On-line Combination Of Capillary Electrophoresis Research Articles

Implementation of Modern Therapeutic Drug Monitoring and Lipidomics Approaches in Clinical Practice: A Case Study with Colistin Treatment.

Nowadays, lipidomics plays a crucial role in the investigation of novel biomarkers of various diseases. Its implementation into the field of clinical analysis led to the identification of specific lipids and/or significant changes in their plasma levels in patients suffering from cancer, Alzheimer's disease, sepsis, and many other diseases and pathological conditions. Profiling of lipids and determination of their plasma concentrations could also be helpful in the case of drug therapy management, especially in combination with therapeutic drug monitoring (TDM). Here, for the first time, a combined approach based on the TDM of colistin, a last-resort antibiotic, and lipidomic profiling is presented in a case study of a critically ill male patient suffering from Pseudomonas aeruginosa-induced pneumonia. Implementation of innovative analytical approaches for TDM (online combination of capillary electrophoresis with tandem mass spectrometry, CZE-MS/MS) and lipidomics (liquid chromatography-tandem mass spectrometry, LC-MS/MS) was demonstrated. The CZE-MS/MS strategy confirmed the chosen colistin drug dosing regimen, leading to stable colistin concentrations in plasma samples. The determined colistin concentrations in plasma samples reached the required minimal inhibitory concentration of 1 μg/mL. The complex lipidomics approach led to monitoring 545 lipids in collected patient plasma samples during and after the therapy. Some changes in specific individual lipids were in good agreement with previous lipidomics studies dealing with sepsis. The presented case study represents a good starting point for identifying particular individual lipids that could correlate with antimicrobial and inflammation therapeutic management.

An interface for online coupling capillary electrophoresis to dielectric barrier discharge ionization mass spectrometry.

The online combination of capillary electrophoresis (CE) with mass spectrometry (MS) has long been desired for the capability of direct and simultaneous separation and detection with high efficiency, accuracy, and throughput. In this work, a novel CE-MS interface was developed, using dielectric barrier discharge ionization (DBDI). The interface employed a spray tip with a coaxial three-layer structure, into which the CE sample solution, the sheath liquid, and the nebulizing gas were introduced. The spray tip was put between the DBDI outlet and the MS inlet, thus the CE sample solution could be blended with the sheath liquid, then nebulized. The nebulized sample could be ionized by DBDI, and finally analyzed by MS. The key parameters of the interface were optimized. Then, proof-of-concept experiments separating and detecting the mixture of metronidazole and acetaminophen solutions were conducted. The results showed high separation efficiency, low time consumption, high reproducibility, and convenience in operation. In addition, the interface exhibited a high tolerance of non-volatile salts and surfactants, which would be widely used in CE analyses. All of these results demonstrated that the newly developed CE-DBDI-MS interface could be successfully used in CE-MS studies, and could be further utilized in multiple areas involving efficient separation and detection.

Analysis of lysozyme in cheese samples by on-line combination of capillary zone electrophoresis and mass spectrometry

Some methodological aspects of an on-line combination of capillary zone electrophoresis with mass spectrometric detection (CZE–QqQ–MS) were studied in this work as well as the possibilities of using this combination for analysis of the high-molecular mass compounds present in multi-component matrices. All experiments using an on-line combination of capillary electrophoresis with mass spectrometric detection were carried out in cationic mode in covalently-coated capillary. The optimised electrolyte system consisted of 100mmol/L formic acid. Prior to the CZE–QqQ–MS analysis, an extraction of lysozyme from cheese samples using 1mol/L of acetic acid was performed. The LOD was 3.6mg lysozyme per kg and the LOQ was 10.9mg lysozyme per kg. The concentration range of the lysozyme determined in four cheese samples analysed in this work was from 0.5 to 3.3g of lysozyme per kg. The values of the relative standard deviations thus obtained were from 4.6% to 9.3% depending on the cheese sample.

Proteomic patterns established with capillary electrophoresis and mass spectrometry for diagnostic purposes

Proteomics applied in large scale may provide a useful diagnostic tool. We developed an online combination of capillary electrophoresis with mass spectrometry, allowing fast and sensitive evaluation of polypeptides found in body fluids. Utilizing this technology, polypeptide patterns from urine are established within 45 minutes. About 900 to 2500 polypeptides as well as their concentrations are detected in individual urine samples without the need for specific reagents such as antibodies. To test this method for clinical application, we examined spot urine samples from 57 healthy individuals, 16 patients with minimal change disease (MCD), 18 patients with membranous glomerulonephritis (MGN), and 10 patients with focal segmental glomerulosclerosis (FSGS). One-hundred seventy-three polypeptides were present in more than 90% of the urine samples obtained from healthy individuals, while 690 polypeptides were present with more than 50% probability. These data permitted the establishment of a "normal" polypeptide pattern in healthy individuals. Polypeptides found in the urine of patients differed significantly from the normal controls. These differences allowed the distinction of specific protein spectra in patients with different primary renal diseases. Abnormal pattern of proteins were found even in urine from patients in clinical remission. The data indicate that capillary electrophoresis with mass spectrometry coupling provides a promising tool that permits fast and accurate identification and differentiation of protein patterns in body fluids of healthy and diseased individuals, thus enabling diagnosis based on these patterns.

Development of a Robust Capillary Electrophoresis–Mass Spectrometer Interface with a Floating Sheath Liquid Feed

The on-line combination of capillary electrophoresis (CE) with electrospray ionisation mass spectrometry (ESI-MS) has attracted major attention for the in-depth analysis of complex samples. However, CE-MS coupling is not straightforward. We present a novel coaxial sheath liquid CE-MS interface, which is robust and can be used for both hyphenated techniques, liquid chromatography-mass spectrometry (LC-MS) and CE-MS, alternatively on the same mass spectrometer. The two separation techniques can be switched within minutes. To obtain a stable ion spray and avoid electrical problems, the CE-power supply is used to produce the potential for the CE separation and the ESI sprayer tip simultaneously. The necessary sheath liquid is delivered by a pump which floats on the ion sprayer potential of the mass spectrometer, avoiding any current flow towards ground. The sole parameter which has to be adjusted to adapt to different CE conditions is a variable resistor. Analytical applications such as peptide mixture analysis and drug screening are presented.

Analysis of histones by on-line capillary zone electrophoresis–electrospray ionisation mass spectrometry

The on-line combination of capillary electrophoresis and electrospray ionisation mass spectrometry was applied for the determination of some basic histones from calf thymus. The separation performance of those basic proteins was significantly improved by coating the capillaries with hydroxypropylmethylcellulose. The coating appeared to mask effectively the underlying silanol groups thus avoiding undesirable adsorption of the histones onto the capillary walls, while it was also shown to be an effective way to avoid contamination of the mass spectrometer. Finally, capillary electrophoresis–electrospray ionisation mass spectrometry with coaxial sheath liquid was successfully applied to the analysis of histones using a simple dialysis step of the sample as sample pretreatment.

On-line capillary electrophoresis with Fourier transform ion cyclotron resonance mass spectrometry

The role of capillary electrophoresis (CE) in chemical and biochemical characterization is growing rapidly due to its speed, resolution, and flexibility for the manipulation of extremely small samples. CE was first combined with mass spectrometry (MS) at our laboratory. In this communication we report results for the first on-line combination of CE with Fourier transform ion cyclotron resonance (FTICR) mass spectrometry, an approach that is capable of providing both high CE and MS resolution and high sensitivity. The advantages of FTICR include the ability to simultaneously realize ultrahigh MS resolution/mass measurement accuracy and high sensitivity, as well as the capability for higher order tandem MS methods (i.e., MS[sup n], where n [ge] 2) for structural studies because of its nondestructive detection method. 20 refs., 3 figs.