Dex.measured (mg/kg DS) Dex.recovery (%)

Figure 20: Sensitivity of copper complex method to determine dextran T2000 in sucrose solutions

4.1.2Haze method sensitivity

Haze method reflects a pattern of variation in dextran measured similar to that of Roberts’s method whereas the recovery pattern was different (Figure 21 to Figure 23). The recovery percentage increased with the increasing of dextran concentrations for the three molecular weights considered (R = 0.96, 0.89, 0.74 for T40, T500 and T2000 respectively). Testifying recovery percentages against 100 % with the least sum of square (LSS) criterion, the Haze method was with the best for the molecular weight of T2000 (Figure 23).

In the Haze method, dextran concentration and molecular weight factors and their interactions were found to be significant in their effects on the recovery percentages (P < 0.0001), which points at a dependent relationship between the two factors. Similar pattern of significance for the estimated dextran T500 and T2000 were recorded (P<0.0001). The accurate of Haze method with low dextran molecular mass was shown in Figure 21. The results show the dextran recovery at concentrations lower than 1000 mg/kg DS and at concentrations above 1500 mg/kg DS of T40 were

not accurate compared with the dextran recovery of experiments with T500 and T2000.

Dex. measured (mg/kg DS) Dex. recovery (%)

Figure 21: Sensitivity of Haze method to determine dextran T40 in sucrose solutions

Dex.measured (mg/kg DS) Dex. recovery (%)

Figure 22: Sensitivity of Haze method to determine dextran T500 in sucrose solutions

Dex.measured (mg/kg DS) Dex. recovery (%)

Figure 23: Sensitivity of haze method to determine dextran T2000 in sucrose solutions

According to the recovery patterns (Figure 18 to Figure 23) and the least sum of square (LSS) criterion, (Roberts method, 179, 553, 109, Haze method, 8428, 2535, 682 for T40, T500 and T2000 respectively), the Robert’s method can be considered to be more precise. However, the overall factors including the method, like concentration, molecular weight and their interaction were considered to discover another pattern of variation in recovery percentages and determined dextran. For the recovery percentages, all the factors, including the method and their interactions are significant (P < 0.0001) whereas for the estimated dextran the method has no main effect (P = 0.348).

From the above mentioned discussion, the sensitivities of Robert’s and Haze method for determination of different dextran molecular mass fractions are summarized in Table 7. The data demonstrate that the Robert’s method was more accurate for different dextran molecular mass fractions than the Haze method. Furthermore, the Haze method was too inaccurate to be genuinely useful as a dextran analysis method especially, with low dextran molecular mass fractions. These results are consistent with results from (Clarke et al., 1986; Curtin and McCowage, 1986; DeStefano and Irey, 1986; Sarkar and Day, 1986).