**Multisyringe Flow Injection Analysis for Environmental Monitoring: Applications and Recent Trends**

Marcela A. Segundo1, M. Inês G. S. Almeida1,2 and Hugo M. Oliveira1 *1REQUIMTE, Department of Chemistry, Faculty of Pharmacy, University of Porto, 2School of Chemistry, University of Melbourne, 1Portugal 2Australia* 

### **1. Introduction**

282 Environmental Monitoring

International Organization for Standardization (ISO). (2008). *Quality Management Systems*,

International Organization for Standardization (ISO). (2010). *Sampling Airborne Radioactive* 

Luetzelschwab, J.; Storey, C.; Zraly, K. & Dussinger, D. (2000). Self Absorption of Alpha and Beta Particles in a Fiberglass Filter. *Health Physics*, Vol. 79, No. 4, (October 2000), pp. 425-430

Maiello, M. & Hoover, M. (2010). *Radioactive Air Sampling Methods*, CRC Press, ISBN 978-0-

McFarland, A.; Mohan, A.; Ramakrishna, N.; Rea, J. & Thompson, J. (2000). *Deposition 2001a,* 

Recknagle, K.; Yokuda, S.; Ballinger, M. & Barnett, J. (2009). Scaled Tests and Modeling of

Simpkins, A. (2000). *Maximally Exposed Offsite Individual Location Determination for NESHAPS* 

Smith, B., Barnett, J. & Ballinger, M. (2011). *Assessment of the Losses Due to Self Absorption by* 

Stevens, D. & Toureau, A. (1963). *The Effect of Particle Size and Dust Loading on the Shape of* 

U.S. Environmental Protection Agency (EPA). (1989). *Methods for Estimating Radionulide* 

U.S. Environmental Protection Agency (EPA). (2002a). *National Emissions Standards for* 

U.S. Environmental Protection Agency (EPA). (2002b). *Test Methods for Measuring* 

Information, EPA/240/B-06/001, Washington, District of Columbia, USA U.S. Environmental Protection Agency (EPA). (2007). *CAP88-PC Version 3.0 User Guide*, Office of Radiation and Indoor Air, Washington, District of Columbia, USA Washington Administrative Code (WAC). (2005). *Radiation Protection – Air Emissions*, Statute

Wight, G. (1994). *Fundamentals of Air Sampling*, CRC Press LLC (Lewis Publishers), ISBN 0-

Law Committee, WAC-246-247, Olympia, Washington, USA

87371-826-7, Boca Raton, Florida, USA

(40 CFR 60), Appendix D, Washington, District of Columbia, USA

National Laboratory, PNNL-20098, Richland, Washington, USA

*Materials From the Stacks and Ducts of Nuclear Facilities*, ISO, ISO 2889:2010, Geneva,

*Version 1.0. Deposition: Software to Calculate Particle Penetration Through Aerosol Transportation Systems*, Texas A&M University, NUREG/GR-0006, College Station,

Effluent Stack Sampling Location Mixing. *Health Physics*, Vol. 96, No. 2, (February

*Compliance*, Westinghouse Savannah River Company, WSRC-RP-2000-00036, Aiken,

*Mass Loading on Radioactive Particulate Air Stack Sample Filters*, Pacific Northwest

*Alpha Pulse Height Spectra of Air Sample Filters*, Atomic Energy Research Establishment, AERE-R 4249, Harwell, Berkshire, England, United Kingdom Till, J. & Grogan, H. (Eds.). (2008). *Radiological Risk Assessment and Environmental Analysis*, Oxford University Press, ISBN 978-0-19-512727-0, New York, New York, USA U.S. Department of Energy (DOE). (1991). *Environmental Regulatory Guide for Radiological Effluent* 

*Monitoring and Environmental Surveillance (DOE/EH-0173T)*, Assistant Secretary for Environment, Safety and Health, DE91-013607, Washington, District of Columbia, USA

*Emissions.* U.S. Government Printing Office, 40 Code of Federal Regulations Part 60

*Emissions of Radionuclides Other Than Radon From Department of Energy Facilities*. U.S. Government Printing Office, 40 CFR 61, Subpart H, Washington, District of

*Radionuclide Emissions From Stationary Sources*. U.S. Government Printing Office, 40 CFR 61, Appendix B, Method 114, Washington, District of Columbia, USA U.S. Environmental Protection Agency (EPA). (2006). *Guidance on Systematic Planning Using* 

*the Data Quality Objective Process (EPA QA/G-4)*, Office of Environmental

ISO, ISO 9001:2008, Geneva, Switzerland

8493-9717-2, Boca Raton, Florida, USA

Switzerland

Texas, USA

2009), pp. 164-174

South Carolina, USA

Columbia, USA

Multisyringe flow injection analysis (MSFIA) was introduced by Víctor Cerdà and coworkers in 1999 (Cerdà et al., 1999) as a robust alternative to its predecessor flow injection techniques, combining the multi-channel operation of flow injection analysis (Ruzicka & Hansen, 1975) with the possibility of flow reversal and selection of the exact volume of sample and reagent required for analysis as presented in sequential injection analysis (Ruzicka & Marshall, 1990). Generally, flow injection systems are automation tools where, in opposition to batch conventional assays, physico-chemical equilibrium is not attained prior to determination. Hence, flow injection analysis is based in three principles: (1) reproducible sample injection or insertion in a flowing carrier stream; (2) controlled dispersion of the sample zone; and (3) reproducible timing of its movement from the injector point to the detection system.

Since its inception, MSFIA has been the basis for automation of more than 120 different assays, reviewed in several publications (Almeida et al., 2011; Magalhães et al., 2009; Maya et al., 2009; Segundo & Magalhães, 2006). This type of automatic flow injection systems is based on the utilization of a multisyringe burette, depicted schematically in Fig. 1A and 1B. It is a multiple channel piston pump, containing up to four syringes, driven by a single motor of a usual automatic burette and controlled by computer software through a serial port. A two-way commutation valve is connected to the head of each syringe, allowing optional coupling to the manifold lines or to the solution reservoir.

Because the four syringes are driven by the same motor, all pistons move at once in the same direction either delivering (dispense operation) or loading the syringes (pickup operation) with liquids. Considering that the commutation valves can be placed in two positions, there are four possibilities for flow management as depicted in Fig. 1C. Hence, when the pistons are moving upwards, it is possible to dispense liquid into the flow system or send it back to its reservoir. This feature enables that only the necessary amount of reagent solution is introduced into the flow system. Furthermore, when the pistons are moving downwards, it is possible to refill the syringes with solutions present in the respective vessel or to aspirate solutions from the system in order to perform the sampling operation.

Multisyringe Flow Injection

the four positions.

diffusion or dialysis units), for instance.

tubing (Almeida et al., 2008).

10 times (Almeida et al., 2006).

**2. Applications of MSFIA to environmental monitoring** 

in environmental samples as illustrated in Tables 1 and 2.

Analysis for Environmental Monitoring: Applications and Recent Trends 285

Syringes with different volumes, ranging from 0.5 to 25 ml are available, enabling the application of a wide range of flow rates. For example, for a 5 ml syringe, flow rates ranging from 0.28 to 15 ml min-1 may be attained (Miró et al., 2002). Nevertheless, once the flow rate (and volume) is fixed for one syringe, it is also defined for the other channels, and it will depend on the ratio between syringe capacities as different syringes can be placed in any of

Finally, MSFIA manifolds are not restricted to the syringes and the respective commutation valves. The presence of four digital outputs, each capable of providing 12 V/0.5 A, allows the utilization of up to 12 additional commutation valves, also controlled through the multisyringe apparatus. These extra commutation valves are often necessary to assemble a flow network, where analyte determination and sample treatment can be implemented by including confluences for reagent addition, suitable detectors (spectrophotometers, fluorimeters, flame or atomic emission spectrometers) and devices for mass transfer (gas

MSFIA systems have been successfully applied to the determination of more than 20 species

Several applications were targeted to plant macronutrients, such as potassium and phosphorus, and also to micronutrients, including boron, iron and selenium (Table 1). These species were quantified in different types of water (natural and seawater) and also in soil extracts or even soil slurries when applying flame emission spectrometry for determination of potassium (Almeida et al., 2008). The introduction of aqueous samples in flow systems is rather trivial, while manipulation of samples containing suspended solids is not common, requiring a special manifold design employing larger commutation valves and large bore

In fact, solid environmental samples were successfully handled within MSFIA systems. Extraction of potassium contained in 1.8 g of soil was performed in-line, prior to potentiometric determination. The soil was placed in a container where 9 ml of Morgan extractant solution was delivered automatically by one of the syringes. After 6 min, in-line filtration took place, and a small portion of filtrate (100 µl) was sent to the potentiometric detector after in-line addition of an ionic strength adjusting buffer. Different soils were analyzed consecutively without carry-over effects and the filtration unit was reutilized up to

Besides the determination of total extractable content, MSFIA systems have been employed to dynamic fractionation testing schemes, profiting from its inherent capabilities of controllable flow programming. In fact, Miró and co-workers developed a multiple stirredflow chamber assembly, containing up to three parallel extractors, to perform sequential extraction of readily mobilizable fractions of trace elements (Cu, Cd, Ni, Pb, Zn) in fly ashes (Boonjob et al., 2008). Though the detection step was performed off-line (not automated) on each 10 ml fraction collected, the MSFIA system still provided information about overall extractable pools in less than 2 hours, a drastic reduction of time when compared to 18 to 24 hours required per fraction in equilibrium leaching tests. Moreover, the implementation of a sequential leaching scheme was easily accommodated in MSFIA, due to its inherent flow features and also by housing different extracting solutions (water, 0.11 M acetic acid, 0.11 M acetic acid/acetate buffer) simultaneously in each syringe of the multisyringe burette.

Fig. 1. Schematic representation of multisyringe apparatus, with indication of the different components (A) or simplified (B). Flow management possibilities for one syringe during operation of multisyringe apparatus are also given (C). MS = multisyringe; S = syringe, V = commutation valve.

Fig. 1. Schematic representation of multisyringe apparatus, with indication of the different components (A) or simplified (B). Flow management possibilities for one syringe during operation of multisyringe apparatus are also given (C). MS = multisyringe; S = syringe,

V = commutation valve.

Syringes with different volumes, ranging from 0.5 to 25 ml are available, enabling the application of a wide range of flow rates. For example, for a 5 ml syringe, flow rates ranging from 0.28 to 15 ml min-1 may be attained (Miró et al., 2002). Nevertheless, once the flow rate (and volume) is fixed for one syringe, it is also defined for the other channels, and it will depend on the ratio between syringe capacities as different syringes can be placed in any of the four positions.

Finally, MSFIA manifolds are not restricted to the syringes and the respective commutation valves. The presence of four digital outputs, each capable of providing 12 V/0.5 A, allows the utilization of up to 12 additional commutation valves, also controlled through the multisyringe apparatus. These extra commutation valves are often necessary to assemble a flow network, where analyte determination and sample treatment can be implemented by including confluences for reagent addition, suitable detectors (spectrophotometers, fluorimeters, flame or atomic emission spectrometers) and devices for mass transfer (gas diffusion or dialysis units), for instance.
