Online Microextraction Coupled with HPLC-ABTS for Rapid Analysis of Antioxidants from the Root of Polygonum bistorta

Table 2

The HPLC methods for analysis of PB.

No.	Sample preparation				HPLC separation			Reference
	Method	Sample (mg)	Solvents	Time (min)	Instruments	Time (min)	Total time (min)
1	Ultrasonic extraction	200	25 mL 20% methanol	40	HPLC	40	80	[1]
2	Ultrasonic extraction and reflux heated extraction	500	60 mL 20% methanol	90	HPLC	95	185	[2]
3	Heated extraction	10000	100 mL 50% methanol and 100 mL 80% methanol	120	HPLC	60	180	[27]
4	Ultrasonic extraction	2000	50 mL 20% methanol	30	HPLC	70	100	[28]
Current study	Online HPLC extraction	0.17	—	—	HPLC	22	22	—