Comparing ELISA and LC-MS/MS: A Simple, Targeted Postmortem Blood Screen

2021 ◽  
Author(s):  
Dina M Swanson ◽  
Julia M Pearson ◽  
Theresa Evans-Nguyen
Keyword(s):  
Mass Spectrometry ◽  
Sample Preparation ◽  
Limit Of Detection ◽  
Screening Method ◽  
Chemical Properties ◽  
Forensic Toxicology ◽  
Enzyme Linked Immunosorbent Assay ◽  
Minimal Sample ◽  
Elisa Testing ◽  
Postmortem Blood

Abstract A comprehensive screening method that is specific, accurate, and customizable is necessary in any forensic toxicology laboratory. Most laboratories utilize some form of immunoassay testing as it is reliable and sensitive with minimal sample preparation and is relatively inexpensive to simultaneously screen for multiple classes of drugs with different chemical properties. However, accessibility to more specific technology and instrumentation such as mass spectrometry has increased and therefore using immunoassay as the screening method of choice may be revisited. A screening method for 42 drugs in postmortem blood was developed and validated following the Organization of Scientific Area Committees for Forensic Science (OSAC) guidelines for toxicology method validation. The method was developed using minimal sample preparation of postmortem blood consisting only of a protein precipitation. Only two internal standards were used which greatly reduces the cost of implementing this method. Limit of detection (LOD), interference studies, processed sample stability and ion suppression/enhancement were examined. Additionally, over 100 case samples were analyzed by both the current enzyme linked immunosorbent assay (ELISA) testing procedure and the proposed liquid chromatography tandem mass spectrometry (LC-MS/MS) screening method. The comparison determined that the LC/MS-MS method performed as well as or better than the ELISA in nearly all cases. The ability to add additional target drugs increases the laboratory’s scope of analysis as well. This method is ideal for forensic laboratories wishing to improve screening while working within budget constraints.

LC-MS-MS vs ELISA: Validation of a Comprehensive Urine Toxicology Screen by LC-MS-MS and a Comparison of 100 Forensic Specimens

2019 ◽  
Vol 43 (9) ◽  
pp. 734-745 ◽  
Author(s):  
Kristin W Kahl ◽  
Joshua Z Seither ◽  
Lisa J Reidy
Keyword(s):  
Mass Spectrometry ◽  
Limit Of Detection ◽  
Screening Method ◽  
Driving Under The Influence ◽  
Cost Comparison ◽  
Enzyme Linked Immunosorbent Assay ◽  
Screening Methods ◽  
Limits Of Detection ◽  
The Cost ◽  
Urine Specimens

Abstract Toxicology laboratories commonly employ immunoassay methodologies to perform an initial drug screen on urine specimens to direct confirmatory testing. Due to limitations of immunoassay testing and the need to screen for a broader range of drugs with lower limits of detection at a lower cost, mass spectrometry screening techniques have gained favor in the toxicology field. A liquid chromatography–tandem mass spectrometry (LC-MS-MS) urine screening panel was developed and validated for 52 drugs and metabolites. A simple dilute-and-shoot with enzymatic hydrolysis technique was utilized to prepare the urine specimens for analysis. Limit of detection, interference, ionization suppression/enhancement, carryover and stability of processed specimens were assessed during validation. To evaluate the toxicological results obtained from utilizing the LC-MS-MS in comparison with the laboratory’s current enzyme-linked immunosorbent assay (ELISA) panel, 100 authentic urine specimens from suspected driving under the influence and drug-facilitated crime cases were analyzed using both methodologies and the results were compared. In addition, the cost of each methodology was evaluated and compared. The validated LC-MS-MS method had limits of detection that were equal to or lower than the concentrations validated for ELISA cutoffs, had fewer exogenous interferences, and the cost of screening per specimen was reduced by ~70% when compared to ELISA. Comparing the toxicology results of forensic urine specimens demonstrated that by only using ELISA, the laboratory was unable to detect benzoylecgonine in 26%, lorazepam in 33% and oxymorphone in 60% of the positive specimens. Additional analytes detected using the LC-MS-MS method were zolpidem and/or metabolite, gabapentin, tramadol and metabolite, methadone and metabolite, meprobamate and phentermine. The results of the validation, the toxicological result comparison and the cost comparison showed that the LC-MS-MS screening method is a simple, sensitive and cost-effective alternative to ELISA screening methods for urine specimens.

scholarly journals Comparative Analysis of ELISA Immunoassay and LC-QTOF for Opiate Screening

2020 ◽  
Vol 44 (4) ◽  
pp. 410-413
Author(s):  
Dickson Kennedy ◽  
Mata Dani
Keyword(s):  
Mass Spectrometry ◽  
Comparative Analysis ◽  
Screening Method ◽  
Enzyme Linked Immunosorbent Assay ◽  
Blood Samples ◽  
Flight Mass Spectrometry ◽  
Low Concentrations ◽  
Postmortem Blood ◽  
Targeted Screening ◽  
Liquid Chromatography Tandem Mass

Abstract A comparative analysis of enzyme-linked immunosorbent assay (ELISA) and quadrupole time-of-flight mass spectrometry (LC-QTOF) for the detection of opioids in blood samples is presented. The Orange County Crime Lab (OCCL) was concerned that the opioid drug class was not accurately detected at low concentrations due to the use of LC-QTOF as a non-targeted screening method for multiple classes of drugs. In order to investigate this issue, 968 ante-mortem and postmortem blood samples were analyzed by ELISA for the presence of the following opioids: morphine, morphine-glucuronide, codeine, codeine-glucuronide, hydrocodone, hydromorphone, hydromorphone-glucuronide, oxycodone, oxymorphone and oxymorphone-glucuronide. All samples had been previously analyzed by LC-QTOF. Overall, 84 samples tested positive for opioids. Discrepant samples between ELISA and LC-QTOF were analyzed by a liquid chromatography tandem mass spectrometry confirmation method in order to determine the true composition of the sample. Upon review of the discrepant samples, no forensically relevant concentration of opioids was missed by LC-QTOF. Thus, the ability of the OCCL’s LC-QTOF screening method was verified to detect opioids at low concentrations.

Identification of Suvorexant in Blood Using LC–MS-MS: Important Considerations for Matrix Effects and Quantitative Interferences in Targeted Assays

2019 ◽  
Vol 44 (3) ◽  
pp. 245-255 ◽  
Author(s):  
Britni Skillman ◽  
Sarah Kerrigan
Keyword(s):  
Matrix Effects ◽  
Limit Of Detection ◽  
Chemical Properties ◽  
Internal Standard ◽  
Forensic Toxicology ◽  
Calibration Model ◽  
Physico Chemical ◽  
Limit Of Quantitation ◽  
Liquid Chromatography Tandem Mass ◽  
Electrospray Interface

Abstract Suvorexant (Belsomra®) is a novel dual orexin receptor antagonist used for the treatment of insomnia. The prevalence of suvorexant in forensic samples is relatively unknown, which demonstrates the need for robust analytical assays for the detection of this sedative hypnotic in forensic toxicology laboratories. In this study, suvorexant was isolated from whole blood using a simple acidic/neutral liquid–liquid extraction followed by analysis by liquid chromatography tandem mass spectrometry (LC–MS/MS). Matrix effects were evaluated qualitatively and quantitatively using various extraction solvents, proprietary lipid clean-up devices and source conditions. The method was validated in terms of limit of detection, limit of quantitation, precision, bias, calibration model, carryover, matrix effects and drug interferences. Electrospray is a competitive ionization process whereby compounds in the droplet compete for a limited number of charged sites at the surface. As such, it is capacity-limited, and LC–MS-based techniques must be carefully evaluated to ensure that matrix effects or coeluting drugs do not impact quantitative assay performance. In this report, we describe efforts to ameliorate such effects in the absence of an isotopically labeled internal standard. Matrix effects are highly variable and heavily dependent on the physico-chemical properties of the substance. Although there is no universal solution to their resolution, conditions at the electrospray interface can mitigate these issues. Using this approach, the LC–MS/MS assay was fully validated and limits of detection and quantitation of 0.1 and 0.5 ng/mL suvorexant were achieved in blood.

Development and Validation of a Method for Quantification of 28 Psychotropic Drugs in Postmortem Blood Samples by Modified Micro-QuEChERS and LC–MS-MS

2020 ◽  
Author(s):  
Taís B Rodrigues ◽  
Damila R Morais ◽  
Victor A P Gianvecchio ◽  
Elvis M Aquino ◽  
Ricardo L Cunha ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Forensic Toxicology ◽  
Sample Volume ◽  
Weighting Factor ◽  
Liquid Extraction ◽  
Analytical Toxicology ◽  
Limit Of Quantification ◽  
Liquid Liquid Extraction ◽  
Postmortem Blood ◽  
Development And Validation

Abstract The development of new sample preparation alternatives in analytical toxicology leading to quick, effective, automated and environmentally friendly procedures is growing in importance. One of these alternatives is the QuEChERS, originally developed for the analysis of pesticide residues, producing cleaner extracts than liquid–liquid extraction, and easier separation of aqueous and organic phases. However, there are few published studies on the miniaturization of this technique for forensic toxicology, especially in postmortem analysis. We developed and validated a modified micro-QuEChERS and LC–MS-MS assay to quantify 16 antidepressants, 7 antipsychotics and 3 metabolites and semi-quantify norfluoxetine and norsertraline in postmortem blood. The calibration curve was linear from 1 to 500 ng/mL, achieved an r > 0.99, with all standards quantifying within ±15% of target except ±20% at the limit of quantification of 1 ng/mL for 26 substances. The F test was applied to evaluate if the variance between replicates remained constant for all calibrators. Six weighting factors were analyzed (1/x, 1/x2, 1/x0,5, 1/y, 1/y2 and 1/y0,5), with the weighting factor with the lowest sum of residual regression errors (1/x2) selected. No endogenous or exogenous interferences were observed. Method imprecision and bias were <19.0% and 19.7%, respectively. Advantages of this method include a low sample volume of 100 µL, simple but effective sample preparation and a rapid 8.5-min run time. The validated analytical method was successfully applied to the analysis of 100 authentic postmortem samples.

scholarly journals Determination of the Synthetic Cannabinoids JWH-122, JWH-210, UR-144 in Oral Fluid of Consumers by GC-MS and Quantification of Parent Compounds and Metabolites by UHPLC-MS/MS

2020 ◽  
Vol 21 (24) ◽  
pp. 9414
Author(s):  
Nunzia La Maida ◽  
Manuela Pellegrini ◽  
Esther Papaseit ◽  
Clara Pérez-Mañá ◽  
Lourdes Poyatos ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Performance ◽  
Oral Fluid ◽  
High Resolution Mass Spectrometry ◽  
Synthetic Cannabinoids ◽  
Screening Method ◽  
Forensic Toxicology ◽  
Gas Chromatography Mass Spectrometry ◽  
Limit Of Quantification

The consumption of synthetic cannabinoids (SCs) has significantly increased in the last decade and the analysis of SCs and their metabolites in human specimens is gaining interest in clinical and forensic toxicology. A pilot study has been carried out using a combination of an initial last generation gas chromatography-mass spectrometry (GC-MS) screening method for the determination of JWH-122, JWH-210, UR-144) in oral fluid (OF) of consumers and an ultra-high performance liquid chromatography high resolution mass spectrometry (UHPLC-HRMS) confirmatory method for the quantification of the parent compounds and their metabolites in the same biological matrix. OF samples were simply liquid-liquid extracted before injecting in both chromatographic systems. The developed methods have been successfully validated and were linear from limit of quantification (LOQ) to 50 ng/mL OF. Recovery of analytes was always higher than 70% and matrix effect always lower than 15% whereas intra-assay and inter-assay precision and accuracy were always better than 16%. After smoking 1 mg JWH-122 or UR-144 and 3 mg JWH-210, maximum concentration of 4.00–3.14 ng/mL JWH-122, 8.10–7.30 ng/mL JWH-210 ng/mL and 7.40 and 6.81 ng/mL UR-144 were measured by GC-MS and UHPLC-HRMS respectively at 20 min after inhalation. Metabolites of JWH 122 and 210 were quantified in OF by UHPLC-HRMS, while that of UR144 was only detectable in traces. Our results provide for the first time information about disposition of these SCs and their metabolites in consumers OF. Last generation GC-MS has proven useful tool to identify and quantify parent SCs whereas UHPLC-HRMS also confirmed the presence of SCs metabolites in the OF of SCs consumers.

scholarly journals Determination of Cyclamate in Foods by Ultraperformance Liquid Chromatography/Tandem Mass Spectrometry

2008 ◽  
Vol 91 (5) ◽  
pp. 1095-1102 ◽  
Author(s):  
Robert Sheridan ◽  
Thomas King
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Sample Preparation ◽  
Tandem Mass Spectrometry ◽  
Limit Of Detection ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Limit Of Quantitation ◽  
Liquid Chromatography Tandem Mass

Abstract A highly sensitive and selective method that requires minimal sample preparation was developed for the confirmation and quantitation of cyclamate in a variety of foods by high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). Sample preparation consisted of homogenization followed by extraction and dilution of cyclamate with water. HPLC separation was achieved using a bridged ethyl hybrid C18 high-pressure column with a mobile phase consisting of 0.15 acetic acid and methanol. Under electrospray ionization negative conditions, quantitation was achieved by monitoring the fragment m/z 79.7 while also collecting parent ion m/z 177.9. Two food matrixes, diet soda and jelly, were subjected to a validation procedure in order to evaluate the applicability of the method. The cyclamate limit of detection for both matrixes was determined to be 0.050 g/g with a limit of quantitation of 0.150 g/g. The correlation coefficient of the calibration curves was >0.9998 from 0.0005 to 0.100 g/mL. The method has been used for the determination of cyclamate in several foods and the results are presented.

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

2021 ◽  
Vol 156 (Supplement_1) ◽  
pp. S34-S34
Author(s):  
S Dalal ◽  
D Jhala
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Sample Preparation ◽  
Drugs Of Abuse ◽  
Limit Of Detection ◽  
Gas Chromatography Mass Spectrometry ◽  
Liquid Chromatography Mass Spectrometry ◽  
Laboratory Practice ◽  
Ion Suppression ◽  
Chromatography Mass Spectrometry

Abstract 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.

scholarly journals Optimization of a minimal sample preparation protocol for imaging mass spectrometry of unsectioned juvenile invertebrates

2019 ◽  
Vol 55 (4) ◽  
pp. e4458 ◽  
Author(s):  
Katherine E. Zink ◽  
Denise A. Tarnowski ◽  
Mark J. Mandel ◽  
Laura M. Sanchez
Keyword(s):  
Mass Spectrometry ◽  
Sample Preparation ◽  
Imaging Mass Spectrometry ◽  
Minimal Sample
Sign in / Sign up

Export Citation Format

Share Document