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Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.12, #9)


Improving the quality of potentiometric pH measurements by M. J. Guiomar; H. M. Lito; M. Filomena Camões; Catarina M. Viçoso (pp. 447-453).
Like all experimentally determined physical and chemical properties, pH measurements are affected by the limited precision and accuracy of the measurement procedures. Fundamental studies of pH standards, based on measurement of the potential of an electrochemical cell without transference, known as the Harned cell, containing a platinum–hydrogen electrode and a silver–silver chloride reference electrode, indicate that vapour condensation phenomena on potentiometric cell walls not immersed in the thermostatic bath are a major source of error in assessment of pH values. In this work a study was conducted on phthalate buffer, 0.05 mol kg−1 KHPhth, and results are reported for the effect of this phenomenon on the assignment of pH values and on their corresponding uncertainties. Identification and quantification of this effect constitute an original contribution to improvement of the primary method of pH measurement and, therefore, more rigorous pH (PS) values.

Keywords: pH measurement; Evaporation–condensation phenomena; Uncertainty components; Traceability chain


Underestimation of total arsenic concentration in groundwater samples determined by hydride generation quartz furnace atomic absorption spectrometry due to sample characteristics by A. Ramesh Kumar; P. Riyazuddin (pp. 455-458).
Total arsenic concentrations in groundwater samples determined by hydride generation quartz furnace atomic absorption spectrometry may underestimated due to a loss of quartz cell surface “conditioning.” This loss of quartz cell surface “conditioning” is due to the analysis of many samples that do not contain measurable quantities of the analyte. This process is further accelerated by the use of high concentrations of sodium tetrahydroborate and hydrochloric acid. Analysis of the highest calibration standard in between the samples and the use of low concentrations of sodium tetrahydroborate and hydrochloric acid could minimize the error arising from this source.

Keywords: Hydride generation atomic absorption spectrometry; Arsenic determination; Ground water; Conditioning of quartz cell


An international intercomparison for 19-norandrosterone in human urine: the Comité Consultatif pour la Quantité de Matière (CCQM) Pilot Study CCQM-P68 by Lindsey G. Mackay; Daniel Burke; Michael J. Welch; Susan Tai; Chris Mussell; Gavin O’Connor; Della Sin; Cheng Wing-chi (pp. 459-464).
Under the auspices of the Comité Consultatif pour la Quantité de Matière (CCQM) a laboratory intercomparison, CCQM-P68, was co-ordinated by the National Measurement Institute of Australia (NMIA) in 2005 involving the analysis of the steroid 19-norandrosterone (19-NA) in human urine. 19-NA is the major metabolite of nandrolone, a commonly abused anabolic agent. It is routinely tested by many sports drug testing laboratories and several national metrology institutes have developed reference methods to provide reference values for the certification of reference materials. The material distributed for the intercomparison was a freeze-dried human urine candidate reference material containing 19-NA at a level close to the allowed World Anti-Doping Agency (WADA) cut-off for this anabolic agent, i.e. 2 ng/ml. Four national/designated metrology institutes participated in the intercomparison and their results for this complex analysis were in excellent agreement, with a relative standard deviation (RSD) of only 1.7%. The expanded uncertainties at the 95% level of confidence for the reported results ranged from 3.7 to 7.0% at the 2.15 ng/g level.

Keywords: Steroids; Nandrolone; 19-norandrosterone; Urine; Laboratory intercomparison; Reference method


Determination of 19-norandrosterone in CCQM-P68. NIST results using an isotope dilution liquid chromatography/tandem mass spectrometry method by Susan S. -C. Tai; Bei Xu; Michael J. Welch (pp. 465-468).
The US National Institute of Standards and Technology (NIST) participated in an international interlaboratory study under the auspices of the Consultative Committee for Amount of Substance (CCQM) for the determination of 19-norandrosterone (19-NA) in urine, the principal metabolite of nandrolone and certain other synthetic testosterone substitutes banned for use by the World Antidoping Agency (WADA). Prior to this study, NIST developed a candidate reference measurement procedure based upon isotope dilution liquid chromatography/tandem mass spectrometry. This method was applied to a urine sample distributed to the participants in the study by the Australian National Measurement Institute, Pymble, Australia (NMIA). The NIST results were in very good agreement with those from the other participants, all of whom used methods based upon gas chromatography/mass spectrometry. All known significant sources of uncertainty were evaluated, resulting in a relative expanded uncertainty of less than 5% (coverage factor k = 2).

Keywords: 19-Norandrosterone (19-NA); Urine; Isotope dilution; Liquid chromatography/tandem mass spectrometry (LC/MS/MS); CCQM; Laboratory intercomparison


Analysis of 19-norandrosterone in human urine by gas chromatography–isotope-dilution mass spectrometry: method adopted by LGC for participation in the Comité Consultatif pour la Quantité de Matière (CCQM) Pilot Study P68 by Chris Mussell; Céline S. J. Wolff Briche; Chris Hopley; Gavin O’Connor (pp. 469-474).
The method used at LGC for analysis of “total” 19-norandrosterone (19-norandrosterone glucuronide plus “free” 19-norandrosterone) in urine for the Comité Consultatif pour la Quantité de Matière Pilot Study (CCQM-P68) is described. The analytical method used was a modified version of the method developed at the National Measurement Institute of Australia, which used a hydrolysis and derivatisation procedure first described by the German Sports University. This method is routinely used by World Anti-Doping Agency-accredited laboratories for sports drug testing. The main modifications made to the method were the use of 19-norandrosterone glucuronide as a calibration standard and 19-norandrosterone glucuronide-d4 as an isotopically labelled internal standard, and the use of a bench-top quadrupole gas chromatograph–mass spectrometer. The results produced by LGC (2.14 ± 0.15 ng g−1 expanded uncertainty, coverage factor k = 2) were in excellent agreement with those from other participating national metrology institutes and thus further validates the exact-matching isotope-dilution mass spectrometric procedures used at LGC for a wide range of reference measurement applications, including measurement of ng g−1 levels of steroids in a biological matrix.

Keywords: Isotope-dilution mass spectrometry; Nandrolone in urine; Norandrosterone; Norandrosterone glucuronide; Reference method; Steroids


A high-accuracy method of analysis of 19-norandrosterone in human urine as utilised for the international laboratory intercomparison CCQM-P68 by Lindsey G. Mackay; Daniel Burke; Fong-Ha Liu; Nigel Sousou; Veronica V. Vamathevan; Judy Cuthbertson; Chris Mussell; Richard B. Myors (pp. 475-482).
A high-accuracy exact-matching isotope dilution mass spectrometry (IDMS) method for 19-norandrosterone (19-NA) in human urine was developed at NMIA for the certification of a freeze-dried human urine reference material (CRM NMIA MX002). The method utilised GC/HRMS analysis following hydrolysis, solvent extraction, HPLC fractionation and derivatisation. The method development included investigation of all potential analytical biases for the different stages of the method and included development of a confirmatory LC/MS/MS method. The measurement uncertainty of the reference method was rigorously investigated with the achieved expanded uncertainty being less than 4% at the 95% level of confidence. The method was used in the Comité Consultatif pour la Quantité de Matière (CCQM) pilot study CCQM-P68 which was an interlaboratory intercomparison for the analysis of 19-NA in human urine in which four national metrology institutes (NMIs) participated in. The agreement in the results from the NMIA method with those from the other NMIs was excellent.

Keywords: Steroids; Nandrolone; 19-Norandrosterone; Urine; Reference method; Isotope dilution mass spectrometry; Certified reference material


Determination of 19-norandrosterone in human urine by isotope dilution gas chromatography-high resolution mass spectrometry by Wing-Chi Cheng; Tsan-Sang Yau; Wai-Nang Cheng; Kok-Choi Cheng; Della Wai-Mei Sin (pp. 483-490).
An accurate and precise method for the determination of total 19-norandrosterone (19-NA), a major metabolite of nandrolone, in human urine was developed based on isotope dilution gas chromatography-high resolution mass spectrometry (ID GC-HRMS). The 19-NA glucuronide, together with deuterated 19-NA (d4-19-NA) (as the internal standard, IS), was subjected to enzymatic hydrolysis using β-glucuronidase, followed by solid phase extraction (XtractT, mixed-mode column) and liquid–liquid extraction cleanup. The native and deuterated analogues of 19-NA were then derivatised to the corresponding bis(trimethylsilyl) derivatives using N-methyl-N-trimethylsilyltrifluoroacteamide (MSTFA):NH4I:Dithiothretitol (1,000:2:3 w/w). Identification was achieved under selected ion monitoring of the respective trimethylsilyl derivatives at ion masses m/z 405.26450 and 420.28800 for 19-NA and m/z 409.28920 and 424.31270 for d4-19-NA within the specific time windows (±1% of the relative retention time to the calibration standard). A linear calibration curve (r 2 > 0.9995) was obtained based on seven calibration points (five replicates at each level) in the range 0.05–10 ng/g. The detection limit for 19-NA was found to be 4 pg/g. The method has been applied for the determination of 19-NA by fortifying 19-NA glucuronide at three concentrations (0.2, 2.1 and 7.2 ng/g) in blank urine samples with excellent accuracy and reproducibility. To circumvent the iterative process of exacting matching, a single-point calibration procedure was adopted, where the acceptance criteria for the isotopic ratio in the sample (RF s) and calibration blends (RF c) was set close to unity (0.95–1.05). This method was successfully applied in a pilot inter-comparison study, with results in good agreement with the fortified value and other participants’ results (relative standard deviation, RSD < 2.0%) with an expanded relative uncertainty (coverage factor of 2 at 95% confidence level) of 4.7%. It was found in our determination that the main contributors to the uncertainty budget originated from the measurements of the purity of the reference material and the response factor of the calibration standard.

The WADA Proficiency Testing Program as an integral part of the fight against doping in sport by Victoria Ivanova; Thierry Boghosian; Olivier Rabin (pp. 491-493).
This article provides a brief perspective of the World Anti-Doping Agency (WADA) in the context of the fight against doping in sport and of the WADA Proficiency Testing Program as an essential element of the World Anti-Doping Program. The WADA Proficiency Testing Program exists within the framework of the WADA-accredited laboratories and is aimed at improving the effectiveness of the fight against doping by testing the ability of the laboratories to reliably identify and measure the substances and methods defined in the WADA Prohibited List. The paper provides an overview of the WADA Proficiency Testing scheme with respect to organization, test composition and evaluation of anti-doping methods and techniques. Scientific research is mentioned in the context of WADA’s involvement in generating reference materials for improvement of analytical activities of the WADA-accredited laboratories. WADA’s funding of a reference material for 19-norandrosterone in human urine is illustrated as an example.

Keywords: Accreditation; Anti-doping; Proficiency testing; WADA

A forgotten fact about the standard deviation by Matthias Roesslein; Marco Wolf; Bruno Wampfler; Wolfhard Wegscheider (pp. 495-496).
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