A novel and nonderivatization method for the determination of valproic acid in human serum by two‐dimensional liquid chromatography

Two-dimensional liquid chromatography with reversed phase in both dimensions: A review

Two-dimensional liquid chromatography (2D-LC), and in particular comprehensive two-dimensional liquid chromatography (LC×LC), offers increased peak capacity, resolution and selectivity compared to one-dimensional liquid chromatography. It is commonly accepted that the technique produces the best results when the separation mechanisms in the two dimensions are completely orthogonal; however, the use of similar separation mechanisms in both dimensions has been gaining popularity as it helps avoid difficulties related to mobile phase incompatibility and poor column efficiency. The remarkable advantages of using reversed phase in both dimensions (RPLC×RPLC) over other separation mechanisms made it a promising technique in the separation of complex samples. This review discusses some physical and practical considerations in method development for 2D-LC involving the use of RP in both dimensions. In addition, an extensive overview is presented of different applications that relied on RPLC×RPLC and 2D-LC with reversed phase column combinations to separate components of complex samples in different fields including food analysis, natural product analysis, environmental analysis, proteomics, lipidomics and metabolomics.

A novel method for the quantification of anlotinib in human plasma using two-dimensional liquid chromatography

A simple, efficient, and stable detection method of two-dimensional liquid chromatography (2D-LC) was established and validated to determine anlotinib in the human plasma. The 2D-LC system comprises a first-dimensional column (LC1), an intermediate transfer column, and a second-dimensional column (LC2). With simple protein precipitation treatment, the samples were processed directly for detection. The analysis cycle time was completed within 9.50 min. For the anlotinib concentrations, the calibration curve was linear over the 5.00-320.00 ng/mL range. The intra-day and inter-day precision ranges were 0.77-6.22% and 1.92-4.26%, respectively, for anlotinib concentrations. The recoveries were in the range of 97.85-102.50%. A total of 135 plasma samples from 94 patients were analyzed by our method. The plasma concentrations of patients were in the range of 5.17-106.38 ng/mL, in which the female had a higher plasma concentration (6.44-106.38 ng/mL). The simultaneous application of dexamethasone can increase the anlotinib concentration in the plasma. In our clinical application, we found that the factors that affect the plasma concentration include the time and dose of the medication, gender, and drug interactions. The method appears to be sensitive, precise, selective, and suitable for determining the concentration of anlotinib in the plasma sample.

Application of the Westgard Multi-rule Theory to Internal Quality Control Evaluation of Voriconazole for Therapeutic Drug Monitoring

Background:

There is no worldwide recognized reference internal quality control method for Therapeutic Drug Monitoring (TDM) of voriconazole (VCZ) by Liquid Chromatography (LC). In this study, we aimed to develop an internal quality control method for TDM of VCZ, evaluate it by the Westgard multi-rule theory, and guarantee the analytical quality of the assays.

Methods:

The plasma concentration of VCZ was detected by two-dimensional liquid chromatography with ultraviolet detection (2D-LC-UV) method. The internal quality control results accompanying with TDM of VCZ in our laboratory from July 2019 to January 2020 were collected and retrospectively studied. The Levey-Jennings quality chart and Z-score quality chart were drawn and Westgard multirules of 12s/13s/22s/R4s/41s/10x were applied to assess the suitable quality control method for TDM of VCZ.

Results:

The 2D-LC-UV method was well suited to monitor the plasma concentration of VCZ and increase the real-time capability of TDM for VCZ. Combined with Westgard multi-rules, the quality control charts of Levery-Jennings and Z-score both can timely discover and judge the systematic errors and random errors for the internal quality control results. 86 batches of quality control products were assessed and 7 times warnings and 6 times out of control were detected.

Conclusion:

The Westgard multi-rules, with high efficacy in determining detection errors, has important application value in the internal quality control for TDM of VCZ. The developed quality control method can improve the accuracy and reliability for VCZ measurement by the 2D-LC-UV method and further promote the clinical rational use of the drug.