scholarly journals Consideration of Sample Matrix Effects and “Biological” Noise in Optimizing the Limit of Detection of Biosensors

ACS Sensors ◽  
2020 ◽  
Vol 5 (11) ◽  
pp. 3290-3292
Author(s):  
Jean-Francois Masson
Keyword(s):  
Matrix Effects ◽  
Limit Of Detection ◽  
Biological Noise ◽  
Sample Matrix

scholarly journals Validation of a New Sensitive Method for the Detection and Quantification of R and S-Epimers of Ergot Alkaloids in Canadian Spring Wheat Utilizing Deuterated Lysergic Acid Diethylamide as an Internal Standard

Toxins ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 22
Author(s):  
Jensen Cherewyk ◽  
Taylor Grusie-Ogilvie ◽  
Barry Blakley ◽  
Ahmad Al-Dissi
Keyword(s):  
Spring Wheat ◽  
Matrix Effects ◽  
Limit Of Detection ◽  
Ergot Alkaloids ◽  
Internal Standard ◽  
Lysergic Acid ◽  
Lysergic Acid Diethylamide ◽  
Relative Standard ◽  
Validation Parameters ◽  
Sensitive Method

Ergot sclerotia effect cereal crops intended for consumption. Ergot alkaloids within ergot sclerotia are assessed to ensure contamination is below safety standards established for human and animal health. Ergot alkaloids exist in two configurations, the R and S-epimers. It is important to quantify both configurations. The objective of this study was to validate a new ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for quantification of six R and six S-epimers of ergot alkaloids in hard red spring wheat utilizing deuterated lysergic acid diethylamide (LSD-D3) as an internal standard. Validation parameters such as linearity, limit of detection (LOD), limit of quantification (LOQ), matrix effects, recovery and precision were investigated. For the 12 epimers analyzed, low LOD and LOQ values were observed, allowing for the sensitive detection of ergot epimers. Matrix effects ranged between 101–113% in a representative wheat matrix. Recovery was 68.3–119.1% with an inter-day precision of <24% relative standard deviation (RSD). The validation parameters conform with previous studies and exhibit differences between the R and S-epimers which has been rarely documented. This new sensitive method allows for the use of a new internal standard and can be incorporated and applied to research or diagnostic laboratories.

Assessing matrix, interferences and comparability between the Abbott Diagnostics and the Beckman Coulter high-sensitivity cardiac troponin I assays

2018 ◽  
Vol 56 (7) ◽  
pp. 1176-1181 ◽  
Author(s):  
Peter A. Kavsak ◽  
Paul Malinowski ◽  
Chantele Roy ◽  
Lorna Clark ◽  
Shana Lamers
Keyword(s):  
Cardiac Troponin ◽  
Troponin I ◽  
Matrix Effects ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Mean Difference ◽  
Plasma Samples ◽  
Matrix Interferences ◽  
Heparin Plasma ◽  
Edta Plasma

Abstract Background: Analytical evaluation of high-sensitivity cardiac troponin (hs-cTn) assays, with particular attention to imprecision, interferences and matrix effects, at normal cTn concentrations, is of utmost importance as many different clinical algorithms use concentration cutoffs <10 ng/L for decision-making. The objective for the present analytical study was to compare the new Beckman Coulter hs-cTnI assay (Access hsTnI) to Abbott’s hs-cTnI assay in different matrices and for different interferences, with a focus on concentrations <10 ng/L. Methods: The limit of blank (LoB) and the limit of detection (LoD) were determined in different matrices for the Beckman hs-cTnI assay. Passing-Bablok regression and difference plots were determined for 200 matched lithium heparin and EDTA plasma samples for the Beckman assay and 200 lithium heparin samples for the Abbott assay. Both EDTA and heparin plasma samples were also evaluated for stability under refrigerated conditions, for endogenous alkaline phosphatase interference and for hemolysis and icterus. Results: The Beckman hs-cTnI assay LoB was 0.5 ng/L with the following range of LoDs=0.8–1.2 ng/L, with EDTA plasma yielding lower concentrations as compared to lithium heparin plasma (mean difference=−14.9%; 95% CI=−16.9 to 12.9). Below 10 ng/L, lithium heparin cTnI results from the Beckman assay were on average 1.1 ng/L (95% CI=0.7 to 1.5) higher than the Abbott results, with no difference between the methods when using EDTA plasma (mean difference =−0.1 ng/L; 95% CI=−0.3 to 0.2). Low cTnI concentrations were less effected by interferences in EDTA plasma. Conclusions: The Access hsTnI method can reliably detect normal cTnI concentrations with both lithium heparin and EDTA plasma being suitable matrices.

Comparison of Manual and Benzenesulfonyl Chloride-Semiautomated Thiochrome Methods for Determination of Thiamine in Foods

1981 ◽  
Vol 64 (3) ◽  
pp. 616-622
Author(s):  
Abdel-Gawad M Soliman
Keyword(s):  
Matrix Effects ◽  
Linear Regression Analysis ◽  
Food Products ◽  
Benzenesulfonyl Chloride ◽  
Sample Matrix ◽  
Sample Extract ◽  
Before And After ◽  
Aoac Method ◽  
Reproducible Method ◽  
Manual Methods

Abstract A semiautomated procedure was used to measure the fluorescence of sample extracts before and after the addition of benzenesulfonyl chloride (BSC). Addition of BSC inhibited thiochrome formation and provided a more representative blank based on the fluorescence of all the reactants except thiochrome. Thiamine standard was added to each sample extract so that thiamine concentration could be calculated after correcting for sample matrix effects on thiochrome fluorescence. Twenty food products were analyzed using this method, and the results were compared with those obtained using the manual AOAC method. The mean percent recoveries and standard deviations were 100.2 ± 5.3 and 101.1 ± 10.1 for the BSC-semiautomated and the AOAC manual methods, respectively. Replicate analyses using the BSC method gave an average coefficient of variation of 2.8%. Linear regression analysis showed that the BSC method gave higher values, with a mean increase of 14.8%, than those obtained using the manual method. Sixty-four percent of this difference was due to elimination of the column purification step and 36% was due to correcting for sample matrix effects on thiochrome and blank fluorescence. The BSC method provides a rapid, accurate, and reproducible method for thiamine assay in different food products, especially for those foods with low thiamine levels.

scholarly journals Revisiting the Neuroblastoma Cell-Based Assay (CBA-N2a) for the Improved Detection of Marine Toxins Active on Voltage Gated Sodium Channels (VGSCs)

Toxins ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 281 ◽  
Author(s):  
Jérôme Viallon ◽  
Mireille Chinain ◽  
Hélène Taiana Darius
Keyword(s):  
High Throughput Screening ◽  
Matrix Effects ◽  
Limit Of Detection ◽  
Neuroblastoma Cell ◽  
Consensus Protocol ◽  
Limit Of Quantification ◽  
Voltage Gated ◽  
Starting Point ◽  
Fish Samples ◽  
Seafood Products

The neuroblastoma cell-based assay (CBA-N2a) is widely used for the detection of marine biotoxins in seafood products, yet a consensus protocol is still lacking. In this study, six key parameters of CBA-N2a were revisited: cell seeding densities, cell layer viability after 26 h growth, MTT incubation time, Ouabain and Veratridine treatment and solvent and matrix effects. A step-by-step protocol was defined identifying five viability controls for the validation of CBA-N2a results. Specific detection of two voltage gated sodium channel activators, pacific ciguatoxin (P-CTX3C) and brevetoxin (PbTx3) and two inhibitors, saxitoxin (STX) and decarbamoylsaxitoxin (dc-STX) was achieved, with EC50 values of 1.7 ± 0.35 pg/mL, 5.8 ± 0.9 ng/mL, 3 ± 0.5 ng/mL and 15.8 ± 3 ng/mL, respectively. When applied to the detection of ciguatoxin (CTX)-like toxicity in fish samples, limit of detection (LOD) and limit of quantification (LOQ) values were 0.031 ± 0.008 and 0.064 ± 0.016 ng P-CTX3C eq/g of flesh, respectively. Intra and inter-assays comparisons of viability controls, LOD, LOQ and toxicity in fish samples gave coefficients of variation (CVs) ranging from 3% to 29%. This improved test adaptable to either high throughput screening or composite toxicity estimation is a useful starting point for a standardization of the CBA-N2a in the field of marine toxin detection.

Determination of ketamine and norketamine in hair and evaluation of polydrug use in ketamine abusers using hair analysis in Korea

2020 ◽  
Author(s):  
Jongsook Rhee ◽  
Jihyun Kim ◽  
Moonhee Jang ◽  
Ilchung Shi ◽  
Sangki Lee
Keyword(s):  
Mass Spectrometry ◽  
Matrix Effects ◽  
Limit Of Detection ◽  
Gas Chromatography Mass Spectrometry ◽  
Controlled Drugs ◽  
Hair Samples ◽  
Limit Of Quantitation ◽  
Liquid Chromatography Tandem Mass ◽  
Forensic Service

Abstract This study evaluated hair samples from 28 subjects who had measurable ketamine levels among the samples requested from 2016 to 2017 into Seoul Institute National Forensic Service in Korea. Ketamine in the hair was extracted by using a solution of 1% hydrochloric acid in methanol for 16 h. Extracts were analyzed using gas chromatography mass spectrometry (GC-MS) or liquid chromatography tandem mass spectrometry (LC-MS-MS). LC-MS-MS method was validated by determining the limit of detection (LOD), limit of quantitation (LOQ), linearity, intra- and inter-accuracy, precision, and matrix effects. In 59 ketamine-positive hair or hair segments from 28 ketamine abusers, the ketamine concentration was found to be in the range of 0.011-335.8 ng/mg (mean, 13.6; median, 1.8), and the norketamine concentration was found to be in the range of 0.001-35.7 ng/mg (mean, 7.5; median, 0.44). The ratio of norketamine to ketamine concentration in hair was in the range of 0.01-1.46 (mean, 0.34; median, 0.26). The distribution of ketamine concentration in hair samples was as follows: 0.01-0.1 ng/mg in 11 samples (18.6%), 0.1-5 ng/mg in 33 samples (55.9%), 5-10 ng/mg in 4 samples (6.8%), 10-15 ng/mg in 2 samples (3.4%), 15-20 ng/mg in 4 samples (6.8%), 40-45 ng/mg in 2 samples (3.4%), 45-50 ng/mg in 1 samples 1.7%) and &gt;100 ng/mg in only 2 samples (3.4%). In the hair of ketamine-abusers, 26 of 28 subjects had simultaneously ketamine with detectable levels of other controlled drugs, including MDMA (n=9), MA (n=3), MDMA/MA (n=3), MDMA/PMA (n=3), MDMA/PMA/MA (n=2), cocaine (n=1), and other drugs (n=5, propofol, zolpidem or benzodiazepines). In most of the hair samples were detected ketamine with other controlled drugs: MDMA (60.7%), MA (28.6%), PMA(17.9%), zolpidem (17.9%), and propofol (14.3%) in the frequency of abuse. In conclusion, most of the ketamine-abusers (92.9%) would be polydrug abusers, who were concomitantly abusing other controlled substances.

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.

scholarly journals Single-Laboratory Validation of the Biosense Direct Competitive Enzyme-Linked Immunosorbent Assay (ELISA) for Determination of Domoic Acid Toxins in Shellfish

2007 ◽  
Vol 90 (4) ◽  
pp. 1000-1010 ◽  
Author(s):  
Hans Kleivdal ◽  
Sven-Inge Kristiansen ◽  
Mona V Nilsen ◽  
Lyn Briggs
Keyword(s):  
Immunosorbent Assay ◽  
Domoic Acid ◽  
Matrix Effects ◽  
Limit Of Detection ◽  
Method Comparison ◽  
Cross Reactivity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Shellfish Poisoning ◽  
Relative Standard

Abstract Method validation was conducted for an enzyme-linked immunosorbent assay (ELISA) for the determination of domoic acid (DA) toxins, known to give amnesic shellfish poisoning (ASP) symptoms, in shellfish. The calibration curve range of the assay is approximately 10260 pg/mL, with a dynamic working range for DA toxins in shellfish from 0.01 to at least 250 mg/kg. The ASP ELISA showed no significant cross-reactivity to structural analogs, and proved to be robust to deliberate alterations of the optimal running conditions. The shellfish matrix effects observed with mussels, oysters, and scallops were eliminated by diluting shellfish extracts 1:200 prior to analysis, leading to a limit of detection at 0.003 mg/kg. Thirteen blank shellfish homogenates were spiked with certified mussel material containing DA to levels in the range of 0.125 mg DA/kg, and analyzed in quadruplicate on 3 different days. The relative standard deviation (RSD) under intra-assay repeatability conditions ranged from 6.5 to 13.1%, and under interassay repeatability conditions the RSD ranged from 5.7 to 13.4%, with a mean value of 9.3%. The recoveries ranged from 85.5 to 106.6%, with a mean recovery of 102.2%. A method comparison was conducted with liquid chromatography with ultraviolet detection, using naturally contaminated scallop samples (n = 27) with DA levels at 0244 mg/kg. The overall correlation coefficient was 0.960 and the slope of the regression was 1.218, indicating a good agreement between the methods.

Alpha-Methylfentanyl and Beta-Hydroxyfentanyl LC–MS-MS Quantification in Rat Plasma after Long-Term Ethanol Exposure

2020 ◽  
Vol 44 (8) ◽  
pp. 896-904
Author(s):  
Lihong Lyu ◽  
Rui Chen ◽  
Lu Li ◽  
Hongbin Duan ◽  
Yao Chen ◽  
...  
Keyword(s):  
Illicit Drug ◽  
Matrix Effects ◽  
Limit Of Detection ◽  
Multiple Reaction Monitoring ◽  
Plasma Concentrations ◽  
Rat Plasma ◽  
Ethanol Exposure ◽  
Pharmacokinetic Parameters ◽  
Control Group ◽  
Science Field

Abstract Fentanyl and its analogues are highly abused drugs that dominate the illicit drug trade. alpha-Methylfentanyl (A-F) and beta-hydroxyfentanyl (B-F) are two fentanyl analogues that require the development of rapid detection technologies. The current study established and validated a rapid and high-sensitivity liquid chromatography–tandem mass spectrometry (LC–MS-MS) method to measure A-F and B-F concentrations in rat plasma following intravenous drug administration (20 μg/kg). Because fentanyl is primarily metabolized by the liver, we evaluated the concentrations of A-F and B-F in vivo in rats, in a control group and a group with liver damage induced by 55 days of oral ethanol gavage (6.5 g/kg, 22.5% v/v). Liquid–liquid extraction and LC–MS-MS operating in the positive ion multiple reaction monitoring mode were used. A C18 column was used, and the mobile phase consisted of 0.1% formic acid aqueous and acetonitrile. The limit of detection was 3 pg/mL (S/N &gt; 5) for A-F and B-F. The calibration curves were linear within the concentration range of 0.01–5 ng/mL (R2 = 0.9991) and 0.005–20 ng/mL (R2 = 0.9999) for A-F and B-F, respectively. Extraction recoveries were 91.3%–97.6% with RSD ≤ 11.2% and 90.5%–94.3% with RSD ≤ 10.5% for A-F and B-F, respectively. Plasma matrix effects were 80.61%–84.58% for A-F and 80.67%–81.33% for B-F with RSD ≤ 13.9%. The validated assay indicated no significant differences in pharmacokinetic parameters (AUC0-t, Cmax and T1/2) derived from the assessment of A-F and B-F plasma concentrations between control and ethanol-exposed rats. This assay, for which the LOD was 3 pg/mL for A-F and B-F may help the forensic science field to determine fentanyl analogue-related causes of death and identify illicit drug tampering.

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