Simulated Urine Samples Research Articles

A Cerium Hexacyanoferrate (III) Nanoparticle‐modified Carbon Paste Electrode: Voltammetric Characterization and Behavior in the Presence of Dopamine

AbstractThis study describes a fast and simple methodology for the preparation of Cerium (III) Hexacyanoferrate (II) (CeHCF) nanoparticles (NPs). The NPs were characterized by fourier transform infrared (FTIR), x‐ray diffraction (XRD), scanning electron microscopy (SEM) and cyclic voltammetry (CV). The CeHCF cyclic voltammogram indicate a well‐defined redox pair assigned as Fe2+/Fe3+ in the presence of cerium (III), with a formal potential of Eθ′=0.29 V (v=100 mV s−1, KNO3; 1.0 mol/L, pH 7.0). The carbon paste electrode modified with CeHCF (CeHCF‐CPE) was applied to the catalytic electrooxidation of dopamine applying Differential Pulse Voltammetry (DPV). DPV showed linear response at two concentration ranges, from 9.0×10−7 to 8.0×10−6 and 9.0×10−6 to 1.0×10−4 mol/L, with an LOD of 1.9×10−7 and 1.0×10−5 mol/L, respectively. The CeHCF‐CPE exhibited selectivity against substances commonly found in biological samples, with redox potentials close to that of dopamine, such as urea and ascorbic acid (AA). Subsequently the CeHCF‐CPE was successfully applied to the detection of dopamine in simulated urine samples, with recovery percentages ranging between 99 and 103%.

Towards on-site detection of cadmium in human urine

Cadmium (Cd) is a non-essential toxic heavy metal. Human exposure to Cd occurs from multiple sources, including diet, tobacco smoke, fossil fuel combustion, and various contaminated sources. This work reports a rapid method for Cd2+ detection in simulated urine samples containing glucose (GLC) and human urine using the electrochemical technique of square wave anodic stripping voltammetry (ASV). Electrochemical techniques for onsite analysis and detection are preferred for their quick response time, application simplicity, inexpensive instrumentation, and potential portability. This approach is a step forward towards Cd2+ detection in biological fluids, despite their composition complexity due to possible interference of its constituents. Application of a simple, well controlled, and uniform carbon nanotube (CNT) thin film generated through spinnable CNT arrays enabled us to increase the surface area of traditional glassy carbon electrodes and made possible the detection of nanomolar concentration of Cd ions in urine samples. This voltammetric technique led to 1.9 nM limit of detection (LOD) in simulated urine, and 5.85 nM (female) and 324 nM (male) LOD in human urine. The developed method would facilitate high throughput screening of human urine samples for assessing Cd exposure in future studies.

A 3D printed centrifugal microfluidic platform for automated colorimetric urinalysis

Colorimetric urinalysis is a commonly performed test for rapid and low-cost diagnosis. Conventional colorimetric urinalysis is manually conducted using dipsticks and suffers from difficulties in control of sample distribution and color interpretation. This paper reports a microfluidic platform for conducting automated colorimetric urinalysis. Centrifugal microfluidic technology was used for regulating the distribution of urine sample in designed volume and time sequence. The prototype of the microfluidic chip was fabricated using 3D printing technology. To test the feasibility of the prototype system, commercial urinalysis strips were integrated with the microfluidic system for detecting glucose, specific gravity, PH, and protein from simulated urine sample. The color change of the strips was recorded using a smartphone and analyzed to quantify the interested parameters. The H (hue), S (saturation) and V (value) coordinates of the HSV color space were extracted and related to the change of the four parameters. The intensity change of V channel showed good representation of the change of glucose concentration and specific gravity. The intensity change of S channel decreased as the increase of PH and protein concentration. The proposed Lab-on-CD platform has potential for automating colorimetric urinalysis to reduce the user errors, thus to made the testing results conducted by non-professionals more reliable.

Newborn screening for 3-hydroxy-3-methylglutaric aciduria using direct analysis in real-time mass spectrometry.

A novel method utilizing ambient thermal desorption ionization with a direct analysis in real-time source integrated with mass spectrometry (DART-MS) was established and applied to the rapid analysis of 3-hydroxy-3-methylglutaric (3-HMG) acid in the neonatal urine. Instrument parameter settings were optimized to obtain high sensitive and accurate determination of 3-HMG acid. The use of helium gas heated to temperature of 400°C was observed to permit deprotonation, 3-HMG acid producing an abundant (M-H)- (m/z 161) in the negative ion mode. The calibration curve was determined to be linear over the range of 0.05-5mg/L, with the correlation coefficient r=0.9988 and the relative standard deviations (n=6) in the range of 1.5-11.8%. The limit of detection was 0.002mg/L, and the limit of quantitation was 0.007mg/L. The recoveries ranged from 88.0% to 123.1%. Four urine samples from patients and four simulated urine samples were investigated. The results of DART-MS were in agreement with the values determined using established methods at the hospitals. The proposed method demonstrated significant potential in the application of the high-throughput screening in newborn screening.

Assessing reusability of microfluidic devices: Urinary protein uptake by PDMS-based channels after long-term cyclic use

In the search for transformative technologies for person-centered health monitoring, reusability of microfluidic chips would be a critical design consideration in many biomedical applications. With this unmet need in mind, in this study, we develop and validate a novel microfluidic platform for automated sample pumping with an integrated channel-cleaning procedure. The proposed system leverages micropumps and on-chip solenoid valves to dynamically control fluid flow. We provide a thorough characterization of the custom-designed chip, including quantitative measures of the protein uptake by the chip, as well as cross-contamination using both simulated samples and human urine samples. The effectiveness of the cleaning procedure is assessed by testing the samples collected from the cleaning chip with commercially available urine dipstick protein tests. The results of the longitudinal protein level measurement of the urine samples after the cleaning cycles show high accuracy of protein measurement and negligible protein cross-contamination. Additionally, the cleaning procedure after pumping each sample results in a very low protein uptake (150 ng/cm2). We have also demonstrated that the efficiency of the automated cleaning microfluidic device can be further improved by an anti-fouling coating via PLL-g-PEG pretreatment and a posttreatment via Trypsin. The developed platform could potentially be further miniaturized and integrated into point-of-care devices to provide an effective cleaning process and to enable the reusability of microfluidic devices.

Ultrasonic Preparation of Porous Silica-Dye Microspheres: Sensors for Quantification of Urinary Trimethylamine N-Oxide.

Trimethylamine N-oxide (TMAO), the N-oxide metabolite of trimethylamine (TMA), is a key index in the determination of a wide variety of human cardiac or kidney diseases. A colorimetric sensor array comprising ultrasonically prepared silica-dye microspheres was developed for rapid, portable, and sensitive detection of urinary TMAO. To prepare the sensor array, 13 different organically modified silica (ormosil)-dye composites were synthesized from the hydrolysis/pyrolysis of ultrasonically sprayed organosiloxane precursors under optimized reaction conditions; the resulting products are uniformly sized nanoporous microspheres that are effective colorimetric sensors for various volatile analytes. The effective quantification of aqueous TMAO (which is not volatile) was based on sensing the volatile TMA produced from a simple catalytic reduction of TMAO in situ. RGB color-change patterns from digital images of the sensor array permit precise discrimination among a wide range of TMAO concentrations (10-750 μM) in simulated urine samples; both hierarchical cluster analysis and principal component analysis achieve >99% accuracy in data classification. The calculated limit of detection of urinary TMAO is ∼4 μM, which is substantially below the median level of healthy subjects (∼380 μM). The array of sensors could be simplified to only a couple of strongly responsive elements for the ease of field use, and the process could be developed as a point-of-care tool in combination with digital imaging for the early diagnosis of cardiovascular or kidney diseases from the measurement of fasting urinary level of TMAO.

Determining the effect of different environmental conditions on Ebola virus viability in clinically relevant specimens

In 2013–2016, West Africa experienced the largest and longest Ebola virus disease outbreak ever documented. The wide geographic spread and magnitude of the outbreak often limited the timely and rapid testing of diagnostic samples from patients with suspected Ebola virus disease, raising questions regarding the optimal storage and shipping conditions of clinically relevant specimens, including EDTA-whole blood, plasma, capillary blood, urine and seminal fluid (associated with sexual transmission of the Ebola virus after recovery from the disease). Therefore, the aim of our study was to identify the extent to which storage temperature and clinical specimen type influence Ebola virus viability. Virus infectivity was determined using a fluorescent focus-forming assay. In our study, we show that Ebola virus was the most stable in EDTA-whole blood and plasma samples, whereas rapid decay of infectivity was observed in simulated capillary blood, urine and semen samples, especially when these samples were stored at higher temperatures. The analysis of variance results demonstrated that both temperature and clinical specimen type have significant effects on virus viability, whereas donor differences were not observed. Repeated freeze and thaw cycles of the samples also had a notable impact on virus viability in EDTA-whole blood and urine. Due to the rapid temperature- and specimen-dependent degradation of the virus observed here, our study highlights the importance of proper clinical sample storage at low temperatures during transportation and laboratory analysis.

Highly selective hydrazone based reversible colorimetric chemosensors for expeditious detection of CN− in aqueous media

Abstract Herein we have described the design and syntheses of two novel hydrazone based N, O donor Schiff-base colorimetric sensors L 1 and L 2 for selective sensing of cyanide ions in 2:1 CH 3 CN-H 2 O mixture. L 1 and L 2 have been characterized by 1 H NMR, IR spectroscopy, HRMS spectrometry and elemental analyses. Interactions of L 1 and L 2 with CN − provide remarkable color change from yellow to red (for L 1 ) and yellow to pink (for L 2 ) along with change in the absorption maxima, enabling naked-eye sensing of CN − ion, without use of any expensive equipment. From the job’s plot analyses, HRMS spectral studies and 1 H NMR analyses, 1:1 binding stoichiometry of chemosensor L 1 and 1:2 binding stoichiometry of chemosensor L 2 towards cyanide ion have been confirmed. The detection limits reach up to 1.3 µM for L 1 and 1.0 µM for L 2 which are lower than the maximum permissible level of CN − in drinking water set by WHO. The other competitive anions (OAc − , F − , Cl − , Br − , I − , H 2 PO 4 − , NO 2 − , NO 3 − , HSO 4 − , N 3 − , CO 3 2− , PO 4 3− , S 2− , and BO 3 3− ) showed very negligible interference for detection of cyanide at that concentration level. The sensing mechanism has further been confirmed by DFT studies. Both the chemosensors L 1 and L 2 have been successfully applied for the determination of CN − ions in real water samples and simulated urine samples.

Nickel hexacyanoferrate supported at nickel nanoparticles for voltammetric determination of rifampicin

A rapid and simple method for voltammetric determination of rifampicin (RIF) using a glassy carbon electrode (GCE) modified with nanostructured nickel hexacyanoferrate (NiHCF) was developed. The sensor was prepared through an unusual method to NiHCF electrosynthesis, starting from nickel nanoparticles previously deposited on the surface of different electrodes (glassy carbon, ITO and gold electrode) under potentiodynamic conditions. X ray diffractograms of Ni nanoparticles thin film were obtained for different stages of NiHCF films formation indicating a homogeneous distribution throughout the substrate with a mean size around 40 nm and an irregular shape. EQCM studies showed that the nature of cations can promote strong alterations on the voltammetric and microgravimetric profile during the growth of NiHCF due to the ion transport mechanisms of redox reactions. Both voltammetric and microgravimetric behavior were studied in the presence of sodium, lithium and potassium ions and the best responses were found using potassium ions as supporting electrolyte. The presence of RIF promoted a decrease in the cathodic peak current of NiHCF, suggesting an interaction between the antibiotic and Ni species presented at the electrode surface. The variation in the current signal was proportional to the RIF concentration and it was adopted for its quantification, allowing the construction of a linear analytical curve from 5.0 × 10−6 to 5.0 × 10−4 mol L−1 with a limit of detection of 2.6 μmol L−1. The method was successfully applied for RIF determination in simulated human urine samples with good agreement between the added and recovery values.

A simple benzildihydrazone derived colorimetric and fluorescent ‘on–off-on’ sensor for sequential detection of copper(II) and cyanide ions in aqueous solution

Herein, we have developed a simple, environment friendly fluorescent turn-off and colorimetric sensor for the rapid detection of Cu2+ ions in aqueous solution by using organic Schiff base ligand benzildihydrazone-N,N'-bis(2-hydroxy-4-diethylamino-1-formylbenzene) (L). Binding interaction between L and various metal ions was established by UV–vis and fluorescent measurements showing favourable coordination towards Cu2+ and almost no interference with the other metal ions, i.e., Na+, Ba2+, Fe3+, Co2+, Ni2+, Zn2+, Cd2+, Ca2+, Hg2+, Pb2+,Cr3+, Ag+ and Al3+. L exhibited binding-induced colour change from yellow to light red. The obtained L-Cu2+ complex could be used as a new cascade sensor for detecting cyanide anion (CN−). The corresponding detection limits were found to be 7.3×10−10M for Cu2+ (lowest ever known in the family of fluorescent colorimetric Schiff base chemo-sensor) and 1.5×10−7M for CN−. To further assess the analytical performance of this sensing system, the concentrations of Cu2+ and CN−1 ions were determined in real water samples and simulated urine sample.

The Peeing Pitcher: An Inquiry-Based, Laboratory Case Study of the Endocrine and Renal Systems

In this inquiry-based lab, students are provided with a case study involving a young boy with a head injury exhibiting various symptoms, as well as simulated blood and urine samples to help diagnose the boy's disease. Throughout the course of the lab, students research, design, and conduct a series of tests culminating in a patient prognosis. All of the materials, which simulate the blood, urine, and testing compounds, are readily available at the grocery store or online. This real-world problem engages the students to think about negative feedback systems, patient symptoms, the hormones associated with blood glucose levels and urine production, as well as the detection techniques employed by physicians to diagnose patients. Diagnostic methods, testing procedures, and the disease itself make this lab extraordinarily relevant to the lives of students, as evidenced by our students’ reactions to the lab.

Carbon paste electrode modified with ferrimagnetic nanoparticles for voltammetric detection of the hormone estriol

A very simple, novel and environmentally-friendly electrochemical detector for estriol, based on a carbon paste electrode modified with ferrimagnetic nanoparticles, is proposed herein. The ferrimagnetic nanoparticles increase the surface area of the electrode and act as a catalyst for the electrochemical reaction of estriol. Estriol is an estrogen naturally produced by women during pregnancy. Its imbalance may engender disruption of the endocrine system, thereby impairing human growth and reproduction. Estriol is also considered to be an emergent pollutant. The proposed modified carbon paste electrode was used for the determination of estriol by anodic square-wave voltammetry. In 0.1molL−1 B-R buffer (pH6.0), estriol presented a well-defined single oxidation peak at +0.68V, indicating that under these conditions the electrochemical process is irreversible. The overall reaction rate is controlled by an adsorption step. Two protons and two electrons are involved in the estriol oxidation. The calibration curve for estriol showed good linearity in the concentration range of 0.86 to 32.0ppm (R2=0.997). The detection and quantification limits achieved were 0.79 and 2.41ppm, respectively. The proposed modified electrode was successfully applied to the analysis of pharmaceutical and simulated urine samples; the results being comparable to those obtained using the UV–vis technique.

Ultrasensitive Sensing Material Based on Opal Photonic Crystal for Label-Free Monitoring of Transferrin.

A new opal photonic crystal (PC) sensing material, allowing label-free detection of transferrin (TRF), is proposed in the current study. This photonic crystal was prepared via a vertical convective self-assembly method with monodisperse microspheres polymerized by methyl methacrylate (MMA) and 3-acrylamidophenylboronic acid (AAPBA). FTIR, TG, and DLS were used to characterize the components and particle size of the monodisperse microspheres. SEM was used to observe the morphology of the PC. The diffraction peak intensity decreases as the TRF concentration increase. This was due to the combination of TRF to the boronic acid group of the photonic crystal. After condition optimization, a standard curve was obtained and the linear range of TRF concentration was from 2 × 10-3 ng/mL to 200 ng/mL. Measurement of TRF concentration in simulated urine sample was also investigated using the sensing material. The results indicated that the PC provided a cheap, label-free, and easy-to-use alternative for TRF determination in clinical diagnostics.

Prospective assessment of the false positive rate of the Australian snake venom detection kit in healthy human samples

The Snake Venom Detection Kit (SVDK; bioCSL Pty Ltd, Australia) distinguishes venom from the five most medically significant snake immunotypes found in Australia. This study assesses the rate of false positives that, by definition, refers to a positive assay finding in a sample from someone who has not been bitten by a venomous snake. Control unbroken skin swabs, simulated bite swabs and urine specimens were collected from 61 healthy adult volunteers [33 males and 28 females] for assessment. In all controls, simulated bite site and urine samples [a total of 183 tests], the positive control well reacted strongly within one minute and no test wells reacted during the ten minute incubation period. However, in two urine tests, the negative control well gave a positive reaction (indicating an uninterpretable test). A 95% confidence interval for the false positive rate, on a per-patient rate, derived from the findings of this study, would extend from 0% to 6% and, on a per-test basis, it would be 0–2%. It appears to be a very low incidence (0–6%) of intrinsic true false positives for the SVDK. The clinical impresssion of a high SVDK false positive rate may be mostly related to operator error.

The application of supported liquid extraction in the analysis of benzodiazepines using surface enhanced Raman spectroscopy

Benzodiazepines are among the most frequently prescribed medicines for anxiety disorders and are present in many toxicological screens. These drugs are often administered in the commission of drug facilitated sexual assaults due their effects on the central nervous system. Due to the potency of the drugs, only small amounts are usually given to victims; therefore, the target detection limit for these compounds in biological samples has been set at 50ng/mL. Currently the standard screening method for detection of this class of drug is the immunoassay; however, screening methods that are more sensitive and selective than immunoassays are needed to encompass the wide range of structural variants of this class of compounds.Surface enhanced Raman spectroscopy (SERS) can be highly sensitive and has been shown to permit analysis of various benzodiazepines with limits of detection as low as 6ng/mL. This technique permits analytical results in less than 2min when used on pure drug samples. For biological samples, a key issue for analysis by SERS is removal of exogenous salts and matrix components. In this paper we examine supported liquid extraction as a useful preparation technique for SERS detection. Supported liquid extraction has many of the benefits of liquid–liquid extraction along with the ability to be automated. This technique provides a fast and clean extraction for benzodiazepines from urine at a pH of 5.0, and does not produce large quantities of solvent waste.To validate this procedure we have determined figures of merit and examined simulated urine samples prepared with commonly appearing interferences. It was shown that at a pH 5.0 many drugs that are prevalent in urine samples can be removed, permitting a selective detection of the benzodiazepine of interest. This technique has been shown to provide rapid (less than 20min), sensitive, and specific detection of benzodiazepines with limits of detection between 32 and 600ng/mL and dynamic range of 32–25,000ng/mL. It provides the forensic community with a sensitive and specific screening technique for the detection of benzodiazepines in drug facilitated assault cases.

Quantification of myo-inositol, 1,5-anhydro- D-sorbitol, and D-chiro-inositol using high-performance liquid chromatography with electrochemical detection in very small volume clinical samples.

Inositol is a six-carbon sugar alcohol and is one of nine biologically significant isomers of hexahydroxycyclohexane. Myo-inositol is the primary biologically active form and is present in higher concentrations in the fetus and newborn than in adults. It is currently being examined for the prevention of retinopathy of prematurity in newborn preterm infants. A robust method for quantifying myo-inositol (MI), D-chiro-inositol (DCI) and 1,5-anhydro- D-sorbitol (ADS) in very small-volume (25 μL) urine, blood serum and/or plasma samples was developed. Using a multiple-column, multiple mobile phase liquid chromatographic system with electrochemical detection, the method was validated with respect to (a) selectivity, (b) accuracy/recovery, (c) precision/reproducibility, (d) sensitivity, (e) stability and (f) ruggedness. The standard curve was linear and ranged from 0.5 to 30 mg/L for each of the three analytes. Above-mentioned performance measures were within acceptable limits described in the Food and Drug Administration's Guidance for Industry: Bioanalytical Method Validation. The method was validated using blood serum and plasma collected using four common anticoagulants, and also by quantifying the accuracy and sensitivity of MI measured in simulated urine samples recovered from preterm infant diaper systems. The method performs satisfactorily measuring the three most common inositol isomers on 25 μL clinical samples of serum, plasma, milk, and/or urine. Similar performance is seen testing larger volume samples of infant formulas and infant formula ingredients. MI, ADS and DCI may be accurately tested in urine samples collected from five different preterm infant diapers if the urine volume is greater than 2-5 mL.

Time-resolved fluorescence-based assay for rapid detection of Escherichia coli

Fast and simple detection of pathogens is of utmost importance in health care and the food industry. In this article, a novel technology for the detection of pathogenic bacteria is presented. The technology uses lytic-specific bacteriophages and a nonspecific interaction of cellular components with a luminescent lanthanide chelate. As a proof of principle, Escherichia coli-specific T4 bacteriophage was used to infect the bacteria, and the cell lysis was detected. In the absence of E. coli, luminescent Eu3+–chelate complex cannot be formed and low time-resolved luminescence signal is monitored. In the presence of E. coli, increased luminescence signal is observed as the cellular contents are leached to the surrounding medium. The luminescence signal is observed as a function of the number of bacteria in the sample. The homogeneous assay can detect living E. coli in bacterial cultures and simulated urine samples within 25min with a detection limit of 1000 or 10,000 bacterial cells/ml in buffer or urine, respectively. The detection limit is at the clinically relevant level, which indicates that the method could also be applicable to clinical settings for fast detection of urine bacteria.

Are They Bloody Guilty? Blood Doping with Simulated Samples

In this practice-based lab, students are provided with four Olympic athlete profiles and simulated blood and urine samples to test for illegal substances and blood-doping practices. Throughout the course of the lab, students design and conduct a testing procedure and use their results to determine which athletes won their medals fairly. All of the materials, which simulate the blood, urine, and testing compounds, are available at the grocery store. This real-world problem engages students to think about blood doping, hormones associated with red-blood-cell production, and detection techniques employed by the World Anti-Doping Agency. The Olympics, as well as the news coverage of Lance Armstrong’s admission to blood doping in 2013, makes this lab more relevant to students’ lives, which is supported by our students’ reactions to the lab.

Semiquantitative analysis on microfluidic thread-based analytical devices by ruler

This paper describes a simple and semiquantitative method for analytical detection by measuring the length of colour change on indicator treated threads using a ruler. Thread-based analytical devices (μTADs), fabricated from two types of threads (cotton and polyester), provide an easy-to-use platform for the rapid measurement of analyte concentrations in aqueous solutions. Multiple threads were fixed to a supporting polymer film to allow capillary wicking of liquid samples, free from contact with outside surfaces. In this method, interaction between deposited reagents and analytes within samples produces coloured zones of differing lengths on the threads. The length of the coloured zones correlates with the concentrations of the analytes in the samples. The diagnostic application of the length measurement method, using μTADs, was demonstrated through the successful testing of two different bioassays, for protein and nitrite, in simulated human urine samples. Additionally, it was shown that this method can be used for the rapid analysis of environmental samples such as Ni2+ in water. Furthermore, the length measurement method can be applied to perform simultaneous assays to quantify the concentrations of different biomarkers present within the same sample. Finally, it was also compared with currently used colorimetric methods on thread, which were reported by us and others previously, and was shown to have higher accuracy and simplicity.

P2.054 Optimal Processing of Chlamydia Trachomatis Simulated Samples from Proficiency Testing Panels by Dilution with Cobas© PCR Media

BackgroundProficiency materials are designed to resemble true clinical samples, yet challenges exist in procuring sufficient quantity of patient material. Simulated samples are often provided for this testing. Matrix effect with...