Green Analytical Method for Simultaneous Determination of Glucosamine and Calcium in Dietary Supplements by Capillary Electrophoresis with Capacitively Coupled Contactless Conductivity Detection

Table 1

Determination of glucosamine and Ca²⁺ in commercial dietary supplements from pharmacies in Vietnam, using CE-C⁴D and HPLC, ICP-OES as the reference methods.

Sample no	Types of pills	Glucosamine					Ca^2+
		CE-C^4D (mg/μ)	Label (mg/μ)	HPLC (mg/μ)	CE-LBL (%)	CE-HPLC (%)	CE-C^4D (mg/μ)	Label (mg/μ)	ICP-OES (mg/μ)	CE-LBL (%)	CE-ICP (%)
S1	Tablet	479.0	488.0	450.0	−1.84	6.44	26.30	25.00	24.90	5.20	5.62
S2	Tablet	494.0	457.0	464.0	8.10	6.47	41.90	40.00	44.80	4.75	−6.47
S3	Tablet	616.0	625.0	613.0	−1.44	0.49	36.60	35.00	36.90	4.57	−0.81
S4	Tablet	223.0	211.0	230.0	5.69	−3.04	48.50	50.00	47.50	−3.00	2.11
S5	Hard capsule	111.0	107.0	118.0	3.74	−5.93	49.40	48.00	47.70	2.92	3.56
S6	Hard capsule	324.0	342.0	344.0	−5.26	−5.81	7.82	8.00	7.80	−2.25	0.26
S7	Hard capsule	643.0	616.0	676.0	4.38	−4.88	55.43	60.00	60.30	−7.62	−8.08

CE-LBL: CE-label deviation the deviation of the result obtained with CE-C⁴D from that indicated on the label; CE-LBL (%) = {(C_CE-C4D − C_label)/C_label} × 100%. CE-HPLC: CE-HPLC deviation, CE-ICP : CE-ICP deviation; they are the deviation of the result obtained with CE-C⁴D from that with the standard reference method (HPLC and ICP-OES); CE-HPLC (or CE-ICP) (%) = {(C_CE-C4D − C_reference)/C_reference} ‐ 100% mg/μ : mg per unit (e.g., tablet or capsule).