This certificate is designed in accordance with ISO 17034 and ISO Guide 31. This reference material (RM) was designed,produced and verified in accordance with ISO/IEC 17025, ISO 17034 and a registered quality management system ISO 9001.

1. Xylene(CAS?No.?: 1330-20-7)?contains?o-xylene(CAS?No.?: 95-47-6,RT:27.536min),m-Xylene(CAS?No.?: 108-38-3,RT:26.287min)?and?pXylene(CAS?No.?: 106-42-3,RT:26.287min).
(二甲苯（CAS?No.?: 1330-20-7)?包含鄰二甲苯（CAS?No.?: 95-47-6）出峰時(shí)間為27.536min，間二甲苯（CAS?No.?: 108-38-3）出峰時(shí)間為26.287min 和對二甲苯（CAS?No.?: 106-42-3）出峰時(shí)間為26.287min)

This RM is intended for use in a laboratory as a calibration and quality control standard or in method development for analytical techniques.

The certified value(s) and uncertainty(ies) are determined in accordance with ISO 17034 with an 95% confidence level (k=2). Uncertainty is based on the Total Combined Uncertainty, including uncertainties of preparation, purity of neat materials, homogeneity, stability testing.

The balances used for gravimetric measurements are calibrated with weights traceable to the national standards. The calibration of the balances is verified annually by an external accredited calibration service. This analysis method has been verified using an approach consistent with ISO 17034:2016 & ISO 17025:2017.

Random replicate samples of the final packaged RM have been analysed to prove homogeneity consistent with ISO 17034.

The RM should be stored in the original sealed bottle at the indicated temperature.