Metrological generation of SI-traceable gas-phase standards and reference materials for (semi-) volatile organic compounds

EN 16516 sets specifications for the determination of emissions into indoor air from construction products. Reliable, accurate and SI-traceable measurement results of the emissions are the key to consumer protection. Such measurement results can be obtained by using metrologically traceable reference materials. Gas-phase standards of volatile organic compounds (VOCs) in air can be prepared by a variety of dynamic methods according to the ISO 6145 series. However, these methods are not always applicable for semi-volatile organic compounds (SVOCs) due to their high boiling point and low vapour pressure. Therefore, a novel dynamic gas mixture generation system has been developed. With this system gas-phase standards with trace level VOCs and SVOCs in air can be prepared between 10 nmol mol^-1 and 1000 nmol mol^-1. The VOCs and SVOCs in this study have normal boiling points ranging from 146 °C to 343 °C. Metrologically traceable reference materials of the gas-phase standard were obtained by sampling of the VOC gas-phase standard into Tenax TA® sorbent material in SilcoNert® coated stainless steel tubes. Accurately known masses between 10 ng and 1000 ng per VOC were sampled. These reference materials were used to validate the dynamic system. Furthermore, the storage and stability periods of the VOCs in the reference materials were determined as these are crucial characteristics to obtain accurate and SI-traceable reference materials. In a Round Robin Test (RRT), the reference materials were used with the aim of demonstrating the feasibility of providing SI-traceable standard reference values for SVOCs for interlaboratory comparison purposes. Based on the results from the validation, the storage and stability studies and the RRT, gas-phase standards and reference materials of VOCs and SVOCs with relative expanded uncertainties between 5 % and 12 % (k = 2) have been developed. These reference standards can be used as calibrants, reference materials or quality control materials for the analysis of VOC emissions.

In this repository data from the validation, the storage and stability studies and the RRT are published which is used for the manuscript "Metrological generation of SI-traceable gas-phase standards and reference materials for (semi-) volatile organic compounds" published in Measurement Science and Technology.

The following files can be found in this repository:

- The following files contain data from the validation.Variation1_day1, Variation1_day2, Variation1_day3, Variation2_day1, Variation2_day2, Variation2_day3, Variation3_day1, Variation3_day2, Variation3_day3, Variation4_day1 and Variation4_day2. During the validation 4 different variations have been used and these have been tested on 3 or 2 days. The data contain information about the settings to obtain the gas-phase standard, reference materials and spiked tubes and the analysis data. 

- The "ANOVA validation data" file contains the ANOVA calculations used to obtain the repeatability standard deviation and reproducibility standard deviation.

- The figure "Chromatogram VOCs used for the validation" is a copy of a chromatogram

- The file "Storage and stability studies data" contains formation about the settings to obtain the gas-phase standard, reference materials and spiked tubes and the analysis data. 

- The figure "Chromatogram VOCs used for the storage and stability studies" is a copy of a chromatogram.

- The file "RRT data" contains information about the settings to obtain the gas-phase standard, reference materials and spiked tubes and the analysis data. 

- The file "Report Homogeneity RRT" is a report on the homogeneity study performed during the RRT.

- The figure "Chromatogram VOCs used for the RRT" is a copy of a chromatogram.

- The file "VSL-Tubes-results-RR18-a". The dataset contains the results of a round robin test which tested the proficiency to analyse volatile organic compounds (VOC) of laboratories dealing with the determination of emissions from building materials. For this analysis check the participants were asked to send own sampling tubes filled with the adsorbent Tenax TA^®, which were loaded with a reference gas mixture containing the compounds: styrene [100-42-5], n-decane [124-18-5], R(+)limonene [5989-27-5], 1,2,4-trimethylbenzene [95-63-6], decamethylcyclopentasiloxane [541-02-6], dimethylphthalate [131-11-3], dibutylphthalate [84-74-2], naphthalene [91-20-3], n-hexadecane [544-76-3] and eicosane [112-95 8]. These tubes were sent back to the participants for immediate analysis. The list of compounds was disclosed in advance. For all statistical evaluations, the mean values of the laboratories were used instead of all single measurement values. Expert laboratories: Laboratories who had successfully participated in the three former round robin tests (2014; 2016; 2018) organized by BAM were defined as expert laboratories. Their reported data were used to calculate the reference mean (ref. mean) and the reference standard deviation (ref st. dev.). Reference mean: The reference mean is determined as the robust mean value using the Hampel estimator (see Section C.5.3 in ISO 13528) on the basis of the results of the expert laboratories. It is a weighted arithmetic mean, with lower weights for outlying values. Standard deviation for proficiency assessment: The reference standard deviation for proficiency assessment is determined as the robust reproducibility standard deviation according to the Q method (see Section C.5.2 in ISO 13528) based on the results of the expert laboratories.