Expanded Uncertainty Research Articles

A Method for Estimating the Resultant Expanded Uncertainty Value Based on Interval Arithmetic

The article describes a method for determining the resultant expanded uncertainty value in the case of analyzing an uncertainty budget with many components. It employs interval arithmetic, known for its low calculation complexity compared to other methods in the literature. The article includes a detailed explanation of the proposed method and showcases its applications. Results are compared with those from the Monte Carlo method and assumptions based on the central limit theorem. The relative error in estimating the resulting expanded uncertainty value typically stays within ±5% of the Monte Carlo method’s result.

Development and validation of LC-MS/MS method for trace analysis of acrylamide, acrylic acid and N, N-methylene bis acrylamide in sandy loam soil

Acrylamide and N, N-methylene bis acrylamide are most commonly used monomer and crosslinker compounds employed in synthesis of super absorbent hydrogels. When applied as soil conditioners, there are apprehensions that these hydrogels degrade over time and thus may release the toxic monomers in the soil. A method was thus developed using Liquid Chromatography tandem mass spectrometry (LC-MS/MS) for the trace level quantification of acrylamide (AD), acrylic acid (AA) and N,N-methylene-bis-acrylamide (MBA) in sandy loam soil amended by two test hydrogels the Pusa Hydrogel and SPG 1118 hydrogel prepared using AD and MBA. The MRM (multiple reaction monitoring) transitions were optimized for both the compounds. Soil samples were extracted using dispersive solid-phase extraction (dSPE) with a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) technique, employing acetonitrile. All analytes were quantified at trace levels within a five-minute run using UHPLC equipped with a C-18 column.Single laboratory validation of the developed method in soil matrix was conducted based on specificity, linearity, sensitivity, accuracy, precision, matrix effect and measurement of uncertainty. LC-MS/MS exhibited a linear response in the concentration range of 0.001 to 1 µg mL−1, with correlation coefficient >+0.99. Acceptable recovery (within 70–120 %) with repeatability (%RSD ≤20 %) was obtained at 0.01 to 1 µg g–1 fortification levels. LOQ (Limit of quantification) of the method for AD, AA and MBA in soil matrix were 0.05, 1 and 0.01 µg g–1, respectively. Both intra-laboratory repeatability and intermediate precision at LOQ suggested well acceptable precise (HorRat≈ 0.3) method for quantification. Matrix enhancement effect was observed in the order: AA>AD>MBA. The Expanded Uncertainty (EU) in soil matrix at LOQ was 21.64 %, 28 % and 19 % for AD, AA and MBA respectively. Groundnut and wheat grown with application of the hydrogels showed no detectable residues of monomers in soil samples (total n = 60) near the root zone at the time of crop harvesting.

Estimation of the Resultant Expanded Uncertainty of the Output Quantities of the Measurement Chain Using the Discrete Wavelet Transform Algorithm

This paper discusses the role of the discrete wavelet transform algorithm in processing error signals present in the input quantities of the algorithm. In considering the error model of the measurement chain, the parameters of the error signals in the input quantities of the wavelet transform algorithm are estimated. Subsequently, in accounting for the algorithm’s properties, the parameters of its output values are determined, and the resulting uncertainty values of the output quantities of the measurement chain are estimated. The interval reduction arithmetic method is employed in the calculations for estimating the expanded uncertainty. All findings were validated through measurements conducted using the implemented measurement chain.

Utilization of a High-Pressure Vibrating Tube Densimeter for Liquids at Temperatures Down to 100 K

A high-pressure vibrating tube densimeter, specified by the manufacturer for temperatures from (263 to 473) K at pressures up to 140 MPa, was tested at temperatures down to 100 K and from vacuum to pressures up to 10 MPa. To verify the functionality and overall performance under these conditions, the densimeter was calibrated with measurements under vacuum as well as methane and propane as reference fluids. The calibration range is T = (120 to 200) K at pressures from (2.0 to 10.0) MPa. To evaluate the recorded data, two established calibration models were used to describe the dependence of the densimeter's oscillation period on the investigated reference fluids' temperature, pressure, and density. The experiments showed that the vibrating tube densimeter is operational even at temperatures down to 100 K, but exhibits a shift of its vacuum resonance when subjected to thermal cycling at temperatures below 180 K. Accordingly, the calibration models were modified with respect to how the vacuum resonance is considered. Then, the determined calibration parameters reproduce the densities of the reference fluids within ± 0.10 kg·m−3 for the calibration model that performed better for the present study. Measurements on pure ethane and argon validate the calibration of the densimeter. Here, the densities are within (− 0.47 to 0.16) kg·m−3 of values calculated with the respective reference equation of state. The estimated combined expanded uncertainty (k = 2) in density for the validation measurements ranges from (0.52 to 1.13) kg·m−3 or is less than 0.1 % for liquid densities.

Investigations of Flow Boiling in Mini-Channels: Heat Transfer Calculations with Temperature Uncertainty Analyses

The article aims to explore boiling heat transfer in mini-channels with a rectangular cross-section using various fluids (HFE-649, HFE-7000, HFE-7100, and HFE-7200). Temperature measurements were conducted using infrared thermography for the heated wall and K-type thermocouples for the working fluid. The 2D mathematical model for heat transfer in the test section was proposed. Local heat transfer coefficients between the heated wall and the working fluid were determined from the Robin condition. The problem was solved by means of the finite element method (FEM) with Trefftz functions. The values of the heat transfer coefficient that were obtained were compared with the results calculated from Newton’s law of cooling. The average relative differences between the obtained results did not exceed 4%. The study included uncertainty analyses for temperature measurements with K- and T-type thermocouples. Expanded uncertainties were calculated using the uncertainty propagation and Monte Carlo methods. Precisely determining the uncertainties in contact temperature measurements is crucial to ensure accurate temperature data for subsequent heat transfer calculations. The results of the heat transfer investigations were compared in terms of fluid temperature, heat transfer coefficients, and boiling curves. HFE-7200 consistently exhibited the highest fluid temperature and temperature differences at boiling incipience, while HFE-7000 demonstrated the highest heat transfer coefficients. HFE-649 showed the lowest heat transfer coefficients. The boiling curves exhibited a typical shape, with a notable occurrence of ‘nucleation hysteresis phenomena’. Upon the analysis of two-phase flow patterns, bubbly and bubbly-slug structures were observed.

Metrological characteristic of the pipette method (GOST 12536-2014) for determining soil granulometric composition

The aim of the study. To calculate precision indicators (repeatability and reproducibility) and uncertainty in determining the granulometric (grain) composition of soils using the pipette method. Methods. Using the pipette method the content of the following granulometric fractions was determined in soil samples: 0,1–0,05 mm, 0,05–0,01 mm, 0,01–0,005 mm, 0,005–0,002 mm, 0,002–0,001 mm, less than 0,01 mm, less than 0,001 mm. The determination of pH of the salt extract was carried out by potentiometric technique, and organic matter was measured photometrically. For each aliquot of the sample 16 single measurements were obtained for each soil fraction. Based on these data, precision indicators were assessed under conditions of intra-laboratory repeatability and reproducibility, uncertainty indicators were assessed as well. Main results. The following intralaboratory quality indicators were obtained for the method of determining the granulometric (grain) composition of soils using the pipette method: 1) The value of the intralaboratory repeatability indicator of analysis results (σr) ranged 0,4–1,8%. 2) The relative indicator of intralaboratory precision (σR) was within the 0,7–2,9% range. 3) Expanded uncertainty (U) for different soil fractions ranged from 0,9 to 3,9%. Conclusions. The calculated metrological characteristics of determining the granulometric (grain) composition of soils using the pipette method facilitates the internal control of the measurements quality, promoting the quality and confidence in the laboratory work.

Supplementary comparison on a platinum resistance thermometer calibration from -70 °C to 250 °C

Main textThis supplementary comparison was about the calibration of platinum resistance thermometers in the range of -70 °C to 250 °C. Four laboratories participated in the comparison: Emirates Metrology Institute (EMI) from United Arab Emirates, SASO-NMCC from Saudi Arabia, QGOSM from Qatar and Tubitak UME from Türkiye. These Institutes are full or associated (Tubitak UME) members of the GULFMET Regional Metrology Organization.The pilot institute was Emirates Metrology Institute, who also provided the two transfer platinum resistance thermometers and monitor their stability during the comparison.The measurements of the comparison were performed between April 2019 and February 2021 and the circulation of the instruments was without problems, except for a delay of four months between the laboratories QGOSM and EMI due to the Coronavirus pandemic.The weighted mean of the measurements from all laboratories was used to produce the W ratios and R 0.01 reference values of the thermometers and no laboratory was excluded from this weighted mean. Note that this comparison is an RMO supplementary comparison, so the weighted mean values generated are used only as a baseline for reporting the results, and they have no particular meaning of reference values in the sense of the key comparisons.The results show a satisfactory agreement between the participating laboratories (|En| <1), except for two set-points: -35 °C and 100 °C, for one of the two transfer thermometers, for one of the laboratories. Combined expanded uncertainties for R 0.01 were equivalent to about 0.004 °C for the laboratories using water triple point cells as a reference, and 0.010 °C for QGOSM laboratory using ice point as reference. For the other measurement points, R values, were having equivalent combined expanded uncertainties ranging from 0.0060 °C to 0.010 °C for UME, 0.008 °C to 0.016 °C for EMI, 0.012 °C to 0.024 °C for SASO-NMCC and 0.014 °C to 0.054 °C for QGOSM. The mentioned uncertainties refer to the most stable of the transfer thermometers used in the comparison.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Isochoric bubble point data for binary systems of 1 (ethane) in 2 (decane, undecane, dodecane and tridecane)

In this communication, a new set of vapour liquid equilibrium (bubble point) data were obtained for ethane-decane, ethane-undecane, ethane-dodecane and ethane-tridecane binary systems. The datasets were obtained using constant-volume (isochoric) method. The datasets cover temperatures from 260 to 373 K and pressures from 0.6 to 10 MPa for all binary systems. A total of five compositions were studied for each of the binary systems ranging from ethane rich compositions to compositions rich in decane, undecane, dodecane and tridecane respectively. Datasets obtained were used to adjust the binary interaction parameters (BIP) for Peng-Robinson (PR), Perturbed Chain Statistical Associating Fluid Theory (PC-SAFT) and the Multi-Fluid Helmholtz Energy Approximation (MFHEA) equations of state (EoS). Quadratic temperature dependent BIP functions were obtained for PR-EoS using a combination of datasets from this work and those published in the literature for the ethane-decane and ethane-dodecane binary systems. Correlation of the datapoints from this work with the PR-EoS, PC-SAFT-EoS and MFHEA EoS yielded very low average absolute deviations (AADs) of less than 5 % for all the datasets. Expanded uncertainties associated with each of the bubble point temperatures and pressures obtained are also reported at 95 % confidence interval. Expanded uncertainties in all the compositions studied were found to be less than 0.002 at 95 % confidence interval.

The CM–CRDS Method for Measuring the Carbon Isotope Ratio in Vanillin With an Expanded Uncertainty of Less Than 0.1 %

The CM–CRDS Method for Measuring the Carbon Isotope Ratio in Vanillin With an Expanded Uncertainty of Less Than 0.1 %

A Fast Method for Determination of Ethylene Oxide Using Gas Chromatography Coupled with Mass Spectrometry GC-MS/MS

The ongoing influx of information regarding the presence of ethylene oxide in food requires the implementation of a simple and quick analytical procedure. This paper propounds one such effective procedure for the analysis of ethylene oxide (EtO) bactericides by GC-MS/MS in food. The presented method is based on the derivatization of ethylene oxide to 2-chloroethanol, with both the number of extraction steps and the volume of extraction solvent having been minimized. The purification of the final extract through a syringe filter has proved to significantly reduce the amount of recovery obtained. Since the definition of residue pesticide ethylene oxide, according to the directive 868/2015, states that ethylene oxide is the sum of ethylene oxide and 2-chloroethanol expressed as ethylene oxide, the validated method allows for the determination of this definition. The presented method has turned out to be faster than other methods and it complies with the latest European guidelines for the analysis of pesticide residues outlined in the SANTE/11312/2021 document. Linearity, limits of detection and quantification, matrix effects, accuracy, and precision of the method have been assessed with respect to the above-mentioned document. Expanded uncertainty RSDr was less than or equal to 20%, while the recovery achieved oscillated within the range of 70–120%. The laboratory has been accredited for using the described procedure of the chromatographic method, the competence of which has been confirmed by numerous proficiency tests.

Rapid and selective screening of organic peroxide explosives using acid-hydrolysis induced chemiluminescence

Organic peroxide explosives (OPEs) are unstable, non-military, contemporary security threats often found in improvised explosive devices. Chemiluminescence (CL) can be used to detect OPEs, via radical formation consisting of peroxide moieties (-O-O-) under acidic conditions. However, selectivity for specific OPEs is hampered by the ubiquitous background of H2O2. Herein, we report the differentiation of hexamethylene triperoxide diamine (HMTD), triacetone triperoxide (TATP), and methyl ethyl ketone peroxide (MEKP) by specific flow injection analysis–CL (FIA-CL) signal profiles, after H2SO4 treatment. The radical degradation pathway of each structure, and its corresponding FIA-CL profile, was explored using mass spectrometry to reveal the rapid loss of -O-O- from TATP and HMTD structures, while MEKP formed CL signal-sustaining oligomers, as opposed to the immediate attenuation of H2O2. The CL response for OPEs in an aqueous media, measured via the described FIA-CL method, enabled ultra-trace limits of detection down to 0.40 μM for MEKP, 0.43 μM for HMTD, and 0.40 μM for TATP (combined linear range 1–83 μM with 95% confidence limit, n = 12). Expanded uncertainties of measurement (UM) of MEKP = ±0.98, HMTD = ±1.03, and TATP = ±1.1 (UM included probabilities of false positive and false negative as well as standard deviations of % recoveries and limit of detections of OPEs). Direct aqueous sample introduction via FIA-CL thus offers the prospect of rapid and selective screening of OPEs in security-heightened settings (e.g., airports), averting false positives from more ubiquitous H2O2.

Uncertainty Evaluation in calibration of Engineer’s Steel Rulers and Measuring Tapes; GUM and Monte Carlo Methods

Engineer’s steel rulers and measuring tapes are considered versatile dimensional measuring tools for many industrial applications. Calibrations of these tools are carried out by comparing their scales with reference length standards. The reference standards can be geodetic baselines provided by a laser interferometer system or linear encoder that integrated in well-designed guideway. This work aims to study not only the calibration process for steel rulers and measuring tapes but also the affecting parameters on this process and the assessment of associated uncertainty by different evaluation methods. In this paper, a 1000 mm engineer’s steel ruler and 5000 mm measuring tape are calibrated. A calibration system of precise guideway provided by linear encoder of 1 µm resolution are used. Associated uncertainties have been estimated based on GUM and Monte Carlo Simulation (MCS) methods. The parameters that may affect the calibration processes are carefully studied through the uncertainty evaluation. Expanded uncertainties of about 20 µm and 80 µm for calibration of 1000 mm engineer’s steel ruler and 5000 mm measuring tape respectively are achieved.

Uncertainty Evaluation in calibration of Engineer’s Steel Rulers and Measuring Tapes; GUM and Monte Carlo Methods

Engineer’s steel rulers and measuring tapes are considered versatile dimensional measuring tools for many industrial applications. Calibrations of these tools are carried out by comparing their scales with reference length standards. The reference standards can be geodetic baselines provided by a laser interferometer system or linear encoder that integrated in well-designed guideway. This work aims to study not only the calibration process for steel rulers and measuring tapes but also the affecting parameters on this process and the assessment of associated uncertainty by different evaluation methods. In this paper, a 1000 mm engineer’s steel ruler and 5000 mm measuring tape are calibrated. A calibration system of precise guideway provided by linear encoder of 1 µm resolution are used. Associated uncertainties have been estimated based on GUM and Monte Carlo Simulation (MCS) methods. The parameters that may affect the calibration processes are carefully studied through the uncertainty evaluation. Expanded uncertainties of about 20 µm and 80 µm for calibration of 1000 mm engineer’s steel ruler and 5000 mm measuring tape respectively are achieved. This study presents two issues. (1) it is first documented work in the study of uncertainty assessment and related parameters in this calibration type. (2) application of Monte Carlo Simulation (MCS) method in uncertainty evaluation in calibration of these tools.

Real-time monitoring of the rubber belt tension in an industrial conveyor

The paper presents a novel system for monitoring of the work of industrial belt conveyor. It is based on the strain gauges placed directly on the roller surface that measure pressing force of the belt on the roller. Automatical operation of the measurement system minimizes impact of an operator on the measurement results. Experimental researches included the stability of indications during 5 days, Type A uncertainty estimation and equipment variation EV calculations. Expanded uncertainty calculated for the level of confidence 95% was below 0.1% of the actually measured value, and percentage repeatability %EV = 9.5% was obtained. It can be considered satisfactory, since usually it is required %EV &lt; 10% for new measurement systems.

Simultaneous extraction/derivatization for the analysis of sulfite by capillary electrophoresis: A high-throughput reference method to meet the demand of seafood inspection

Sulfite is widely used to prevent enzymatic browning in shrimp and lobster processing. However, sulfite may cause allergy in sensitive consumers. Thus, regulatory agencies set limits for its use. Sulfite is usually controlled by the normalized Monier-Williams (MW) titrimetric method that allows a limited number of samples to be analyzed. This manuscript consolidates an innovative method for sulfite inspection in seafood by capillary zone electrophoresis with diode array detector (CZE-DAD). A simple, fast, and simultaneous extraction and derivatization method was developed to provide high throughput for analytical routine. The high instability of the sulfite was suppressed by its derivatization with formaldehyde producing hydroxymethylsulfonate. The evaluation of its analytical performance yielded excellent results in compliance with the strict parameters required for metrological accreditation. The CZE-DAD method was selective and specific when submitted to confirmatory evaluations by liquid chromatography coupled to mass spectrometry. The limit of detection (3.50 mg kg−1), limit of quantitation (11.7 mg kg−1) and recoveries (99–103%) were adequate for sample analysis. The measurement uncertainty was estimated by the propagation of errors and experimental standard uncertainties (precision, accuracy, and analytical curves) and type B uncertainties from traceable measurement instruments. The low relative uncertainty (10%) and the adequate reproducibility demonstrated method suitability. The CZE-DAD results were compared to the MW method through the respective expanded standard uncertainties and normalized error. This new method is promising to be used in seafood inspection and continuous laboratory evaluations using instrumentation not very expensive to acquire and maintain.

Calibration of multicomponent force and moment transducers using uniaxial force standard machines integrated with tilted plates

Traceability of multicomponent force and moment transducers (MCFMTs) is a metrological priority as stated within the document of future strategy 2017–2027 of the Consultative Committee of Mass and Related Quantities of Bureau International des Poids et Mesures (BIPM). In this paper, a calibration system using force standard machines (FSMs) integrated with tilted plates is described. The main advantage of this method is the possibility to apply force and moment components using existing uniaxial FSMs without the necessity to modify them or to develop specific ones. On the other hand, force and moment components cannot be fully independently applied. Expanded uncertainties of the applied side forces and moments are in the order of around 5%, acceptable for several industrial applications. A procedure for the calibration and the uncertainty assessment of MCFMTs is also provided. Calibration results, in terms of main and cross-talk sensitivities, of a six-components transducer are shown. This method is easily implementable and can be adopted to improve the current standard.

Validation of lipid profile measurement methods and establishment of reference values in a sub-Saharan African population.

Validated reference values and procedures are needed to ensure optimal diagnosis of dyslipidemia in sub-Saharan Africa. We aimed to validate an analysis method and establish reference intervals of lipid profile parameters in Cameroonians using this method. On a cross-sectional study conducted from November 2019 to August 2020 in Yaoundé, we have analyzed blood samples with Cobas® 6000. We subscribed to ASQUALAB's External Quality Assessments (EQA) and Outsourced Internal Quality Controls (IQC). Reproducibility, repeatability, correctness accuracy and uncertainty were evaluated using IQC. Consenting adult participants were conveniently sampled, excluding those with any condition that may affect lipid profile. Descriptive statistics were reported accordingly, agreement was assessed with Bland-Altman analysis, and reference intervals were defined according to CLSI and IFCC recommendations. The coefficients of variation for repeatability, reproducibility, and correctness bias ranged between 0.6% and 6%, with all values within the normal range. Expanded uncertainty of total cholesterol, HDL and triglycerides measurements were, respectively, 0.45, 0.24 and 0.18. We included 422 participants with a mean age of 30.2 (10.9) years and 248 (58.8%) females. Reference intervals for total cholesterol, HDL, triglycerides and LDL were, respectively, 2.94-6.02 mmol/L, 0.90-2.06 mmol/L, 0.35-1.36 mmol/L, 1.37-4.13 mmol/L. These intervals were similar between sex and ethnic groups, but lower in younger participants. Lipid profile measurement with Cobas® 6000 is a reliable and accurate analysis in our context. Specific reference intervals must be used in African population, with further studies need for different age subgroups.

Reference Standards for Nerve Conduction Studies of Individual Nerves of Lower Extremity With Expanded Uncertainty in Healthy Korean Adults

Objective To develop a set of reference standards for tibial motor, common peroneal motor, sural sensory, and superficial peroneal sensory nerve conduction studies (NCSs) with expanded uncertainty in a healthy Korean population.MethodsStandardized procedures were conducted for individual lower extremity NCSs of 199 healthy participants in their 20s (n=100) and 50s (n=99). Mean values and expanded uncertainties for parameters were analyzed with thorough consideration of multiple uncertainty factors under the International Guide to the Expression of Uncertainty in Measurement. In addition, side-to-side differences in onset latency, amplitude, and nerve conduction velocity (NCV) were analyzed.ResultsMean (reference range) for distal onset latency, baseline to negative peak amplitude, NCV of tibial motor nerve in males in their 20s were 4.3 ms (3.1–5.4 ms), 7.1 mV (3.4–10.9 mV), and 50.7 m/s (42.2–59.3 m/s), respectively; sural sensory nerve baseline to negative peak amplitude in males in their 20s was 21.7 μV (8.3–35.2 μV). Including the aforementioned data, we present a vast dataset of normative mean values and expanded uncertainties for NCSs of the leg in a healthy Korean population. Furthermore, upper limits for normal side-to-side differences for onset latency, amplitude, and NCV of each nerve are suggested.ConclusionTo our knowledge, this is the first study to present the reference standards of leg NCSs with consideration for multifactorial uncertainties in an Asian population. We expect these results to help practitioners make reliable and reproducible clinical decisions.

Influence of Concept Drift on Metrological Performance of Low-Cost NO2 Sensors

Low-Cost Air Quality Monitoring Systems (LCAQMS) and Machine Learning techniques are enabling a new paradigm in Air Quality Monitoring Networks. Nevertheless, compliance with Data Quality Objective (DQO) is still an open point. The assessment of various calibration models proposed in literature has ever neglected the Concept Drift, i.e. the differences in data distributions associated with input and target variables of the streaming data coming from dynamic nonstationary environments. The influence of the concept drift is investigated on the maintenance of the (calibrated) low-cost instrumentation. The data from mid-term co-location campaigns are firstly used to train a Multiple Linear Regression as calibration model. Then, an original methodology based on the Two-Sample Kolmogorov-Smirnov Test is proposed for automatically detecting the presence of the concept drift. The time evolution of the Relative Expanded Uncertainty is considered as well, to highlight the negative influence of the concept shift on the metrological performance of the LCAQMS, proving the need for the estimation of a new calibration model during the maintenance of the instrumentation in order to match the DQOs. A quantitative analysis is carried out on the distances among the training and test distributions about the input and outputs of the calibration model by correlating them with the time evolution of uncertainty. The scheme of an add-on block based on the proposed approach is designed for the continuous monitoring of the metrological performance exhibited by the calibration model. This management of the concept drift is expected to allow the long-awaited achievement of DQOs.

Assessing method performance for polycyclic aromatic hydrocarbons analysis in sediment using GC-MS: method validation and principal component analysis for quality control

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) belong to the persistent organic pollutant class and are ubiquitously present in the environment. As a consequence of their high hydrophobicity, PAHs in aquatic environments tend to rapidly sink down to the bottom sediments which are the most important reservoirs of PAHs in the aquatic environment. This paper presents the validation and further performance evaluation of a method modified in-house for PAHs’ sample preparation and analysis in sediment using gas chromatography-mass spectrometry (GC-MS). The method validation covers determining the calibration linear range, method detection and quantitation limits, method recovery and precision, method uncertainty and further internal and external quality control steps. Principal component analysis was used to identify the influence of different variables on method performance and indicated main clustering by PAH molecule size. The results of a two-year quality control programme show that the variations in method performance were not statistically significant in comparison to the parameters set during the validation experiments. Trueness expressed as recovery was very similar for spiked sediment samples and the analysed certified reference material (CRM) (70.6–113%). Expanded uncertainty ranged from 40.4% to 50.9% with higher values noted for the highly hydrophobic PAHs benzo(a)pyrene and benzo(g,h,i)perylene.