Simultaneous Determination Of Multiple Analytes Research Articles

Application of the QuEChERS Strategy as a Useful Sample Preparation Tool for the Multiresidue Determination of Pyrrolizidine Alkaloids in Food and Feed Samples: A Critical Overview

The identification of concerning high levels of pyrrolizidine alkaloids (PAs) in a wide variety of food products has raised the occurrence of these natural toxins as one of the main current issues of the food safety field. Consequently, a regulation with maximum concentration levels of these alkaloids has recently been published to monitor their occurrence in several foodstuffs. According to legislation, the analytical methodologies developed for their determination must include multiresidue extractions with high selectivity and sensitivity, as a set of 21 + 14 PAs should be simultaneously monitored. However, the multiresidue extraction of these alkaloids is a difficult task due to the high complexity of food and feed samples. Accordingly, although solid-phase extraction is still the technique most widely used for sample preparation, the QuEChERS method can be a suitable alternative for the simultaneous determination of multiple analytes, providing green extraction and clean-up of samples in a quick and cost-effective way. Hence, this review proposes an overview about the QuEChERS concept and its evolution through different modifications that have broadened its applicability over time, focusing mainly on its application regarding the determination of PAs in food and feed, including the revision of published works within the last 11 years.

Chemiluminescence microarray immunoassay for multiple aminoglycoside antibiotics based on carbon nanotube-assisted signal amplification.

The simultaneous determination of multiple analytes has been an urgent demand in screening of antibiotic residues in food products of animal origin due to its higher analysis efficiency. Five aminoglycoside antibiotics (AGAs) have been monitored in milk, including gentamicin (GEN), kanamycin (KAN), neomycin (NEO), and streptomycin/dihydrostreptomycin (STR/diSTR). A chemiluminescence microarray immunoassay (CLMIA) based on nitrocellulose membrane had been developed for the detection of multiple AGAs, which the LODs for STR, KAN, NEO, and GEN were 4.74ng/mL, 4.97ng/mL, 2.99ng/mL, and 4.42ng/mL respectively. To improve the sensitivity of immunoassay, single-well carbon tubes (SWCNTs) were utilized as solid support for loading horseradish peroxidase-labelled goat anti-mouse antibody to obtain the multi-enzyme particles. After the optimization of usage of multi-enzyme particles and antibodies, the enhanced CLMIA was established and evaluated. The LODs were 1.25ng/mL for STR, 0.64ng/mL for KAN, 0.38ng/mL for GEN, and 0.39ng/mL for NEO, which was improved by threefold, sevenfold, 11-fold, and sevenfold compared with the conventional CLMIA developed. These methods presented higher specificity and repeatability. Finally, the enhanced CLMIA based on CNT-assisted multi-enzyme particles was utilized to analyze twenty-five milk samples from local market and dairy farm, which all the results were below the LOD. The enhanced CLMIA showed the great application potential for the detection of multiple targets simultaneously and provided efficient tool for the screening of pollutants in food.

ZnO/Ag nanorods as a prominent SERS substrate contributed by synergistic charge transfer effect for simultaneous detection of oral antidiabetic drugs pioglitazone and phenformin

It is popular and promising to explore a prominent surface-enhanced Raman scattering (SERS) substrate for simultaneous determination of multiple analytes in drug safety and quality monitoring. To achieve the goal, in this work, we constructed a plasmonic metal/semiconductor oxide heterostructure by depositing Ag nanoparticles (NPs) on ZnO nanorods. The ZnO/Ag substrate exhibited prominent SERS performance by using rhodamine 6 G as the probe molecule, including transferable nature onto various available substrate, high enhancement factor, stability and uniformity. The synergistic charge transfer effect was systematically studied, including the effects of the Ag loading amount and laser wavelength, photoluminescence, UV–vis spectra and XPS analysis. The ZnO/Ag substrate was developed as a SERS probe for separate and simultaneous detection of two oral antidiabetic drugs (OADs), pioglitazone (PIO) and phenformin (PHE) in human urine. The detection limits were as low as 1 and 5 nM for PIO and PHE (respectively) with good selectivity and satisfactory recoveries. This type of SERS substrate will be suitable for rapid and noninvasive determination of OADs in clinic applications.

Profiling intact steroid sulfates and unconjugated steroids in biological fluids by liquid chromatography-tandem mass spectrometry (LC-MS-MS)

Within the combined DFG research project "Sulfated Steroids in Reproduction" an analytical method was needed for determining sulfated and unconjugated steroids with highest specificity out of different biological matrices such as aqueous solution, cell lysate and serum. With regard to this analytical challenge, LC-MS-MS presents the technique of choice because it permits (1) analysis of the intact steroid conjugate, (2) allows for simultaneous determination of multiple analytes (profiling, targeted metabolomics approach) and (3) is independent of phenomena such as cross-reactivity. Sample work up consisted of incubation of sample with internal standards (deuterium labeled steroids) followed by solid phase extraction. Only serum samples required a protein precipitation step prior to solid phase extraction. The extract was divided in two parts: six steroid sulfates (E1S, E2S, AS, 16-OH-DHEAS, PREGS, DHEAS) were analyzed by C18aQ-ESI-MS-MS in negative ion mode and eleven unconjugated steroids (E3, 16-OH-DHEA, E1, E2, (4)A, DHEA, T, 17-OH-PREG, Prog, An, PREG) were analyzed by C18-APCI-MS-MS in positive ion mode. For steroid sulfates, we found high sensitivities with LoQ values ranging from 0.08 to 1 ng mL(-1). Unconjugated steroids showed LoQ values between 0.5 and 10 ng mL(-1). Calibration plots showed excellent linearity. Mean intra- and inter-assay CVs were 2.4% for steroid sulfates and 6.4% for unconjugated steroids. Accuracy - determined in a two-level spike experiment - showed mean relative errors of 5.9% for steroid sulfates and 6.1% for unconjugated steroids. In summary, we describe a novel LC-MS-MS procedure capable of profiling six steroid sulfates and eleven unconjugated steroids from various biological matrices.

Application of thermally reduced graphene oxide modified electrode in simultaneous determination of dihydroxybenzene isomers

Thermally reduced graphene oxide (TRGO) was used as an excellent electrocatalyst for the construction of electrochemical sensor for simultaneous determination of dihydroxybenzene isomers including hydroquinone (HQ), catechol (CC) and resorcinol (RC). The surface morphology and structure of TRGO were investigated by utilizing transmission electron microscope, scanning electron microscopy, atomic force microscope, Raman spectroscopy and X-ray diffraction. The electrode modified with TRGO shows excellent electrocatalytic activity toward the oxidation of HQ, CC and RC. As a result, the oxidation peaks of three isomers in pH 6.0 PBS can be clearly discriminated due to large peak potential separation among them. In addition, HQ and CC can be simultaneously determined by using differential pulse voltammetry without any separation step. Under the optimized condition, the detection limits of HQ and CC are 0.75 and 0.8 μM (S/N = 3) with linear ranges of 1–500 μM in the presence of 50 μM isomer, respectively. The proposed method was successfully applied to the simultaneous determination of CC and HQ in synthetic water sample with reliable recovery. The proposed sensor has some important advantages such as low cost, ease of preparation, good stability and high reproducibility. Therefore, the present work promises for the application of graphene modified electrode in the simultaneous determination of multiple analytes.

Development of an Evidence biochip array kit for the multiplex screening of more than 20 anthelmintic drugs

Anthelmintic drugs are used in clinical and veterinary practice for the treatment of infections caused by parasitic worms. Their extensive use in food-producing animals can cause the presence of residues in food. For consumer protection it is necessary to monitor the levels of anthelmintic residues to ensure that they remain within the legally permitted maximum acceptable concentrations. For this purpose, the use of multiplex screening methods is advantageous. Biochip array technology allows the simultaneous determination of multiple analytes from a single sample at a single point in time. This study reports the development of an Evidence biochip array for the multiplex screening of anthelmintic drugs. Simultaneous competitive chemiluminescent immunoassays are employed. The solid support and vessel is the biochip, which contains an array of discrete test sites. The assays were applied to the semiautomated bench-top analyser Evidence Investigator. The aminobenzimidazoles assay detected aminomebendazole, albendazole 2-aminosulphone and aminoflubendazole, the avermectins assay detected emamectin benzoate, eprinomectin, abamectin, ivermectin and doramectin, the benzimidazoles assay detected albendazole sulphone, albendazole, albendazole sulphoxide, oxibendazole, oxfendazole and flubendazole, the thiabendazole assay detected cambendazole, thiabendazole and 5-hydroxythiabendazole and the triclabendazole assay detected ketotriclabendazole, triclabendazole and triclabendazole sulphoxide. The limits of detection ranged from 0.3 ppb (aminobenzimidazoles) to 2.0 ppb (levamisole) in milk and from 0.15 ppb (aminobenzimidazoles) to 6.5 ppb (levamisole) in tissue. The average recovery range was 71-135 %. This multianalytical approach on a biochip platform is applicable to the screening of more than 20 anthelmintic drugs in different food matrices, leading to consolidation of tests and enhancement of the test result output.

Simultaneous Determination of Nitrite and Nitrate Ions by Air-Segmented Amplitude-Modulated Multiplexed Flow Analysis

The concept of amplitude-modulated multiplexed flow analysis has been extended to the simultaneous determination of multiple analytes in a sample. A sample solution containing nitrite and nitrate ions is delivered from two channels, but the flow rates are varied at different frequencies. One of the channels has a reduction column for converting nitrate ions to nitrite ions. Downstream, the absorbance of the diazo-coupling product is monitored after the merging of both solutions with a Griess reagent. The signal is analyzed by a fast Fourier transform (FFT) in real time. From the thus-obtained amplitude, a µmol dm(-3) level of the ions can be determined. The introduction of air bubbles is effective to reduce any axial dispersion, and hence to improve the sensitivity.

Amplitude modulated multiplexed flow analysis

We propose a new concept, amplitude modulated multiplexed flow analysis, for the simultaneous determination of multiple analytes from a single continuous analytical signal. The flow rates ( F S1 and F S2) of two sample solutions are independently varied in response to trigonometric voltage signals each at a different anharmonic frequency. With the total flow rate F T held constant, the solutions are merged with a reagent solution that is aspirated to the confluence point at the flow rate of F T − F S1 − F S2. Downstream, the analytical signal due to the mixed reacted solution, V d, is monitored. V d will show a complicated profile resulting from the trigonometrically varying flow rates of the sample solutions. The signal contains information on the multiple analytes. The signal can be demodulated to the contribution of each sample solution through fast Fourier transform (FFT). The amplitudes of the separated wave components are related to the concentration of the analytes in the sample solutions. By moving a window for FFT analysis with time, temporal profile of amplitudes can be obtained in real-time. We demonstrate the concept by applying it to the simultaneous determination of food dyes and to that of ferrous ions in two sample solutions.

Alternative calibration approaches for LC–MS quantitative determination of coeluted compounds in complex environmental mixtures using multivariate curve resolution

Different calibration approaches including external calibration, standard addition and internal standard are evaluated for quantification of coeluted compounds in liquid chromatography with MS spectrometry detection in scan mode and using multivariate curve resolution. These different calibration approaches are proposed to cope with sensitivity changes and matrix effects encountered in the analysis of complex natural environmental samples. By using them, multivariate curve resolution analysis of MS data in scan mode gave similar quantitative results to those obtained by LC–MS in selected ion monitoring (SIM) mode (in both cases errors were below 16% for internal standard combined with standard addition strategy), and it provided at the same time a means of analyte confirmation via their resolved pure MS spectra, and a means to gather a larger amount of information about the whole chromatographic process and to facilitate the simultaneous determination of multiple analytes in the same chromatographic run using the same experimental and instrumental conditions.

Simultaneous Detection of Multiple Analytes Using Copalis Technology: A Reduction to Practice

Coupled Particle Light Scattering (Copalis) is a homogeneous immunoassay technology that enables the simultaneous determination of multiple analytes in serum, plasma, or whole blood (1) . The Copalis system measures changes in light-scattering properties of particles when they form antibody-mediated complexes. The system can measure two types of events: polystyrene microparticle coagglutination and polystyrene-gold colloid microparticle coupling. In the first format, polystyrene microparticles are differentiated from their complexed aggregates as a function of antigen concentration or serological response. The second format measures the broadening of the microparticle light scatter histogram as gold particles are attached. In both cases, light scattering analysis is performed as particles flow singly through a finely focused laser beam. The ability to differentiate various sizes of polystyrene microparticles allows the system to measure multiple analytes or serological responses simultaneously. This capability has been demonstrated by the ToRC assay (toxoplasma, rubella, cytomegalovirus), in which antibodies to three different infectious agents are detected simultaneously (2) . In the present work, we demonstrate the application of Copalis technology to a variety of areas of diagnostic medicine in which the simultaneous measurement of multiple analytes or variables may be advantageous, including infectious disease, autoimmunity, and reproductive endocrinology. This format is useful for detecting the presence of antibodies to infectious agents or autoantigens, which are coated onto latex microparticles. By using only forward-scatter measurement, Copalis instrumentation …

Detection of hepatitis B surface antigen in whole blood by coupled particle light scattering (Copalis™)

Coupled particle light scattering (Copalis) is a homogeneous immunoassay technology that permits simultaneous determination of multiple analytes in serum, plasma, or whole blood. Copalis differentiates monomeric latex microparticles from latex aggregates and cells on the basis of their unique light scatter properties. Copalis readily discriminates small (approximately 0.1 micron) differences in latex microparticle size. Therefore, multiple simultaneous assays are configured by the use of mixtures of different-size latex microparticles. The Copalis research immunoassay for hepatitis B surface antigen (HBsAg) is configured in a sandwich format where the extent of light scatter histogram broadening due to HBsAg-mediated binding of colloidal gold to latex provides the basis for antigen quantification. Simultaneous Copalis forward- and wide-angle light scatter measurements allow discrimination of latex microparticles from the cell components of whole blood. Consequently, direct detection of HBsAg in unprocessed whole-blood samples by Copalis is feasible.

Development of an integrated thermal biosensor for the simultaneous determination of multiple analytes

A flow injection thermal microbiosensor was designed for the simultaneous determination of multiple analytes. The biosensor consisted of five thin-film thermistors which were located along a single microchannel. The device was fabricated on a quartz chip by micromachining. The feasibility of employing this system for the detection of two independent enzyme reactions was demonstrated using two different pairs of enzymes, urease–penicillinase and urease–glucose oxidase. The enzymes were immobilized on agarose beads, which were then sequentially packed into distinct regions of the microchannel. Using this method, samples containing urea mixed with penicillin V or with glucose were simultaneously analysed. Linear ranges of up to 20 mmol l–1 urea, 40 mmol l–1 penicillin V and 8 mmol l–1 glucose (saturated with O2) were obtained using a flow rate of 30 µl min–1 and a sample volume of 20 µl. The relative standard deviations for urea and penicillin V assays were 1.13 and 2.42% for the first 100 samples and 1.17 and 2.78% for 200 samples, respectively. The sensor is capable of analysing 25 samples per hour.