Sulfite Determination by an Inhibitor Biosensor-based Mushroom (Agaricus Bisporus) Tissue Homogenate

Figures & data

Figure 1. Optimum pH. [Phosphate buffers with pHs 6, 6.5, 7, 7.5 and 8, and tris-HCl buffers with pHs 8.5 and 9 were used. Buffer concentrations were 0.05 M. Catechol, substrate, and sulfite, as an inhibitor, concentrations were 100×10⁻⁶ and 150×10⁻⁶ M, respectively. T = 35° C. (S.D. values for data points are given as differentiation in dissolved oxygen concentration (mg/mL): pH 6 (0.005), pH 6.5 (0.007), pH 7(0.004), pH 7.5 (0.005), pH 8 (0.005), pH 8.5 (0.007), pH 9 (0.0025)].

Figure 2. Optimum temperature. [Working conditions: pH 6.5, 0.05 M phosphate buffer was used. Catechol, substrate, and sulfite, as an inhibitor, concentrations were 100×10⁻⁶ and 150×10⁻⁶ M, respectively. (S.D. values for data points are given as differentiation in dissolved oxygen concentration (mg/mL): 20°C (0.002), 25°C (0.005), 30°C (0.005), 35°C (0.0025), 40°C (0.005), 45°C (0.0075)].

Figure 3. The effect of substrate type on sulfite determination. [Substrate types used: -•-•-: Catechol, -▪-▪-: Ascorbic acid and -▴-▴-: Pyrogallol. The concentrations of these substrates were constant as 100×10⁻⁶ M. Working conditions: pH 6.5, 0.05 M phosphate buffer and T = 35 °C. (S.D. values for data points of catechol: 50×10⁻⁶ M (0.0025), 75×10⁻⁶ M (0.0025), 100×10⁻⁶ M (0.0025), 150×10⁻⁶ M (0.005), 200×10⁻⁶ M (0.005), 300×10⁻⁶ M (0.005). S.D. values for data points of ascorbic acid: 50×10⁻⁶ M (0.002), 75×10⁻⁶ M (0.002), 100×10⁻⁶ M (0.0015), 150×10⁻⁶ M (0.0025), 200×10⁻⁶ M (0.0025), 300×10⁻⁶ M (0.0025)].

Figure 4. The effect of substate concentration. [Substrate concentrations tested: -•-•-: 100×10⁻⁶, -▪-▪-:200×10⁻⁶, and -▴-▴-: 50×10⁻⁶ M. Working conditions: pH 6.5, 0.05 M phosphate buffer and T = 35 °C. (S.D. values for data points of 100×10⁻⁶ M catechol: 50×10⁻⁶ M (0.005), 75×10⁻⁶ M (0.005), 100×10⁻⁶ M (0.004), 150×10⁻⁶ M (0.004), 200×10⁻⁶ M (0.005), 300×10⁻⁶ M (0.0075). S.D. values for data points of 200×10⁻⁶ M catechol: 50×10⁻⁶ M (0.005), 75×10⁻⁶ M (0.005), 100×10⁻⁶ M (0.0075), 150×10⁻⁶ M (0.0075), 200×10⁻⁶ M (0.0075), 50×10⁻⁶ M (0.0075). S.D. values for data points of 50×10⁻⁶ M catechol: 50×10⁻⁶ M (0.0075), 75×10⁻⁶ M (0.0075), 100×10⁻⁶ M (0.01), 150×10⁻⁶ M (0.01), 200×10⁻⁶ M (0.01), 50×10⁻⁶ M (0.025)].

Figure 5. Sulfite calibration graph. [Working conditions: pH 6.5, 0.05 M phosphate buffer and T = 35°C. Catechol concentration was 100×10⁻⁶].

Table 1. Sulfite analysis in some real samples by the biosensor and by the enzymatic reference method [10].

	Found sulfte (ppm)
Sample	Reference^a	Biosensor^a	% Relative error
Pickle water 1	4200	4320	102.9
Pickle water 2	5440	5520	101.5
Pickle water 3	4756	4801	101
Beer	182	193	106
Vinegar	903	955	105.8

^aMean of three determinations.

Abass, A.K., Hart, J.P., Cowell, D. (2000). Development of an amperometric sulfite biosensor based on sulfite oxidase with cytochrome c, as electron acceptor, and a screen-printed transducer. Sens. Actuators B-Chem. 62: 148–153.

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