Bead injection

Ruzicka, J. and Scampavia, L., From flow injection to bead injection, Anal. Chem., 71, 257A-263A, 1999. 

The utilization of sequential injection analysis coupled with HPLC systems increases the reliability of an HPLC analysis considerably because the primary factor that contributes to the increasing uncertainty is the sample preparation. It is always necessary to look to the most reliable methods for sample preparation, because only these methods will give the best results after the automation by using sequential injection analysis. The best coupling must be concerned with the selectivity and sensitivity assured by a sequential analysis system and by the selectivity and sensitivity of the HPLC technique. The introduction of bead injection considerably improves the reliability of the discussed system. 

Development of the sequential injection analyser, as well as intensive studies exploiting beads (including magnetic beads) [80—82], led to the appearance of flow analysers incorporating bead injection [83] and lab-on-valve [84] devices. 

The bead injection system was designed to operate in the sequential injection mode. It is possible to carry out bead injection analysis in a low-cost flow injection system with a unidirectional pump and without a computer, mainly for applications where samples and reagents are abundant and when there is no need for micro-volume control. To this end, it is necessary to use a flow cell able to achieve bead retention, accommodation of chemical reactions and detection [87,88]. 

The bead injection system was initially used for drug discovery [89], trace metal determinations [86] and in-vivo cellular metabolism evaluation [90—92]. Its potential for the determination of inorganic and organic chemical species, especially for agronomical, environmental, and pharmaceutical analysis, as well as nutrient monitoring, has been emphasised elsewhere [93—96]. 

There are many variants of analytical flow systems, e.g., segmented flow analysis, flow injection analysis, sequential injection analysis, multisyringe flow injection analysis, batch injection analysis, mono-segmented flow analysis, flow-batch analysis, multi-pumping flow analysis, all injection analysis and bead injection analysis, all of which have acronyms [176]. In view of the existence of several common features, however, all flow analysers can be broadly classified as either segmented or unsegmented, with the most common example of the later mode being the flow injection analyser. 

C.C. Oliveira, E.A.G. Zagatto, J. Ruzicka, G.D. Christian, A bead injection system for copper determination, Anal. Lett. 33 (2000) 929. 

S.K. Hartwell, G.D. Christian, K. Grudpan, Bead injection with a simple flow-injection system an economical alternative for trace analysis, Trends Anal. Chem. 23 (2004) 619. 

S.K. Hartwell, D. Somprayoon, P. Kongtawelert, S. Ongchai, O. Arppomchayanon, L. Ganranoo, et al., Online assay of bone specific alkaline phosphatase with a flow injection-bead injection system, Anal. Chim. Acta 600 (2007) 188. 

I. Lahdesmaki, L.D. Scampavia, C. Beeson, J. Ruzicka, Detection of oxygen consumption of cultured adherent cells by bead injection spectroscopy, Anal. Chem. 71 (1999) 5248. 

I. Lahdesmaki, C. Beeson, G.D. Christian, J. Ruzicka, Measurement of cellular stimulation through monitoring pH changes by bead injection fluorescence microscopy, Talanta 51 (2000) 497. 

J.B. Quintana, M. Miro, J.M. Estela, V. Cerda, Automated on-line renewable solid-phase extraction-liquid chromatography exploiting multisyringe flow injection-bead injection lab-on-valve analysis, Anal. Chem. 78 (2006) 2832. 

X.-B. Long, M. Miro, E.H. Hansen, Universal approach for selective trace metal determinations via sequential injection-bead injection-Lab-on-Valve using renewable hydrophobic bead surfaces as reagent carriers, Anal. Chem. 77 (2005) 6032. 

J. Ruzicka, Lab-on-valve universal microflow analyzer based on sequential and bead injection, Analyst 125 (2000) 1053. 

Reversed flow (Fig. 3.4e). This is a powerful tool for kinetic methods (see also 8.6.4). It requires a stop/start feature in addition to gearing for reverse drive, and has been exploited mainly in sequential and bead injection determinations. An example is the kinetic turbidimetric determination of phytic acid in food samples relying on the influence of the analyte concentration on the rate of calcium oxalate crystallisation [10]. The sample and reagents were aspirated and then the flow was reversed, directing the sample zone towards the flow cell, where its central portion was stopped for 30 s, monitored and discarded. 

The reagent is generally packed in a mini-column strategically positioned in the analytical path. Alternatively, it can be fixed on the inner walls of the manifold or on fluidised beads, e.g., in bead injection systems. 

The mini-column can be placed between the injection port and the detection unit (Fig. 8.19), and the solutions involved (sample, wash, eluent and conditioning) are sequentially passed through the column. The flow system can be manual or computer-controlled. This manifold geometry is exemplified by the flow injection chemiluminometric determination of zinc and cadmium [207], After sorption of the analytes as chloro-complexes, two different eluting solutions were injected, allowing sequential determinations the resin was reconditioned by the water carrier stream. This geometry can also be implemented in sequential injection analysis and bead injection analysis, as demonstrated in the... 

Another possibility is to take advantage of functionalised moving beads, which are inherent to the bead injection system (see 2.4.1). The analyte interacts with a specific reagent on the bead surface, thus forming a detectable species on the solid phase. Alternatively, an auxiliary reagent can be introduced into the system to perform this function [240]. By stopping the beads at the detector, the chemical species formed can be directly detected. The use of magnetic beads to achieve this has been comprehensively reviewed [201]. 

Copper Natural waters Chelex-100 UV-Vis 0.5 pg L"1 Bead injection system with [240] a Jet Ring flow cell ... 

Thiamine Pharmaceutical formulations Cis — alkylated polystyrene/ divinylbenzene) Fluorimetry 31 ng mL-1 Bead injection system [519]... 

J.H. Wang, E.H. Hansen, M. Miro, Sequential injection—bead injection—lab-on-valve schemes for on-line solid phase extraction and preconcentration of ultra-trace levels of heavy metals with determination by electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry, Anal. Chim. Acta 499 (2003) 139. 

E.C. Vidotti, V.C. Almeida, C.C. Oliveira, Exploiting the bead injection concept for sequential determination of copper and mercury ions in river-water samples, Talanta 64 (2004) 993. 

Another field where the utilization of flow system decreases both the uncertainty and the degree of contamination by the operator is the analysis of radionucleids using bead injection.321 The proposed method has a low level of uncertainty, high objectivity, and low contamination from both system operator and sample. 

Miro M, Jonczyk S, Wang J and Hansen EH (2003) Exploiting the bead-injection approach in the integrated sequential injection lab-on-valve format using hydrophobic packing materials for on-line matrix removal and preconcentration of trace levels of cadmium in environmental and biological samples via formation of non-charged chelates prior to ETAAS detection. J. Anal Atom Spectrom 18 BOOB. 

Amjjan P., Lapanantnoppakhum S., Sooksamiti P., Jakmunee J., Hartwell S. K., Jayasvati S., Christian G. D. and Grudpan K. (2002) Determination of trace iron in beer using flow-injection systems with in-valve column and bead injection. Talanta, 58,1327-1334. 

The manipulation of antigen-antibody interactions and subsequent detection of several analytes has been achieved using SIA. Whilst many of these applications have involved the use of SIA with bead injection (to be discussed later), some have used SIA for the direct analysis of cellular and bodily fluids. 

The utility of bead injection SIA for separation and preconcentration has been well demonstrated by the selective determination of strontium-90, americium-241, and technetium-99 along with various isotopes of plutonium and curium whose radionuclide activity was determined in nuclear waste samples using liquid scintillation counting. 

After preconcentration, these samples can then be back-extracted into a similar solvent or into a matrix that is more compatible with the detection system. The use of SIA with bead injection was demonstrated for the preconcentration of nickel and bismuth on a cation-exchange resin prior to detection by electrothermal atomic absorption spectrometry (ETAAS) or ICP-MS. 

Wang J, Hansen EH, and Miro M (2003) Sequential injection-bead injection-lab-on-valve schemes for on-line... 

Online analysis Online sample processing techniques such as flow injection provide advantages such as reliability, sample economy, ease of automation, measurement standardization, high speed, optional sample dilution, and the ability to derivatize the analyte so as to suit the analyzer/detector. These procedures facilitate the online monitoring of fermentation substrate materials, respiratory gases, and biomass. The modifications to flow injection analysis for accurate discontinuous flow operation include sequential injection analysis and bead injection spectroscopy. The most recent invention in online techniques is the introduction of the Lab-on-a-Valve, which opens the way to development of a novel type of microflow analytical system monitored by UV-visible spectrophotometry using fiber optics. This system is an ideal tool for fermentation monitoring. 

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