I am looking for standards about connectors for hoses e.g. quick connector. The material of the hose is PTFE braided with stainless steel. The maximum pressure is 400 kPa. The liquid is tetraydrothiofene (THT).
I'm assuming that you're talking about about relatively small bore hose, starting at 10 mm but no bigger than 30 mm. Connectors/couplings in this range are usually proprietary and subject to patent protection. There are no codes specific to self sealing quick couplings. If a connection is threaded, the thread will usually be machined to a standard form. Testing is usually done to meet industry norms, eg test pressure at 1.5 times maximum working pressure.
I don't know if this is relevant to your situation but if the coupling has an elastomeric seal, either as the main seal or as a back-up, always check that the seal is compatible with the fluid being carried.