Quality assurance of chemical measurements

Taylor, John Κ.

doi:10.1021/ac00237a001

Cited by 228 publications

(189 citation statements)

References 3 publications

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“…The LOD and LOQ for determination of 1-hydroxypyrene by this method were calculated as 3.3S 0 and 10S 0 respectively [22], where S 0 is the standard deviation from the analysis of eight artificial urine samples spiked at a concentration at 20 ng/L.…”

Section: Limit Of Detection (Lod) and Limit Of Quantitation (Loq)-mentioning

confidence: 99%

1,2-Dimethylimidazole-4-sulfonyl chloride, a novel derivatization reagent for the analysis of phenolic compounds by liquid chromatography electrospray tandem mass spectrometry: Application to 1-hydroxypyrene in human urine

Spink

2007

Journal of Chromatography B

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A novel derivatization method employing 1,2-dimethylimidazole-4-sulfonyl chloride (DMISC) to improve the mass spectrometric response for phenolic compounds in liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) and tandem mass spectrometry (LC-ESI-MS/MS) is described. Several environmentally relevant compounds, including chloro-, aryl-and alkylphenols, steroidal estrogens, and hydroxy-polycyclic aromatic hydrocarbons (OHPAHs), were selected to evaluate this technique. A facile derivatization procedure employing DMISC results in dimethylimidazolesulfonyl (DMIS) derivatives that are stable in aqueous solution. These DMIS derivatives produced intense [M+H] + ions in positive-ion LC-ESI-MS. The product ion spectra of the [M+H] + ions of simple phenols were dominated by ions representing the DMIS and dimethylimidazole moieties, whereas product ion spectra of the DMIS derivatives of OHPAHs with three or more fused aromatic rings showed prominent ArO + ions, the relative intensity of which increased with the number of rings. The DMIS derivatives of the selected phenolic compounds showed excellent chromatographic properties. To substantiate the utility of derivatization with DMISC, an analytical method employing enzyme hydrolysis, solid phase extraction, derivatization with DMISC, and analysis by LC-ESI-MS/MS with multiple reaction monitoring for determination in human urine of 1-hydroxypyrene, a widely used biomarker for the assessment of human exposure to PAHs, was developed and validated.

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Section: Limit Of Detection (Lod) and Limit Of Quantitation (Loq)-mentioning

confidence: 99%

1,2-Dimethylimidazole-4-sulfonyl chloride, a novel derivatization reagent for the analysis of phenolic compounds by liquid chromatography electrospray tandem mass spectrometry: Application to 1-hydroxypyrene in human urine

Spink

2007

Journal of Chromatography B

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“…QA includes promoting, monitoring, and evaluating the overall laboratory testing process. QA is typically accomplished by auditing the test management (e.g., collecting and identifying specimen and reporting test results), quality control, and personnel performance and training [18].…”

Section: Quality Assurance and Quality Controlmentioning

confidence: 99%

“…Taylor method (LOD=3S 0 , where S 0 is the extrapolated standard deviation [SD] as the concentration of the analyte approaches zero based on a series of measurements at low concentrations plotted against their calculated SDs) when the need to estimate the false-negative rate is remote or when the assay is used infrequently [18]. Several different approaches exist to estimate laboratory test results below the LOD (<LOD) that can be used to derive population estimates, such as a reference interval.…”

Section: Lodmentioning

confidence: 99%

Analytical Considerations in the Clinical Laboratory Assessment of Metals

2014

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The presence of metals in the environment is ubiquitous and humans are constantly being exposed to them. As such, a general concern exists about potential health consequences that result from the exposure to metals. The continued efforts of environmental scientists to measure metals in clinical specimens are important for defining the extent of human exposure to these chemicals. Laboratory methods to measure the concentration of metals in human blood or urine are available, and they can be used to assess the extent of human exposure to these chemicals. However, several considerations should be reviewed when requesting a laboratory measurement of metals because some factors can affect the test result or its interpretation. These considerations are discussed in this article and include pre-analytical, analytical, and postanalytical factors. Clinicians with this knowledge will be able to request these laboratory tests for their patients with enhanced confidence.

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“…Calibrants at 80, 800, 2000, and 8000 nM (ϳ15 to 1500 ng/mL) for all analytes, and at 8 nM (1.8 ng/mL) for BHETEE only were found to have individual accuracies between 89% and 113% and individual run-to-run precision Ͻ15% RSD for all transitions. For quantitative analysis at ultra-trace levels, these accuracies°and°precisions°are°considered°acceptable° [43].°Fig-ures of merit were roughly estimated from a few experiments rather than rigorously determined because our only intent was to assess the feasibility of developing a quantitative mass spectrometry method predicated on the superoxide adduct rather than to perform a complete validation. Limitations of this report therefore include the low number of quantitative experiments performed, the lack of internal standards and the number and distribution of calibrants across a wide dynamic range.…”

Section: Evaluation Of Superoxide Adduct For Quantitative Analysismentioning

confidence: 99%

“…This result illustrates the exceptional response of BHETEE compared with the other analytes. For the purposes of this report, the instrument limit of detection (LOD) and limit of quantitation (LOQ) were calculated as 3S 0 and 10S 0 , respectively, where S 0 is "the value of the standard deviation°as°the°concentration°approaches°zero"° [43].°S 0 was estimated at 95% CL as the y-intercept of the linear regression of the estimated standard deviations of three calibrators°versus°their°expected°concentrations° [43]. LODs based on S 0 estimated from this method agree with the experimental results in that the calculated LODs are between the lowest calibrator that was accurately measured and the lowest calibrator analyzed, but not°detected.°For°brevity,°the°data°presented°in°Table°3 represents figures of merit for observations derived from the product of four analyses and three precursor/ product ion transitions.…”

Section: Evaluation Of Superoxide Adduct For Quantitative Analysismentioning

confidence: 99%

Mass spectral behavior of the hydrolysis products of sesqui- and oxy-mustard type chemical warfare agents in atmospheric pressure chemical ionization

Lemire

Ash

Johnson

et al. 2007

J. Am. Soc. Mass Spectrom.

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Bis(2-hydroxyethylthio)alkanes and bis(2-hydroxyethylthioalkyl)ethers are important biological and environmental degradation products of sulfur mustard analogs known as sesqui-and oxy-mustards. We used atmospheric pressure chemical ionization mass spectrometry (APCI MS) to acquire characteristic spectra of these compounds in positive and negative ionization modes. Positive APCI mass spectra exhibited and [M -3H] Ϫ ; and both positive and negative APCI mass spectra contained fragment ions due to in-source collision-induced dissociation. Product ion scans confirmed the origin of fragment ions observed in single-stage MS. Although the spectra of these compounds were very similar, positive and negative APCI mass spectra of the oxy-mustard hydrolysis product, bis(2-hydroxyethylthiomethyl)ether, differed from the spectra of the other compounds in a manner that suggested a rearrangement to the sesqui-mustard hydrolysis product, bis(2-hydroxyethylthio)methane. We evaluated the [M ϩ O 2 ] Ϫ adduct ion for quantification via liquid chromatography-MS/MS in the multiple-reaction monitoring (MRM) mode by constructing calibration curves from three precursor/product ion transitions for all the analytes. Analytical figures of merit generated from the calibration curves indicated the stability and suitability of these transitions for quantification at concentrations in the low ng/mL range. Thus, we are the first to propose a quantitative method predicated on the measurement of product ions generated from the superoxide adduct anion of the sesqui-and oxy-mustard hydrolysis products. [5,6]. More specifically, the sesqui-mustard 1,2-bis(2-chloroethylthio)ethane (Agent Q) and the oxy-mustard bis(2-chloroethylthioethyl)ether (Agent T) are major components in the weapons-grade munitions designated HQ and HT, respectively [7]. As vesicants, these compounds are two to five times more potent than HD [8] with estimated human LC 50 -time relationships for inhalation exposure of 300 mg-min/m 3 (Agent Q) and 400 mgmin/m 3 (Agent T) [9] compared with 1500 mg-min/m 3 (HD) [10]. Thus, although the biological effects of exposure to HQ and HT are similar to those observed for HD, the presence of Agent Q or T increases the activity of these mixtures [10]. Sesqui-and oxymustards are a public health concern because of the risk of exposure to personnel involved in the destruction of chemical weapon stockpiles or to victims of a terrorist or military attack involving these agents.The biological fate of HD has been extensively studied [11][12][13][14][15] and three metabolic pathways: glutathione conjugation followed by ␤-lyase metabolism, hydrolysis, and direct oxidation at the sulfur atom, have been elucidated and are believed to be responsible for the HD metabolites excreted in urine [13]. Likewise, environmental degradation of HD has been well characterized [5,16] and occurs primarily through hydrolysis to form thiodiglycol (TDG) and oxidation to form sulfoxides and sulfones [17]. Although the fate of sesqui-and oxy-mustards has not been as exten...

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Quality assurance of chemical measurements

Cited by 228 publications

References 3 publications

1,2-Dimethylimidazole-4-sulfonyl chloride, a novel derivatization reagent for the analysis of phenolic compounds by liquid chromatography electrospray tandem mass spectrometry: Application to 1-hydroxypyrene in human urine

1,2-Dimethylimidazole-4-sulfonyl chloride, a novel derivatization reagent for the analysis of phenolic compounds by liquid chromatography electrospray tandem mass spectrometry: Application to 1-hydroxypyrene in human urine

Analytical Considerations in the Clinical Laboratory Assessment of Metals

Mass spectral behavior of the hydrolysis products of sesqui- and oxy-mustard type chemical warfare agents in atmospheric pressure chemical ionization

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