MRM3-based UHPLC-MS/MS method for quantitation of total florfenicol residue content in milk and withdrawal study profile of milk from treated cows

Simultaneous Determination of Amphenicols in Animal-Derived Foods by Solvent and Solid Phase Extraction With Ultrahigh-Performance Liquid Chromatography Tandem Mass Spectrometry

BACKGROUND

The consumption of foods containing amphenicols, a type of antibiotic, is a major concern for human health. A stable and accurate detection method can provide technical support for food-safety monitoring.

OBJECTIVE

An effective and efficient method was established for determining amphenicols in animal-derived foods through the simultaneous use of solid-phase extraction (SPE) cleanup and ultrahigh-performance liquid chromatography/mass spectrometry (UPLC-MS/MS).

METHOD

Samples were extracted using 1.0% ammoniated ethyl acetate solution, degreased with n-hexane, and then concentrated and cleaned using a C18 SPE column. Next, gradient elution was performed using methanol and 0.05% aqueous ammonia as the mobile phase, followed by separation using a C18 column. The target compound was detected using electrospray ionization, both in positive and negative modes, through multiple reaction monitoring, and quantified using an internal-standard method.

RESULTS

The content of chloramphenicol (CAP), florfenicol (FF), and florfenicol amine (FFA) (content range: 0.2-8.0 µg/kg) as well as that of thiamphenicol (TAP; content range: 1.0-40.0 µg/kg) show a good linear relationship, with a correlation coefficient of r > 0.999. Furthermore, recoveries of 86.7-111.9% and relative standard deviations of <9.0% were achieved. The limits of detection and quantification are obtained as 0.03-0.33 and 0.1-1.0 μg/kg, respectively.

CONCLUSIONS

The proposed method has excellent stability and accuracy, and can be successfully used for the qualitative and quantitative determination of amphenicols, i.e., CAP, TAP, FF, and FFA residues in 210 animal-derived food samples, of which FF and FFA were detected in four samples.

HIGHLIGHTS

A stable and accurate method was successfully established for the simultaneous determination of CAP, TAP, FF, and FFA in animal-derived foods using UPLC-MS/MS. Effective sample pretreatment was established, lipids were removed using n-hexane, concentration and cleanup were achieved with the C18 SPE column, and matrix effects were effectively reduced, thus improving the method's accuracy and stability. The method was validated for eight common animal-source foods, including beef, lamb, pork, chicken, egg, milk, fish, and honey. This method has good applicability for CAP, TAP, FF, and FFA in animal-derived foods.

A strategy of accuracy quantification by extending the concentration monitoring coverage based on online double collision energy of ultra-high performance liquid chromatography tandem mass spectrometry: The pharmacokinetics of Toddalia asiatica as a case study

To facilitate the safety, efficacy and rationality of clinical application of traditional Chinese medicines (TCMs), pharmacokinetic research played an indispensable role. The key challenge during pharmacokinetic investigation lied at the substantial fluctuation of compound concentrations in the plasma over the course of absorption. Taking the pharmacokinetics of six compounds after administration of Toddalia asiatica (TA) as an example, an efficient strategy was established by introducing the online double collision energy (ODCE) into the quantification process applying ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). During the analytical program, double collision energy (DCE) was optimized to establish the dual calibration curve (DCC) with large concentration monitoring coverage (CMC) for meeting the wide content range of certain target compounds. Method validation test was performed in terms of linearity, precision, sensitivity, matrix effect, recovery, etc. The results displayed that the CMC of todarolactone with high exposure in plasma was extended from 1.25-2,500 ng/mL to 1.25-125,000 ng/mL. Furthermore, a rapid UHPLC-MS/MS method integrated with ODCE was successfully applied to the determination of six compounds in rat plasma, revealing an extremely high plasma concentration of todarolactone (16,662 ng/mL). This strategy could expand the range of quantification while retaining extraordinary sensitivity. Consequently, it could be a fit-for-purpose strategy to quantify compounds over a wide concentration range for in vivo process monitoring.

Antibiotic exposure associated with nighttime sleep duration and daytime sleepiness in newlyweds

Few studies have explored the relationship between antibiotic exposure and sleep in newlyweds. We applied the actor-partner interdependence moderation model to estimate the relationships of antibiotic exposure with nighttime sleep duration (weekday, weekend, and average sleep durations) and daytime sleepiness in newlyweds. We found that 99.0% of the 2698 enrolled individuals were exposed to at least one antibiotic. Among the newlyweds, exposure to florfenicol (β, - 0.077; 95% confidence interval [CI], - 0.143, - 0.011), exposure to chloramphenicols (- 0.086 [- 0.160, - 0.011]), and exposure to veterinary antibiotics (VAs) (- 0.106 [- 0.201, - 0.010]) were negatively associated with weekday sleep duration. Florfenicol, chloramphenicols, and VAs were also inversely related to average sleep duration in the newlyweds. Ciprofloxacin and cyadox exposure was significantly associated with an increase of 0.264 (0.030, 0.497) and (0.375 [0.088, 0.663]) Epworth Sleepiness Scale (ESS) scores in the newlyweds, respectively. Gender moderated the actor-partner effects of erythromycin and tetracyclines on the newlyweds' weekday sleep duration and ESS scores. Overall, exposure to florfenicol, chloramphenicols, and VAs shortened weekday and average sleep durations of newlyweds. Exposure to ciprofloxacin and cyadox promoted daytime sleepiness. Gender moderated the actor-partner effects of specific antibiotics on the weekday sleep duration and ESS scores of the newlyweds.

Development and validation of an LC-MS/MS assay with multiple stage fragmentation for the quantification of alachlor in McF-7 cells

Alachlor is one of the most widely used herbicides and can also be a carcinogenic compound. It is of great significance to establish a sensitive analytical method for the determination of alachlor in the environment and organisms. In this study, a high-performance liquid chromatography tandem mass spectrometry cubed (LC/MS³) method was developed and validated to quantify alachlor in human breast cancer cells (McF-7 cells). The cell samples were processed by simple protein precipitation with acetonitrile, then the analytes were separated on a Waters AcQuity® UPLC BEH (2.1 × 50 mm I.D, 1.7 μm) column using the gradient elution with solvent A (0.1 % formic acid) and solvent B (acetonitrile) at a flow rate of 0.5 mL/min. MS³ detection in positive ion mode was used to detect the analytes. The MRM³ transitions at m/z 270.1 → 238.0 → 162.1 and 312.2 → 238.1 → 147.2 were used to determine alachlor and butachlor, respectively. The run time for each sample was only 4 min. This method was validated for various parameters including accuracy, precision, selectivity, linearity, lower limit of quantitation (LLOQ), etc. The LC/MS³ assay was linear in the concentration range 0.5-50 ng/mL (R² ≥ 0.995). For all concentrations, the precision is < 9.49 %, and the intra-day and intra-day accuracy is < 13.05 %. Cytotoxic potential of alachlor against McF-7 cell lines was measured by MTT method after 48 h of incubation. For alachlor, half maximal inhibitory concentration (IC₅₀) on McF-7 cells was 87.95 µg/mL. This method was successfully applied to cellular pharmacokinetic study of alachlor in McF-7 cells after administration with a dose of 20 μg/mL.