Rapid determination of short chain carnitines in human plasma by electrospray ionisation-ion trap mass spectrometry using capillary electrophoresis instrument as sampler

Quantitative analysis of thymosin β4 in whole saliva by capillary electrophoresis–mass spectrometry using multiple ions monitoring (CE-MIM-MS.)

Thymosin β4 (Tβ4) is a peptide present in almost any tissue and in extracellular media in mammals, having multiple amazing functions as wound healing, stimulation of angiogenesis, and suppression of inflammation. This study describes its determination in saliva through CE-MS using multiple ions monitoring scan mode by isolating the four most intense multicharged ions present in the MS spectra of the peptide. This scan modality, by reducing the baseline noise and interferences, increases the sensitivity and specificity in biological matrices. The CE-MS separation was optimized by studying different parameters influencing CE analysis, sample injection, and MS ionization, that is, the nebulizer gas flow, the sheath liquid, and BGE composition. The proposed technique can unambiguously identify in short time Tβ4 in saliva after a very fast and reduced sample pretreatment procedure. The method was validated for quantitation showing linearity of the response in the range 0.25 (lower limit of quantification) to 4 μM (average R2 0.996 ± 0.005) and intra- and interassay precision and accuracy at three different concentrations with RSD values in the range of 7–16%. It was successfully applied to the analysis of Tβ4 in whole saliva showing a variable peptide content from individual to individual (in the range of 0.3–1.4 μM) and in different days from the same individual. CE-MS in multiple ions monitoring scan mode provides a fast, selective, and economic method requiring only very few microliters of sample.

A liquid chromatography and tandem mass spectrometry method for the determination of potential biomarkers of cardiovascular disease

A simple, accurate and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitation of α-ketoglutaric acid (α-KG), L-carnitine (L-CAR) and acetyl-L-carnitine (acetyl-L-CAR) in human urine as potential biomarkers of cardiovascular disease. The separation was performed using an isocratic elution of 0.1% formic acid in water and acetonitrile (97:3, v/v) on an Acclaim 120 C8 column (150 mm × 4.6 mm, 3.0 μm). The flow rate of the mobile phase was 1.2 mL/min and the total assay run time was 3 min. Detection was performed on a triple-quadrupole mass spectrometer in selected reaction monitoring (SRM) mode via an electrospray ionization (ESI) source in positive and negative ion modes. This method covered a linearity range of 0.1-500 ng/mL for L-CAR and acetyl-L-CAR and 1-1000 ng/mL for α-KG with lower limits of quantification (LLOQ) of 0.08 ng/mL for L-CAR, 0.04 ng/mL for acetyl-L-CAR and 0.8 ng/mL for α-KG. The intra-day and inter-day precision and accuracy of the quality control samples exhibited relative standard deviations of less than 5.54% and relative error values from -5.95% to 3.11%. Analyte stability was evaluated under various sample preparation, analysis and storage conditions and varied from -9.89% to -0.47%. A two-step solid-phase extraction (SPE) procedure using silica gel and quaternary amine cartridges was used for urine sample cleanup. The average recoveries for all analyzed compounds were better than 86.64% at three concentrations. The method was successfully applied for the quantitation of α-KG, L-CAR and acetyl-L-CAR in human urine samples.

Development and validation of a capillary electrophoresis tandem mass spectrometry analytical method for the determination of Leu-Val-Val- and Val-Val-hemorphin-7 peptides in cerebrospinal fluid

A CE-tandem MS method was optimised and validated for selective and specific determination of LVV- and VV-hemorphin-7 peptides in cerebrospinal fluid. These two small peptides originate from haemoglobin beta chains. They possess relevant biological activity and recently a potential biomarker role in posterior cranial fossa paediatric brain tumour disease was evidenced. The separation was optimised using formic acid as background electrolyte and a water/methanol mixture, containing 0.1% (v/v) formic acid, as sheath liquid. The two peptides, differing in only one amino acid of the sequence at the N-terminal side were baseline separated in less than 15 min. The method allowed a very reduced and rapid sample pretreatment and was successfully applied to hemorphins determination in patient samples without matrix interferences. The method successfully passed bioanalytical validation showing linearity, accuracy and precision data on cerebrospinal fluid matrix within the acceptable values. The analysis of cerebrospinal fluid of patients affected by different posterior cranial fossa tumour forms confirmed our previous findings showing the absence of hemorphins in the pre-surgical cerebrospinal fluid and their presence in the post-ones and controls. The present method saves costs and time due to capillary electrophoresis miniaturisation and to the absence of chromatographic column and gradient elution and allows numerous injections per sample starting from few microlitres of cerebrospinal fluid.

N-acetyl cysteine directed detoxification of 2-hydroxyethyl methacrylate by adduct formation

Cytotoxicity of the dental resin monomer 2-hydroxyethyl methacrylate (HEMA) and the protective effects of N-acetyl cysteine (NAC) on monomer-induced cell damage are well demonstrated. The aim of our study was to analyze the hypothesis that the protection of NAC from HEMA cytotoxicity might be due to direct NAC adduct formation. To this end, using HPLC we first measured the actual intracellular HEMA concentrations able to cause toxic effects on 3T3-fibroblasts and then determined the decrease in intracellular and extracellular HEMA levels in the presence of NAC. In addition, by capillary electrophoresis coupled with mass spectrometry analysis (CE-MS), we evaluated NAC-HEMA adduct formation. HEMA reduced 3T3 cell vitality in a dose- and time-dependent manner. The concentration of HEMA inside the cells was 15-20 times lower than that added to the culture medium for cell treatment (0-8 mmol/L). In the presence of 10 mmol/L NAC, both intracellular and extracellular HEMA concentrations greatly decreased in conjunction with cytotoxicity. NAC-HEMA adducts were detected both in the presence and absence of cells. Our findings suggest that the in vitro detoxification ability of NAC against HEMA-induced cell damage occurs through NAC adduct formation. Moreover, we provide evidence that the actual intracellular concentration of HEMA able to cause cytotoxic effects is at least one magnitude lower than that applied extracellularly.