Excellence in Laboratory Practice with the Validation of Opiate Confirmation using Liquid Chromatography/Mass Spectrometry

Introduction/Objective Veterans are more susceptible to opioid addiction as they are more likely to suffer from chronic pain which leads to increased need of confirmed identification of opiates in toxicology laboratories. Gas chromatography-mass spectrometry (GC-MS) had been a long-accepted method for the quantitative analysis of opiates in urine, but requires tedious, time-consuming, and complex sample preparation steps. On the other hand, liquid chromatography-mass spectrometry (LC/MS) has comparatively simpler sample preparation steps, can handle three times the number of specimens, much faster turnaround times and produces equally valid results. However, the validation experience of this simpler detection method has not been well published, particularly in a Veterans Healthcare Clinical Laboratory setting. Methods/Case Report The quality assurance goal of the validation is to demonstrate that the Agilent 6410 Triple Quadrupole LC/MS (Wilmington DE) is able to identify the same opiate drug analytes performed by the GC-MS. Method to method correlation, within run precision, day to day precision, carryover study, matrix (ion) suppression study, and a limit of detection study were performed as part of this validation. Results (if a Case Study enter NA) For the total of 156 specimens run for the method comparison, there was 94.9% agreement, or 148/156 samples were concordant. The 8 discrepancies had drugs that were present below the cutoff limit of the LC/MS. Within run precision with 20 replicates of negative, positive, and at the cutoff were run with all results as expected. The day to day precision of a positive and negative sample run over 10 days also yielded results as expected. The carryover study demonstrated minimal carryover. The matrix (ion) suppression study showed ion suppression at 16.8%, which is below the amount needed to affect analyte concentrations. The LC/MS was highly sensitive with a limit of detection of >97% at 25 ng/mL. Thus, the result of comparison showed good concordance. Conclusion LC/MS is a simpler, more efficient method of opiate testing that is comparable to GC-MS for the detection of opiate drugs of abuse in urine. This is an example of excellence in laboratory practice by extending the best quality laboratory care with proper validation of instrument methods conducive to laboratory workflow.

Improved Sensitivity in Hydrophilic Interaction Liquid Chromatography-Electrospray-Mass Spectrometry after Removal of Sodium and Potassium Ions from Biological Samples

Inorganic ions, such as sodium and potassium, are present in all biological matrices and are sometimes also added during sample preparation. However, these inorganic ions are known to hamper electrospray ionization -mass spectrometry (ESI-MS) applications, especially in hydrophilic interaction liquid chromatography (HILIC) where they are retained and can be detected as adducts and clusters with mobile phase components or analytes. The retention of inorganic ions leads to co-elution with analytes and as a result ion-suppression, extensive adduct formation and problems with reproducibility. In the presented work, a sample preparation method using cation exchange solid phase extraction (SPE) was developed to trap Na+ and K+ ions from human blood plasma and head and neck cancer cells for the analysis of small cationic, anionic as well as neutral organic analytes. The investigated analytes were small, hydrophilic compounds typically in focus in metabolomics studies. The samples were analyzed using full-scan HILIC-ESI-quadrupole time of flight (QTOF)-MS with an untargeted, screening approach. Method performance was evaluated using multivariate data analysis as well as relative quantifications, spiking of standards to evaluate linearity of response and post-column infusion to study ion-suppression. In blood plasma, the reduction of sodium and potassium ion concentration resulted in improved sensitivity increased signal intensity for 19 out of 28 investigated analytes, improved linearity of response, reduced ion-suppression and reduced cluster formation as well as adduct formation. Thus, the presented method has significant potential to improve data quality in metabolomics studies.

Minimizing ion competition boosts volatile metabolome coverage by secondary electrospray ionization orbitrap mass spectrometry

Secondary electrospray ionization high-resolution mass spectrometry (SESI-HR-MS) is an emerging technique for the detection of volatile metabolites. However, sensitivity and reproducibility of SESI-HRMS have limited its applications in untargeted metabolomics profiling. Ion suppression in the SESI source has been considered to be the main cause. Here, we show that besides ion suppression, ion competition in the C-trap of Orbitrap instruments is another important factor that influences sensitivity and reproducibility of SESI-MS. Instead of acquiring the full mass-to-charge ratio (m/z) range, acquisition of consecutive m/z windows to minimize the ion competition effect allows the detection of more features. m/z window ranges are optimized to fill the C-trap either with an equal number of features or an equal cumulative intensity per window. Considering a balance between maximizing scanning speed and minimizing ion competition, splitting the m/z = 50-500 range into 4 windows is selected for measuring human breath and bacterial culture samples on SESI-Orbitrap MS, corresponding to a duty cycle of 2.3 s at a resolution of 140’000. In a small cohort of human subjects, the proposed splitting into 4 windows allows three times more features to be detected compared to the classical full m/z range method.

Development and validation of an LC–MS/MS method for the bioanalysis of the major metamizole metabolites in human plasma

Aim: Metamizole is a frequently used antipyretic and analgesic prodrug, yet its pharmacokinetics has not been thoroughly studied in infants and with coadministered medications. Thus, an LC–MS/MS method was developed to quantify the four major metamizole metabolites in human plasma. Methodology: Pre- and postcolumn infusion was installed to enable robust analyte retention and electrospray ionization following deproteinization of plasma samples. Results: The method was linear (R > 0.996), accurate (93.1–106.0%) and precise (≤12.7%). Mean recovery was more than 91.8% and ion suppression less than 13.1% for all analytes. Pharmacokinetic profiles were reproducible after 4 years at -80°C except for the formylated metabolite (-22.2%). Conclusion: The method fulfilled pertinent criteria of validation guidelines and required only little sample volume. The method therefore qualifies for metamizole analyses in children.

Automated Post-Column Sample Manipulation Prior to Detection in Liquid Chromatography: A Review of Pharmaceutical and Bioanalytical Applications

: Automated post-column sample manipulation is undoubtedly one of the most challenging approaches in liquid chromatography for the improvement of method selectivity and sensitivity. With the post-column analyte derivatization being the most-abundant approach approach of this category, other strategies typically comprise post-column infusion of internal standard or other reagents prior to mass spectrometric detection to enhance the ionization efficiency of the analyte or to compensate the ion suppression/enhancement. : In this review, on-line post column methodologies focused on the quality control of pharmaceuticals and biomedical applications will be presented and discussed. Emphasis will be given on the automation capabilities of such systems.