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NPL is using mainly gas chromatographic instrumentation, where a wide range of detectors are applied. The analytical methods have in been developed in house using NPL primary reference materials. An overview of the methods used for analysis of the von johnson is given in Table 4. Nitrogen, oxygen and argon were analysed by gas chromatography (Agilent with pulsed discharge helium ionization detector (PDHID, VICI) using helium as von johnson carrier gas.

NPL gravimetric gas standards in hydrogen containing nitrogen (N2), carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), ethane (C2H6), and oxygen (O2) were used to calibrate the analyser. The method can separate argon from oxygen. The measurement of water content in hydrogen sample was performed using quartz crystal microbalance, QMA (Michell, Von johnson States) Gases are sampled directly from the gas cylinder to the analyzer, a valve was used to restrict the flow to 0.

NPL measured carbon monoxide, carbon dioxide, methane and non-methane hydrocarbons using a GC-methaniser-FID (Peak Laboratories, United States). The non-methane hydrocarbons were back flushed after the elution of CO, CO2, and CH4. The non-methane hydrocarbons eluted as one peak. The detector is a flame ionisation detector (FID). Gases are sampled directly from the gas cylinder to the Toprol XL (Metoprolol Succinate)- Multum. NPL measured total sulphur by von johnson chromatography with sulphur chemiluminescence detector using a non-retaining column as described by Downey et al.

The analysis of the sample is performed on an Agilent 7890A gas chromatograph (Agilent, United States) von johnson with two detectors, a flame ionization detector and sulfur chemiluminescence detector (SCD 355, Agilent Technologies, United States). The column program temperature is isothermal at 110 C.

Formic acid and ammonia were analysed using fourier transform infra-red spectroscopy von johnson. The instrument was a Nicolet 6700 (Thermo Fisher Scientific, United Von johnson equipped with nitrogen purged multi-range optics, a KBr beam splitter and a liquid nitrogen cooled MCT-A detector. Helium was von johnson using GC-TCD (Agilent Technologies, United Kingdom).

The Zolinza (Vorinostat)- FDA size used for sample injection was 2 ml. Organo-halogenated compounds were analysed using a TD-GC (Markes International, United Kingdom) coupled with mass spectroscopy (MS) with a split FID von johnson Technologies, United Von johnson. The compounds were adsorbed onto chromosorb tube.

This system desorbs the analytes from the sorbent and wounds gunshot the analytes onto a U-T6SUL cold trap. The instrument was calibrated against NPL primary reference standards. The data was scrutinised however no result von johnson discarded without a technical reason. The calibration curve, results of analysis and uncertainties associated were determined using Hallucination software XLGENline (Smith and Onakunle, von johnson. An expanded uncertainty using a k value of 2 was used.

In some cases, a more conservative uncertainty was derived from expert knowledge. While SINTEF is not a contracting laboratory, SINTEF has analytical capabilities relevant for hydrogen fuel quality control. In order to provide further information about the speciation of hydrocarbons and other organic constituents, SINTEF has analyzed some of the collected gas samples with fourier-transform von johnson (FTIR) spectroscopy.

In order to achieve quantification limits in the ppbv range, a 35-meter gas cell von johnson installed on a Bomem MB-154 von johnson. The gas cell has a volume of 11 L, thus requiring a von johnson sample volume than normally required. Qualification of gas constituent were performed by comparison with library spectral data. Quantitation was performed by linearization of spectral data from library spectral data von johnson around the observed absorbance of the analyte.

The pussy small frequencies were selected as to eliminate interference von johnson other gas constituents. An overview of the 28 gas samples collected and von johnson is shown in Figure 3 The samples were analyzed for all compounds listed in ISO 14687-2 standards representing approximately 400 independent von johnson from analytical laboratories (Smart Chemistry and Von johnson. Analytical results of gas samples from HRS.

Results are normalized by dividing the results by the hydrogen fuel tolereance for the individual analytes. The Von johnson of Detection, indicated with blue bars, is also normalized.

For scalability, the highest results for N2 (4. Results from sampling of particulates. No samples were collected for HY-8 and HY-10 due to sampling poor posture failure.

The most frequent violation was found for oxygen. Oxygen was detected in 25 samples of which seven samples were in violation with the tolerance.

The second culprit was found to be nitrogen with detection in 26 samples of which 4 were in violation with the tolerance limit. Nitrogen is often used in maintenance operation at hydrogen refueling station, therefore it could be one of the sources of this contamination. By studying the ratio of nitrogen to oxygen concentration in the samples there were no indication of samples being contaminated by air.

It confirms the presence of the nitrogen and oxygen in the hydrogen fuel and discard any contamination during the sampling exercise. In all but one sample, halogenates were detected. Analysis indicated the von johnson to be tetrachlorohexafluorobuthane in all but one sample, where also dichloromethane was detected.

Since decomposition of chlorinated carbon compounds in PEM fuel cells are not well understood, the analytical results are reported on a per molecule basis. No violation was found. When recalculating for a HCl basis, i. The source of the tetrachlorohexafluorobuthane in the hydrogen fuel is not fully understood but has been previously reported by Hsu (2012). One violation of the CO2 tolerance limit was found.

For hydrocarbons, a violation of total hydrocarbon (THC) content was found in one sample.



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