BS ISO 20921:2019规定了用于纺织生产的棉纤维中氮同位素比率的测定。它不仅适用于棉织品，也适用于从棉田采集的原棉。购买本文件时可获得的所有当前修订均包含在购买本文件中。

BS ISO 20921:2019 specifies the determination of the ratio of nitrogen isotopes in cotton fibres that are used for textile production. It applies not only to cotton textiles but also to raw cotton taken from cotton fields.All current amendments available at time of purchase are included with the purchase of this document.