Simple Instrumental Setup Research Articles

Lab-in-Syringe, a Useful Technique for the Analysis and Detection of Pollutants of Emerging Concern in Environmental and Food Samples.

Lab-in-syringe is a new approach for the integration of various analytical extraction steps inside a syringe. Fully automated dispersive liquid-liquid microextraction is carried out in-syringe using a very simple instrumental setup. Dispersion is achieved by aspiration of the organic phase and then the watery phase into the syringe as rapidly as possible. After aggregation of the solvent droplets, the organic phase is pushed towards the detector allowing a highly sensitive spectrophotometric or fluorimetric detection. This technique is very useful not only for the preconcentration of analyte, but also for the elimination of their interferences. In this work, its application is described using solvents that are lighter and denser than water. The magnetically assisted variant and its coupling to different instruments has been also described with the aim of increasing the resolution of complex samples, especially useful for the determination of emerging contaminants.

Impact of Anthropogenic Activities on Underwater Noise Pollution in Venice

We illustrate the implementation and results of a field experiment, consisting of recording continuous signal from a hydrophone 3 m deep in the Venetian lagoon. We simultaneously recorded audio signal through a microphone placed on a nearby pier. We investigate the potential of this simple instrumental setup to explore the small touristic boat traffic contribution to the underwater noise. The ultimate goal of our work is to contribute to quantifying underwater noise pollution due to motorboat passages and its impact on the ecosystem. Efforts such as ours should help to identify measures that could diminish noise pollution, focusing specifically on the aspects that are most disruptive to underwater life. After this preliminary test, more work can be planned, involving the deployment of a larger network of similar instruments around the lagoon. At this point, we can conclude that (i) our instruments are sensitive enough to detect motorboats and identify some of their characteristics; (ii) the area of interest is characterized by a large (approx. 20 dB) day/night difference in ambient noise; and (iii) the historic center of Venice and its immediate surroundings are particularly noisy, in comparison to other similarly studied locations.

Towards comprehensive non-target screening using heart-cut two-dimensional liquid chromatography for the analysis of organic atmospheric tracers in ice cores

Non-target screening of secondary organic aerosol compounds in ice cores is used to reconstruct atmospheric conditions and sources and is a valuable tool to elucidate the chemical profiles of samples with the aim to obtain as much information as possible from one mass spectrometric measurement. The coupling of mass spectrometry to chromatography limits the results of a non-target screening to signals of compounds within a certain polarity range based on the utilized stationary phases of the columns. Comprehensive two-dimensional liquid chromatography (LCxLC) introduces a second column of different functionality to enable the analysis of a broader range of analytes. Conventional LCxLC requires complex instrumental setups and is difficult to implement for most laboratories. In this work we demonstrate an approach to approximate a comprehensive non-target screening using a simple instrumental setup employing two columns of orthogonal functionalities (HILIC and reversed-phase), an additional pump, and an additional six-port valve. The void volume of the first dimension is transferred to the reversed-phase column to analyze low-polarity compounds during the re-equilibration of the HILIC. Method validation showed adequate repeatability and detection limits for two selected void volume markers and application to snow samples collected at the high-alpine research station Jungfraujoch yielded a total of 270 signals. Comparison to the one-dimensional HILIC approach revealed 175 signals exclusively detected in the two-dimensional method, of which 23 were detected in the second dimension. Detailed analysis of the chemical composition showed consistency with expected compounds in snow samples like lignin or cellulose combustion products from biomass burning or secondary organic aerosol constituents. The results confirmed that one-dimensional chromatography was not sufficient to cover the entire range of compounds and the developed two-dimensional approach will improve the information content from non-target screening while maintaining time of analysis and a simple instrumental setup.

Introducing Frontal Chromatography-Inductively Coupled Plasma-Mass Spectrometry as a Fast Method for Speciation Analysis: The Case of Inorganic Arsenic.

A frontal chromatography-ICP-MS method (FC-ICP-MS) is proposed as an innovative approach for fast elemental speciation analysis: inorganic arsenic speciation was selected as the first case study to prove the feasibility of the technique and to explore its potentialities and limits. The principal benefits of the FC-ICP-MS approach are the short analysis time and the very simple instrumental setup. As(III) and As(V) front separation is performed over a strong anion exchanger at pH 7.5. After the optimization of the instrumental setup and the frontal chromatographic parameters, As(III) and As(V) concentrations up to 240 μg/kg can be determined within 120-140 s using different univariate and multivariate calibration approaches. Best results in terms of accuracy in prediction were obtained using the partial least squares (PLS) calibration achieving limits of detection of 0.18 and 0.21 μg/kg for As(III) and As(V), respectively. This approach was also used to establish the figures of merit of the method. The proved feasibility and good performances (in terms of analysis time and accuracy) of this technique lay the groundwork for future applications of FC-ICP-MS for the speciation of other elements.

Development of Low-Cost Abbe Refractometer

Refractive index and Abbe number are major physical properties of optical materials including glasses and transparent polymers. Refractive index is, in fact, not a constant number and is varied as a function of optical wavelength. The full refractive index spectrum can be obtained using a spectrometer. However, for optical component designers, three refractive indices at the wavelengths of 486.1 nm, 589.3 nm and 656.3 nm are usually sufficient for most of the design tasks, since the rest of the spectrum can be predicted by mathematical models and interpolation. In this paper, we propose a simple optical instrumental setup that determines the refractive indices at three wavelengths and the Abbe number of solid and liquid materials.

High Figure of Merit (FOM) of Bragg Modes in Au-Coated Nanodisk Arrays for Plasmonic Sensing.

Gold-coated nanodisk arrays of nearly micron periodicity are reported that have high figure of merit (FOM) and sensitivity necessary for plasmonic refractometric sensing, with the added benefit of suitability for surface-enhanced Raman scattering (SERS), large-scale microfabrication using standard photolithographic techniques and a simple instrumental setup. Gold nanodisk arrays are covered with a gold layer to excite the Bragg modes (BM), which are the propagative surface plasmons localized by the diffraction from the disk array. This generates surface-guided modes, localized as standing waves, leading to highly confined fields confirmed by a mapping of the SERS intensity and numerical simulations with 3D finite element method. The optimal gold-coated nanodisk arrays are applied for refractometric sensing in transmission spectroscopy with better performance than nanohole arrays and they are integrated to a 96-well plate reader for detection of IgY proteins in the nanometer range in PBS. The potential for sensing in biofluids is assessed with IgG detection in 1:1 diluted urine. The structure exhibits a high FOM of up to 46, exceeding the FOM of structures supporting surface plasmon polaritons and comparable to more complex nanostructures, demonstrating that subwavelength features are not necessary for high-performance plasmonic sensing.

Determining sunspot positions in the classroom using the Carrington method

The method developed by Richard Carrington nearly 150 years ago is still very useful in order to determine the sunspot heliographic coordinates, owing to its simplicity and low cost equipment required. In this paper, we present a very detailed explanation of the procedure, along with an example of an application. With regard to this, the method can be employed successfully for educational purposes, due to the noticeable accuracy that it provides using a simple instrumental setup.

Multi-spot, label-free detection of viral infection in complex media by a non-reflecting surface

The measurement of the intensity of light reflected by interfaces with extremely low reflectivity in water enables the label-free, multiplex detection of bio-molecular interactions. The binding of targets in solution to surface-immobilized probes (e.g. antibodies) can be quantified using a simple instrumental set-up, comprising a LED source and a camera. The condition of low reflectivity can be achieved by using a perfluorinated plastic substrate with refractive index very close to that of water. Here we show that, despite its simplicity, the method enables label-free detection in complex samples with high absorbance and turbidity. Diagnostic markers of Tomato spotted wilt virus are revealed in crude plant extracts of Datura stramonium leaves at early stage of infection. The measuring procedure requires only the addition of the sample into a cuvette and the acquisition of a series of images for a few minutes. The light reflectivity of the spots of specific antibodies increases more rapidly if the sample is prepared with infected plants.

Multi-spot, Label-free Detection of Biomarkers in Complex Media by Reflectionless Surfaces

Abstract The measurement of the intensity of light reflected by interfaces with extremely low reflectivity in water enables the label-free, multiplex quantification of the binding between immobilized probes (e.g. antibodies) and targets in solution using extremely simple instrumental set-up. Here we show that, despite its simplicity, the method enables label-free detection in complex samples characterized by high absorbance and turbidity. Diagnostic markers of Tomato spotted wilt virus are revealed in crude plant extracts of Datura stramonium leaves with early stage infections.

Lab in a syringe: fully automated dispersive liquid–liquid microextraction with integrated spectrophotometric detection

A new approach for the integration of various analytical steps inside a syringe (Lab in a Syringe) is presented. Fully automated dispersive liquid-liquid microextraction with integrated spectrophotometric detection is carried out in-syringe using a very simple instrumental setup. The lighter-than-water organic droplets released in the extraction step accumulate at the head of the syringe, where two optical fibers are placed on both sides of the syringe, facing each other and enabling the in situ quantification of the extracted compounds. By this, monitoring of the progressively accumulating droplet in the head of the syringe was further possible. In this first report, the developed instrumental setup has been applied to the determination of the dye rhodamine B in water samples and soft drinks. The main parameters influencing the extraction such as the selection of the extractant and disperser solvents, extractant/disperser and organic/water phase ratios, pH of the aqueous phase, extraction flow rates, and extraction time were investigated. Under the selected conditions, rhodamine B was quantified in a working range of 0.023-2 mg L(-1) with a limit of detection of 0.007 mg L(-1). Good repeatability values of up to 3.2% (RSD) were obtained for ten consecutive extractions. The enrichment factor for a 1 mg L(-1) rhodamine B standard was 23, and up to 51 extractions were accomplished in 1 h.

Competitive Reporter Monitored Amplification (CMA) - Quantification of Molecular Targets by Real Time Monitoring of Competitive Reporter Hybridization

BackgroundState of the art molecular diagnostic tests are based on the sensitive detection and quantification of nucleic acids. However, currently established diagnostic tests are characterized by elaborate and expensive technical solutions hindering the development of simple, affordable and compact point-of-care molecular tests.Methodology and Principal FindingsThe described competitive reporter monitored amplification allows the simultaneous amplification and quantification of multiple nucleic acid targets by polymerase chain reaction. Target quantification is accomplished by real-time detection of amplified nucleic acids utilizing a capture probe array and specific reporter probes. The reporter probes are fluorescently labeled oligonucleotides that are complementary to the respective capture probes on the array and to the respective sites of the target nucleic acids in solution. Capture probes and amplified target compete for reporter probes. Increasing amplicon concentration leads to decreased fluorescence signal at the respective capture probe position on the array which is measured after each cycle of amplification. In order to observe reporter probe hybridization in real-time without any additional washing steps, we have developed a mechanical fluorescence background displacement technique.Conclusions and SignificanceThe system presented in this paper enables simultaneous detection and quantification of multiple targets. Moreover, the presented fluorescence background displacement technique provides a generic solution for real time monitoring of binding events of fluorescently labelled ligands to surface immobilized probes. With the model assay for the detection of human immunodeficiency virus type 1 and 2 (HIV 1/2), we have been able to observe the amplification kinetics of five targets simultaneously and accommodate two additional hybridization controls with a simple instrument set-up. The ability to accommodate multiple controls and targets into a single assay and to perform the assay on simple and robust instrumentation is a prerequisite for the development of novel molecular point of care tests.

Bridge Monitoring and Performance Evaluation

Over fifty percent of our nation’s 560,000-plus bridges are obsolete or structurally deficient. To upgrade or replace these structures would require a serious budget. In order to shorten this list of bridges and to improve their ratings, state DOTs are investigating new repair techniques and better performance evaluation tools in order to implement the new drive to sustainability within the infrastructure. The research presented herein focused on the evaluation of current US bridge analysis and rating procedures for the North Carolina Department of Transportation (NCDOT). To evaluate these procedures, several bridges were rated with commercially available software and a newly developed spreadsheet program. In parallel, the bridges were also load tested for comparison, from which, it was concluded that the NCDOT’s bridge rating software directly follows the latest AASHTO requirements. The experimental results, however, also proved that the bridges had significant strength reserves associated to several factors, such as, girder/deck composite action, impact and distribution factors, material strength, and contribution of non-structural elements. In this research, a simplified bridge testing protocol was developed from which it was concluded, that a relatively simple instrumentation setup could be effective in the load rating of bridges through testing. The data gathered through these instruments provide vital performance data for normal traffic conditions, as well as during extreme loading conditions and evacuations, which could lead to less restrictive load ratings and removal of the structurally deficient classification, yielding a more sustainable structure.

Foredune accretion under offshore winds

Experiments carried out at Magilligan Strand on the north coast of Ireland suggest that topographic steering of offshore winds is an important facet of the aeolian sediment transport system at this location. A five-day study (18–22 June 2005) investigated the pattern of airflow over the foredune while simultaneously collecting data on sediment flux. A simple instrument setup was used to characterise the airflow: a sonic anemometer was placed at the dune crest, with another on the mid-beach. Horizontal traps, electronic and integrating, measured sediment flux on the supra-tidal beach. Results show that offshore wind flow deviated from its original direction in the lee of the dune (seaward of foredune). The change in direction was not a simple steering of flow to a singular new direction, but rather flow separation resulting in turbulent multidirectional flow — including reversal. Traps located at the foot of the dune scarp recorded sediment transport during events forced by offshore winds. Data from sediment traps, wind and observational evidence have been used to argue that sedimentation was occurring in this zone. When budgeting for sediment movement within beach–dune systems it is important to take into account the effect of secondary airflow patterns during offshore winds and their role in constructive processes of foredune formation, particularly in post-storm recovery.

Development of a Simple Instrumental Setup for the Separation of Benzoic Acids by Comprehensive Liquid Chromatography with Microbore Columns and Monolithic Columns

A simple instrumental setup for the separation of benzoic acid derivatives using comprehensive liquid chromatography is presented. The separation system consists of a 1 mm i.d. microbore anion exchange column coupled to a monolithic reversed phase column, using a simple interface realized by the combination of two conventional sixport valves. Thereby, the eluate from the first dimension could be transferred to the second chromatographic dimension throughout the whole run without any losses. Employing the combination of two different separation mechanisms namely ion exchange and reversed‐phase chromatography allowed the resolution of all test analytes in less than 14 minutes.

Dual-cloud point extraction as a preconcentration and clean-up technique for capillary electrophoresis speciation analysis of mercury

A novel dual-cloud point extraction (dCPE) technique is proposed in this paper for the sample pretreatment of capillary electrophoresis (CE) speciation analysis of mercury. In dCPE, cloud point was carried out twice in a sample pretreatment. First, four mercury species, methylmercury (MeHg), ethylmercury (EtHg), phenylmercury (PhHg), and inorganic mercury (Hg(II)) formed hydrophobic complexes with 1-(2-pyridylazo)-2-naphthol (PAN). After heating and centrifuging, the complexes were extracted into the formed Triton X-114 surfactant-rich phase. Instead of the direct injection or analysis, the surfactant-rich phase containing the four Hg species was treated with 150 μL 0.1% (m/v) l-cysteine aqueous solution. The four Hg species were then transferred back into aqueous phase by forming hydrophilic Hg– l-cysteine complexes. After dCPE, the aqueous phase containing the Hg– l-cysteine complexes was subjected into electrophoretic capillary for mercury speciation analysis. Because the concentration of Triton X-114 in the extract after dCPE was only around critical micelle concentration, the adsorption of surfactant on the capillary wall and its possible influence on the sample injection and separation in traditional CPE were eliminated. Plus, the hydrophobic interfering species were removed thoroughly by using dCPE resulted in significant improvement in analysis selectivity. Using 10 mL sample, 17, 15, 45, and 52 of preconcentration factors for EtHg, MeHg, PhHg, and Hg(II) were obtained. With CE separation and on-line UV detection, the detection limits were 45.2, 47.5, 4.1, and 10.0 μg L −1 (as Hg) for EtHg, MeHg, PhHg, and Hg(II), respectively. As an analysis method, the present dCPE–CE with UV detection obtained similar detection limits as of some CE–inductively coupled plasma mass spectrometry (ICPMS) hyphenation technique, but with simple instrumental setup and obviously low costs. Its utilization for Hg speciation was validated by the analysis of the spiked natural water and tilapia muscle samples.

Modified Dual Lifetime Referencing Method for Simultaneous Optical Determination and Sensing of Two Analytes

Simultaneous fluorometric sensing of two analytes becomes possible using a modified dual lifetime referencing (m-DLR) method. In this scheme, two luminescent indicators are needed that have overlapping absorption and emission spectra but largely different decay times. They are excited by a single light source, and both emissions are measured simultaneously. In the frequency domain m-DLR method, the phase of the short-lived fluorescence of a first indicator is referenced against that of the long-lived luminescence of the second indicator. The analytical information is obtained by measurement of the phase shifts at two modulation frequencies. The method is demonstrated to work for the case of dually sensing oxygen and carbon dioxide. It benefits from simple instrumentation and optical setup. The approach is perceived to be of wide applicability. Examples include (1) analysis of two luminescent analytes, (2) analytical determinations that make use of two probes, and (3) sensing of two species such as carbon dioxide and oxygen (as demonstrated here), or oxygen and chlorophyll, provided the luminophores meet the condition of having largely different decay times and overlapping absorption and emission spectra.

Simple reversed-phase liquid chromatographic assay for simultaneous quantification of free mycophenolic acid and its glucuronide metabolite in human plasma

A reversed-phase HPLC-UV method, involving simple instrumental setup and mobile phase without ion-pairing reagent, was developed and validated for direct simultaneous quantification of free mycophenolic acid (MPA) and its major metabolite MPA-glucuronide (MPAG) in human plasma. Both free MPA and MPAG were isolated from plasma samples using ultrafiltration prior to analysis. Each chromatographic run was completed within 13 min. The optimized method showed good performance in terms of specificity, linearity ( r 2 = 0.9999), sensitivity (limit of quantitation (LOQ): 0.005 mg/L for MPA; 1 mg/L for MPAG), and intra- and inter-day precision (R.S.D. < 7%). This assay was successfully applied to free MPA and MPAG measurements in clinical samples.

Potentials of multisyringe flow injection analysis for chemiluminescence detection

In this paper, multisyringe flow injection analysis (MSFIA) is presented as a powerful and promising tool for automated liquid-phase chemiluminescence (CL) assays. The capability of operation under discontinuous forward flow regime while handling minute, well-defined volumes of sample and reagents in a multicommuted format offers unrivalled analytical features. As opposed to the parent flow injection (FI) and sequential injection (SI) analysis, CL reactions with divergent pH and kinetic demands can be easily implemented in a single protocol sequence, as demonstrated in the bulk of the text via luminol-based methods. MSFIA is proven extremely suitable for accommodating enzymatic CL assays in a renewable fashion by exploiting soluble enzymes, with no need for the typical immobilization procedures used in FI and SI systems. Solid-phase CL sensors have also gained full advantage of the benefits of MSFIA. In this context, a novel optosensor devised for on-line monitoring of trace levels of orthophosphate is described. Similar configurations are proposed for the selective and sensitive determination of metals, Vitamins, nutrients and saccharides in environmental and biological samples as well as beverages, which denotes the versatility of this automated flow technique. Special emphasis is also given to the simple instrumental set-up, including a dedicated flow-through luminometer, arranged for a multitude of CL assays.

Phosphorescent porphyrin probes in biosensors and sensitive bioassays.

Platinum(II) and palladium(II) complexes of porphyrins and related tetrapyrrolic pigments emit strong phosphorescence at room temperatures, which is characterized by long lifetimes falling into the sub-millisecond range and long-wave spectral characteristics. These features make the dyes useful as probes for a number of bioanalytical applications, particularly those employing time-resolved fluorescent detection. They can provide high sensitivity and selectivity, together with rather simple instrumental set-up. A number of analytical systems are now under development that are based on the use of phosphorescent porphyrin probes. Experimental results are presented on the following systems: (i) fibre-optic phosphorescence lifetime-based oxygen sensor on the basis of hydrophobic platinum-porphyrins and development of advanced sensing materials and prototype instrumentation; (ii) practical applications of the optical oxygen sensor, including a sensitive immunosensor that employs glucose oxidase labels, a rapid screening method for cell viability in microtitre-plate format, non-destructive measurement of oxygen in packaged foods and reagentless biosensors for metabolites (glucose, lactate); and (iii) the use of water-soluble platinum- and palladium-porphyrins as labels for ultra-sensitive time-resolved phosphorescence immunoassays.

Evaluation of copper‐based electrodes for the analysis of aminoglycoside antibiotics by CE‐EC

AbstractAminoglycoside antibiotics including gentamicin, bekanamycin, tobramycin, lincomycin, neomycin, kanamycin, and ribostamycin have been determined by CE‐EC with copper clectrodes. Both copper wall‐jet electrodes (WJEs) and copper on‐capillary electrodes (OCEs) were evaluated. The OCEs provided μM detection limits, superior stability and reproducibility (2–3% relative standard deviation in oxidation current), and a simple instrumental set‐up without the need for capillary/electrode alignment. The analytical capabilities of the Cu‐OCE were examined, following the optimization of CE conditions, for the seven aminoglycosides above; and the practical utility of this approach was demonstrated through the determination of aminoglycoside antibiotics in three pharmaceutical preparations.