Determination of Sugars in Molasses by HPLC Following Solid-Phase Extraction

Figures & data

TABLE 1 Effect of sample pretreatment on sugars in molasses

Pretreatment method	Rate of decoloration (%)	Rate of total sugar loss (%)
Macroporous resin (XDA-8 resin)	86.54	11.32
C18 SPE column (Sep-Pak)	87.19	0.69

TABLE 2 Comparison of two columns on the sugar separation^a

Chromatographic column	Agilent Zorbax carbohydrate column	Utimate^TM XB-NH2 column
Retention time (min)
Fructose	8.62	7.19
Glucose	9.70	7.87
Sucrose	13.22	11.17
Capacity factor
Fructose	1.51	1.39
Glucose	1.83	1.68
Sucrose	2.85	1.66
Column pressure (psi)	847	1012

^aBoth determination conditions: mobile phase of acetonitrile and water (75: 25, v/v), flow rate 1.0 mL/min, column temperature 30°C, RID temperature 35°C.

FIGURE 1 HPLC-RID chromatogram of a standard mixture of three carbohydrates with a maltose internal standard. Determination conditions: mobile phase of acetonitrile and water (75: 25, v/v), flow rate 1.0 mL/min, column temperature 30°C, and RID temperature 35°C.

FIGURE 2 HPLC-RID chromatogram of three carbohydrates in molasses samples with a maltose internal standard. Determination conditions: mobile phase of acetonitrile and water (75: 25, v/v), flow rate 1.0 mL/min, column temperature 30°C, and RID temperature 35°C.

TABLE 3 Parameters of quantitative analysis for three carbohydrates

Component	Regression equation	The squared correlation coefficient (R^2)	Linear range (g/L)	Detection limits (g/L)
Fructose	y = 1.11x + 0.117	0.9986	3.30–16.48	0.16
Glucose	y = 1.11x - 0.0719	0.9994	1.80–9.02	0.04
Sucrose	y = 1.27x - 0.396	0.9954	5.94–29.70	0.08

TABLE 4 The precision for fructose, glucose, and sucrose (n = 5)^a

	Peak area ratios of each sugar to IS
Component	1	2	3	4	5	RSD (%)
Fructose	0.5439	0.6113	0.6031	0.6074	0.6083	4.81
Glucose	0.2679	0.2912	0.2942	0.3016	0.2847	4.42
Sucrose	1.2236	1.3091	1.2882	1.3132	1.3422	3.43

^an is the number of samples analyzed.

TABLE 5 Results of spiked recovery test (n = 3)^a

Component	Amount of sample (g/L)	Added amount (g/L)	Detected amount (g/L)	Recovery (%)	Average recovery (%)	RSD (%)
Fructose	2.667	1.441	4.138	101.26	100.33	2.10
		2.641	5.356	101.82
		4.490	7.063	97.91
Glucose	1.397	0.674	2.040	95.35	100.30	4.30
		1.226	2.651	102.31
		2.084	3.548	103.23
Sucrose	5.535	2.787	8.148	94.46	96.40	1.80
		5.029	10.455	97.81
		8.549	13.824	96.94

^an is the number of samples analyzed.

TABLE 6 Results of sample determination by SPE (n = 4)^a

Component (g/L)	1	2	3	4	Average concentration (g/L)	RSD (%)
Fructose	2.684	2.647	2.667	2.671	2.667	0.57
Glucose	1.389	1.402	1.436	1.359	1.397	2.28
Sucrose	5.520	5.437	5.536	5.651	5.536	1.59

^an is the number of samples analyzed.

TABLE 7 Results of sample determination by direct injection (n = 3)^a

Component (g/L)	1	2	3	Average concentration (g/L)	RSD (%)
Fructose	2.795	2.741	2.58	2.705	4.13
Glucose	1.401	1.412	1.39	1.401	0.97
Sucrose	5.417	5.470	5.811	5.566	3.85

^an is the number of samples analyzed.