Multiple Reaction Monitoring Mode Research Articles

A fully validated LC‑MS/MS method for quantifyingbevacizumab in plasma samples from patients with NSCLC and its implications in therapeutic drug monitoring.

Given the increasing use of bevacizumab in combinatorial drug therapy for a multitude of different cancer types, there is a need for therapeutic drug monitoring to analyze the possible correlation between drug trough concentration, and therapeutic effect and adverse reactions. An ultra-performance liquid chromatography tandem-mass spectrometry method was then developed and validated to determine bevacizumab levels in human plasma samples. Chromatographic separation was achieved on a Shimadzu InertSustainBio C18 HP column, whereas subsequent mass spectrometric analysis was performed using a Shimadzu 8050CL triple quadrupole mass spectrometer equipped with an electro-spray ionization source in the positive ion mode. In total, three multiple reaction monitoring transitions of each of the surrogate peptides were chosen with 'FTFSLDTSK' applied as the quantification peptide whereas 'VLIYFTSSLHSGVPSR' and 'STAYLQMNSLR' were designated as the verification peptides using the Skyline software. This analytical method was then fully validated, with specificity, linearity, lower limit of quantitation, accuracy, precision, stability, matrix effect and recovery calculated. The linearity of this method was developed to be within the concentration range 5-400 µg/ml for bevacizumab in human plasma. Subsequently, eight patients with non-small cell lung cancer (NSCLC) were recruited and injected with bevacizumab over three periods of treatment to analyze their steady-state trough concentration and differences. To conclude, the results of the present study suggest that bevacizumab can be monitored in a therapeutic setting in patients with NSCLC.

HPLC-MS/MS method development and validation for the determination of tetradecapeptide in human plasma

Introduction. The number of peptide drugs being developed and registered has increased in recent years. Therefore, modern analytical approaches and methods are required to determine these substances in biological matrices during pharmacokinetic studies. Peptides are structurally intermediate between small molecules and biopolymers, making it difficult to develop methods for determining them using High Performance Liquid Chromatography with Tandem Mass Spectrometry (HPLC-MS/MS). Peptide derivatization can help achieve optimal chromatographic separation and increase method sensitivity.Aim. To develop and validate a method for the determination of the tetradecapeptide (TDP) threonyl-glutamyl-lysyl-lysyl-arginyl-arginyl-glutamayl-threonyl-valyl-glutamyl-arginyl-glutamyl-lysyl-glutamate in human plasma by HPLC-MS/MS.Materials and methods. The determination of TDP in human plasma was performed by HPLC-MS/MS. Sample preparation included a combination of blood plasma protein precipitation with propionic acid solution in methanol, liquid-liquid extraction with chloroform, and peptide derivatization with propionic anhydride. Internal standard (IS) was threonyl-glutamyl-lysyl-lysyl-arginyl-arginyl-glutamayl-threonyl-leucyl-glutamyl-arginyl-glutamyl-lysyl-glutamate. Chromatographic separation was performed in gradient mode, eluent A was 0.1 % formic acid solution in water, eluent B was 0.1 % formic acid in acetonitrile. Column: Waters XBridge C18, 4.6 × 50 mm, 5 µm. Ionization source was electrospray in positive mode. Multiple reaction monitoring (MRM) transitions for 4-substituted TDP propionate were: 681.30 → 73.95 m/z, 681.30 → 84.00 m/z, 681.30 → 101.90 m/z, 681.30 → 140.10 m/z, and for 4-substituted IS propionate: 686.00 → 74.10 m/z, 686.00 → 84.05 m/z, 686.00 → 102.00 m/z, 686.00 → 140.00 m/z.Results and discussion. Validation of the developed method was carried out in accordance with the requirements of Eurasian Economic Union and the following parameters were determined: selectivity, matrix effect, calibration curve, accuracy and precision, recovery, lower limit of quantification, sample carryover, stability.Conclusion. The method for the determination of TDP in human blood plasma by HPLC-MS/MS was developed and validated. The analytical range was 5.00–1000.00 ng/mL, allowing the method to be used to study TDP pharmacokinetics.

A rapid and sensitive LC-MS/MS method for quantifying oxycodone, noroxycodone, oxymorphone and noroxymorphone in human plasma to support pharmacokinetic drug interaction studies of oxycodone.

A sensitive and reliable LC-MS/MS method was developed and validated for the quantification of oxycodone and metabolites in human plasma. The method has a runtime of 6min and a sensitivity of 0.1μg/L for all analytes. Sample preparation consisted of protein precipitation. Separation was performed on a Kinetix biphenyl column (2.1 × 100 mm, 1.7μm), using ammonium formate 5mm in 0.1% aqueous formic acid and methanol LC-MS grade 100% in gradient elution at a flow rate of 0.4ml/min. Detection was performed in multiple reaction monitoring mode using positive electrospray ionization. The method was linear over the calibration range of 0.1-25.0μg/L for oxycodone, noroxycodone and noroxymorphone and 0.1-5.0μg/L for oxymorphone. The method demonstrated good performance in terms of intra- and interday accuracy (86.5-110.3%) and precision (CV 1.7-9.3%). The criteria for the matrix effect were met (CV < 15%) except for noroxymorphone, for which an additional method was applied to compensate for the matrix effect. Whole blood samples were stable for 4h at room temperature. Plasma samples were stable for 24 h at room temperature and 3months at -20°C. Furthermore, the method was successfully applied in a pharmacokinetic drug interaction study of oxycodone and enzalutamide in patients with prostate cancer.

Therapeutic Drug Monitoring of 6 New-Generation Antiseizure Medications Using a Mass Spectrometry Method: Analysis of 2-Year Experience in a Large Cohort of Korean Epilepsy Patients.

New-generation antiseizure medications (ASMs) are increasingly prescribed, and therapeutic drug monitoring (TDM) has been proposed to improve clinical outcome. However, clinical TDM data on new-generation ASMs are scarce. To develop and validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for therapeutic drug monitoring (TDM) of 6 new-generation ASMs in serum and analyze the clinical TDM data from a large cohort of Korean patients with epilepsy. Stable isotope-labeled internal standards were added to protein precipitations of serum. One microliter of sample was separated on Agilent Poroshell EC-C18 column, and lacosamide, perampanel, gabapentin, pregabalin, vigabatrin, and rufinamide were simultaneously quantified by Agilent 6460 triple-quad mass spectrometer in multiple-reaction monitoring mode. Linearity, sensitivity, precision, accuracy, specificity, carryover, extraction recovery, and matrix effect were evaluated. TDM data of 458 samples from 363 Korean epilepsy patients were analyzed. The method was linear with limit of detection less than 0.05 μg/mL in all analytes. Intraassay and interassay imprecisions were less than 5% coefficient of variation. Accuracy was within ±15% bias. Extraction recovery ranged from 85.9% to 98.8%. A total of 88% (403 of 458) were on polypharmacy, with 29% (118 of 403) using concomitant enzyme inducers. Only 38% (175 of 458) of the concentrations were therapeutic, with 53% (244 of 458) being subtherapeutic. Drug concentration and concentration-to-dose ratio were highly variable among individuals in all 6 ASMs. A simple and rapid LC-MS/MS method for TDM of 6 ASMs was developed and successfully applied to clinical practice. This large-scale TDM data could help establish an effective monitoring strategy for these drugs.

Simultaneous Screening of 172 Veterinary Drugs by Modified QuEChERS-LC-MS/MS in TCM Galli Gigerii Endothelium Corneum.

An analytical method was developed for the screening of 172 veterinary drugs in traditional Chinese medicine Galli Gigerii Endothelium Corneum by high-performance liquid chromatography tandem mass spectrometry. The samples were pretreated by a modified QuEChERS method. A Zorbax Eclipse plus C18 column (1.8μm, 3.0 × 150mm2, Agilent) was used for the separation of analytes by gradient elution. All analytes were detected by electrospray ionization mass spectrometry with multiple reaction monitoring mode. Good linearity with R ≥ 0.99 was exhibited for all analytes within the respective range. The recoveries of all monitored analytes ranged from 55.4 to 127.6% at three spiked levels (limit of quantitation-LOQ, 2-fold LOQ, 10-fold LOQ), with relative standard deviations <17.8%. The estimated LOQ levels were 0.2-20μg/kg. The application of this method provides a reference for the safety control of traditional Chinese medicines.

LC-MS/MS method for quick detection of vonoprazan fumarate in human plasma: Development, validation and its application to a bioequivalence study.

A liquid chromatography-tandem mass spectrometry method with vonoprazan fumarate-d4 as a stable isotope-labeled internal standard was developed and validated aiming at quantification of vonoprazan fumarate in human plasma for a bioequivalence study. Chromatographic separation was achieved by acetonitrile one-step protein precipitation using a gradient elution of 0.1% formic acid aqueous solution and acetonitrile with a run time of 3.65 min. Detection was carried out on a tandem mass spectrometer in multiple reaction monitoring mode via a positive electrospray ionization interface. The multiple reaction monitoring mode of precursor-product ion transitions for vonoprazan fumarate and vonoprazan fumarate-d4 were m/z 346.0 → 315.1 and 350.0 → 316.0, respectively. The linear range was 0.150-60.000 ng/ml. This method was fully validated with acceptable results in terms of selectivity, carryover, lower limit of quantification, calibration curve, accuracy, precision, dilution effect, matrix effect, stability, recovery and incurred sample reanalysis. A successful application of this method was realized in the bioequivalence study of vonoprazan fumarate tablet (20 mg) among healthy Chinese volunteers.

Application of cobalt-cerium-iron ternary layered double hydroxide for extraction of perfluorooctane sulfonate followed by HPLC-MS/MS analysis

Herein, Ce-doped CoFe layered double hydroxide (LDH), noted as CoCeFe ternary LDH, was prepared using the co-precipitation route. Prosperous synthesis of CoFe LDH and prosperous partial replacement of iron cations with cerium cations in CoCeFe ternary LDH were confirmed by X-ray diffraction patterns, energy-dispersive X-ray spectroscopy, and elemental dot-mapping images. Nanosheet morphology was recognized for CoFe LDH and CoCeFe ternary LDH from scanning electron microscopy and transmission electron microscopy micrographs. In the following, a dispersive solid phase extraction (DSPE) method was developed using the synthesized CoCeFe ternary LDH as a sorbent for extracting perfluorooctanesulfonic acid (PFOS) from wastewater samples. For the selective analysis of PFOS, high-performance liquid chromatography-tandem mass spectroscopy (HPLC-MS/MS) in multiple reaction monitoring mode was used. Analytical parameters such as the limit of detection equal to 0.02 μg/L, with a linear range of 0.05–300 μg/L, the limit of quantification equal to 0.05 μg/L, and an enrichment factor equal to 23.3 were achieved for PFOS at the optimized condition (sorbent: 5 mg of CoCeFe ternary LDH, eluent type and volume: 150 μL mobile phase, pH: 3, adsorption time: 3 min, and desorption time: 5 min). The developed strategy for the analysis of PFOS was tested in real wastewater samples, including petrochemical and copper mine wastewater. The amount of analytes in real samples was calculated using the standard addition method, and good relative recovery in the range of 89%–105% was obtained. The main novelty of this research is the application of CoCeFe ternary LDH to extract the PFOS from wastewater using the DSPE method for determination by HPLC-MS/MS.

Development, validation, and clinical application of a UPLC-MS/MS method for omadacycline determination in human serum

BackgroundOmadacycline is the first aminomethyl-tetracycline variety to successfully enter clinical applications. To support regular therapeutic drug monitoring (TDM) in clinical practice, an ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) method was developed that would allow omadacycline quantification in human serum. MethodsProteins were precipitated from serum samples using methanol. Tigecycline was used as the internal standard. Mobile phase A was formic acid in water (0.1% v/v) and mobile phase B was methanol. UPLC-MS/MS was performed for analyte separation using a gradient elution program at a flow rate of 0.3 mL/min and a total run time of 5 min. The chromatography column was a ZORBAX PRHD SB-Aq (3 × 50 mm, 1.8 μm, Agilent, USA). The multiple reaction monitoring transitions at m/z = 557.4/470.3 and 586.5/513.3 were selected for omadacycline and tigecycline in the positive mode, respectively. ResultsThe validated curve ranges were 0.5–25.0 μg/mL. This method exhibited acceptable selectivity, matrix effects, and recovery. The inter- and intra-run accuracies ranged from 93.5% to 114.8%, and the inter- and intra-run precisions were between 1.29% and 5.55%. ConclusionsThe LC-MS/MS method provided a simple, specific, and rapid quantification of omadacycline in the serum of patients with pulmonary infection.

Assessment of Health Risks Associated with the Presence of Phthalate Esters in Tea Samples: A Comprehensive Analysis

This study presents novel insights into the occurrence of phthalate esters (PAEs) in tea samples consumed in Turkey. Employing multiple reaction monitoring (MRM) mode with precursor-product ion transitions, quantitative and qualitative analyses of PAEs were conducted using an LC-MS/MS system. A dispersive solid-phase extraction (dSPE) technique was utilized to determine the PAE contents in the tea samples. The limit of detection for all PAEs ranged from 0.350 to 1.882 ng/mL, while the limit of quantification ranged from 1.165 to 6.273 ng/mL. Moreover, strong correlations were observed with R2 values exceeding 0.996 for all PAEs, indicating robustness. Recovery studies demonstrated satisfactory results, falling within the range of 92.20% to 97.24%, indicating effective retrieval. The relative standard deviation values for the target PAEs ranged from 3.22% to 5.54%. The study findings indicate that PAE levels in the tea samples generally comply with permissible limits set by EU regulations, except for DBP (1807.70±1478.86 ng/mL). Notably, DBP and DINP (941.44±852.80 ng/mL) were identified as the predominant plasticizers in the tea samples. Health risk assessment, conducted through hazard quotient and hazard index calculations across various age groups, consistently yielded values below 1 for DEP, DEHP, DINP, BBP, and DBP, suggesting minimal non-carcinogenic health risks associated with tea consumption across all age groups. Furthermore, the intake of individual phthalate esters, including DEP, DEHP, DINP, BBP, and DBP, remained below acceptable daily limits defined by the EFSA. Although some tea products exhibited slightly elevated PAE levels, overall, the study emphasizes the importance of continuous monitoring and regulations to ensure the safety of packaged tea and mitigate potential long-term exposure risks linked to PAEs.

Simultaneous determination of 11 oral targeted antineoplastic drugs and 2 active metabolites by LC-MS/MS in human plasma and its application to therapeutic drug monitoring in cancer patients

Interindividual exposure differences have been identified in oral targeted antineoplastic drugs (OADs) owing to the pharmacogenetic background of the patients and their susceptibility to multiple factors, resulting in insufficient efficacy or adverse effects. Therapeutic drug monitoring (TDM) can prevent sub-optimal concentrations of OADs and improve their clinical treatment. This study aimed to develop and validate an LC-MS/MS method for the simultaneous quantification of 11 OADs (gefitinib, imatinib, lenvatinib, regorafenib, everolimus, osimertinib, sunitinib, tamoxifen, lapatinib, fruquintinib and sorafenib) and 2 active metabolites (N-desethyl sunitinib and Z-endoxifen) in human plasma. Protein precipitation was used to extract OADs from the plasma samples. Chromatographic separation was performed using an Eclipse XDB-C18 (4.6 × 150 mm, 5 μm) column with a gradient elution of the mobile phase composed of 2 mM ammonium acetate with 0.1 % formic acid in water (solvent A) and methanol (solvent B) at a flow rate of 0.8 mL/min. Mass analysis was performed using positive ion mode electrospray ionization in multiple-reaction monitoring mode. The developed method was validated following FDA bioanalytical guidelines. The calibration curves were linear over the range of 2–400 ng/mL for gefitinib, imatinib, lenvatinib, regorafenib, and everolimus; 1–200 ng/mL for osimertinib, sunitinib, N-desethyl sunitinib, tamoxifen, and Z-endoxifen; and 5–1000 ng/mL for lapatinib, fruquintinib, and sorafenib, with all coefficients of correlation above 0.99. The intra- and inter-day imprecision was below 12.81 %. This method was successfully applied to the routine TDM of gefitinib, lenvatinib, regorafenib, osimertinib, fruquintinib, and sorafenib to optimize the dosage regimens.

Position-specific isomers of monohydroxy fatty acids in the land-atmosphere interface: identification and quantification

Due to a wide variety and similar physicochemical properties of monohydroxy saturated fatty acids (OH-FAs) isomers as biomarkers, previously reported OH-FAs in environmental samples were mainly restricted to the α-, β-, (ω-1)- and ω-OH-FA isomers. Here, N,N-dimethylethylenediamine (DMED) labeling coupled with ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) analysis with multiple reaction monitoring mode (MRM) was developed to screen, identify and quantify position-specific isomers of OH-FAs (C8-C18). An identification strategy of positional isomers of OH-FAs, including α-, β-, 4 to (ω-2)-, (ω-1)- and ω-OH-FAs, was established by integrating the characteristics of peak intensity ratios of product ions based on the library of OH-FAs. Meanwhile, d4-DMED-labeled OH-FA standards as internal standards were adopted for the relative quantification of positional isomers. The extraction processes were optimized for different interface-environmental samples. Our method offers a promising tool to investigate position-specific isomers of OH-FAs in the land-atmosphere interface.

Simultaneous Determination of Ibrutinib, Dihydroxydiol Ibrutinib, and Zanubrutinib in Human Plasma by Liquid Chromatography-Mass Spectrometry/Mass Spectrometry.

Ibrutinib and zanubrutinib are Bruton tyrosine kinase inhibitors used to treat mantle cell lymphoma, chronic lymphocytic leukemia, and small lymphocytic lymphoma. Dihydroxydiol ibrutinib (DHI) is an active metabolite of the drug. A liquid chromatography-tandem mass spectrometry method was developed to detect ibrutinib, DHI, and zanubrutinib in human plasma. The method involved a protein precipitation step, followed by chromatographic separation using a gradient of 10 mM ammonium acetate (containing 0.1% formic acid)-acetonitrile. Ibrutinib-d5 was used as an internal standard. Analytes were separated within 6.5 minutes. The optimized multiple reaction monitoring transitions of m/z 441.1 → 304.2, 475.2 → 304.2, 472.2 → 455.2, and 446.2 → 309.2 were selected to inspect ibrutinib, DHI, zanubrutinib, and the internal standards in positive ion mode. The validated curve ranges included 0.200-800, 0.500-500, and 1.00-1000 ng/mL for ibrutinib, DHI, and zanubrutinib, respectively. The precisions of the lower limit of quantification of samples were below 15.5%, the precisions of the other level samples were below 11.4%, and the accuracies were between -8.6% and 8.4%. The matrix effect and extraction recovery of all compounds ranged between 97.6%-109.0% and 93.9%-105.2%, respectively. The selectivity, accuracy, precision, matrix effect, and extraction recovery results were acceptable according to international method validation guidelines. A simple and rapid method was developed and validated in this study. This method was used to analyze plasma concentrations of ibrutinib and zanubrutinib in patients with mantle cell lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, or diffuse large B-cell lymphoma. The selected patients were aged between 44 and 74 years.

Probe Electrospray Ionization Tandem Mass Spectrometry for the Detection and Quantification of Benzodiazepines.

Legally prescribed benzodiazepines (BZDs) and designer BZDs are widely misused and must be determined in multiple contexts (eg, overdose, drug-facilitated sexual assaults, or driving under the influence of drugs). This study aimed to develop a method for measuring serum BZD levels using probe electrospray ionization (PESI) mass spectrometry and an isotope dilution approach. A tandem mass spectrometer equipped with a probe electrospray ionization source in multiple reaction monitoring mode was used. Isotope dilution was applied for quantification using a deuterated internal standard at a fixed concentration for alprazolam, bromazepam, diazepam, nordiazepam, oxazepam, temazepam, zolpidem, and zopiclone. This method included designer BZDs: clonazolam, deschloroetizolam, diclazepam, etizolam, flualprazolam, flubromazepam, flubromazolam, meclonazepam, nifoxipam, and pyrazolam. Sample preparation was done by mixing 10 µL of serum with 500 µL of an ethanol/ammonium formate 0.01 mol/L buffer. Complete validation was performed, and the method was compared with liquid chromatography coupled with mass spectrometry (LC-MS/MS) and immunoassays (IC) by analyzing 40 real samples. The analysis time for identification and quantification of the 18 molecules was 2.5 minutes. This method was fully validated, and the limits of quantification varied from 5 to 50 mcg/L depending on the molecule. In the 40 real samples, 100% of molecules (n = 89) were detected by both LC-MS/MS and PESI-MS/MS, and regression analysis showed excellent agreement between the 2 methods (r2 = 0.98). On IC, bromazepam and zolpidem were not detected in 2 and 1 cases, respectively. PESI-MS/MS allows serum BZD detection and measurement. Given the isotope dilution approach, a calibration curve was not required, and its performance was similar to that of LC-MS/MS, and its specificity was higher than that of IC.

An Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometric Method for the Simultaneous Determination of Eighteen Marker Compounds in the Traditional Herbal Formula Bopyeo-Tang.

Bopyeo-tang (BPT), comprising six medicinal plants, has been used for the treatment of respiratory diseases such as pulmonary fibrosis and chronic obstructive pulmonary disease. In this study, we developed and validated a quantitative method for the quality assessment of BPT using ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS). Eighteen marker compounds were separated on an Acquity UPLC BEH C18 reversed-phase column (2.1 mm × 100 mm, 1.7 μm) via gradient elution with a 0.1% aqueous formic acid-acetonitrile mobile phase. The multiple-reaction monitoring mode was used to improve analysis speed and accuracy. The coefficients of determination, limits of detection, and limits of quantitation of the 18 marker compounds were 0.9991-0.9996, 0.36-24.45 μg/L, and 1.07-73.35 μg/L, respectively. The recovery was 85.19-110.25%, and the relative standard deviation of precision was ≤9.01%. When applied to a typical BPT sample, the method revealed a range of concentrations from below the quantitative limit (one compound only) to a maximum of 3.20 mg/freeze-dried g. This method will be used for quality control of BPT preparations.

Simple and Practical Method for the Quantitative High-Sensitivity Analysis of N-Nitroso Duloxetine in Duloxetine Drug Products Utilizing LC-MS/MS.

The high-sensitivity analytical method for the determination of N-nitroso duloxetine (NDXT), which can be carcinogenic and harmful in duloxetine drug products, was successfully developed utilizing liquid chromatography-tandem mass spectrometry (LC-MS/MS). Tandem mass spectrometric detection at positive electrospray ionization in multiple reaction monitoring (MRM) mode was then employed for the determination of NDXT. The quantitative range for NDXT was found in 0.075-3.75 ng/mL in terms of concentration in the dilution solvent for duloxetine active pharmaceutical ingredient (API) and capsules and 0.075-1.875 ng/mL for duloxetine tablets, and the recovery rates were in the range of 82.5-91.6% for the API, 91.0-113.4% for capsules, and 70.6-109.1% for tablets, respectively. The repeatability was 6.9% with a %RSD of n = 9 for the API, 10.9% with a %RSD of n = 9 for capsules, and 21.6% with a %RSD of n = 9 for tablets, respectively. For reproducibility, the %RSD of the n = 6 measurements between the two sites was 3.5%. The calibration curve of NDXT in the concentration range of 0.075-3.75 ng/mL was carried out, and the correlation coefficient (R) was found to be 1.000. The sample solution was stable for 7 days. The applicability of the determination of the content of NDXT in a variety of duloxetine drug products was demonstrated. This manuscript seeks to aid the risk assessment process of NDXT in duloxetine drug products through providing a fast and reliable quantitative LC-MS/MS analytical method.

[Determination of 35 prohibited pesticide residues in Saussurea costus by modified QuEChERS method based on multi-walled carbon nanotubes coupled with gas chromatography-tandem mass spectrometry].

Saussurea costus, a perennial herb belonging to the Asteraceae family, is a vital ingredient in traditional Chinese medicine. Increased demands for the herb have led to its widespread cultivation in China, but the corresponding increase in pesticide use has raised concerns about pesticide residues. Such residues would affect the safety and global market potential of Saussurea costus. Thus, a simple method is crucial to detect pesticide residues. The QuEChERS technique, in combination with gas chromatography-tandem mass spectrometry (GC-MS/MS), is commonly used for residue detection. However, traditional adsorbents may be unable to purify complex herbal mixtures well, affecting accuracy and instrument performance. Choosing suitable purification materials for Saussurea costus samples with complex matrices is of significant importance. This study focused on the detection of 35 prohibited pesticides in Saussurea costus. A rapid detection method was established by combining the QuEChERS technique with GC-MS/MS and utilizing a combination of multiwalled carbon nanotubes (MWCNTs), octadecylsilane-bonded silica gel (C18), and anhydrous magnesium sulfate (MgSO4) as the purification adsorbent. The samples were extracted with acetonitrile, purified by an improved QuEChERS process, subjected to GC-MS/MS analysis in multiple reaction monitoring (MRM) mode, and quantified using the internal standard method. The purification effects of four materials (C18, MWCNTs, N-propyl ethylenediamine (PSA), and graphitized carbon black (GCB)) and their optimal dosages were investigated by considering the matrix characteristics of the samples. An orthogonal experimental design was employed to optimize the ratio of adsorbent combinations, and the optimal adsorbent combination was determined to be 450 mg of MgSO4, 400 mg of C18, and 50 mg of MWCNTs. Matrix effect (ME) evaluation of the S. costus matrix showed that 31 target compounds strongly exhibited matrix-enhancement effects. Thus, matrix-matched calibration was employed in this study. Methodological investigation revealed that the standard curves for the 35 pesticides exhibited good linearity, with correlation coefficients (r2) greater than 0.9970. The average recoveries at three spiked levels ranged from 69.6% to 126.9%, and the relative standard deviations (RSDs) for parallel groups were all less than 10%. The limits of detection (LODs) and quantification (LOQs) ranged from 0.2 to 5.4 μg/kg and from 0.6 to 18.1 μg/kg, respectively. The developed method was used to screen and detect 35 pesticide residues in 20 batches of S. costus samples, and the target compounds were detected in six batches. The proposed method is simple, sensitive, and accurate. Thus, it is suitable for the rapid screening and detection of the 35 pesticide residues in S. costus and provides technical support for the cultivation, production, and quality control of the herb.

Quantifying carboxymethyl lysine and carboxyethyl lysine in human plasma: clinical insights into aging research using liquid chromatography-tandem mass spectrometry

ObjectiveThe objective of this study was to establish a methodology for determining carboxymethyl lysine (CML) and carboxyethyl lysine (CEL) concentrations in human plasma using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The test results were also used for clinical aging research.MethodsHuman plasma samples were incubated with aqueous perfluorovaleric acid (NFPA), succeeded by precipitation utilizing trichloroacetic acid, hydrolysis facilitated by hydrochloric acid, nitrogen drying, and ultimate re-dissolution utilizing NFPA, followed by filtration. Cotinine-D3 was added as an internal standard. The separation was performed on an Agela Venusil ASB C18 column (50 mm × 4.6 mm, 5 μm) with a 5 mmol/L NFPA and acetonitrile/water of 60:40 (v/v) containing 0.15% formic acid. The multiple reaction monitoring mode was used for detecting CML, CEL, and cotinine-D3, with ion pairs m/z 205.2 > 84.1 (for quantitative) and m/z 205.2 > m/z 130.0 for CML, m/z 219.1 > 84.1 (for quantitative) and m/z 219.1 > m/z 130.1 for CEL, and m/z 180.1 > 80.1 for cotinine-D3, respectively.ResultsThe separation of CML and CEL was accomplished within a total analysis time of 6 minutes. The retention times of CML, CEL, and cotinine-D3 were 3.43 minutes, 3.46 minutes, and 4.50 minutes, respectively. The assay exhibited linearity in the concentration range of 0.025–1.500 μmol/L, with a lower limit of quantification of 0.025 μmol/L for both compounds. The relative standard deviations of intra-day and inter-day were both below 9%, and the relative errors were both within the range of ±4%. The average recoveries were 94.24% for CML and 97.89% for CEL.ConclusionThe results indicate that the developed methodology is fast, highly sensitive, highly specific, reproducible, and suitable for the rapid detection of CML and CEL in clinical human plasma samples. The outcomes of the clinical research project on aging underscored the important indicative significance of these two indicators for research on human aging.

Simultaneous Quantification of Nine Target Compounds in Traditional Korean Medicine, Bopyeo-Tang, Using High-Performance Liquid Chromatography-Photodiode Array Detector and Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Bopyeo-tang (BPT) is composed of six medicinal herbs (Morus alba L., Rehmannia glutinosa (Gaertn.) DC., Panax ginseng C.A.Mey., Aster tataricus L.f., Astragalus propinquus Schischkin, and Schisandra chinensis (Turcz.) Baill.) and has been used for the treatment of lung diseases. This study focused on establishing an analytical method that can simultaneously quantify nine target compounds (i.e., hydroxymethylfurfural, mulberroside A, chlorogenic acid, calycosin-7-O-glucoside, 3,5-dicaffeoylquinic acid, quercetin, kaempferol, schizandrin, and gomisin A) from a BPT sample using high-performance liquid chromatography with a photodiode array detector (HPLC-PDA) and ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS). The separation of compounds in both analyses was performed on a C18 reversed-phase column using the gradient elution of water-acetonitrile as the mobile phase. In particular, the multiple reaction monitoring mode was applied for quick and accurate detection in UPLC-MS/MS analysis. As a result of analyzing the two methods, HPLC-PDA and UPLC-MS/MS, the coefficient of determination of the regression equation for each compound was ≥0.9952, and recovery was 85.99-106.40% (relative standard deviation (RSD) < 9.58%). Precision testing of the nine compounds was verified (RSD < 10.0%). The application of these analytical assays under optimized conditions for quantitative analysis of the BPT sample gave 0.01-4.70 mg/g. Therefore, these two assays could be used successfully to gather basic data for clinical research and the quality control of BPT.

A Simple and Rapid LC-MS/MS Method for the Quantification of Nirmatrelvir/Ritonavir in Plasma of Patients with COVID-19.

The combined prescriptions of nirmatrelvir/ritonavir and other drugs are limited due to potential drug-drug interactions, so therapeutic drug monitoring (TDM) becomes particularly important. In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established for determination of the nirmatrelvir/ritonavir in plasma of patients with COVID-19, providing technical and theoretical support for the TDM. Plasma samples were processed by protein precipitation using acetonitrile, and analytes were separated on an Agilent Poroshell 120 SB-C18 (2.1 × 75 mm, 2.7 μm) column at 35°C. Acetonitrile and 0.1% formic acid in water (52 : 48) were utilized as the mobile phases at a flow rate of 0.3 mL/min. In the multiple reaction monitoring (MRM) mode, nirmatrelvir and ritonavir were monitored using precursor/product ions: m/z 500.2/110.1 and 721.3/296.1, respectively, with selinexor as the internal standard. The linear range of both analytes was 2.0 ng/mL to 5000 ng/mL with good inter- and intraday precision and accuracy, and the recovery was 92.0%-107% for nirmatrelvir and 85.7%-106% for ritonavir. Finally, this method was successfully applied to monitor the exposure levels of nirmatrelvir/ritonavir in plasma samples from hemodialysis patients.

Ultra-performance liquid chromatography-tandem mass spectrometry for quantification of pyrethroid pesticide residues in freshwater fish and shrimp

A sophisticated Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) approach was devised for the concurrent quantification of pyrethroid pesticide residues in freshwater fish and shrimp. This analytical method involved ultrasonic extraction using acetonitrile, succeeded by sample purification employing Primary Secondary Amine (PSA) and Zirconium Dioxide Silica (Z-Sep+) following low-temperature centrifugation. Chromatographic separation was achieved with an ACQUITY UPLC BEH C18 column utilizing a mobile phase of a 2 mmol/L ammonium formate aqueous solution and methanol, with detection conducted through ESI + ionization in Multiple Reaction Monitoring (MRM) mode. The assay demonstrated exceptional linearity for seven pyrethroids across a concentration range of 0.5–10 μg/L, evidenced by correlation coefficients surpassing 0.999. Detection limits were established between 0.08 and 0.52 μg/kg, and the lower limits of quantification ranged from 0.28 to 1.72 μg/kg. Furthermore, recovery rates for blank samples were outstanding, ranging from 91.40% to 108.83% at concentrations of 1.0, 4.0, and 20.0 μg/kg, with Relative Standard Deviations (RSDs) between 0.94% and 8.13%. This methodology proved to be rapid, convenient, sensitive, and robust, offering stable recovery rates. Notably, it facilitated the detection of seven pyrethroid pesticide residues in freshwater fish and shrimp within an expedited timeframe of 15 min. This pioneering technique constitutes a significant advancement in the development of new methods for ensuring food safety.