Detection Limit Of Method Research Articles

Combination of fabric phase sorptive extraction with UHPLC-ESI-MS/MS for the determination of adamantine analogues in human urine

Herein, fabric phase sorptive extraction – a member of sorbent-based microextraction family – is utilized for the rapid isolation of selected antiviral drugs namely amantadine, memantine and rimantadine from human urine prior to their analysis with UHPLC-MS/MS. Fabric phase sorptive extraction membrane coated with sol–gel sorbent coated poly(propylene glycol)-poly(ethylene glycol)-poly(propylene glycol) sorbent was identified as the optimum extraction membrane for the target analytes. Due to the engineered affinity of the fabric phase sorptive extraction towards the analytes, the extraction proceeds in relatively short time (20 min) while its high permeability permits the extraction of biological samples without any other pretreatment. Following selection of the appropriate membrane, significant parameters including extraction time, sample volume, membrane size, elution solvent, etc were optimized. The drugs were analyzed under positive electrospray ionization using multi-reaction monitoring mode. The method was linear in the range of 5 – 100 ng mL−1 by constructing weighted matrix-matched calibration curves. The intra-day and inter-day accuracy were ranged between – 18.7 to + 18.1% and – 18.3 to + 16.1%, respectively. The precision of the method (intra-day, inter-day) were less than 18.5 % in all cases. The method limits of detection were in the range of 0.2 – 0.8 ng mL−1 while the lower limit of quantitation was set at 5 ng mL−1 for all analytes. The developed analytical scheme was efficiently applied to the analysis of the target drugs in human urine and could be adopted as a rapid and robust green analytical tool for clinical applications.

Total organic fluorine (TOF) analysis by completely converting TOF into fluoride with vacuum ultraviolet

Quantifying total organic fluorine (TOF) in water is vital in monitoring the occurrence and persistence of all fluorine-containing organic compounds in the environment, while currently most studies focus on analyzing individual fluorine-containing organic compounds. To fill the technology gap, we herein proposed to convert TOF completely into fluoride with vacuum ultraviolet (VUV) photolysis, followed by analysis of fluoride with ion chromatography. Results showed that the tailored VUV photoreactor achieved satisfying recoveries of fluorine from ten model TOF compounds not only in ultrapure water (83.9 ± 2.0% to 109.4 ± 0.8%) but also in real water samples (92.1 ± 1.0%–106.2 ± 15.7%). Unlike other ultraviolet-based processes that favor alkaline conditions, this VUV process preferred either neutral or acidic conditions to defluorinate selected compounds. While the mechanisms remain to be explored in the future, it has been evidenced that the photo-degradation and photo-defluorination rates of these TOF compounds varied significantly among compounds and operation conditions. The method obtained a method detection limit (MDL) of 0.15 μg-F/L, which is lower than the MDLs of many other TOF analytical methods, along with excellent calibration curves for concentrations ranging from 0.01 to 10.0 mg-F/L. Notably, minimizing fluoride in sample prior to photoconversion was necessary to avoid subtraction-induced errors for TOF measurement, especially when the fluoride/TOF ratio was high. The robust VUV is also green for sample pretreatment due to its unreliance of chemicals or additives.

Identifying Cereals through Elemental Analysis with Microwave Plasma Optical Emission Spectroscopy: Experiment for Analytical Chemistry Lab

Elemental analysis is performed in a variety of ways in food and environmental sciences; thus, we have designed an activity in which students gain experience with research-level lab techniques in a real-world context through the quantification of key elements in breakfast cereals using microwave plasma optical emission spectroscopy (MP-OES). The experiment described here is a skill building assignment to scaffold into more advanced projects with research-level instrumentation and in analytical chemistry courses. Students compare their results to the nutrition facts published by the distributors in order to identify their cereals, emphasizing precision and accuracy in instrumental analysis and good standard operating procedures (SOPs). Although cereals were chosen on the basis of the relevance of fortified minerals in this study, variations of this method may be used for the analysis of different food products. The student learning objectives of this experiment include developing SOPs for emission spectroscopy, creating and using standard curves to determine detection limits and elemental concentrations, presenting results using the proper format along with using statistical techniques such as standard deviation and method detection limit, and writing a report following the form of a technical journal article. MP-OES is a relatively new, sensitive, and inexpensive technique for elemental analysis, making it a practical choice for an undergraduate laboratory.

New Residue Analysis Method for Four Task-Specific Ionic Liquids in Water, Soil and Plants.

With the extensive application of task-specific ionic liquids (TSILs), their environmental impact has attracted increasing attention. However, no studies involving residue analyses of TSILs have been reported in the literature thus far. In the present study, residues of four TSILs ([C2NH2MIm]BF4, [HOEMIm]BF4, [HOEMIm]NO3, [MOEMIm]BF4) were analyzed by high-performance liquid chromatography-tandem mass spectrometry. The limit of detection of instrument was approximately 10-15g. Residual TSILs were extracted from soil and plant samples by the accelerated solvent extraction method. In water, soil and plants, the coefficient of variation was 0.38%-4.43%, and the method detection limits of the four TSILs were lower than 1.40ngg-1. These results meet the standards of residue analysis. The present study can provide an analysis method for studying TSIL residues and toxicity in the environment.

Paper-based detection of Epstein-Barr virus using asymmetric polymerase chain reaction and gold silicon particles

A new paper-based lateral flow nucleic acid (LFNA) test platform was established in this study using asymmetric polymerase chain ceaction (A-PCR) for signal amplification. This new method allowed a visual detection of Epstein-Barr virus (EBV) nucleic acids with high specificity and low cost. In addition, as part of our strategy we employed a sandwich system of capture probe (CP)/gold nanoparticles (AuNPS) and silicon dioxide (SiO2) (AuNPS@SiO2) nanospheres/target DNA/avidin complexes as the sensing platform. Biotin-labeled target DNA was obtained by A-PCR and later introduced in the LF device. The CP/target DNA/AuNPS@SiO2 complexes were captured on the test zone by the specific reaction between biotin and avidin, and the remaining CP/AuNPS@SiO2 particles were captured on the quality control zone by the hybridization between CP and a quality control probe. Au@SiO2 accumulation in the test and quality control zones of the device enabled a visual detection of the specific target sequences. The method detection limit was 50 nM of the target DNA, which was lower than that of the LFNA biosensor (LFNAB) without PCR amplification and Au@SiO2 particles. In conclusion, the novel paper-based platform described here is a low cost, efficient and fast visual detection method that offers high sensitivity and other benefits compared to alternative methods in use.

Green fabrication of Moringa oleifera seed as efficient biosorbent for selective enrichment of triazole fungicides in environmental water, honey and fruit juice samples

Reutilization of plant wastes is an eco-friendly way to simultaneously to treat toxic contaminated matrices. A micro-solid-phase extraction using a low-cost biosorbent was developed for enrichment and preconcentration of triazole fungicides prior to high performance liquid chromatographic analysis. Moringa oleifera seed were chosen as a biosorbent material. Vortex agitator was used to increase the contact between analytes and biosorbent, and improve the mass transfer rate and, therefore the extraction efficiency increased. Characterisation of the biosorbent material was performed using scanning electron microscopy and fourier transformed infrared spectroscopy. The parameters affecting the extraction efficiency were investigated in detail. The optimum extraction conditions allowed the use of 0.1 mg Moringa oleifera seed powder, 30 μL of 1 mol L-1 formic acid, 200 μL of acetonitrile as desorption solvent and extraction time 12 min. Employing the best conditions, this method provided wide linear range between 10 and 500 µg L-1 (coefficient of determination greater than 0.99), low method detection limit (30–50 µg L-1) and good precisions with relative standard deviations greater than 5.0%. The developed method was used to analyze triazole fungicides in environmental water, honey and fruit juice samples. Acceptable relative recovery ranging from 70.00 to 112.00%, were gained. This study provides a simple, environmental friendly and low cost method to utilize Moringa oleifera seeds.

"Switch-Off-On" Detection of Fe3+ and F- Ions Based on Fluorescence Silicon Nanoparticles and Their Application to Food Samples.

An approach to the detection of F− ions in food samples was developed based on a “switch-off-on” fluorescence probe of silicon nanoparticles (SiNPs). The fluorescence of the synthetic SiNPs was gradually quenched in the presence of Fe3+ ion and slightly recovered with the addition of F− ion owing to the formation of a stable and colorless ferric fluoride. The fluorescence recovery exhibited a good linear relationship (R2 = 0.9992) as the concentration of F− ion increased from 0 to 100 μmol·L−1. The detection limit of the established method of F− ion was 0.05 μmol·L−1. The recovery experiments confirmed the accuracy and reliability of the proposed method. The ultraviolet–visible spectra, fluorescence decays, and zeta potentials evidenced the fluorescence quenching mechanism involving the electron transfer between the SiNPs and Fe3+ ion, while the fluorescence recovery resulted from the formation of ferric fluoride. Finally, SiNPs were successfully applied to detect F− ions in tap water, Antarctic krill, and Antarctic krill powder.

Zirconium-Based Metal-Organic Framework Mixed-Matrix Membranes as Analytical Devices for the Trace Analysis of Complex Cosmetic Samples in the Assessment of Their Personal Care Product Content.

A device comprising a zirconium-based metal–organic framework (MOF) mixed-matrix membrane (MMM) framed in a plastic holder has been used to monitor the content of personal care products (PCPs) in cosmetic samples. Seven different devices containing the porous frameworks UiO-66, UiO-66-COOH, UiO-67, DUT-52, DUT-67, MOF-801, and MOF-808 in polyvinylidene fluoride (PVDF) membranes were studied. Optimized membranes reach high adsorption capacities of PCPs, up to 12.5 mg·g–1 benzophenone in a 3.0 mg·L–1 sample. The MMM adsorption kinetics, uptake measurements, and isotherm studies were carried out with aqueous standard solutions of PCPs to ensure complete characterization of the performance. The studies demonstrate the high applicability and selectivity of the composites prepared, highlighting the performance of PVDF/DUT-52 MMM that poses uptakes up to 78% for those PCPs with higher affinity while observing detection limits for the entire method down to 0.03 μg·L–1. The PVDF/DUT-52 device allowed the detection of parabens and benzophenones in the samples, with PCPs found at concentrations of 1.9–24 mg·L–1.

Detection of Benzo[a]pyrene Diol Epoxide Adducts to Histidine and Lysine in Serum Albumin In Vivo by High-Resolution-Tandem Mass Spectrometry.

Electrophilic diol epoxide metabolites are involved in the carcinogenicity of benzo[a]pyrene, one of the widely studied polycyclic aromatic hydrocarbons (PAHs). The exposure of humans to this PAH can be assessed by measuring stable blood protein adducts, such as to histidine and lysine in serum albumin, from their reactive metabolites. In this respect, measurement of the adducts originating from the genotoxic (+)-anti-benzo[a]pyrene diol epoxide is of interest. However, these are difficult to measure at such low levels as are expected in humans generally exposed to benzo[a]pyrene from air pollution and the diet. The analytical methods detecting PAH-biomarkers still suffer from low selectivity and/or detectability to enable generation of data for calculation of in vivo doses of specific stereoisomers, for evaluation of risk factors and assessing risk from exposures to PAH. Here, we suggest an analytical methodology based on high-pressure liquid chromatography (HPLC) coupled to high-resolution tandem mass spectrometry (MS) to lower the detection limits as well as to increase the selectivity with improvements in both chromatographic separation and mass determination. Method development was performed using serum albumin alkylated in vitro by benzo[a]pyrene diol epoxide isomers. The (+)-anti-benzo[a]pyrene diol epoxide adducts could be chromatographically resolved by using an HPLC column with a pentafluorophenyl stationary phase. Interferences were further diminished by the high mass accuracy and resolving power of Orbitrap MS. The achieved method detection limit for the (+)-anti-benzo[a]pyrene diol epoxide adduct to histidine was approximately 4 amol/mg serum albumin. This adduct as well as the adducts to histidine from (−)-anti- and (+/−)-syn-benzo[a]pyrene diol epoxide were quantified in the samples from benzo[a]pyrene-exposed mice. Corresponding adducts to lysine were also quantified. In human serum albumin, the anti-benzo[a]pyrene diol epoxide adducts to histidine were detected in only two out of twelve samples and at a level of approximately 0.1 fmol/mg.

Comprehensive Evaluation of Blood Plasma and Serum Sample Preparations for HRMS-Based Chemical Exposomics: Overlaps and Specificities.

Sample preparation of biological samples can have a substantial impact on the coverage of small molecules detectable using liquid chromatography-high-resolution mass spectrometry (LC-HRMS). This initial step is particularly critical for the detection of externally derived chemicals and their metabolites (internal chemical exposome) generally present at trace levels. Hence, our objective was to investigate how blood sample preparation methods affect the detection of low-abundant chemicals and to propose alternative methods to improve the coverage of the internal chemical exposome. We performed a comprehensive evaluation of 12 sample preparation methods (SPM) using phospholipid and protein removal plates (PLR), solid phase extraction plates (SPE), supported liquid extraction cartridge (SLE), and conventionally used protein precipitation (PPT). We implemented new quantitative and qualitative criteria for nontargeted analyses (detection frequency, recoveries, repeatability, matrix effect, low-level spiking significance, method detection limits, throughput, and ease of use) to amply characterize these SPM in a step-by-step-type approach. As a final step, PPT and one PLR plate were applied to cohort plasma and serum samples injected in triplicate to monitor batch repeatability, and annotation was performed on the related data sets to compare the respective impacts of these SPM. We demonstrate that sample preparation significantly affects both the range of observable compounds and the level at which they can be observed (only 43%-54% of total features are overlapping between the two SPM). We propose to use PPT and PLR on the same samples by implementing a simple analytical workflow as their complementarity would allow the broadening of the visible chemical space.

Propacetamol in dogs: First description of its pharmacokinetics after intravenous and oral administration

Propacetamol is a prodrug form of paracetamol (APAP) licensed for human use as a pain reliever in postoperative care. It is prescribed if APAP cannot be administered orally or rectally to a patient and for patients in whom nonsteroidal anti-inflammatory drugs are contraindicated. In this study, we aimed to quantify the pharmacokinetics of APAP and its metabolites, paracetamol sulfate (PS), paracetamol glucuronide (PG), and N-acetyl-p-benzoquinone imine (NAPQI), after a single oral and intravenous (IV) administration of 30 mg/kg of propacetamol to six healthy adult Labrador dogs according to a 2 × 2 crossover study. The analyses were performed using a validated HPLC-MS/MS method.PS and PG exposures were higher than that of APAP, while NAPQI concentrations were constantly below the detection limit of the analytical method. IV propacetamol administration produced 30% more APAP than oral administration. However, propacetamol released a significantly lower amount of active moiety in dogs than in humans. The propacetamol dose administered in this study did not produce plasma APAP concentrations above the threshold sufficient to provide analgesia in adult humans (4 μg/mL). In conclusion, direct IV injection of APAP instead of propacetamol might be a better clinical option for pain relief in dogs.

Extraction and Pyrolysis-GC-MS analysis of polyethylene in samples with medium to high lipid content

While it is recognised that humans are constantly exposed to plastics, there are limitations in understanding the extent of this exposure, particularly dietary exposure. This lack of information is partly due to challenges with the analysis of complicated matrices. This study aimed to assess the impact of medium to high lipid content (> 3%) food samples on the accurate quantification of polyethylene (PE), using pyrolysis-gas chromatography mass spectrometry, and develop an alternative sample processing strategy. Analysis of saturated, monounsaturated and polyunsaturated fats was demonstrated to form the same pyrolysis products as PE, producing a significant interference hindering quantification. An extraction protocol was developed that involves enzyme digestion to break the lipids into smaller chain fatty acids, removal of these interferences with pressurised liquid extraction washes, before a final extraction of the PE by pressurised liquid extraction. This new method was validated through the analysis of three medium- to high-fat content foods: cow’s milk, eggs and lamb meat, where PE recoveries were acceptable (104% to 127%). Method detection limits were also significantly reduced from 1.9 to 0.05 µg/injection (380 to 10 µg/g) with the new protocol, through the removal of matrix background. PE traces were observed in the three food matrices of 72-240 µg/g, significantly reduced as compared to samples extracted with the old method where concentrations of 12-32 mg/g were calculated, demonstrating the potential for overestimation of dietary exposure. Finally, a simple protocol is reported for future studies to (i) determine if an interference is present and (ii) sample processing methods to remove identified interferences.

Organophosphate ester metabolites in human breast milk determined by online solid phase extraction coupled to high pressure liquid chromatography tandem mass spectrometry.

The analysis of metabolites of organophosphate esters (OPEs) in human breast milk is essential to evaluate OPE and OPE metabolite exposure of newborns. In the current study, an analytical method which only needs a small amount of breast milk (100μl) was developed and validated for six diester metabolites and three hydroxylated metabolites applying salt-induced liquid-liquid extraction (SI-LLE) and dispersive solid phase extraction (d-SPE) for sample preparation and online solid phase extraction coupled to high pressure chromatography tandem mass spectrometry (online-SPE-HPLC-MS/MS) for quantitative measurement. The final method consisted of an extraction with formic acid (FA)/acetonitrile (1:200, v/v) and a cleanup with C18 d-SPE. The final extracts were trapped on a C18 cartridge with application of a wash step of 2ml 0.1% FA milli-Q/methanol (98:2, v/v). Method detection limits (MDLs) ranging from 21.7ng/l for BBOEHEP to 500ng/l for BCIPP and average recoveries ranging from 58% for 5-OH-EHDPHP to 120% for BCIPP were achieved. Thirty-three breast milk samples from the LINC (Linking EDCs in maternal Nutrition to Child health) cohort collected in three distinct areas in The Netherlands were analyzed using the validated method. BCEP, BCIPP, BCIPHPP, BDCIPP, and 5-OH-EHDPHP were not detected in any of the samples, while BBOEP was the most frequently detected metabolite with a concentration range of <MDL to l.47ng/ml, followed by DPhP and BBOEHEP, detected in ranges of <MDL to 0.09 and <MDL to 0.027ng/ml. The results indicated that OPEs entering the human body are only to a limited extent excreted via breast milk.

Assessment of biogenic amine production by lactic acid bacteria isolated from Serbian traditionally fermented foods

The aim of this study was to monitor the production of biogenic amines by 156 selected lactic acid bacteria (LAB) strains isolated from Serbian traditionally fermented sausages and cheeses. The method for the determination of biogenic amines is liquid chromatography tandem mass spectrometry (LC-MS/MS). The measured concentrations of putrescine, cadaverine, tryptamine and spermidine (except in 13 LAB strains) were below the detection limit of the analytical method (0.1 mg/L), whereas those of histamine, tyramine and spermine were above the limit of detection, but still not significant. Tyramine was the only amine that had a measured concentration of 59.89 ± 0.06 mg L-1. Most of the tested LAB strains produced tyramine in broth below 26 mg L-1 with the exception of Enterococcus faecalis strains (59.89 ± 6.66 mg L-1) and Enterococcus faecium strains (47.33 ± 8.58 mg L-1). The low concentrations of biogenic amines are considered non-significant from both a technological and safety point of view.

Fluorescent probe visualization for selective detection of cuprous ion.

Cuprous ion is an essential element for human life activities. However, excessive cuprous can cause dysfunction of the human body system. To help explain this evolving biology, we report a fluorescent probe for detecting unstable Cu(I). Cu(I) undergoes a metal complexation reaction with the sulfur element in the probe, resulting in a photoelectron transfer (PET) effect. The probe fluorescence is greatly suppressed, and rapid and selective visual detection of Cu(I) in the inorganic environment is realized. There is also a good linear relationship between the probe fluorescence intensity and the Cu(I) concentration (R2 = 0.992), which can realize the quantitative detection of Cu(I). When the probe concentration is 0.1μM, the detection limit is 15nM, and the detection limit of the visual method is as low as 0.1μM. This work provides a valuable starting point for real-time monitoring of the Cu(I) concentration in a human anaerobic environment based on active probes.

Simple and Rapid Detection of ESBL blaSHV gene from an Urban River in Tokyo by Loop-Mediated Isothermal Amplification.

Extended-spectrum β-lactamases (ESBLs) are produced mainly by gram-negative bacteria in Enterobacteriaceae. One of the major types of ESBLs is sulfhydryl variable (SHV) -type ESBL. Herein, we attempted to develop a simple and rapid method for the detection of the ESBL blaSHV gene by loop-mediated isothermal amplification (LAMP) . The five-primer set designed could amplify blaSHV gene at an isothermal temperature of 65℃. The detection limit of the LAMP method with the LF loop primer was 1 copy/tube, which was 10,000-fold more sensitive than that of the conventional PCR. The LAMP assay could also detect the direct amplification of blaSHV gene from a single river water sample in Tokyo. The LAMP method has great potential for applications in hospital, soil and water environment, food, and livestock.

Determination Method for Pyrroloquinoline Quinone in Food Products by HPLC-UV Detection Using a Redox-Based Colorimetric Reaction.

We have developed an HPLC-UV method for the determination of pyrroloquinoline quinone (PQQ), which utilizes a redox-based colorimetric reaction. In the proposed colorimetric reaction, the redox reaction between PQQ and dithiothreitol generates superoxide anion radicals that can convert 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride (INT) to formazan dye. After PQQ separation on an octadecyl silica column, it was mixed online with dithiothreitol and INT, and the formed formazan dye was monitored by absorbance at 490 nm. The detection limit (S/N = 3) of the proposed method was 7.6 nM (152 fmol/injection). The proposed method could selectively detect PQQ in food products without any clean-up procedures.

Development of an in–syringe gas–assisted density tunable solidification of floating organic droplet–based dispersive liquid phase microextraction method coupled with HPLC–MS/MS for monitoring amikacin in biological fluids

A new sample preparation method named in–syringe gas–assisted density tunable dispersive liquid phase microextraction based on solidification of floating organic droplet has been introduced. This method was coupled with high–performance liquid chromatography–tandem mass spectrometry and used for the extraction and quantification of amikacin in plasma and exhaled breath condensate (EBC) samples of the patients receiving amikacin. In the proposed approach, an inert gas is bubbled into a syringe barrel containing aqueous solution of the analyte and a mixture of low density extraction solvent and volatile density modifier. Consequently, the density modifier is evaporated and the analyte is migrated into the released extractant droplets. Basic parameters affecting efficiency of the developed method were optimized. Under optimum conditions, the method limits of detection were 0.06 and 0.29 ng/mL in EBC and plasma, respectively. The extraction recoveries were 90% and 87% in EBC and plasma, respectively. Also, the obtained relative standard deviations were below 9.5% and 9.8% for EBC and plasma, respectively. Considering these results, the developed method provides a quick and efficient way to determine amikacin in patients’ biological fluids and can be used widely in drug monitoring and clinical studies.

First Report of Crown Gall of Kiwifruit (Actinidia deliciosa) Caused by Agrobacterium fabacearum in China and the Establishment of Loop-Mediated Isothermal Amplification Technique.

Kiwifruit is moderately sweet and sour and quite popular among consumers; it has been widely planted in some areas of the world. In 2019, the crown gall disease of kiwifruit was discovered in the main kiwifruit-producing area of Guizhou Province, China. This disease can weaken and eventually cause the death of the tree. The phylogeny, morphological and biological characteristics of the bacteria were described, and were related to diseases. The pathogenicity of this species follows the Koch hypothesis, confirming that A. fabacearum is the pathogen of crown gall disease of kiwifruit in China. In this study, Loop-mediated isothermal amplification (LAMP) analysis for genome-specific gene sequences was developed for the specific detection of A. fabacearum. The detection limit of the LAMP method is 5 × 10−7 ng/μL, which has high sensitivity. At the same time, the amplified product is stained with SYBR Green I after the reaction is completed, so that the amplification can be detected with the naked eye. LAMP analysis detected the presence of A. fabacearum in the roots and soil samples of the infected kiwifruit plant. The proposed LAMP detection technology in this study offers the advantages of ease of operation, visibility of results, rapidity, accuracy and high sensitivity, making it suitable for the early diagnosis of crown gall disease of kiwifruit.

Green detection of trace cyanuric acid and free chlorine together via ion chromatography

Chlorinated cyanurates (CCAs) are a type of disinfectants currently used worldwide for fight of Coronavirus. However, CCAs upon dosed into water can release not only free chlorine (FC), a strong disinfectant, but also cyanurate (CYA), a persistent compound potentially harmful to human and environment. Therefore, detecting CYA and FC in water are very important not only for ensuring sufficient disinfection but also for monitoring the impacts of FC and CYA on receiving watershed. However, conventional analytical methods for them are mostly based on colorimetric methods, which have high method detection limits (MDLs) and rely on chemical reactions that are likely sensitive to coexisting chemicals. To overcome these issues, we herein proposed a facile and reaction-free method to detect CYA and FC together in just one run by ion chromatography (IC) equipped with both conductivity and ultraviolet absorbance detectors. The method features obvious advantages over colorimetric methods in being lower MDLs (3.6 μg/L for CYA and 9.0 μg/L for FC), environmental-friendly (i.e., no organic solvent involved), and more resistant to alkaline solution. With this method, trace levels of CYA (i.e., 34–44 μg/L), which were nondetectable by conventional method, were found in two river water samples, implying that the local environment was already polluted by CCAs during the pandemic period. Overall, this study demonstrates a robust tool that may assist better understanding and monitoring the fate and transport of trace CCA derivatives in water.