Quantification Precision Research Articles

A Validated HPLC Multichannel DAD Method for the Simultaneous Determination of Amoxicillin and Doxycycline in Pharmaceutical Formulations and Wastewater Samples

The quality of marketed pharmaceutical formulations must be guaranteed to attain better remedial effects and lower toxicity. The wide exploitation of antibiotics may lead to their presence as residues in body fluids and wastewaters, potentially toxic to human health. Consequently, determining antibiotics in pharmaceutical formulations and water samples is of significant importance. This paper aims to explore the possibilities of a high-performance liquid chromatography coupled with diode array detection (HPLC-DAD) method to obtain a simple, fast, and efficient analytical tool for the simultaneous determination of antibiotics in pharmaceutical formulations and environmental samples. The method was completely validated with regard to specificity, linearity, detection and quantification limits, precision, accuracy, and robustness according to the requirements of existing guidelines, and was proven to be reliable and suitable for the envisioned application. The linearity study was conducted for the calibration curves in the range of 10–100 μg/mL. The limits of detection and quantification were found to be 0.2 and 0.7 μg/mL for amoxicillin and 0.3 and 1.0 μg/mL for doxycycline, respectively. The high recovery of drugs from their commercial pharmaceutical formulations (93%) and from wastewater samples (98%) indicated good accuracy and precision. The method is robust for small or deliberate changes to the chromatographic parameters, and it was successfully applied for the quantitative determination of amoxicillin and doxycycline in wastewater and commercial tablets. The obtained results proved that the validated method is appropriate for its intended use in the routine quality control and assay of both antibiotics studied.

Development and Analytical Validation of a 6-Plex Reverse Transcription Droplet Digital PCR Assay for the Absolute Quantification of Prostate Cancer Biomarkers in Circulating Tumor Cells of Patients with Metastatic Castration-Resistant Prostate Cancer.

Gene expression in circulating tumor cells (CTCs) can be used as a predictive liquid biopsy test in metastatic castration-resistant prostate cancer (mCRPC). We developed a novel 6-plex reverse transcription droplet digital PCR (RT-ddPCR) assay for the absolute quantification of 4 prostate cancer biomarkers, a reference gene, and a synthetic DNA external control (DNA-EC) in CTCs isolated from mCRPC patients. A novel 6-plex RT-ddPCR assay was developed for the simultaneous absolute quantification of AR-FL, AR-V7, PSA, and PSMA, HPRT (used as a reference gene), and a synthetic DNA-EC that was included for quality control. The assay was optimized and analytically validated using DNA synthetic standards for each transcript as positive controls. Epithelial cellular adhesion molecule (EpCAM)-positive CTC fractions isolated from 90 mCRPC patients and 11 healthy male donors were analyzed, and results were directly compared with reverse transcription quantitative PCR (RT-qPCR) for all markers in all samples. Linear dynamic range, limit of detection, limit of quantification, intra- and interassay precision, and analytical specificity were determined for each marker. Application of the assay in EpCAM-positive CTC showed positivity for AR-FL (71/90; 78.9%), AR-V7 (28/90; 31.1%), PSA (41/90; 45.6%), PSMA (38/90; 42.2%), and HPRT (90/90; 100%); DNA-EC concentration was constant across all samples. Direct comparison with RT-qPCR for the same markers in the same samples revealed RT-ddPCR to have superior diagnostic sensitivity. Our 6-plex RT-ddPCR assay was highly sensitive, specific, and reproducible, and enabled simultaneous and absolute quantification of 5 gene transcripts in minute amounts of CTC-derived cDNA. Application of this assay in clinical samples gave diagnostic sensitivity and specificity comparable to, or better than, RT-qPCR.

Monitoring hydrocarbon levels during bioremediation by enhanced bio-stimulants using GC-FID

The efficacy of bio-stimulants on the remediation of hydrocarbon polluted soil was assessed using Gas Chromatography with Flame Ionization Detector (GC-FID). The enhanced bio-stimulants were discarded melon pulps, discarded breadfruit pulps and poultry droppings. These were applied to the polluted soil in the ratio of 1:5; the blend was observed for sixty days. Inferring from the chromatographs, the carbon compounds present in the polluted and remediated soils ranged from C12 – C40 with varying concentrations; C12 to C19 were dominant, C9 to C11 were residual with negligible concentrations. The total petroleum hydrocarbon (TPH) of polluted soil was 42,229.73 mg/kg, and the remediated soils were: biodegraded melon pulp - 23,786.3 mg/kg, biodegraded breadfruit pulp - 15,322.82 mg/kg, and chicken droppings, - 7,314.29 mg/kg. The results indicated that TPH of the polluted soil was reduced by 43.67% in sample remediated with biodegraded melon pulp, 63.71% in sample remediated with biodegraded breadfruit pulp, and 82.67% in sample remediated with chicken droppings. Therefore, a decreasing order of the effectiveness of the bio-stimulants is thus: chicken droppings > biodegraded breadfruit pulp > biodegraded melon pulp. The higher remediation potential of poultry droppings is attributable to high nitrogenous content. The study showed that the aforementioned bio-stimulants are effective in remediation of petroleum polluted soil. GC-FID detected the hydrocarbon present and their concentrations in the polluted and remediated soils. GC-FID is preferred to other analytical techniques due to its precision in identification and quantification of hydrocarbon fractions.

Harmonization and qualification of an IFN-γ Enzyme-Linked ImmunoSpot assay (ELISPOT) to measure influenza-specific cell-mediated immunity within the FLUCOP consortium.

Influenza continues to be the most important cause of viral respiratory disease, despite the availability of vaccines. Today’s evaluation of influenza vaccines mainly focuses on the quantitative and functional analyses of antibodies to the surface proteins haemagglutinin (HA) and neuraminidase (NA). However, there is an increasing interest in measuring cellular immune responses targeting not only mutation-prone surface HA and NA but also conserved internal proteins as these are less explored yet potential correlates of protection. To date, laboratories that monitor cellular immune responses use a variety of in-house procedures. This generates diverging results, complicates interlaboratory comparisons, and hampers influenza vaccine evaluation. The European FLUCOP project aims to develop and standardize assays for the assessment of influenza vaccine correlates of protection. This report describes the harmonization and qualification of the influenza-specific interferon-gamma (IFN-γ) Enzyme-Linked ImmunoSpot (ELISpot) assay. Initially, two pilot studies were conducted to identify sources of variability during sample analysis and spot enumeration in order to develop a harmonized Standard Operating Procedure (SOP). Subsequently, an assay qualification study was performed to investigate the linearity, intermediate precision (reproducibility), repeatability, specificity, Lower and Upper Limits of Quantification (LLOQ-ULOQ), Limit of Detection (LOD) and the stability of signal over time. We were able to demonstrate that the FLUCOP harmonized IFN-γ ELISpot assay procedure can accurately enumerate IFN-γ secreting cells in the analytical range of 34.4 Spot Forming Units (SFU) per million cells up to the technical limit of the used reader and in the linear range from 120 000 to 360 000 cells per well, in plates stored up to 6 weeks after development. This IFN-γ ELISpot procedure will hopefully become a useful and reliable tool to investigate influenza-specific cellular immune responses induced by natural infection or vaccination and can be an additional instrument in the search for novel correlates of protection.

Superhydrophobic Nanosilica Decorated Electrospun Polyethylene Terephthalate Nanofibers for Headspace Solid Phase Microextraction of 16 Organochlorine Pesticides in Environmental Water Samples.

A new solid phase micro extraction (SPME) fiber coating composed of electrospun polyethylene terephthalate (PET) nanofibrous mat doped with superhydrophobic nanosilica (SiO2) was coated on a stainless-steel wire without the need of a binder. The coating was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectrometer (FTIR) techniques and it was used in headspace-SPME of 16 organochlorine pesticides in water samples prior to gass chromatography micro electron capture detector (GC-µECD) analysis. The effects of main factors such as adsorption composition, electrospinning flow rate, salt concentration, extraction temperature, extraction time, and desorption conditions were investigated. Under the optimum conditions, the linear dynamic range (8–1000 ng L−1, R2 > 0.9907), limits of detection (3–80 ng L−1), limits of quantification (8–200 ng L−1), intra-day and inter-day precisions (at 400 and 1000 ng L−1, 1.7–13.8%), and fiber-to-fiber reproducibility (2.4–13.4%) were evaluated. The analysis of spiked tap, sewage, industrial, and mineral water samples for the determination of the analytes resulted in satisfactory relative recoveries (78–120%).

Food analysis: a practical guide

Food analysis: a practical guide

Quantification of Gut Microbiota Dysbiosis-Related Organic Acids in Human Urine Using LC-MS/MS.

Urine organic acid contains water-soluble metabolites and/or metabolites—derived from sugars, amino acids, lipids, vitamins, and drugs—which can reveal a human’s physiological condition. These urine organic acids—hippuric acid, benzoic acid, phenylacetic acid, phenylpropionic acid, 4-hydroxybenzoic acid, 4-hydroxyphenyl acetic acid, 3-hydroxyphenylpropionic acid, 3,4-dihydroxyphenyl propionic acid, and 3-indoleacetic acid—were the eligible candidates for the dysbiosis of gut microbiota. The aim of this proposal was to develop and to validate a liquid chromatography–tandem mass spectrometry (LC-MS/MS) bioanalysis method for the nine organic acids in human urine. Stable-labeled isotope standard (creatinine-d3) and acetonitrile were added to the urine sample. The supernatant was diluted with deionized water and injected into LC-MS/MS. This method was validated with high selectivity for the urine sample, a low limit of quantification (10–40 ng/mL), good linearity (r > 0.995), high accuracy (85.8–109.7%), and high precision (1.4–13.3%). This method simultaneously analyzed creatinine in urine, which calibrates metabolic rate between different individuals. Validation has been completed for this method; as such, it could possibly be applied to the study of gut microbiota clinically.

Between-day reliability of cytokines and adipokines for application in research and practice.

Purpose: This study assessed the biological reliability of peripheral human cytokines and adipokines, and the influence of participant characteristics on total error. This has essential application to interventional cytokine measurement to ensure that reported results are interpreted with confidence. Methods: Participants (49% female, 18–85 years, n = 84) completed two consecutive-day testing sessions. Participants provided a venous blood sample at the same time of day across two consecutive days, under standardized participant presentation, including 24-h rested and 12-h fasted conditions. Multiplex immunoassay was used to assess inflammatory analytes from samples (predominantly plasma). Repeat measurements were conducted between-day for total precision quantification, and technical (technique) error was negated from the total to provide an estimate of biological (attributed to participant presentation) error. Results: Whilst there was no evidence of statistically significant biological error, a small amount of biological error was consistently present across most analytes (∼3.3%/0.07 pg/ml), which was largest for measurement of leptin (7.3%/210 pg/ml). There was also an influence of sex on reliability of leptin and adiponectin (total model explained 6–7% of error variation), where females demonstrated the greatest error. Conclusion: Biological error reported in this study should be applied to any future study or individual with a repeated measurement of cytokine concentrations over time that maintain best practice procedures (12-h fasted, 24-h rested). In most cases, raw error should be used, with exceptions for women for measurement of leptin and adiponectin. This approach will ensure that results are reported with certainty for improved reporting of intervention efficacy.

The direct immersion solid phase microextraction coupled with the LC–MS method for ex vivo determination of selected date-rape drugs in the human blood samples

Nowadays, solid phase microextraction is developing rapidly. The use of this extraction technique allowed for the reduction of toxic solvents usage, easy automatization, and integration with other techniques. In this study, the use of DI-SPME/LC–MS to determine selected date-rape drugs (benzodiazepines, ketamine, and cocaine) is presented. The determined values of validation parameters: limits of detection (LOD = 0.6–4.9 ng cm−3), and quantification (LOQ = 25 or 50 ng cm−3), intra-day and inter-day precision (CV = 0.87–10.7% and 4.96–16.1%, respectively), recovery (RE = 94.6–106.7%) and matrix effect (81.7–116.5%) indicated that the tested method could be used to determine the concentration of date-rape drugs in blood samples. The evaluation of the method according to the principles of White Analytical Chemistry showed that the DI-SPME/LC–MS method was characterized by satisfactory analytical quality, greenness, and economical use. The use of this method met the requirements of Green Chemistry. The significant advantages of this method were the quick analytical procedure, partial automation of the extraction stages, high sensitivity, lower sample, and reagent consumption.Graphical abstract

Magnetic covalent-organic frameworks-based extraction followed by UHPLC-MS/MS for determination and pharmacokinetic study of trace angoroside C in rat plasma after oral administration of Xuanbo Shuangsheng Granule.

The composition of the traditional Chinese medicine compound preparation is complex, while the content of each active ingredient is extremely low, which brings difficulties to the plasma concentration detection. In this study, the magnetic covalent-organic frameworks were synthesized by a simple one-step Schiff base reaction and applied for the specific extraction of trace angoroside C in rat plasma prior to ultra-high-performance liquid chromatography-tandem mass spectrometry detection. The synthesized magnetic covalent-organic frameworks have high magnetic responsiveness (35.67 emu·g-1 ), large surface area (110.9 m2 ·g-1 ), and strong stability. The as-prepared material can quickly extract angoroside C from plasma with high extraction efficiency, be easily separated with a magnet afterward, and can be reused for at least five times. The established method was systematically validated showing good linearity (0.1-5ng·ml-1 ), low limit of quantification (0.1ng·ml-1 ), good accuracy (93.18-105.36%), and good precision (percentage relative standard deviation 3.60-10.90%). Finally, the method was used to the pharmacokinetic study of trace angoroside C in rats after oral administration of Xuanbo Shuangsheng Granule.

Enhanced Reproducibility and Precision of High-Throughput Quantification of Bacterial Growth Data Using a Microplate Reader.

This study aimed to develop a repeatable, reliable, high-throughput protocol to monitor bacterial growth in 96-well plates and analyze the maximum growth rate. The growth curves and maximum growth rates of two bacterial species were determined. Issues including (i) lid condensation, (ii) pathlength correction, (iii) inoculation size, (iv) sampling time interval, and (v) spatial bias were investigated. The repeatability of the protocol was assessed with three independent technical replications, with a standard deviation of 0.03 between the runs. The maximum growth rates of Bacillus mycoides and Paenibacillus tundrae were determined to be(mean± SD) 0.99 h-1 ± 0.03 h-1 and 0.85 h-1 ± 0.025 h-1, respectively. These bacteria are more challenging to monitor optically due to their affinity to clump together. This study demonstrates the critical importance of inoculation size, path length correction, lid warming, sampling time intervals, and well-plate spatial bias to obtain reliable, accurate, and reproducible data on microplate readers. The developed protocol and its verification steps can be expanded to other methods using microplate readers and high-throughput protocols, reducing the researchers' innate errors and material costs.

Comparative Assessment of Quantification Methods for Tumor Tissue Phosphoproteomics.

With increasing sensitivity and accuracy in mass spectrometry, the tumor phosphoproteome is getting into reach. However, the selection of quantitation techniques best-suited to the biomedical question and diagnostic requirements remains a trial and error decision as no study has directly compared their performance for tumor tissue phosphoproteomics. We compared label-free quantification (LFQ), spike-in-SILAC (stable isotope labeling by amino acids in cell culture), and tandem mass tag (TMT) isobaric tandem mass tags technology for quantitative phosphosite profiling in tumor tissue. Compared to the classic SILAC method, spike-in-SILAC is not limited to cell culture analysis, making it suitable for quantitative analysis of tumor tissue samples. TMT offered the lowest accuracy and the highest precision and robustness toward different phosphosite abundances and matrices. Spike-in-SILAC offered the best compromise between these features but suffered from a low phosphosite coverage. LFQ offered the lowest precision but the highest number of identifications. Both spike-in-SILAC and LFQ presented susceptibility to matrix effects. Match between run (MBR)-based analysis enhanced the phosphosite coverage across technical replicates in LFQ and spike-in-SILAC but further reduced the precision and robustness of quantification. The choice of quantitative methodology is critical for both study design such as sample size in sample groups and quantified phosphosites and comparison of published cancer phosphoproteomes. Using ovarian cancer tissue as an example, our study builds a resource for the design and analysis of quantitative phosphoproteomic studies in cancer research and diagnostics.

Determination of Polycyclic Aromatic Hydrocarbons (PAHS) in Sewage Sludge and Compost by Dispersive Solid-Phase Microextraction (SPME) and Ultra-High Performance Liquid Chromatography (UHPLC) with Diode Array Detection (DAD)

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic that may degrade human health. Organic solvents are commonly used for the extraction of PAHs from solid samples and the analytes are determined chromatographically. This study describes the ultra-high performance iquid chromatography-diode array detection (UHPLC-DAD) determination of PAHs in sewage sludge and compost used as agricultural fertilizer. The PAHS may be transmitted to humans through the food chain. Analytes in the fertilizer were quantitatively extracted into the organic phase in water-dichloromethane-acetonitrile and determined liquid chromatographically. 16 PAHs were selectively extracted in a single clean-up step. For method development, the type and volume of organic solvent, pH of the water, and ultrasonic extraction time were optimized. For method validation, analytical figures of merit were obtained for the linearity, limit of detection (LOD), limit of quantification (LOQ), stability, intra- and inter-day precision, and accuracy. The developed and validated method was used for PAH determination in the fertilizers. Sample analyses were performed with 89–102% recovery values and 0.7–4.1% relative standard deviations.

Cloud Point Extraction Combined with Electrothermal Atomic Absorption Spectrometry

Nowadays, a considerable number of various separation/preconcentration procedures coupled with electrothermal atomic absorption spectrometry (ETAAS) can be found in the published literature. Among separation techniques, cloud point extraction (CPE) has found its regular use in ultratrace analysis of elements. This review offers a more detailed look to the coupling of CPE and ETAAS, especially to the parameters affecting ETAAS quantification of a selected element. Publications, where this combination of separation technique and quantification method is used, describe an achievement of quantitative extraction recoveries, an acceptable precision and low limits of quantification (LOQs) for different (ultra)trace elements in various complex matrices. These results lead to the conclusion that the developed procedures have a great analytical potential for reliable quantification of (ultra)trace elements, even when complicated matrices containing various components are to be analyzed, which is supported by papers mentioned in this review.

A Specific HPLC Method to Determine Residual HEPES in [68Ga]Ga-Radiopharmaceuticals: Development and Validation.

Background: Nowadays, in Nuclear Medicine, clinically applied radiopharmaceuticals must meet quality release criteria such as high radiochemical purity and radiochemical yield. Many radiopharmaceuticals do not have marketing authorization and have no dedicated monograph within European Pharmacopeia (Ph. Eur.); therefore, general monographs on quality controls (QCs) have to be applied for clinical application. These criteria require standardization and validation in labeling and preparation, including quality controls measurements, according to well defined standard operation procedures. However, QC measurements are often based on detection techniques that are specific to a certain chromatographic system. Several radiosyntheses of [68Ga]Ga-radiopharmaceuticals are more efficient and robust when they are performed with 2-[4-(2-hydroxyethyl)piperazin-1-yl] ethanesulfonic acid (HEPES) buffer, which is considered as an impurity to be assessed in the QC procedure, prior to clinical use. Thus, Ph. Eur. has introduced a thin-layer chromatography (TLC) method to quantify the HEPES amount that is present in [68Ga]Ga-radiopharmaceuticals. However, this is only qualitative and has proven to be unreliable. Here we develop and validate a new high-performance liquid chromatography (UV-Radio-HPLC) method to quantify the residual amount of HEPES in 68Ga-based radiopharmaceuticals. Method: To validate the proposed UV-Radio-HPLC method, a stepwise approach was used, as defined in the guidance document that was adopted by the European Medicines Agency (CMP/ICH/381/95 2014). The assessed parameters are specificity, linearity, precision (repeatability), accuracy, and limit of quantification. A range of concentrations of HEPES (100, 80, 60, 40, 20, 10, 5, 3 μg/mL) were analyzed. Moreover, to test the validity and pertinence of our new HPLC method, we analyzed samples of [68Ga]Ga-DOTATOC; [68Ga]Ga-PSMA; [68Ga]Ga-DOTATATE; [68Ga]Ga-Pentixafor; and [68Ga]Ga-NODAGA-Exendin-4 from different batches that were prepared for clinical use. Results: In the assessed samples, HEPES could not be detected by the TLC method that was described in Ph. Eur. within 4 min incubation in an iodine-saturated chamber. Our developed HPLC method showed excellent linearity between 3 and 100 μg/mL for HEPES, with a correlation coefficient (R2) for calibration curves that was equal to 0.999, coefficients of variation (CV%) < 2%, and percent deviation value of bias from 100% to 5%, in accordance with acceptance criteria. The intra-day and inter-day precision of our method was statistically confirmed and the limit-of-quantification (LOQ) was 3 μg/mL, confirming the high sensitivity of the method. The amount of HEPES that was detected with our developed HPLC method in the tested [68Ga]Ga-radiopharmaceuticals resulted well below the Ph. Eur. limit, especially for [68Ga]Ga-NODAGA-Exendin-4. Conclusions: The TLC method that is described in Ph. Eur. to assess residual HEPES in [68Ga]-based radiopharmaceuticals may not be sufficiently sensitive and thus unsuitable for QC release. Our new HPLC method was sensitive, quantitative, reproducible, and rapid for QCs, allowing us to exactly determine the residual HEPES amount in [68Ga]Ga-radiopharmaceuticals for safe patient administration.

Interval-based optimal trajectory tracking control method for manipulators with clearance considering time-dependent reliability constraints

The soaring operating performance of robotic manipulators renders the significance of advanced controller design. However, the uncertainty in practice would unavoidably lead to the failure of manipulators. Meanwhile, the general statistical analysis to uncertainty may be too complicated or tricky and to virtually realize. In this paper, a non-probabilistic uncertainty quantification approach is proposed to simplify the process of system uncertainties. The corresponding response range is attended by collocation method with advantages upon precision and efficiency. Later, a time-dependent reliability (TDR) evaluation is presented by the first-passage theory. The controller design of manipulator system is built with the widely used PID control with the constraint of TDR to ensure manipulator's normal operation under the trajectory tracking course. The proposed method innovates in simplification and precision of uncertainty quantification and response evaluation, as well as the non-probabilistic time-dependent reliability constraints which well suit for controller design for manipulator systems. Three numerical examples are presented to prove the function and effectiveness of the proposed design approach.

Simultaneous quantification of 70 elements in biofluids within 5 min using inductively coupled plasma mass spectrometry to reveal elementomic phenotypes of healthy Chinese adults

High-throughput quantification of the composition of all chemical elements (elementome) in biological samples is essential for understanding their diverse functions in large cohort studies. We, here, established an ICP-MS method to simultaneously quantify 70 elements in 50 μL biofluids within 5 min. This validated method had excellent quantification linearity (R2 > 0.998), sensitivity (with LOD as low as 1.0 ng/L), precision (CV<15%), accuracy (|RE|<20% except Hg), recovery (80–120%), throughput and coverage with minute samples. The method also showed good applicability to multiple biofluids including human serum, plasma, urine and goat serum samples. By using this method, we furture measured 70 elements in blood plasma samples from 758 Chinese adult participants and established the first reference intervals for the concentration of these elements from 127 healthy adults in this population. This offers a high-throughput quantitative elementomics method to define population elementomic phenotypes and for investigating the diverse biological functions of many elements in multiple biological matrices.

Accelerated dual-venc 4D flow MRI with variable high-venc spatial resolution for neurovascular applications.

PurposeDual‐velocity encoded (dual‐venc or DV) 4D flow MRI achieves wide velocity dynamic range and velocity‐to‐noise ratio (VNR), enabling accurate neurovascular flow characterization. To reduce scan time, we present interleaved dual‐venc 4D Flow with independently prescribed, prospectively undersampled spatial resolution of the high‐venc (HV) acquisition: Variable Spatial Resolution Dual Venc (VSRDV).MethodsA prototype VSRDV sequence was developed based on a Cartesian acquisition with eight‐point phase encoding, combining PEAK‐GRAPPA acceleration with zero‐filling in phase and partition directions for HV. The VSRDV approach was optimized by varying z, the zero‐filling fraction of HV relative to low‐venc, between 0%–80% in vitro (realistic neurovascular model with pulsatile flow) and in vivo (n = 10 volunteers). Antialiasing precision, mean and peak velocity quantification accuracy, and test–retest reproducibility were assessed relative to reference images with equal‐resolution HV and low venc (z = 0%).ResultsIn vitro results for all z demonstrated an antialiasing true positive rate at least 95% for RPEAK−GRAPPA = 2 and 5, with no linear relationship to z (p = 0.62 and 0.13, respectively). Bland–Altman analysis for z = 20%, 40%, 60%, or 80% versus z = 0% in vitro and in vivo demonstrated no bias >1% of venc in mean or peak velocity values at any RZF. In vitro mean and peak velocity, and in vivo peak velocity, had limits of agreement within 15%.ConclusionVSRDV allows up to 34.8% scan time reduction compared to PEAK‐GRAPPA accelerated DV 4D Flow MRI, enabling large spatial coverage and dynamic range while maintaining VNR and velocity measurement accuracy.

Flow Injection Analysis System Coupled to Chronoamperometry and Boron-Doped Diamond Electrode for Determination of Synthetic Hormones 17α-Ethinylestradiol and Cyproterone Acetate

Flow injection analysis with chronoamperometry detection using a cathodically pretreated boron-doped diamond electrode (CPT-BDDE) was employed to develop and optimize a novel method for the determination of the hormones 17-α-ethinylestradiol (EE2) and cyproterone acetate (CPA). The electrochemical properties of EE2 and CPA were evaluated by cyclic voltammetry and oxidation peaks were observed at 0.97 V and 1.60 V in 0.04 mol L−1 Britton-Robinson buffer (pH 2.0). Analytical curves were linear in the concentration range from 0.070 to 10.0 µmol L−1 for EE2 and 1.0 to 80.0 µmol L−1 for CPA with detection limits of 0.023 and 0.23 µmol L−1, respectively. The developed methods presented good precision and accuracy for EE2 and CPA quantification in commercial pharmaceutical samples. The obtained results were satisfactory and consistent compared with a reference high-performance liquid chromatography method at a confidence level of 95%. Furthermore, recovery studies carried out in synthetic urine and lake water show that these methods do not suffer any significant matrix interferences and are potentially applicable for the determination of these hormones in real samples. Thus, the developed procedure for EE2 and CPA determination are simple and fast, with an analytical frequency of ∼83 determinations per hour, and attractive for routine analysis.

Removing Malachite Green and Leucomalachite Green From Freshwater and Seawater With Four Water Treatment Agents

Malachite green (MG) residue in aquatic environments can adversely affect food chains. To solve this problem, many adsorbents have been developed to remove MG from aqueous solutions. These adsorbents exhibit benefits in different aspects such as low cost, nontoxicity, and environment friendliness. Zeolite, oyster shell powder (OSP), humic acid (HA), and Chloride dioxide (ClO2) are widely used agents for water purification, indicating their potential to remove MG from both freshwater and seawater. Liquid chromatography tandem mass spectrometry was performed as a valid analytical method for measuring MG and its metabolite leucomalachite green (LMG). The analysis examined linearity, specificity, accuracy, precision, and limit of quantification. We found that three agents—zeolite, OSP, and HA—have high affinity for MG and LMG in both freshwater and seawater because of their physicochemical properties; ClO2 exhibited even greater efficiency for MG and LMG degradation due to its oxidation capacity. The MG removal efficiency of zeolite, OSP and HA in freshwater was 100%, 87.52%, and 100%, respectively. In the MG-containing seawater, the removal efficiency of zeolite, OSP and HA was 95.24%, 6.57%, and 89.36%, respectively. The LMG removal efficiency of zeolite, OSP and HA in freshwater was 100%, 53.56%, and 100%, while in seawater, the LMG removal efficiency of zeolite, OSP and HA was 100%, 62.70%, and 84.65%, respectively. ClO2 treatments in both freshwater and seawater expressed 100% removal efficiency. The adsorption capacity of three water agents in MG-containing freshwater decreased in the order: zeolite = HA &amp;gt; OSP; in MG-containing seawater: zeolite &amp;gt; HA &amp;gt; OSP. Whereas the adsorption capacity of three water agents in LMG-containing freshwater decreased in the order: zeolite = HA &amp;gt; OSP; in LMG-containing seawater: zeolite &amp;gt; HA &amp;gt; OSP. In this study, four water treatment agents are reported to remove MG and LMG from freshwater and seawater, indicating their potential for reducing the amount of hazardous MG and LMG residue in aquatic environments.