Comparison between the proposed potentiometric method and reported electrochemical methods for ephedrine assay.

Parameter	Proposed method	Reported electrochemical liquid membrane methods
		Method I14	Method II17	Method III20	Method IV19	Method V18	Method VI16
Linear range (M)	1.00 × 10−2 to 6.00 × 10−6	1.00 × 10−2 to 1.00 × 10−5	1.00 × 10−2 to 5.00 × 10−5	8.00 × 10−3 to 3.00 × 10−5	1.00 × 10−1 to 2.00 × 10−5	1.00 × 10−2 to 5.00 × 10−5	1.00 × 10−1 to 2.00 × 10−6
Slope	58.86	55.00	58.20	57.00	Nernstian	55.79	56.00
LOD (M)	3.60 × 10−6	4.50 × 10−6	1.00 × 10−4.5	6.20 × 10−6	—	—	1.60 × 10−6
pH range	2–10	4–7	—	4–9	2–8	4–10	4–9
Sample	Herbal products	Pharmaceutical preparations	Pharmaceutical preparations	Pharmaceuticals and biological fluid	Pharmaceutical preparations	Pharmaceutical preparations	Pharmaceutical preparations