On-line Analysis System Research Articles

Integrated set-up of sampling, sample treatment and assay of an intracellular protein during fermentation

A complete system for on-line sampling, sample handling and analysis of fermentation processes has been set up. The system is designed such that a sample is taken from the fermentor, the metabolism of microbial cells is instantaneously arrested, the cells are lysed in order to release intracellular compounds and in a subsequent binding assay the content of target molecules is monitored. The system is constructed based on the flow-injection analysis concept. Good agreement between on-line analysis and off-line analysis is reported.

In Vivo Monitoring of Quantum Dots in the Extracellular Space Using Push−Pull Perfusion Sampling, Online In-Tube Solid Phase Extraction, and Inductively Coupled Plasma Mass Spectrometry

To monitor the dynamic changes of extracellular quantum dots (QDs) in vivo in the livers of anesthetized rats, we developed an automatic online analytical system comprising push-pull perfusion (PPP) sampling, the established in-tube solid phase extraction (SPE) procedure, and inductively coupled plasma mass spectrometry (ICPMS). The method takes advantage of the retention of QDs onto the interior surface of a polytetrafluoroethylene (PTFE) tube as a means of extracting the QDs from complicated push-pull perfusates. For the injected QDs present in the liver extracellular fluid (ECF) at low picomolar levels, a temporal resolution of 10 min was required to collect sufficient amounts of QDs to meet the sensitivity requirements of the ICPMS system. To the best of our knowledge, this study is the first to exploit the PPP technique for the collection of QDs from living animals and PTFE tubing as a SPE adsorbent for the online extraction of QDs and the removal of biological matrix prior to ICPMS analysis of cadmium-containing inorganic nanocrystal. We confirmed the analytical reliability of this method from measurements of the spike recoveries of saline samples; in addition, we demonstrated the systems' applicability through in vivo monitoring of the time-dependent concentration profile of liver extracellular QDs in living rats after intravenous administration.

Implementation of an on-line artificial intelligence district meter area flow meter data analysis system for abnormality detection: a case study

Faster detection of bursts saves water, minimises the inconvenience of interruption to customers and decreases the damaging consequences to infrastructure. Flow monitoring techniques are used by water service providers to monitor leakage, generally through offline application of mass balance type calculations and manual observations of change in night line values. This paper presents the combination of real-time data collection (using cello loggers with General Packet Radio Service communications) and a self-learning, online Artificial Intelligence system for detection of bursts at the District Meter Area level. The system components consist of communications software, a data warehouse and a MATLAB application. The online system continuously analysed a set of 146 DMAs in a case study area every hour generating automated alerts in response to abnormal flow. Specific examples are given, including a validation field test, and overall results are presented for a one year period. 36% of alerts were found to correspond to bursts confirmed by repair data or customer burst reports with only 18% ghosts. The results indicate that the software tool has the potential to reduce lost water and improve customer service hence enhancing water service provider's reputations.

Chiral separation by two-column, semi-continuous, open-loop simulated moving-bed chromatography

A two-column version of a multicolumn, semi-continuous, open-loop chromatograph for chiral separation is presented and validated experimentally. The heart of the process is a flexible node design and cyclic flow-rate modulation that succeed at keeping the mass-transfer zone inside the system without resorting to any recycling technique. One advantage of this streamlined design is the simplicity of its physical realization: regardless of the number of columns, it only requires two pumps to supply feed and desorbent into the system, while the flow rates of liquid withdrawn from the system are controlled by material balance using simple two-way valves. A rigorous model-based optimization approach is employed in the optimal cycle design to generate a solution that is physically realizable in the experimental apparatus. The optimized scheme for two-column operation supplies fresh feed into the system where the composition of the circulating fluid is closest to that of the feedstock fluid, and recovers the purified products, extract and raffinate, alternately at the downstream end of the unit while desorbent is supplied into the upstream end of the system. The feasibility and effectiveness of the two-column process are verified experimentally on the separation of reboxetine racemate, a norepinephrine re-uptake inhibitor, under overloaded conditions. Our set-up employs an automated on-line enantiomeric analysis system, comprising an analytical HPLC set-up with two UV detectors to monitor the composition profile at the downstream end of one of the columns; this monitoring system does not use a polarimeter.

Development of an embedded system and MATLAB-based GUI for online acquisition and analysis of ECG signal

This paper illustrates a low-cost method for online acquisition of ECG signal for storage and processing using a MATLAB-based Graphical User Interface (GUI). The single lead ECG is sampled at a rate of 1 kHz and after digitization, fed to a microcontroller-based embedded system to convert the ECG data to a RS232 formatted serial bit-stream. This serial data stream is then transmitted to a desktop Personal Computer at a rate of 19.2 kbps and a state-of-the art developed software stores it automatically in a temporary data file. The original ECG data is reconstructed from the digital data set by a conversion formula. The MATLAB-based GUI is designed to perform online analysis on the ECG data to compute the different time-plane features and display the same on the GUI along with the ECG signal plot.

A non-oxidative electrochemical approach to online measurements of dopamine release through laccase-catalyzed oxidation and intramolecular cyclization of dopamine

A new electrochemical approach to selective online measurements of dopamine (DA) release in the cerebral microdialysate is demonstrated with a non-oxidative mechanism based on the distinct reaction properties of DA and the excellent biocatalytic activity of laccase. To make the successful transition of the distinct sequential reaction properties of DA from a conceptual determination protocol to a practical online analytical system, laccase enzyme is immobilized onto magnetite nanoparticles and the nanoparticles are confined into a fused-silica capillary through an external magnetic field to fabricate a magnetic microreactor. The microreactor is placed in the upstream of the thin-layer electrochemical flow cell to efficiently catalyze the oxidation of DA into its quinonoid form and thereby initialize the sequential reactions including deprotonation, intramolecular cyclization, disproportionation and/or oxidation to finally give 5,6-dihydroxyindoline quinone. The electrochemical reduction of the produced 5,6-dihydroxyindoline quinone at bare glassy carbon electrode is used as the readout for the DA measurement. The laccase-immobilized microreactor is also found to catalyze the oxidation of ascorbic acid (AA) and 3,4-dihydroxyphenylacetic acid (DOPAC) into electroinactive species and, as such, to eliminate the great interference from both species. Moreover, the successful transition of the mechanism for DA detection from the conventional oxidative electrochemical approach to the non-oxidative one substantially enables the measurements virtually interference-free from physiological levels of uric acid, 5-hydroxytryptamine, norepinephrine, and epinephrine. The current response is linear with DA concentration within a concentration range from 1 to 20 μM with a sensitivity of 3.97 nA/μM. The detection limit, based on a signal-to-noise ratio of 3, is calculated to be 0.3 μM. The high selectivity and the good linearity as well as the high stability of the online method make it very potential for continuous monitoring of cerebral DA release in physiological and pathological processes.

Development of an advanced on‐line position‐specific stable carbon isotope system and application to methyl tert‐butyl ether

We present an advanced system for on-line position-specific carbon isotope analysis. The main limitation of on-line intramolecular isotope ratio measurements has been that optimal pyrolytic fragments are obtained mostly at temperatures where the analyte has not completely reacted. As a result of undetermined isotopic fractionation, the isotopic signatures of the pyrolysis products are not strictly equal to these of the equivalent moieties in the parent molecule. We designed a pyrolytic unit in which both temperature and reaction time are variable parameters, enabling determination of the enrichment factor of the pyrolysis at optimal temperature by construction of a Rayleigh plot. In the case of methyl tert-butyl ether (MTBE) presented here, a 'pre-pyrolysis' fractionation of MTBE leading to a depletion of 0.9 per thousand was discovered and the enrichment factor of the optimal pyrolysis reaction was determined at -1.7 per thousand. Absolute delta(13)C values of two functional groups of MTBE - the methoxy group and the 2-methylpropane group - could be determined with 95% confidence intervals of 0.4 per thousand and 0.5 per thousand, respectively.

Novel, dynamic on-line analytical separation system for dissolution of drugs from poly(lactic acid) nanoparticles

A novel method for investigating drug release in a dynamic manner from nanoparticles including, but not limited to, biodegradable poly(lactic acid) (PLA) is reported. The PLA nanoparticles were prepared by the nanoprecipitation method. Two poorly soluble drugs, beclomethasone dipropionate (BDP) and indomethacin, were encapsulated into PLA nanoparticles, and their dissolution from the nanoparticles were followed in a dynamic way. The on-line method comprised a short column (vessel) packed with the PLA nanoparticles, on-line connected to an analytical liquid chromatographic column via a multiport switching valve equipped with two loops. The system allowed monitoring of the drug release profiles in real time, and the conditions for the drug release could be precisely controlled and easily changed. The effects of solvent composition and temperature on the rate of dissolution of the drugs from the PLA nanoparticles were investigated. The system proved to be linear for the drugs tested over the concentration range 10–3000 ng ( n = 6, R 2 = 0.999 and 0.997 for indomethacin and beclomethasone, respectively) and repeatable (RSD of peak areas <0.5%). The recoveries of the dissolution study were quantitative (120 and 103% for indomethacin and beclomethasone, respectively).

Determination of estrogens and bisphenol A in bovine milk by automated on-line C 30 solid-phase extraction coupled with high-performance liquid chromatography–mass spectrometry

Using triacontyl bonded silica (C 30) as on-line solid-phase extraction (SPE) material and a specially designed on-line analytical system which allowed large sample volume injection, a high speed and robust on-line SPE-HPLC–MS method was established for the analysis of five estrogens and bisphenol A (BPA) in milk samples. The milk sample is pretreated with acetonitrile for protein precipitation and then treated with primary secondary amine for the removal of polar impurities in the matrix. Then the pretreated sample can be automatically loaded by a LC pump. For effective extraction, an offshoot with NH 4Ac solution of high-flow rate was employed to dilute the loaded sample by a mixing tee before sample was loaded onto the C 30 extraction column. In this way, large volume injection (1 mL in this experiment) could be achieved. Some important parameters such as sample loading flow rate, sample dilution ratio and injection volume were optimized. Under the optimized conditions, the recoveries for all analytes range from 71.4 to 97.1% and reproducibility represented as RSDs are less than 15.0% ( n = 5) with milk samples spiked at 0.6 and 15 ng/mL of each analyte. To the authors’ knowledge, it constitutes the first work describing a C 30 on-line SPE-LC–MS analytical method for the screen and monitoring of these estrogens and BPA in milk.

Modeling of Nitrate Adsorption on Granular Activated Carbon (GAC) using Artificial Neural Network (ANN)

High concentrations of N-containing compounds in drinking water cause health problems such as cyanosis among children and cancer of the alimentary canal. Therefore, removal of nitrate from water samples is of significant importance from the health and environmental point of view. In this work, the effective parameters on removal of nitrate by adsorption process, which included the amount of granular activated carbon (m), initial concentration (C0), contact time, pH and temperature (T), were investigated. The removal process was monitored using an on-line spectrophotometric analysis system. It was found that the content of adsorption followed decreasing order: m= 10&gt;5&gt;2&gt;1g, C0= 20&gt;15&gt;25&gt;10 ppm, pH=4&gt;7&gt;10&gt;1 and T=25&gt;35&gt;45&gt;55 0C. The three-layered feed forward back propagation neural network was used for modeling of nitrate adsorption on granular activated carbon. The comparison between the predicted results of the designed ANN model and the experimental data proved that modeling of nitrate adsorption process using artificial neuron network was a good and precise method to predict the extent of adsorption of nitrate on GAC under different conditions.

Characterization of mesoscale spatio‐temporal patterns and variability of remotely sensed Chl a and SST in the Interior Sea of Chiloe (41.4–43.5° S)

This study characterizes the spatial and temporal distribution of chlorophyll a (Chl a) and sea surface temperature (SST) in the Interior Sea of Chiloe in Chile at a moderate spatial resolution using SeaWiFS and MODIS‐Aqua time series data from the Goddard Earth Science (GES) Data and Information Services Center (DISC) imported into the GES DISC Interactive Online Visualization and Analysis System (‘Giovanni’). The Interior Sea of Chiloe is home to Chile's salmon farming industry, the world's second largest salmonid producer. This study undertakes the characterization of the main patterns of spatial and temporal variability of Chl a and SST in the Interior Sea of Chiloe using a continuous set of time series ocean colour and SST data. Both Chl a and SST exhibit a marked spatial and temporal distribution, with values being significantly higher in the northern area (41.4–42.7° S; total area 41.4–43.5° S) and during the spring–summer period. Peak Chl a concentrations tend to occur in a temporal interval from October to April (austral spring–austral autumn), whereas monthly averaged peak SST values occur consistently in the month of February (austral summer). Chl a concentrations exhibit strong interannual variations, with monthly averaged peak Chl a concentrations experiencing a twofold increase between the year with the lowest and highest Chl a peak concentration in the time series. Results suggest that at the present scale of analysis two spatial domains can be distinguished, regarding the differential behaviour of SST and Chl a in the northern and southern areas of the Interior Sea of Chiloe. The concurrent analysis of Chl a time series data with accumulated rainfall time series data as a proxy of solar radiation, on the other hand, supports previous hypothesis suggesting solar radiation to be a limiting factor for phytoplankton development in the Interior Sea of Chiloe. The role of geomorphological factors on pattern formation and the results presented in this study in relation to results from seasonal oceanographic cruises in the area are briefly discussed.

Development of Chemical Accident Classification Codes and Tool for Management in Process Industries

In this study, domestic and international chemical accident databases are analyzed, and a chemical accident reporting system is developed using chemical accident classification codes. These codes are revised by adopting the data collected in 2115 cases of chemical accidents that occurred in S. Korea over the last 20 years. The revised classification codes are composed of 12 upper, 64 middle, and 276 lower classes. The developed database is composed of data input, data list, and data search modules as well as statistic and analysis modules. Module operations help obtain information on relationships between accident data attributes that are not apparent, in addition to simple statistical results. The chemical accident tracking system is available on the Internet, and the data are treated using an on-line analytical system. The records are statistically analyzed to identify type of accidents that occurs frequently in Korean chemical companies, as well as the accident data and materials involved. We expect the results of this study to be useful in reporting for developing a management of system for prevention of chemical accidents, and improve the manageability of the designed system.

An on-line pulse trains analysis system of the wire-EDM process

Ignition delay time (Td) has been widely used to distinguish the abnormal discharges from the normal ones in wire electrical discharge machining (WEDM) process. In this paper an on-line analysis system for the causality of the Td data sequences was developed to evaluate the machining performance of WEDM process. The system is composed of a stand-alone Td processing circuitry and a user-friendly computer program for data analysis. The Td processing circuitry calculates and records the Td of every single electrical discharge in the first place, and then transmits the Td data via an embedded communication port to a desktop or notebook computer. The computer program, after performing the analysis tasks, will display the result in a graphic way. Two mathematical algorithms were employed for the analysis: autocorrelation function and Fourier transform. Through experiments under different working conditions, it was found that the autocorrelation function could be used to detect if arc or short circuit discharges take place consecutively, and to distinguish the WEDM process with similar Td distributions. On the other hand, the spectral analysis revealed that several factors were identified to be able to induce certain periodic patterns of Td data. These factors include the length of wire electrode, the water pressure, etc.

On-line Digestion System for Protein Characterization and Proteome Analysis

An efficient on-line digestion system that reduces the number of sample manipulation steps has been demonstrated for high-throughput proteomics. By incorporating a pressurized sample loop into a liquid chromatography-based separation system, both sample and enzyme (e.g., trypsin) can be simultaneously introduced to produce a complete, yet rapid digestion. Both standard proteins and a complex Shewanella oneidensis global protein extract were digested and analyzed using the automated online pressurized digestion system coupled to an ion mobility time-of-flight mass spectrometer, an ion trap mass spectrometer, or both. The system denatured, digested, and separated product peptides in a manner of minutes, making it amenable to on-line high-throughput applications. In addition to simplifying and expediting sample processing, the system was easy to implement and no cross-contamination was observed among samples. As a result, the online digestion system offers a powerful approach for high-throughput screening of proteins that could prove valuable in biochemical research (rapid screening of protein-based drugs).

Determination of free catecholamines in urine by tandem affinity/ion-pair chromatography and flow injection analysis

Background A system was developed for the simultaneous measurement in urine of free catecholamines (i.e., dopamine, norepinephrine, epinephrine) and creatinine (i.e., an indicator of urine output and volume). This method was based on the use of tandem affinity/ion-pair HPLC and flow injection analysis. Methods The free catecholamines were extracted directly from urine by using an on-line phenylboronic acid affinity column. The extracted solutes were then separated and measured by ion-pair chromatography followed by amperometric detection. Creatinine was measured by an on-line flow injection analysis system based on the Jaffe reaction, which analyzed creatinine as it eluted non-retained from the phenylboronic acid column. Results Various factors were considered in the design and optimization of the phenylboronic acid column, the tandem affinity/ion-pair HPLC columns and the flow injection analysis system. The total analysis time for the final combined system was approximately 16 min per injection at 1 ml/min. This method was found to have good agreement with the expected results for control urine samples. The limits of detection for 20 µl samples (S/N = 3.0) were 1.8, 1.0 and 4.3 µg/l for norepinephrine, epinephrine and dopamine, respectively, while the limit of detection of creatinine was 5.0 mg/l. The linear response of this method extended over a 450 to 930-fold range in concentration for the catecholamines and covered the range of clinical interest. The within-day precision of this method was ± 2.0–2.7%. Conclusions The ability of this method to simultaneously monitor both creatinine and other analytes makes this HPLC/FIA system an attractive method for use in monitoring urinary compounds. With this approach it was possible to provide fast results for small volumes of random urine samples that were collected as part of a psychological study. The same method could also be utilized with 12 or 24 h urine specimens.

Online In-Tube Solid-Phase Extraction Using a Nonfunctionalized PVC Tube Coupled with ICPMS for in Vivo Monitoring of Trace Metals in Rat Brain Microdialysates

We have developed a simple, automatic, online in-tube solid-phase extraction (SPE) method for the preconcentration of trace elements from saline samples. The method takes advantage of the adsorption of trace metal ions onto the interior of a nonfunctionalized PVC tube as a means of separation from the matrix salt. The adsorption of transition metal ions is presumably dominated by Lewis acid/base interactions, which facilitate the formation of metal-PVC complexes. For simultaneous determination of multiple trace metals in the extracellular fluid from the brains of anesthetized rats, we developed an online analytical system comprising microdialysis sampling, the established in-tube extraction procedure, and ICPMS. In the extraction step, the efficiency was optimal when the pH of the sample was adjusted to 8.0 using phosphate buffer. After extraction onto the interior of PVC tube, the adsorbed analytes were eluted with 0.5% HNO 3 prior to online ICPMS measurement. For those elements present in the extracellular fluid at less than nanogram-per-milliliter concentrations (i.e., Cu, Zn, and Mn), a temporal resolution of 12 min was required to collect enough microdialysate to meet the sensitivity requirements of the ICPMS instrument. Noteworthily, because washing and postconditioning the interior of PVC tube are not necessary, a relatively unsophisticated and clean procedure was attained and extremely low detection limits in the range of 5.0 to 510 ng L (-1) were thus obtained for the analysis of Mn, Cu, Zn, Pb, Cd, Ni, and Co in microdialysate samples of 8 microL by ICPMS. To the best of our knowledge, this study is the first to exploit PVC peristaltic tubing as an SPE adsorbent in the laboratory-on-valve mode for online sample treatment and trace metal preconcentration prior to ICPMS measurement. We confirmed the analytical reliability of this method through the analysis of the certified reference material SLEW-3 (estuarine water) and 2670a (human urine) and demonstrated its applicability through simultaneous in vivo monitoring of the basal concentrations and concentration profiles of multiple metal ions in the brain extracellular fluid of a living rat.

Missing methane emissions from leaves of terrestrial plants

AbstractThe controversial claim that attached leaves of terrestrial plants emit CH4 aerobically remains to be corroborated. Here, we report CH4 fluxes and CO2 exchange rates for leaves of the C4 species Zea mays using a high‐accuracy traceable online analytical system. In contrast to earlier results for Z. mays, our measurements provide no evidence for substantial aerobic CH4 emissions from photosynthesizing leaves illuminated with photosynthetically active radiation (λ=400–700 nm), or from dark‐respiring leaves. Preliminary measurements with the same system indicated a similar lack of aerobic CH4 emissions in the light or dark from leaves of the C3 species Nicotiana tabacum. These findings are supported by independent high‐precision 13C‐labeling studies that also failed to confirm substantial aerobic CH4 emissions from plants. Nevertheless, we are not able to exclude the possibility that CH4 emissions from plants may be linked to nonenzymatic processes with an action spectrum lying outside the wavelength range for photosynthesis.

A new fully automated on-line digestion system for ultra trace analysis of mercury in natural waters by means of FI-CV-AFS

A fully automated flow injection (FI) system utilizing the extraordinary oxidation power of bromine monochloride (BrCl) for the transformation of dissolved mercury species to Hg 2+ and oxidation of dissolved organic carbon (DOC) has been developed and coupled to cold vapor (CV) atomic fluorescence spectrometry (AFS) for highly sensitive mercury detection. The system can be applied to natural waters, sea water as well as freshwater and provides a detection limit as low as 16 pg Hg l −1 from a sample volume of 7 ml. The relative standard deviation is about 4–10%. A 3-fold measurement of one sample is completely processed within 15 min. Dissolved organic carbon, chloride and iodide ions are tolerated in concentrations of 15 mg DOC l −1, >21 g Cl − l −1, and 10 mg I − l −1. Validation of the proposed method yielded a good recovery of total mercury in a moorland water sample and in the certified reference material ORMS-3, river water. Investigation of eight real water samples with mercury concentrations in the range of 0.3–1.4 ng l −1 also confirmed the suitability of the proposed method.

Simultaneously monitoring the particle size distribution, morphology and suspended solids concentration in wastewater applying digital image analysis (DIA).

The efficiency of particle sedimentation in wastewater treatment is seriously affected by particle size distribution and morphology. A laser particle size analyzer is typically to analyze particle size distribution in wastewater. However, using this analyzer for on-line monitoring is difficult. This analyzer cannot measure particle morphology. An on-line digital image analysis (DIA) system was setup in this study to simultaneously measure particle size distribution and morphology in wastewater. The DIA measurement results show that the predominant particle size with an equivalent diameter (ED) was 10-40 microm. The particle size distribution measured by the DIA method similar to that measured with the laser particle size analyzer, indicating that the DIA method precisely measures particle size distribution. In addition, the mean fractal dimension (D (f)) of a set of particles was measured simultaneously, resulting in a good linear relationship between suspended solids (SS) precipitation efficiencies in samples. Finally, by combining the DIA measurement results with an artificial neural network (ANN), the SS concentrations of sample can be precisely predicted and the SS precipitation efficiencies were also evaluated.

On-line enantiomeric analysis using high-performance liquid chromatography in chiral separation by simulated moving bed

An automated on-line enantiomeric analysis system comprising an analytical HPLC set-up with two UV detectors sharing the same light source has been employed to monitor the internal composition profile in chiral simulated moving bed chromatography. This monitoring scheme does not use a polarimeter. Using a sampling interface placed between two SMB columns, effluent samples are directed onto a high-efficiency analytical column at a sampling rate faster than the overall dynamics of the preparative unit to achieve on-line enantiomeric analysis of the composition profile. The other UV detector is placed in the SMB loop before the fraction collector to provide instantaneous measurement of the total enantiomeric concentration. The feasibility and effectiveness of the on-line enantimeric monitoring scheme were assessed experimentally on the separation of Tröger’s base racemate, using Chiralpak AD as stationary phase and methanol as eluent. It was found that robust monitoring of the concentration profiles of the individual enantiomers is best achieved when the enantiomeric purity obtained from the peak areas of the on-line enantiomer analysis chromatograms is combined with the on-line UV measurement of total enantiomeric concentration. The accuracy and robustness of the proposed on-line enantiomeric monitoring system open up promising perspectives for process control and dynamic optimization of the SMB.