Flow injection analysis system

The following set of experiments provide examples of the application of flow injection analysis or the characterization of the behavior of a flow injection analysis system. 

Immunosensors promise to become principal players ia chemical, diagnostic, and environmental analyses by the latter 1990s. Given the practical limits of immunosensors (low ppb or ng/mL to mid-pptr or pg/mL) and their portabiUty, the primary appHcation is expected to be as rapid screening devices ia noncentralized clinical laboratories, ia iatensive care faciUties, and as bedside monitors, ia physicians offices, and ia environmental and iadustrial settings (49—52). Industrial appHcations for immunosensors will also include use as the basis for automated on-line or flow-injection analysis systems to analyze and control pharmaceutical, food, and chemical processing lines (53). Immunosensors are not expected to replace laboratory-based immunoassays, but to open up new appHcations for immunoassay-based technology. 

B. Bucur, M. Dondoi, A. Danet, and J.L. Marty, Insecticide identification using a flow injection analysis system with biosensors based on various cholinesterases. Anal. Chim. Acta 539, 195-201 (2005). 

Three methods for trace metal preconcentration were examined liquid-liquid extraction aided by a chelating agent, concentration on a synthetic chelating resin and reductive precipitation with NaBTLt. The latter method gave 1000-fold preconcentration factors with total recovery of Pb and other elements17. Preconcentration of nanogram amounts of lead can be carried out with a resin incorporating quinolin-8-ol (3)18. Enhancement factors of 50-100 can be achieved by such preconcentration procedures followed by determination in a FLA (flow injection analysis) system limits of detection are a few pg Pb/L19. 

Steve Kruse of the City of Lincoln, Nebraska, Waste-water Treatment Plant Laboratory examines a faulty detector module taken from the flow injection analysis system in use in the laboratory. 

Figure 19-11 Flow injection analysis system with enlarged view of chemistry section. Different modular chemistry units are installed for different analyses. [Courtesy Skalar, Inc.. Norcross. GA]... 

To our present knowledge, there has been no detailed report so far studying the initiation step of the synthesis of PEO block co-polymers continuously. Here, a new method is presented that allows the determination on-line of the consumption of Ce(IV) ions in the reaction mixture by means of chronoamperometry and a flow injection analysis system using textile electrodes with a gold surface. 

The (Bio-pF-EIS-CAP) sensors were integrated in flow injection analysis systems. The medium components were monitored online. 

M. Reinecke and T. Scheper, Fast online flow injection analysis system for IgG monitoring in bioprocesses, J. Biotechnol., 59 (1997) 145-153. 

Fig. 24 Recorder output of the flow injection analysis system for triplicate 300 xL sample solutions of Cd(N03 b at a flow rate of 2.5 mL miir1...

A few other types of anion sensors have been mentioned recently in the literature. Tetrathiofulvalene microcrystals immobilised at a platinum electrode displayed electrochemical properties that were affected by the presence of anions in solution, with some selectivity for anions such as bromide [ 145]. A flow-injection analysis system using anion-exchange columns for separation and polyaniline electrodes as detectors could detect dichromate down to 0.004 ppb and could be used for seawater samples [146]. 

M 20] [P 19] The pTAS module is made for performing colorimetric analyses as typically applied in cuvette tests, e.g. for on-site water analysis [30], A continuous test replaces copious manual pipetting of the sampling volumes. The module consists of a micro flow restrictor, a micro mixer and an optical microcuvette for colorimetric analysis. The sample is injected by a conventional FIA (flow injection analysis) system. By close connection, a dead volume of only 2.2 pi is given. 

Veenstra, T. T., Lammerink, T. S. J., van den Berg, A., Elwenspoek, M. C., Characterization method for a new diffusion mixer applicable in micro flow injection analysis systems, in Proceedings of the Micromechanics Europe (MNE)... 

Fernandez, C., A.C.L. Conceicao, R. Rial-Otero, C. Vaz, and J.L. Capelo. 2006. Sequential flow injection analysis system on-line coupled to high intensity focused ultrasound Green methodology for trace analysis applications as demonstrated for the determination of inorganic and total mercury in waters and urine by cold vapor atomic absorption spectrometry. Anal. Chem. 78 2494-2499. 

Haswell, S.J., Development and operating characteristics of micro flow injection analysis systems based on electroosmotic flow. Analyst 1997, 122, 1R-10R. 

Richter T, Bilitewski U (1997) A flow injection analysis system using a bi-enzyme sensor for the determination of ATP, (GBF, Braunschweig, D), 8th European Biotechnology Conference, Budapest, Hungary... 

Takeuchi et al. published a mechanized assay of serum cholinesterase by specific colorimetric detection of the released acid [40]. The cholinesterase reaction was carried out on a thermostatted rack at 30° C with a reaction mixture of serum (10 pL), 50mM barbitone-HCl assay buffer (pH 8.2 140 pL), and 12.5 mM acetylcholine solution (50 pL). The solutions were prepared by programmed needle actions, and a sample blank was also prepared. The reaction was stopped after 9.7 min by injection of the mixture into a flow injection analysis system to determine the quantity of acetic acid formed. The carrier stream (water, at 0.5mL/min) was merged with a stream (0.5mL/min) of 20 mM 2-nitrophenylhydrazine hydrochloride in 0.2 M HC1 and a stream (0.5 mL/min) of 50 mM 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide hydrochloride in ethanol containing 4% of pyridine. The sample was injected into this mixture (pH 4.5), passed through a reaction coil (10 m x 0.5mm) at 60°C, 1.5M NaOH was added, and, after passing through a second reaction coil (lm x 0.5 mm) at 60°C, the absorbance was measured at 540 nm. 

Nie et al. used a flow injection chemiluminescence method for the determination of dipyridamole in Persantin tablets [51]. A flow injection analysis system equipped with a chemiluminescence detector was used. Sodium hypochlorite was used as a chemiluminescent substance, and Triton X-100 was used as an enhancer of the chemiluminescence reaction. Sample solutions (pH 4-6) was injected into 0.2% Triton X-100 and treated with 0.5% sodium hypochlorite, and the chemiluminescence intensity then measured. The calibration graph was linear from 0.04 to 10 pg/mL of Persantin tablets (as its active ingredient dipyridamole), with a detection limit of 11 ng/mL. Recoveries were quantitative and the relative standard deviation ( = 3) was 2.7%. The method has been used to determine Persantin in injection and tablets, and the results obtained using this method agreed with those obtained by the Chinese Pharmacopoeial method. 

Even if sufficient sample size, in volume, may not be available, enrichment techniques that concentrate trace metals in microliter samples are sometimes quite useful because modern instrumental detection systems such as AAS, ICP-AES, ICP-MS, etc. do not need a large sample size. Moreover, if trace metals that have been separated from their major substances can be concentrated in an extremely small area of the polytetrafluoroethylene (PTFE) tube in HSCCC, this would be an ideal flow-injection analysis system for determination of inorganics. From this point of view, the recently developed pH-zone refining technique has great potential for enrichment, especially for instrumental inorganic trace analysis. 

Because the optical rotation detectors only respond to optically active compounds, enantiomeric purity determination to precisions of better than 0.5% can be achieved and is possible in even the complex mixtures. The detection can also be used as part of a flow injection analysis system to determine amount and enantiomeric purity of a drug in dosage form. 

The method of Fan and Dasgupta (1994) relics on tlie reaction of formaldehyde with 1,3-cyclohexane-dione in acidified ammonium acetate to form the fluorescent dihydropyridine derivative in a flow injection analysis system. Formaldehyde trapped in water can be reacted with pararosaniline and sodium sulfite under mild conditions (neutral pH, room temperature equilibration) to produce a colored product that is measured at 570 nm (Petreas et al. 1986). The presence of bisulfite is an interference in this reaction so the method cannot be used to sample atmospheres that contain sulfur dioxide. In addition, the method is reported to suffer from interferences resulting from the presence of other aldehydes and phenol (Hoogenboom et al. 1987). The indirect method of Hoogenboom et al. (1987) relies on the reaction of excess bisulfite in an aqueous solution of formaldehyde with 5,5 -dithiobis(2-nitrobenzoic acid) to form a colored product, the absorbance of which is measured at 412 nm. The method reported by Naruse et al. (1995) relies on the formation of a colored product obtained by reacting the aqueous formaldehyde with acetylacetone and ammonium acetate in acetic acid. Absorbance is measured at 414 nm. 

Methods for the collection and determination of formaldehyde in water show great similarity to those methods for air described above. The methods of Tomkins et al. (1989) and EPA (1992b) for formaldehyde in drinking water and the method of Facchini et al. (1990) for formaldehyde in fog water all rely on the formation of the DNPH derivative followed by HPLC. The method of Dong and Dasgupta (1987) relies on the reaction of formaldehyde in atmospheric water with a diketone (2,4-pentanedione) and ammonimn acetate to form a ftuorescent derivative that is measured spectrophotometrically in a flow injection analysis system. 

Automated Flow Injection Analysis System for Formaldehyde Determination... 

An automated and microprocessor-controlled flow injection analysis system was developed for formaldehyde emission measurements. This system was based on the modified pararosaniline method and a sampling rate of about 40 samples/hour was obtained. 

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