Atomic flow injection

Since 1970, new analytical techniques, eg, ion chromatography, have been developed, and others, eg, atomic absorption and emission, have been improved (1—5). Detection limits for many chemicals have been dramatically lowered. Many wet chemical methods have been automated and are controlled by microprocessors which allow greater data output in a shorter time. Perhaps the best known continuous-flow analy2er for water analysis is the Autoanaly2er system manufactured by Technicon Instmments Corp. (Tarrytown, N.Y.) (6). Isolation of samples is maintained by pumping air bubbles into the flow line. Recently, flow-injection analysis has also become popular, and a theoretical comparison of it with the segmented flow analy2er has been made (7—9). 

FLOW INJECTION ELECTROCHEMICAL HYDRIDE GENERATION ATOMIC ABSORPTION SPECTROMETRY EOR THE DETERMINATION OE ARSENIC... 

A flow-injection system with electrochemical hydride generation and atomic absorption detection for the determination of arsenic is described. This technique has been developed in order to avoid the use sodium tetrahydroborate, which is capable of introducing contamination. The sodium tetrahydroborate (NaBH ) - acid reduction technique has been widely used for hydride generation (HG) in atomic spectrometric analyses. However, this technique has certain disadvantages. The NaBH is capable of introducing contamination, is expensive and the aqueous solution is unstable and has to be prepared freshly each working day. In addition, the process is sensitive to interferences from coexisting ions. 

Lab method using continuous flow or flow injection analysis hydride generation and atomic absorption spectrometry... 

Haghighi, B., Maleki, N., and Safavi, A., Standard Additions in Flow-Injection Analysis with Atomic Absorption Spectrometry, Analytica Chimica Acta 357, 1997, 151-156. 

Kelko-Levai, A., Varga, I., Zih-Perenyi, K., and Lasztity, A., Determination of trace elements in pharmaceutical substances by graphite furnace atomic absorption spectrometry and total reflection X-ray fluorescence after flow injection ion-exchange preconcentration, Spectrochim. Acta Pt. B, 54, 827, 1999. 

Flow-injection (FI) on-line analyte preconcentration and matrix removal techniques greatly enhance the performance of atomic spectrometry [348], By using USN with membrane desolvation (MDS) as the interface, FI sorbent extraction can be directly coupled with ICP-MS for the analysis of organic solutions [349]. 

Samanta G, Chakraborti D. 1996. Flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) and spectrophotometric methods for determination of lead in environmental samples. Environmental Technology 17(12) 1327-1337. 

Fast Fourier Transform Flow Injection Analysis Field Ion Atom Probe Flame-Ionization Detector Field Ion Microscopy... 

A method described by Hirata and Honda [618] uses a flow injection analysis manifold for pH adjustment of a seawater sample, followed by concentration of zinc on a column packed with Chelex 100 resin. The zinc was eluted with nitric acid and determined by atomic absorption spectrometry. The detection limit is 0.5 p,g/l and the relative standard deviation is 2.7% at the 10 ig/l level. 

Olsen et al. [660] used a simple flow injection system, the FIAstar unit, to inject samples of seawater into a flame atomic absorption instrument, allowing the determination of cadmium, lead, copper, and zinc at the parts per million level at a rate of 180-250 samples per hour. Further, online flow injection analysis preconcentration methods were developed using a microcolumn of Chelex 100 resin, allowing the determination of lead at concentrations as low as 10 pg/1, and of cadmium and zinc at 1 pg/1. The sampling rate was between 30 and 60 samples per hour, and the readout was available within 60-100 seconds after sample injection. The sampling frequency depended on the preconcentration required. 

Fang et al. [661] have described a flow injection system with online ion exchange preconcentration on dual columns for the determination of trace amounts of heavy metal at pg/1 and sub-pg/1 levels by flame atomic absorption spectrometry (Fig. 5.17). The degree of preconcentration ranges from a factor of 50 to 105 for different elements, at a sampling frequency of 60 samples per hour. The detection limits for copper, zinc, lead, and cadmium are 0.07, 0.03, 0.5, and 0.05 pg/1, respectively. Relative standard deviations are 1.2-3.2% at pg/1 levels. The behaviour of the various chelating exchangers used was studied with respect to their preconcentration characteristics, with special emphasis on interferences encountered in the analysis of seawater. 

A patented water injection system has been devised for extinguishing oil and gas well fires in case of a blowout. The "Blowout Suppression System" (BOSS) consist of finely atomized water injected to the fluid stream of a gas and oil mixture before it exits a release point. The added water lowers the flame temperature and flame velocities thereby reducing the flame stability. In the case where the flame cannot be completely dissipated, the fire intensity is noticeably deceased, preserving structural integrity and allowing manual intervention activities. A precaution in the use of such a device is that, if a gas release fire is suppressed but the flow is not immediately isolated, a gas cloud may develop and exploded that would be more destructive that the pre-existing fire condition. 

Fang, Z. (1995). Flow Injection Atomic Absorption Spectrometry. Chichester, Wiley. 

Spectrophotometry Flow-injection analysis Gas chromatography Inductively coupled plasma atomic emission spectrometry Miscellaneous... 

It is seen by examination of Table 1.11(b) that a wide variety of techniques have been employed including spectrophotometry (four determinants), combustion and wet digestion methods and inductively coupled plasma atomic emission spectrometry (three determinants each), atomic absorption spectrometry, potentiometric methods, molecular absorption spectrometry and gas chromatography (two determinants each), and flow-injection analysis and neutron activation analysis (one determinant each). Between them these techniques are capable of determining boron, halogens, total and particulate carbon, nitrogen, phosphorus, sulphur, silicon, selenium, arsenic antimony and bismuth in soils. 

Brzezinska-Paudyn et al. [124] compared results obtained in determinations of arsenic by conventional atomic emission spectrometry, flow-injection/hydride generation inductively coupled plasma atomic... 

Inductively coupled plasma atomic emission spectrometric analysis with flow-injection/hydride generation... 

These methods were used to determine arsenic in certified sediments (Table 12.15). Conventional inductively coupled plasma atomic emission spectrometry is satisfactory for all types of samples, but its usefulness was limited to concentrations of arsenic greater than 5pg g-1 dry weight. Better detection limits were achieved using the flow-injection-hydride generation inductively coupled plasma technique in which a coefficient of variation of about 2% for concentrations of lOpg g 1 were achieved. 

AgN03 = silver nitrate CICN = cyanogen chloride CN" = cyanide ion CNATC = cyanides not amenable to chlorination (Rosentreter and Skogerboe 1992) AAS = atomic absorption spectroscopy EPA = Environmental Protection Agency FIA = flow injection analysis GC/ECD = gas chromatograph/electron capture detector HCN = hydrogen cyanide NaOH = sodium hydroxide NIOSH = National Institute for Occupational Safety and Health... 

The analytical techniques used for additives analysis are reviewed below. They are mainly chromatographic but enzymatic, flow injection analysis, inductively coupled plasma-atomic emission spectrometry and atomic absorption methods are also used. 

Cloud point extraction of metal ions. The use of cloud point extraction as a separation technique was first introduced by Watanabe for the extraction of metal ions forming sparingly water soluble complexes [109], Since then, the technique has been applied successfully to the extraction of metal chelates for spectrophotometric, atomic absorption, or flow injection analysis of trace metals in a variety of samples [105-107,110]. Other metal complexes such as AUCI4 or thiocyanato-metal complexes can be extracted directly using nonionic surfactants such as polyoxyethylene... 

Flow injection analysis is based on the injection of a liquid sample into a continuously flowing liquid carrier stream, where it is usually made to react to give reaction products that may be detected. FIA offers the possibility in an on-line manifold of sample handling including separation, preconcentration, masking and color reaction, and even microwave dissolution, all of which can be readily automated. The most common advantages of FIA include reduced manpower cost of laboratory operations, increased sample throughput, improved precision of results, reduced sample volumes, and the elimination of many interferences. Fully automated flow injection analysers are based on spectrophotometric detection but are readily adapted as sample preparation units for atomic spectrometric techniques. Flow injection as a sample introduction technique has been discussed previously, whereas here its full potential is briefly surveyed. In addition to a few books on FIA [168,169], several critical reviews of FIA methods for FAAS, GF AAS, and ICP-AES methods have been published [170,171]. 

Ruzicka, J. Hansen, E. H. Flow-Injection Analysis, Wiley New York, 1981. Valcarcel, M. Gallego, M. Separation techniques. In Flow Injection Atomic Spectroscopy, Bruguera, J. L. Ed., Marcel Dekker New York, 1989. 

A number of applications of flow-injection techniques have been made to flame atomic absorption spectrometry [22]. Although manifolds can be connected directly to the nebuhzer, the response of the spectrometer is dependent on the flow rate of the sample into the nebuhzer [23], and some adjustment to the manifold may be required. The optimum flow rate for maximum response when the sample enters the nebuhzer as a discrete sample plug can be different from that found for analysis of a continuous sample stream. 

Various methods ofachieving preconcentration have been applied, including Hquid -hquid extraction, precipitation, immobihzation and electrodeposition. Most of these have been adapted to a flow-injection format for which retention on an immobihzed reagent appears attractive. Sohd, sihca-based preconcentration media are easily handled [30-37], whereas resin-based materials tend to swell and may break up. Resins can be modified [38] by adsorption of a chelating agent to prevent this. Sohds are easily incorporated into flow-injection manifolds as small columns [33, 34, 36, 39, 40] 8-quinolinol immobilized on porous glass has often been used [33, 34, 36]. The flow-injection technique provides reproducible and easy sample handhng, and the manifolds are easily interfaced with flame atomic absorption spectrometers. 

CONTENTS Preface, Joseph Sneddon. Analyte Excitation Mechanisms in the Inductively Coupled Plasma, Kuang-Pang Li and J.D. Winefordner. Laser-Induced Ionization Spectrometry, Robert B. Green and Michael D. Seltzer. Sample Introduction in Atomic Spectroscopy, Joseph Sneddon. Background Correction Techniques in Atomic Absorption Spectrometry, G. Delude. Flow Injection Techniques for Atomic Spectrometry, Julian F. Tyson. 

Z. FANG in chapter 4 of "Flow Injection Atomic Spectroscopy", edited by J.L. Burguera, M. Dekker, New York, 1989. 

J.L. Manzoori, A. Miyazaki, Indirect inductively coupled plasma atomic emission determination of fluoride in water samples by flow injection solvent extraction. Anal. Chem. 62 (1990) 2457-2460. 

Montero et al. reported an indirect atomic absorption spectrometric method combined with a flow-injection precipitation technique for the determination of procaine in pharmaceutical preparations [53]. The precipitate formed by the injection of Co(II) into a sample stream containing 10 to 110 pM procaine at pH 8.0 to 9.1 was retained on a stainless steal filter, and analyzed at 240.7 nm by an online atomic... 

Flow injection manifold for coupling with atomic spectrometry. The column can be used for preconcentration, matrix removal or chromatography. 

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