution vessel through an active splitter and back. The splitter sampled the dissolution stream and diluted it into a make-up flow which was pumped to a small single quadrupole mass spectrometer. Single ion monitoring was used to quantify the ions of interest. Three different bio-relevant dissolution media were studied to gauge the effect of the sample matrix. Individual dissolution profiles were obtained from a tablet containing three drugs, and lactose as the soluble filler. This was successfully demonstrated with three different bio-relevant media designed to reflect the pH of the different sections of the human gastro-intestinal tract. Component concentrations as low as 0.06 µg/mL (representing 1% dissolution) were detected. The MS dissolution profiles correlated with the visual observation of tablet dissolution. MS gave linear responses with concentration for the individual components, although analysis of the tablet solution indicated that ion suppression is an area for further investigation. An on-line MS system was used to determine the individual dissolution profiles of three drugs and lactose as they were released from the same tablet. The level of each of these components in solution was determined every 10 seconds, and each had a similar release profile. The dissolution profiles were determined using inorganic buffer solutions at three different bio-relevant pHs.

On-line Monitoring of Continuous Flow Chemical Synthesis Using a Portable, Small Footprint Mass Spectrometer

For on-line monitoring of chemical reactions (batch or continuous flow), mass spectrometry (MS) can provide data to (1) determine the fate of starting materials and reagents, (2) confirm the presence of the desired product, (3) identify intermediates and impurities, (4) determine steady state conditions and point of completion, and (5) speed up process optimization. Recent developments in small footprint atmospheric pressure ionization portable mass spectrometers further enable this coupling, as the mass spectrometer can be easily positioned with the reaction system to be studied. A major issue for this combination is the transfer of a sample that is representative of the reaction and also compatible with the mass spectrometer. This is particularly challenging as high concentrations of reagents and products can be encountered in organic synthesis. The application of a portable mass spectrometer for on-line characterization of flow chemical synthesis has been evaluated by coupling a Microsaic 4000 MiD to the Future Chemistry Flow Start EVO chemistry system. Specifically, the Hofmann rearrangement has been studied using the on-line mass spectrometry approach. Sample transfer from the flow reactor is achieved using a mass rate attenuator (MRA) and a sampling make-up flow from a high pressure pump. This enables the appropriate sample dilution, transfer, and preparation for electrospray ionization. The capability of this approach to provide process understanding is described using an industrial pharmaceutical process that is currently under development. The effect of a number of key experimental parameters, such as the composition of the sampling make-up flow and the dilution factor on the mass spectrometry data, is also discussed.

Comparing the effects of high vs. low nitrate on the health, performance, and welfare of juvenile rainbow trout Oncorhynchus mykiss within water recirculating aquaculture systems

Previous research indicates that rainbow trout Oncorhynchus mykiss begin to exhibit health and welfare problems when cultured within water recirculating aquaculture systems (WRAS) operated at low exchange (6.7 days hydraulic retention time) and a mean feed loading rate of 4.1kgfeed/m3 daily makeup flow. These studies could not conclusively determine the causative agent of the health and welfare issues, but accumulation of mean nitrate nitrogen (NO3-N) to approximately 100mg/L was determined to be a potential cause of abnormal swimming behaviors such as “side swimming” and rapid swimming velocity. A subsequent controlled, 3-month study was conducted to determine if NO3-N concentrations of 80–100mg/L resulted in chronic health issues for rainbow trout. Equal numbers of rainbow trout (16.4±0.3g) were stocked within six replicated 9.5m3 WRAS. Three WRAS were maintained with a mean NO3-N concentration of 30mg/L (“low”) resulting from nitrification, and three WRAS were maintained with a mean concentration of 91mg/L (“high”) via continuous dosing of a sodium nitrate stock solution in addition to nitrification. All six WRAS were operated with equal water exchange (1.3 days mean hydraulic retention time) and mean feed loading rates (0.72kgfeed/m3 daily makeup flow), which provided enough flushing to limit the accumulation of other water quality concentrations. Rainbow trout growth was not significantly impacted by the high NO3-N treatment. Cumulative survival for fish cultured within the high NO3-N WRAS was lower and bordered statistical significance, which resulted in total rainbow trout biomass that was significantly lower for this group at study's end. In addition, a significantly greater prevalence of side swimming rainbow trout occurred in the high NO3-N treatment, as was observed during previous research. Swimming speeds were generally greater for rainbow trout cultured in the high NO3-N treatment, but were not always significantly different. Although most water quality variables were controlled, significant differences between treatments for the concentrations of other water quality parameters inhibited definitive conclusions regarding the effect of NO3-N. However, due to the unlikely toxicity of confounding water quality parameters, study results provided strong evidence that relatively low NO3-N levels, 80–100mg/L, were related to chronic health and welfare impacts to juvenile rainbow trout under the described conditions.

Calcium Looping with Enhanced Sorbent Performance: Experimental Testing in A Large Pilot Plant

Postcombustion CO2 capture by Calcium Looping (CaL) has been successfully carried out for more than 700 hours in a 1.7 MWth continuous pilot facility in La Pereda (Spain). The pilot is equipped with two interconnected circulating fluidized bed reactors: a CO2 carbonator, where CaCO3 is formed when CO2 is captured from a combustion flue gas in contact with fine particles of CaO, and an oxy-fired calciner, where a highly concentrated stream of CO2 is generated by decomposing the CaCO3 formed in the carbonator. CaL is a technology that has the potential to achieve a substantial reduction in the cost of CO2 capture because of the capability to recover waste heat and generate more power from the additional fuel fired in the calciner. However, one of the weaknesses of CaL systems is the rapid deactivation of the sorbent. The EU “ReCaL” project (http://recal-project.eu/) aims to develop a robust and simple reactivation process to stabilize sorbent activity in CaL systems, based on the thermodynamic and kinetic ability of the sorbent to increase its CaCO3 conversion under enhanced carbonation conditions. This paper presents a first attempt to demonstrate the concept at the scale of the La Pereda 1.7 MWth pilot plant. It describes the redesign and retrofitting exercise conducted in the pilot and discusses the initial experimental results achieved when one of the loop seals is used as “recarbonator” reactor (putting a small flow of pure CO2 in contact with partially carbonated particles arriving from the carbonator). The findings of this study suggest that recarbonation could be responsible for about 100% increase in the average CO2 carrying capacity of the material used in the CO2 capture step taking place in the carbonator. This could allow CaL systems to operate with very low limestone make-up flow requirements, making this emerging capture technology more competitive.

A novel stop-flow two-dimensional liquid chromatography–mass spectrometry method for lipid analysis

A novel on-line two dimensional liquid chromatography (2D LC) based on stop-flow mode coupled with electrospray ionization mass spectrometry (ESI–MS) method was established to separate lipids in human plasma. Hydrophilic interaction liquid chromatography (HILIC) in the first dimension and reversed-phase liquid chromatography (RP LC) in the second dimension were used to separate the lipids into six fractions based on their polar head groups and further into peaks based on aliphatic chains, respectively. A new stop-flow interface with a trap column and an extra make-up flow was designed to construct this system and trap the components eluted from the first dimension. Moreover, the same length of analytical columns and similar flow rates were used in the first and second dimensions. Therefore, the new stop-flow 2D LC system can avoid the sensitivity decrease caused by the dilution effect, which is the shortcoming of comprehensive 2D LC. Three hundred and seventy-two lipids were identified from plasma extract using this 2D LC coupled with ESI–MS in positive mode, and 88 more lipids were detected than one-dimensional RP LC analysis. Peak capacity of this stop-flow 2D LC was 415, which is similar to that of comprehensive 2D LC. The linearity, repeatability and sensitivity of this method were satisfactory, which demonstrated that this method was also suitable for quantitative analysis. All these results indicated that this on-line 2D LC method is powerful for qualitative and quantitative analysis of complex lipids

Evaluation of a microchip electrophoresis-mass spectrometry platform deploying a pressure-driven make-up flow

Integration of a pressure-driven make-up flow (MUF) into a microchip electrophoresis (MCE) platform in order to facilitate its coupling with electrospray ionization-mass spectrometric detection (ESI-MS) is described. In the glass/PDMS hybrid microchip, a MUF channel was made to intersect with the MCE separation channel at an angle of 45°. The MUF was generated by a syringe pump. Microscopic image results from simulation studies showed that the pressure-driven MUF and the potential-driven electroosmotic flow in the MCE separation channel could be run separately without interfering with each other and mixed well at the joint point by adjusting either the MUF flow rate or the potential applied for MCE separation. The MUF had several desirable functions, including making the start of electrospray easy and cleaning the nanoESI emitter continuously when not spraying. High separation efficiency was achieved with the proposed MCE-nanoESI-MS system in separating an amino acid mixture containing glutamine, serine, threonine, phenylalanine, and glutamic acid. All of them were baseline separated from each other within 3min. Plate numbers of >10,000 (on a 2.5cm MCE separation channel) were obtained. The analytical platform also showed a linear response for quantification of DOPA with a detection limit (S/N=3) of 0.10μM. In addition, on-line derivatization of MCE elutes in order to enhance MS detection sensitivity was easily carried out by adding the tagging reagent into the MUF. These results indicated that the present system might have a good potential in MCE-MS applications.

The impact of calcium sulfate and inert solids accumulation in post-combustion calcium looping systems

Postcombustion CO2 capture by calcium looping (CaL) is being rapidly developed for coal combustion applications. This work discusses the impact of the accumulation of CaSO4 and other inert solids on CO2 capture efficiency and the overall CaL process performance. Several process configurations are considered, and the mass and energy balances and an updated carbonator reactor model are solved for each configuration. The minimum fresh sorbent requirements for sustaining a certain level of CO2 capture efficiency are quantified as well as the effects of an increase in the make-up flow. It was found that the main effect on the CaL process is produced by the sulfur present in the coal fed to the calciner and in the flue gas entering the carbonator. For a typical set of operating conditions it was calculated that the deactivating effect caused by an increase of 0.5% in the sulfur content with respect to a reference coal (low ash content) fed to the calciner is similar to the effect caused by the accumulation of inerts when using a coal with 15% more ash.

Direct coupling of packed column supercritical fluid chromatography to continuous corona discharge ion mobility spectrometry

In this study, packed column supercritical fluid chromatography (SFC) was directly coupled to a continuous corona discharge (CD) ion mobility spectrometer (IMS) with several modifications. The main advantage of the developed detector is its capability to introduce full column effluent up to 2000mLmin−1 CO2 gas directly into the IMS cell relative to 40mLmin−1 CO2 gas as a maximum tolerance, reported for the previous IMS detectors. This achievement was made possible because of using corona discharge instead of 63Ni as an ionization source and locating the inlet and outlet of the CO2 gas in the counter electrode of the CD in opposite direction. In addition, a heated interface was placed between back pressure regulator (BPR) and the IMS cell to heat the output of the BPR for introducing sample as the gas phase into the IMS cell. Furthermore, a make-up methanol flow was introduced between the column outlet and BPR to provide a more uniform flow through the BPR and also to prevent freezing and deposition of the analytes in the BPR. The performance of the SFC-CD-IMS was evaluated by analysis of testosterone, medroxyprogesterone, caffeine, and theophylline as test compounds and figures of merit for these compounds have been calculated.

Modelling the continuous calcination of CaCO3 in a Ca-looping system

The Ca-Looping (CaL) process for CO2 post-combustion capture is a promising technology that has received lot of attention concerning both experimental and modelling aspects in recent years. In this work, a calciner reactor model based on simple fluid-dynamic assumptions and including calcination kinetics is proposed. The main objective of the reactor model is to evaluate the CaCO3 content leaving the calciner or, in other words, the calciner efficiency defined as the fraction of CaCO3 calcined in the reactor, as a function of calciner operating conditions such as solid inventory, calciner temperature, solid circulation rate or fresh sorbent make-up flow. Different analysis have been carried out to determine a feasible operating window of the reactor where high calciner efficiencies are achieved at relatively low temperatures and reasonable solid residence times in the calciner. The results obtained show that typical solid inventories in a range of 8000–12,000mol of Ca/m2 and temperatures of 1173–1183K, will result into such calciner efficiencies well over 95%. These results reinforce the CaL system application at a large scale for CO2 capture and make the model as a valuable tool for interpreting future experimental results obtained from pilot-scale CaL facilities.

Mass Cytometry: Protocol for Daily Tuning and Running Cell Samples on a CyTOF Mass Cytometer

In recent years, the rapid analysis of single cells has commonly been performed using flow cytometry and fluorescently-labeled antibodies. However, the issue of spectral overlap of fluorophore emissions has limited the number of simultaneous probes. In contrast, the new CyTOF mass cytometer by DVS Sciences couples a liquid single-cell introduction system to an ICP-MS. Rather than fluorophores, chelating polymers containing highly-enriched metal isotopes are coupled to antibodies or other specific probes. Because of the metal purity and mass resolution of the mass cytometer, there is no "spectral overlap" from neighboring isotopes, and therefore no need for compensation matrices. Additionally, due to the use of lanthanide metals, there is no biological background and therefore no equivalent of autofluorescence. With a mass window spanning atomic mass 103-203, theoretically up to 100 labels could be distinguished simultaneously. Currently, more than 35 channels are available using the chelating reagents available from DVS Sciences, allowing unprecedented dissection of the immunological profile of samples. Disadvantages to mass cytometry include the strict requirement for a separate metal isotope per probe (no equivalent of forward or side scatter), and the fact that it is a destructive technique (no possibility of sorting recovery). The current configuration of the mass cytometer also has a cell transmission rate of only ~25%, thus requiring a higher input number of cells. Optimal daily performance of the mass cytometer requires several steps. The basic goal of the optimization is to maximize the measured signal intensity of the desired metal isotopes (M) while minimizing the formation of oxides (M+16) that will decrease the M signal intensity and interfere with any desired signal at M+16. The first step is to warm up the machine so a hot, stable ICP plasma has been established. Second, the settings for current and make-up gas flow rate must be optimized on a daily basis. During sample collection, the maximum cell event rate is limited by detector efficiency and processing speed to 1000 cells/sec. However, depending on the sample quality, a slower cell event rate (300-500 cells/sec) is usually desirable to allow better resolution between cells events and thus maximize intact singlets over doublets and debris. Finally, adequate cleaning of the machine at the end of the day helps minimize background signal due to free metal.