Linear Calibration Range Research Articles

Targeted and Untargeted Amine Metabolite Quantitation in Single Cells with Isobaric Multiplexing.

We developed a single cell amine analysis approach utilizing isobarically multiplexed samples of 6 individual cells along with analyte abundant carrier. This methodology was applied for absolute quantitation of amino acids and untargeted relative quantitation of amines in a total of 108 individual cells using nanoflow LC with high-resolution mass spectrometry. Together with individually determined cell sizes, this provides accessible quantification of intracellular amino acid concentrations within individual cells. The targeted method was partially validated for 10 amino acids with limits of detection in low attomoles, linear calibration range covering analyte amounts typically from 30 amol to 120 fmol, and correlation coefficients (R) above 0.99. This was applied with cell sizes recorded during dispensing to determine millimolar intracellular amino acid concentrations. The untargeted approach yielded 249 features that were detected in at least 25 % of the single cells, providing modest cell type separation on principal component analysis. Using Greedy forward selection with regularized least squares, a sub-selection of 100 features explaining most of the difference was determined. These features were annotated using MS2 from analyte standards and accurate mass with library search. The approach provides accessible, sensitive, and high-throughput method with the potential to be expanded also to other forms of ultrasensitive analysis.

Sequential Injection Analysis Method for the Determination of Glutathione in Pharmaceuticals.

A sequential injection analysis method for the determination of glutathione (GSH) in pharmaceuticals has been developed. It is based on the reduction of the Cu(II)-neocuproine complex by GSH and the formation of an orange-yellow colored Cu(I)-neocuproine complex with maximum absorbance at 458 nm. Under optimal conditions the method is characterized by a linear calibration range of 6.0 × 10-7-8.0 × 10-5 mol L-1 (Amax = 3270 CGSH - 0.0010; R2 = 0.9983), limit of detection of 2.0 × 10-7 mol L-1, limit of quantification of 6.7 × 10-7 mol L-1, repeatability (expressed as relative standard deviation) of 3.8%, and sampling rate of 60 h-1. The newly developed method has been successfully applied to the determination of GSH in pharmaceutical samples with no statistically significant difference between the results obtained and those produced by the standard Pharmacopoeia method.

Printed potentiometric, non-enzymatic sensors based on Zr(IV)-porphyrins for determination of lactate

The feasibility of using Zr-porphyrins as ionophores selective towards lactate ions was examined. Zr-tetraphenylporphyrin (Zr-TPP) and Zr-octaethylporphyrin (Zr-OEP) were tested in polyurethane membranes plasticized with dioctyl sebacate or o-nitrophenyl ether and containing cationic or anionic lipophilic sites, respectively. The best lactate response characteristics were registered for membrane plasticized with dioctyl sebacate and doped with Zr-TPP and cationic lipophilic sites. Classical electrodes with this membrane showed high selectivity towards lactate ions with a sensitivity of −76.6 mV dec−1 and linear lactate calibration range from 10−4 M to 10−1 M. Polymeric membranes containing Zr-TPP were then drop-casted on screen-printed transducers with electrodes made of graphene-containing paste. It was found that the potentiometric behavior of these miniature planar sensors is very similar to classical electrodes. In the next step, fully printed sensors, with both graphene electrodes and ion-selective polymeric membranes, were fabricated using aerosol jet printing. The sensitivity of these electrodes towards lactate was −79.01±0.39 mV dec−1 with a linear response range from 10−3.5 M to 10−1 M and a fast response to lactate concentration changes. The proposed electrode demonstrates a rare example of a potentiometric, non-enzymatic sensor for the determination of lactate ions, with the possibility of miniaturization and mass fabrication using printing methods.

Electrocatalysis Using Cobalt Porphyrin Covalently Linked with Multi-Walled Carbon Nanotubes: Hydrazine Sensing and Hydrazine-Assisted Green Hydrogen Synthesis.

Acid-treated multi-walled carbon nanotube (MWCNT) covalently functionalized with cobalt triphenothiazine porphyrin (CoTriPTZ-OH) A3B type porphyrin, containing three phenothiazine moieties (represented as MWCNT-CoTriPTZ) is synthesized and characterized by various spectroscopic and microscopic techniques. The nanoconjugate, MWCNT-CoTriPTZ, exhibits a pair of distinct redox peaks due to the Co2+/Co3+ redox process in 0.1M pH 7.0 phosphate buffer. Further, it electrocatalytically oxidizes hydrazine at a low overpotential with a high current. This property is advantageously utilized for the sensitive determination of hydrazine. The developed electrochemical sensor exhibits high sensitivity (0.99 µAµM-1cm-2), a low limit of detection (4.5 ppb), and a broad linear calibration range (0.1µM to 3.0mM) for the determination of hydrazine. Further, MWCNT-CoTriPTZ is exploited for hydrazine-assisted green hydrogen synthesis. The high efficiency of hydrazine oxidation is confirmed by the low onset potential (0.45V (vs RHE)) and 0.60V (vs RHE) at the current density of 10mA.cm-2. MWCNT-CoTriPTZ displays a high current density (77.29mA.cm-2) at 1.45V (vs RHE).

Sequential thin film microextraction and overcoated thin film microextraction devices for characterization of sparkling wine aroma profiles and partitioning equilibria

Solid Phase Microextraction (SPME) is a commonly used, robust method for characterization of aroma profiles in food matrices. However, challenges such as saturation, swelling, and competition can occur when sampling such complex matrices, resulting in decreased accuracy in the quantitation of polar compounds. In this study, sequential thin film micro-extraction (TFME) was employed to study the aroma profile of sparkling wine, with a focus to evaluate the displacement of polar analytes at extraction times longer than their corresponding equilibrium time. This investigation also describes advancements in the production of TFME devices, specifically the overcoating of hydrophilic-lipophilic balance/polydimethylsiloxane (HLB/PDMS) thin films to increase their matrix compatibility. Sequential thin film micro-extraction and overcoated HLB/PDMS thin films were evaluated for characterization of sparkling wine samples. The results were encouraging, showing that these advancements can decrease competition phenomena and increase the calibration linearity range compared to traditional micro-extraction approaches more commonly used for the characterization of such samples. In addition, multiphase equilibria investigation involving micellar systems enabled by the microextraction technology provides better understanding between wine aroma and its composition.

Enhanced Detection of Lamotrigine Through HPLC Methodology in Bioanalysis

Background: Lamotrigine, an anticonvulsant drug, requires sensitive detection methods in biological and pharmaceutical matrices. Current methods struggle with interference and sensitivity, necessitating the development of improved analytical techniques. Objective: This study aims to develop and validate a highly sensitive HPLC method enhanced by salicylaldehyde derivatization for detecting lamotrigine in pharmaceutical and biological samples, and to differentiate it from Piracetam when co-administered. Methods: A reverse-phase HPLC method was employed, utilizing salicylaldehyde as a derivatizing agent to induce a bathochromic shift in lamotrigine from 315 nm to 415 nm. Optimization of the derivatization reaction included adjustments of pH, reagent concentration, temperature, and time. The standard addition method was applied to evaluate the recovery rates from spiked samples. Results: The optimized method demonstrated a linear calibration range of 1-5 µg/ml with a determination coefficient (R²) of 0.998. Recovery of lamotrigine from pharmaceutical preparations averaged 96.5%, while recovery from deprotonated serum and urine samples of healthy volunteers was 96% with a relative standard deviation (RSD) of 6%. Conclusion: The developed method offers a robust and highly sensitive approach to detect and distinguish lamotrigine in the presence of Piracetam, proving effective for both pharmaceutical and biological sample analysis.

An ultra-selective and non-enzymatic colorimetric sensor based on imprinted polymer for ephedrine assay in urine samples

A novel non-enzymatic, rapid, and portable molecularly imprinted polymer (MIP)-based colorimetric sensor was developed for ephedrine (EPD) assay in urine samples. The EPD-imprinted polymer was provided via the precipitation polymerization method and applied to fabricate an EPD colorimetric sensor utilizing the carbon disulfide and Cu2+ reagents. The calibration curve for different concentrations of EPD was obtained using the captured images on a cell smartphone and associated RGB data. Some effective parameters including pH of the EPD extraction, time of data collection after adding the reagents, and reagents sequence were investigated and optimized. The selectivity of the sensor was studied using different similar structural compounds, which proved the favorable capability of this method for the selective determination of EPD. This sensor platform with a relatively wide linear calibration range (1–100 μM), and the detection limit of 0.6 μM represents the efficient, reliable, and easy approach for EPD assay in urine samples.

Development of a quantification method for arginase inhibitors by LC-MS/MS with benzoyl chloride derivatization

Arginase is an enzyme responsible for converting arginine, a semi-essential amino acid, to ornithine and urea. Arginine depletion suppresses immunity via multiple mechanisms including inhibition of T-cell and NK cell proliferation and activity. Arginase inhibition is therefore an attractive mechanism to potentially reverse immune suppression and thus has been explored as a therapy for oncology and respiratory indications. Small molecules targeting arginase present significant bioanalytical challenges for in vitro and in vivo characterization as inhibitors of arginase are typically hydrophilic in nature. The resulting low or negative LogD characteristics are incompatible with common analytical methods such as RP-ESI-MS/MS. Accordingly, a sensitive, high-throughput bioanalytical method was developed by incorporating benzoyl chloride derivatization to increase the hydrophobic characteristics of these polar analytes. Samples were separated by reversed phase chromatography on a Waters XBridge BEH C18 3.5 μm, 30 × 3 mm column using gradient elution. The mass spec was operated in positive mode using electrospray ionization. The m/z 434.1→176.1, 439.4→181.2, 334.9→150.0 and 339.9→150.0 for AZD0011, AZD0011 IS, AZD0011-PL and AZD0011-PL IS respectively were used for quantitation. The linear calibration range of the assay was 1.00–10,000 ng/mL with QC values of 5, 50 and 500 ng/mL. The qualified method presented herein exhibits a novel, robust analytical performance and was successfully applied to evaluate the in vivo ADME properties of boronic acid-based arginase inhibitor prodrug AZD0011 and its active payload AZD0011-PL.

Superhydrophobic eggshell for fabrication of hydrophobic barrier of paper-based analytical device for colorimetric determination of ammonium ion in water

This work demonstrates the first application of the superhydrophobic eggshell as an environmental-friendly material for fabricating the hydrophobic barrier of a paper-based analytical device (PAD). The eggshell surface was modified by mixing the pulverized chicken eggshell biowaste with stearic acid and a polystyrene binder to accomplish superhydrophobicity. The PAD (10 × 10 mm2) is comprised of the circular-shaped hydrophilic reservoir (Ø 5 mm). The liquid barrier was fabricated by painting both the topside and the underside of the filter paper with the dispersed superhydrophobic eggshell solution. The SEM images revealed that the microsized superhydrophobic eggshell particles absorbed onto the porous surface of the cellulose fibril. A coated surface with a water contact angle of 155.39° ± 1.02° (n = 10) on the paper substrate was achieved, and this indicated superhydrophobicity. The eggshell barrier enabled excellent water and chemical resistance. The fabricated PAD was applied for the colorimetric determination of ammonium cations (NH4+), based on the modified Berthelot reaction. Samples and chromogenic solutions were aliquoted onto the hydrophilic reservoir, with subsequent capture of the optical image of the stable, green-colored product by a smart phone under a light-controlled studio. The green color intensities were evaluated by ImageJ™ and plotted against the standard NH4+ concentrations. A wide linear calibration range 5.0 to 100 mg N/L was achieved with good linearity (r2 > 0.99). The PAD confirmed satisfied analytical recovery (Mean ± SD: 100.6 % ± 0.97, n = 11 samples) and high precision (RSD = 0.85 %: 10-PAD replicate measurements of 1.0 mg N/L). The limit of detection (3 SD of blank/slope) of 1.05 mg N/L was found sensitive enough to monitor the NH4+ contents in freshwater. The results, determined by the developed PAD and ion chromatography, showed no significant difference under the statistical paired t-test at 95 % confidence (tstat = -1.80, tcri = 2.57, n = 6 samples).

Determination, Manufacturing and application of a nanoparticle lead ion-selective electrode as a sensor in flow injection systems

This study involves the construction of ion-selective electrodes for the determination of lead (II) ions and their utilization as sensors in a flow-injection analysis (FIA) system. The electrode was constructed using a simple environmentally friendly method from a green tea extract, and a Lead acetate solution of the cited ions as a cylindrical disc. A vertical, side-to-side cylinder, the whole is created in its centre and another lateral hole is created for the electrical attachment of the electrode, so the prepared electrode is suitable for use with the FIA system. The electrode was studied surface properties and characteristics of this electrode were analysed using X-ray diffraction and Fourier-transform infrared spectroscopy (FTR). via selection of the optimum conditions (i.e. linear calibration range, lowest Nernstian response, lowest detection limit, degree of dilution, and precision and accuracy of their analytical uses). Electrode which gave the best Nernstian response1.00×10<sup>-1</sup> to 1.00×10<sup>-10</sup> M, a correlation coefficient of 0.9980, with lower Nernstian response of 1×10<sup>-10</sup> M and detection limit of 1×10<sup>-11</sup> M. The sampling rate was 120 samples per hour the calculated time of the contact of the sample with the electrode surface is 6 seconds and the degree of dilution is 2.37625.

Determination, Manufacturing and application of a nanoparticle lead ion-selective electrode as a sensor in flow injection systems

This study involves the construction of ion-selective electrodes for the determination of lead (II) ions and their utilization as sensors in a flow-injection analysis (FIA) system. The electrode was constructed using a simple environmentally friendly method from a green tea extract, and a Lead acetate solution of the cited ions as a cylindrical disc. A vertical, side-to-side cylinder, the whole is created in its centre and another lateral hole is created for the electrical attachment of the electrode, so the prepared electrode is suitable for use with the FIA system. The electrode was studied surface properties and characteristics of this electrode were analysed using X-ray diffraction and Fourier-transform infrared spectroscopy (FTR). via selection of the optimum conditions (i.e. linear calibration range, lowest Nernstian response, lowest detection limit, degree of dilution, and precision and accuracy of their analytical uses). Electrode which gave the best Nernstian response1.00×10-1 to 1.00×10-10 M, a correlation coefficient of 0.9980, with lower Nernstian response of 1×10-10 M and detection limit of 1×10-11 M. The sampling rate was 120 samples per hour the calculated time of the contact of the sample with the electrode surface is 6 seconds and the degree of dilution is 2.37625.

Simultaneous determination of sinomenine and its metabolites desmethyl-sinomenine and sinomenine N-oxide in rat plasma by liquid chromatography tandem mass spectrometry.

Sinomenine is an active ingredient extracted from herb medicine, which has been prescribed to treat rheumatoid arthritis in clinics. The present work was to develop a simple method to simultaneously determine sinomenine and its metabolites desmethyl sinomenine and sinomenine N-oxide in rat plasma by liquid chromatography tandem mass spectrometry. Precursor-to-product transitions for detection were m/z 330.2 > 239.1 for sinomenine, m/z 316.2 > 239.1 for desmethyl-sinomenine, m/z 346.2 > 314.1 for sinomenine N-oxide and m/z 286.2 > 153.2 for morphine (internal standard), respectively. During the validation and sample quantification, an excellent linear calibration range was observed for all the analytes with correlation coefficients more than 0.999 (r > 0.99). The extraction recovery was more than 85%. No significant matrix effect and carryover were observed. The precision was less than 6.45%, whereas accuracy ranged from -4.10% to 7.23%. The validated method has been successfully applied to the pharmacokinetic study of sinomenine, desmethyl sinomenine, and sinomenine N-oxide in rat plasma after oral administration of sinomenine at a single dose of 5 mg/kg. The results suggested that sinomenine was rapidly metabolized into its metabolite desmethyl sinomenine and sinomenine N-oxide.

An LC-MS/MS-based platform for the quantification of multiple amyloid beta peptides in surrogate cerebrospinal fluid

IntroductionThe accurate quantification of amyloid beta (Aβ) peptides in cerebrospinal fluid (CSF) is crucial for Alzheimer's disease (AD) research, particularly in terms of preclinical and biomarker studies. Traditional methods, such as the enzyme-linked immunosorbent assay (ELISA), have limitations. These include high costs, labor intensity, lengthy processes, and the possibility of cross-reactivity. ObjectivesThe primary objectives of this research were twofold: to comprehensively characterize Aβ peptides and to develop a reliable and accurate method for the simultaneous quantification of Aβ 1–40 and Aβ 1–42 peptides in surrogate CSF that is traceable to the International System of Units (SI). MethodsWe developed a novel method that combined solid phase extraction (SPE) with isotope dilution liquid chromatography/tandem mass spectrometry (ID-LC/MSMS). SPE was employed to efficiently eliminate matrix interferences, while [15N] Aβ1-40 and [15N] Aβ1-42 served as internal standards to improve accuracy. In addition, we introduced Peptide Impurity Corrected Amino Acid Analysis (PICAA) to ensure traceability to the SI and reliable quantification of Aβ peptides. ResultsThe developed platform demonstrated a linear calibration range of 300–20000 pg/ml for both Aβ1-42 and Aβ1-40 peptides, accompanied by strong correlation coefficients greater than 0.995. Quality Control (QC) samples demonstrated an accuracy of at least 90.0 %. ConclusionThe enhanced specificity and flexibility of the developed platform potentially have implications for Alzheimer's disease diagnosis and future investigations of novel Aβ peptide biomarkers.

Quick and Green Procedure for the Quantification of Chromium in an Anionic Surfactant System

This study aims to establish a facile, user-friendly, accurate, and repeatable spectrophotometric detection method for Cr(III) ions in trace quantities. The method utilises reagent 1-nitroso-2-naphthol (NNPh) in a sodium dodecyl sulphate (SDS) 1.0 % micellar solution, replacing the old, time-consuming, and expensive solvent extraction method that employs hazardous solvents such as carbon tetrachloride and chloroform. SDS surfactant is used to solubilise indissoluble chelates, making the proposed technique easy, rapid, and environmentally friendly. The established method exhibits an improved linear calibration range, sensitivity, limit of detection, and selectivity compared to earlier spectrophotometric methods employing different complexing agents. The stoichiometric ratio between Cr and NNP was observed to be 1 : 3. The molar absorption coefficient (<i>ε</i>) was determined to be 2.05 ∙ 104 l mol<sup>–1</sup> cm<sup>–1</sup> at <i>λ</i><sub>max</sub> 579 nm. The limits of detection for Cr(III) was measured as 3.49 ng l<sup>–1</sup>. A calibration linear curve was achieved in the concentration range of 0.5–5.0 μg ml<sup>–1</sup>. Results obtained showed good comparison with the results obtained by atomic absorption spectrometry. The developed method has been adapted for the analysis of Cr(III) in various alloys, pharmaceutical, environmental, and biological samples.

Direct immersion single-drop microextraction combined with fluorescence detection using an optical probe. Application for highly sensitive determination of rhodamine 6G

The use of an optical probe for fluorescence detection combined with direct immersion single-drop microextraction has been demonstrated as an innovative approach. The optical probe served both as a drop holder for extractant and as a measuring device which made it possible to eliminate the use of cuvettes. A laser and a light emitting diode (LED) were tested as possible light sources. Both of them showed comparable results. However, given the much smaller half-band width of the laser radiation, its use has proven to be preferable since background correction can be eliminated. Direct immersion single-drop microextraction of an ionic association complex of rhodamine 6G with picric acid with subsequent fluorescent detection (λex was 532 nm and 525 nm for laser and LED, respectively; λem was 560 nm for both laser and LED) was used a model system to evaluate the new approach. The extractant phase was a 55 μL amyl acetate microdrop fixed in the optical part of the probe. LOD, LOQ and linear calibration range were found as 0.14, 0.48 and 0.5–10 nmol L−1, and 0.15, 0.50 and 0.5–5 nmol L−1 for laser and LED light sources, respectively. The accuracy of the method was assessed by analyzing real water samples.

Parallel artificial liquid membrane extraction coupled with UPLC-ESI-MS/MS method for high-throughput quantitation of repaglinide in diabetic patients

A high-throughput therapeutic monitoring method was developed for repaglinide (RPG) in diabetic patients, combining parallel artificial liquid membrane extraction (PALME) with ultraperformance liquid chromatography electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). PALME was performed using a 96-well donor plate comprising a donor solution containing a plasma sample, 50 mM phosphate buffer (pH = 8.0), and cetirizine (CTZ) as internal standard. A polypropylene (PP) porous membrane served as a selective support for the liquid membrane (SLM), preventing nonspecific binding produced by other membranes. The extraction was accomplished across SLM made of PP membrane with dodecyl acetate and 1 % trioctylamine (w/w), and the acceptor solution comprised DMSO and 200 mM formic acid (50:50, v/v). The simple workflow for PALME provided analyte enrichment, highly efficient sample cleanup, high throughput analysis, and excellent reproducibility. Method validation met FDA criteria, with a linear plasma calibration range (0.1–100 ng mL−1, r = 0.9995) and a lower limit of quantitation (LLOQ) of 0.1 ng mL−1. Recovery results at 98.9 % affirmed method reliability. The ability to analyze 198 samples per hour, coupled with a reduced amount of solvents, underscores the method's high throughput and eco-friendly profile. The PALME-UPLC-ESI-MS/MS method was successfully applied to therapeutic drug monitoring of RPG in diabetic patients following 2 mg RPG tablet administration, establishing its effectiveness.

Electrochemical detection of oxytetracycline employing sugarcane carbon modified graphite electrode.

The present study used CeO2-Co3O4 quantum dots@porous carbon/multiwalled carbon nanotube (CeO2-Co3O4 QDs@PC/MWCNT/GE) composites to modify graphite electrodes to fabricate high-sensitivity electrochemical sensors to detect the presence of oxytetracycline (OTC). The quantum dots were made from waste sugarcane bagasse. The electrochemical analysis demonstrated the superior electrochemical performance of CeO2-Co3O4 QDs@PC/MWCNT/GE, with a peak current density of 1.276mA/cm2. Electrochemical impedance spectroscopy (EIS) revealed lower impedance values for CeO2-Co3O4 QDs@PC/MWCNT/GE compared to other electrodes, indicating enhanced conductivity. The modified electrode exhibited an enlarged electrochemically active area, with values of 0.602 cm2, almost seven times that of the bare graphite electrode (0.079 cm2). The results showed that the CeO2-Co3O4 QDs@PC/MWCNT/GE had excellent performance for OTC detection, and its linear calibration range was 1.007 × 10-8 to 2.04 × 10-7M (i.e., 0.005-0.1ppm) and 1.007 × 10-6 to 1.209 × 10-4M (i.e., 0.5-60ppm). The limit of detection and limit of quantification were 1.23nM (0.61ppb) and 4.09nM (2.03ppb) (S/N = 3), respectively. The electrode demonstrated long-term stability for up to 7weeks. This method provides a new way to prepare electrochemical sensors for OTC detection.

Development and Validation a UPLC-MS/MS Method for Quantification of Pentoxifylline in Beagle Plasma: Application for Pharmacokinetic Study of Food Effect.

To develop an UPLC-MS/MS method for the quantitative analysis of pentoxifylline in beagle dog plasma and apply it to a pharmacokinetic study of food effect. Sample separation was achieved using a Kinetex Phenyl-Hexyl column (50 × 2.1 mm, 1.7 μm) with a gradient elution program in 5.5 min after a simple protein precipitation with methanol. Using the mobile phase that made up by 0.2% formic acid and 5mM ammonium formate water (A) and methanol (B). Quantitation was carried out using the positive ionization mode with multiple reaction monitoring (MRM). A randomized, single-dose, two-period crossover study was conducted insix fasted or fed beagles that received 400 mg pentoxifylline sustained-release tablets (Brand name: Shuanling™, CSPC Pharmaceutical Group). WinNonlin® software was used to calculate pharmacokinetic parameters. The linear calibration range was 2-1000 ng/mL (r2> 0.99). Both intra- and inter-batch precision were less than 6.27%, and the accuracy ranged from 88.65% to 97.18%. Pentoxifylline was readily absorbed in fasted and fed dogs administered a dose of 400 mg (tmax:1.54h vs 1.83h). Compared to the fasted group, the AUC0→t and Cmax in the fed group increased by 1.71-fold and 1.30-fold, respectively. In the fasted group, the AUC0→t and Cmax values were 4684.08 h•ng/mL and 2402.33 ng/mL, respectively. In the fed group, these values were 8027.75 h•ng/mL and 3119.67 ng/mL. The difference in AUC0-t between the fed and fasted group was statistically significant. The novel optimized UPLC-MS/MS assay is an effective tool for the determination of pentoxifylline and has been successfully applied in pharmacokinetic studies of pentoxifylline in beagle dogs. The administration of pentoxifylline sustained-release tablets with food significantly increased the area under the time curve, and it is recommended that they should be administered during or shortly after feeding.

Analysis of platinum-based anticancer injections cisplatin and carboplatin in blood serum and urine of cancer patients by photometry, fluorometry, liquid chromatography using a Schiff-base as derivatizing reagent

Photometric, fluorometric and liquid chromatographic methods were proposed to analyze Pt(II) from cis-platin and carbo-platin injections after derivatization with reagent 2-oxo-propanoic acid N-phenylhydrazonecarbothioamide. The reagent reacted with metals Au(III), Ag(I), Mn(II), Pt(II), Mo(VI), V(V/IV) to develop their characteristic colors in the pH range 3–12 and were extracted in organic solvent trichloromethane. The photoluminescent behavior of ligand and its metal complexes was investigated to correlate the emission pattern. Liquid chromatographic method was also proposed to analyze cis-platin and carbo-platin anti-cancer drugs based on the pre-column derivatizing platinum(II) with ligand. The complex of platinum was separated and eluted from HPLC column Microsorb C-18, (150 cm x 4.6 mm i.d, 5 µm) comprising eluents - tetrabutyl ammonium bromide (1 mM)-sodium acetate (1 mM)-acetonitrile-water-methanol (02:02:06:22:68 v/v/v/v/v). Metals Au(III), Ag(I), Mn(II), V(IV/V), Mo(VI) were also separated completely. The linear calibration range 0.5–2.5 µg/mL was observed following Beer’s law with detection limit of 150.00 ng/mL Pt(II). The determination of cis-platin and carbo-platin injections by photometric, fluorometric and chromatographic methods showed RSD (n = 3) 1.14–3.12, 0.98–2.84, 0.92–2.72% respectively. The developed methods were employed to analyze cis-platin in samples of serum and urine of cancer patients undergoing chemotherapy and platinum amounts were observed within 45.0—86.0, 49.0—91.0, 42.0—84.0 ng/mL and 82.0—398, 81.0—389, 74.0—391 ng/mL with relative standard deviation (RSD) (n = 4) of 2.28—3.88, 2.40—3.82, 2.52—3.82% and 2.52—3.91, 2.44—3.94, 1.98—3.24% by liquid chromatographic, fluorometric and photometric techniques respectively.

Magnetic perlite based molecularly imprinted polymer on screen printed carbon electrode as a new tyramine electrochemical sensor

This paper describes the design and fabrication of a sensitive electrochemical sensor using a new magnetic pearlite-based molecularly imprinted polymer (MPt/MIP) for the voltammetric determination of tyramine (Tyr). MPt/MIP nanocomposite was synthesized by direct surface-based imprinting procedure using methacrylic acid (MAA) as monomer for MIP and also functional group for magnetic perlite (MPt). The structural properties of MPt/MIP nanocomposite were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), FT-IR spectroscopy, vibrating sample magnetometry (VSM) and via adsorption kinetics and adsorption isotherms. The integrated analytical procedure consists of dispersion of synthesized MPt/MIPs for selective separation of target analyte from sample and their subsequent localization on the surface of a magnetic screen-printed carbon electrode (MSPCE) as a platform for determination of Tyr by differential pulse voltammetry (DPV). The experimental parameters which affect separation efficiency and electrochemical determination were optimized. The developed method provided a linear calibration range of 8.0 to 380.0 ng mL−1 (R2 = 0.998), and a detection limit of 3.8 ng mL−1. The intra-day and inter-day precision (%RSD) were in the range 3.1–4.4 %. The method was successfully applied to the determination of Tyr in real samples with recoveries ranging from 94.2 to 105.2 %.