SIMPLE LABORATORY-MADE AUTOMATED SEQUENTIAL INJECTION ANALYSIS (SIA) DEVICE. II. SIA OPERATIONAL SOFTWARE BASED ON LABVIEW® PROGRAMMING LANGUAGE

Spectrophotometric determination of thiocyanate by sequential injection analysis

Sequential injection analysis (SIA) and response surface methodology: A versatile small volume approach for optimization of photo-Fenton processes

A new amperometric method for the detection of glucose has been developed. A jet ring cell with a renewable solid support (JRR) is connected to a sequential injection analysis (SIA) system. The solid support, consisting of small spherical particles of agarose gel, with a mean bead size of 90 μm, is coupled with the enzyme glucose oxidase (GOD). The suspension is injected through a multiport valve in the SIA-system and is trapped in the JRR cell by a gap of 10 μm between the glassy carbon (GC) working electrode and a stainless steel counter electrode. The subsequent injection of glucose results in formation of hydrogen peroxide, which is detected by oxidation at 1.0 V (vs. Ag/AgCl/KCl (3 M)). Thereafter the suspension is removed by reversing the pump flow and subsequently replaced with fresh suspension for the next determination of glucose. The linear working range for the JRR-sensor, at this stage of the work, is 100 μM - 5 mM.

A reagent-free method based on a photo-induced fluorimetry in a sequential injection system

Determination of salbutamol using sequential injection analysis (SIA) with chemiluminescence and fluorescence detection has been devised. The chemiluminescence signal was emitted during the oxidation of salbutamol by potassium permanganate in sulfuric acid medium. Sodium polyphosphate was used as chemiluminescence enhancer. The fluorescence signal (excitation wavelength 230 nm) was also measured in sulfuric acid medium. Both detection techniques were compared with respect to the application of the methods to the determination of salbutamol in biological materials. The sample pre-treatment takes place directly in the SIA system, when salbutamol is adsorbed on the solid-phase (Baker-carboxylic acid) microcolumn integrated into the system. Sulfuric acid serves both as the reagent and the eluent. The lab-made SIA system consisted of a 2.5-mL Cavro syringe pump, ten-port Vici Valco selection valve and Spectra-Physics FS 970 fluorescence detector, which was lab-modified for chemiluminescence detection. The system was controlled by a PC using originally compiled LabVIEW-supported software. Concentrations, volumes of reagents and flow rates were optimised by a simplex method. Salbutamol was determined in the linear range 0.05-10 microg mL(-1) (RSD 1.53%), with the detection limit (3 sigma) 0.03 microg mL(-1) and sample throughput of 42 samples per hour with chemiluminescence detection in standard solutions. The fluorescence detection enabled the determination of salbutamol in standard solutions in the linear range 0.5-100 microg mL(-1) (RSD 2.69%), with the detection limit 0.2 microg mL(-1) and sample throughput of 24 h(-1). The proposed methods were applied to the determination of salbutamol in human serum and urine. However, serum is a very complicated matrix and the SIA-SPE analysis did not provide satisfactory results. It was possible to determine salbutamol in human urine using this technique. Better recovery was achieved with fluorescence detection.

SIAmate—a compact and modular sequential injection analysis controller

Enantioanalysis of biomedical substances is very important for clinical analysis because the L- and D-enantiomers of the same chiral compound may be markers for different illnesses. A sequential injection analysis (SIA) system using amperometric biosensors as detectors is proposed for the simultaneous determination of L- and D-pipecolic acid (PA). The amperometric biosensors were based on L-amino acid oxidase (L-AAOD) or/and horseradish peroxidase (HRP) for the assay of L-PA and D-amino acid oxidase (D-AAOD) and/or HRP for the assay of D-PA. The linear concentration ranges are of pmol/L to nmol/L magnitude order, with very low limits of detection. The SIA/biosensors system can be used reliably on-line for the simultaneous assay of L- and D-PA from serum samples, with a frequency of 34 samples per hour.

Highly reproducible SERS detection in sequential injection analysis: Real time preparation and application of photo-reduced silver substrate in a moving flow-cell

Glutathione S-transferases (GSTs) are an important group of isoenzymes that play an essential role in the detoxification of carcinogens. In this way, GST P1-1 is considered a suitable and excellent targetable biomarker to differentiate cancer from normal cells. Ruthenium-, iron-, osmium- and iridium-based compounds are considered promising candidates for the next generation of metal anticancer drugs in order to overcome the side effects produced by the anticancer platinum drugs used in clinic. In this work, it was developed a miniaturized approach based on sequential injection analysis (SIA) for the determination of the half maximal inhibitory concentration (IC50) of GSTs. Beyond the advantages presented by SIA systems such as versatility, simplicity, robustness, reliability and efficiency, this specific one present two more important advantages allowing the use of three times less reagent solutions than in batch method and reducing the analysis time from 8 minutes to 5 minutes. The newly developed method was applied to 22 ruthenium, iron, osmium and iridium derivates compounds ethacrynic acid (EA) and flurbiprofen, a cyclooxygenase inhibitor, were shown to be potent GST P1-1 inhibitors. The iridium compound tested is the strongest inhibitor of GST P1-1 (IC50 = 6.7 ± 0.7 µM) in the present work, more effective than EA itself and the ruthenium analogue.

Sequential injection system for phospholipase A 2 activity evaluation: Studies on liposomes using an environment-sensitive fluorescent probe

Sequential injection system with higher dimensional electrochemical sensor signals: Part 1. Voltammetric e-tongue for the determination of oxidizable compounds

A sequential injection analysis (SIA) system for the spectrophotometric determination of L(+)-lactate using lactate oxidase/peroxidase was developed and applied to wine analysis. It incorporates a dialysis unit between the pump and the selecting valve to provide on-line dilution and interference minimization of the sample matrix. A volume of 100 µL of carrier solution trapped in one channel of the dialysis unit, acts as donor and acceptor solution. With an assay cycle of 262 seconds, the system allows a sample throughput of 14 samples per hour and yields precise results (rsd < 2%). Peroxidase (0.0512 IU) and 0.0384 IU of lactate oxidase promote the conversion of L(+)-lactate in 160 µL of sample, allowing its determination within the 0.25 to 2.5 g/L range. A detection limit of 0.074 g/L was calculated. Results are in good agreement with those obtained with the conventional method (Boehringer UV-Kit).

The lead(II)-contaminated aquatic environment may endanger humans and living organism. The maximum tolerable limit of lead(II) in river water is 1 mg/L. Therefore, the development of a sensitive and green analytical method to determine lead(II) is required. In this work, we developed a Sequential Injection Analysis (SIA) system equipped with a valve-mixing and a flow-based UV detector for highly sensitive detection of lead(II). In order to deal with the green chemistry system, the environmentally friendly natural reagent is prepared from the extract of Caesalpinia pulcherrima instead of a commercial synthetic reagent. The extract of Caesalpinia pulcherrima contains several flavonoid compounds which can bind lead(II) ion to form an orange complex compound at a wavelength of 672.4 nm. Various parameters affecting the sensitivity of the proposed method, which includes pH, reaction time, the flow rate to the detector, and stability of Caesalpinia pulcherrima extract, were investigated in detail. The optimum conditions for a complex formation of Pb-Caesalpinia pilcherrima extract were found at pH 4 along with a reaction time of 10s, and the product flow rate to the detector was 200 µL/s. Under the optimum conditions, a linear calibration graph can be constructed in the lead(II) concentration range of 0-800 ppb with a detection limit of 8.9 ppb. The proposed method is successfully applied to determine lead(II) in industrial wastewater samples with satisfied results.

Determination of pesticides fenoxycarb and permethrin by sequential injection chromatography using miniaturized monolithic column

A carbon nanotubes modified silver electrode (CNTs-Ag) was prepared via catalytic chemical vapor deposition and characterized. The morphology, crystallinity, elemental composition, and other quality parameters of the prepared electrode were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman techniques. The characterization results revealed the modification of the silver metal surface with CNTs of good characteristics. A sequential injection analysis (SIA) system was developed for studying the reaction of ascorbic acid with KIO3 using the prepared CNTs-Ag electrode. Electrodes were polarized with both direct current (DC) and periodic square wave (SW). Various experimental conditions affecting the differential electrolytic potentiometric (DEP) peak such as current density, SW bias value, and flow rate were appraised. Under the optimum conditions, good linear responses for ascorbic acid were obtained in the range of 60.0–850.0 µM for both types of polarization with detection limits of 14.0–19.0 µM. The results obtained showed that the periodic polarization method was more sensitive than DC polarization and the electrode response was faster. Ascorbic acid in pharmaceutical tablets was determined with satisfactory results using this method. The prepared CNTs-based electrode exhibited good performance for a long period of use. The method is simple, rapid, and inexpensive for routine analysis.