Table 2.
Insecticide release of spinosad (SP) and emamectin benzoate (EM)-micropheres (SP-EM-microspheres) affected by preparation conditions.
| Conditions | Entrapment rate of SP + EM (%)(a) | Loading of SP + EM (%)(a) | Mean diameter of microspheres (μm) | Span | Kinetic equation of release curve of SP + EM(b) | T 50 (d)(b) |
|---|---|---|---|---|---|---|
| A: external aqueous phase | ||||||
| Not saturated with SP + EM | 84.5 ± 0.67a | 40.6 ± 0.32a | 7.19 ± 0.27a | 1.13 ± 0.023a | Mt/Mz = 30.5t0.29 | 5.45 |
| Saturated with SP + EM | 87.9 ± 0.78a | 42.2 ± 0.38a | 7.11 ± 0.21a | 1.11 ± 0.016a | Mt/Mz = 23.6t0.35 | 8.86 |
| B: distilled water addition (ml) | ||||||
| 0 | 84.5 ± 0.67b | 40.6 ± 0.32b | 7.19 ± 0.27b | 1.13 ± 0.023a | Mt/Mz = 30.5t0.29 | 5.45 |
| 400 | 88.3 ± 0.92a | 41.8 ± 0.44a | 7.58 ± 0.18ab | 1.24 ± 0.082a | Mt/Mz = 30.4t0.38 | 3.70 |
| 800 | 89.6 ± 0.73a | 42.4 ± 0.35a | 7.71 ± 0.22a | 1.24 ± 0.037a | Mt/Mz = 50.5t0.23 | 0.961 |
| C: PLA / PCL ratio | ||||||
| 5:1 | 82.6 ± 0.95ab | 39.7 ± 0.45ab | 7.16 ± 0.26a | 1.14 ± 0.012a | Mt/Mz = 33.7t0.32 | 3.45 |
| 4:2 | 83.4 ± 0.74b | 40.1 ± 0.36b | 7.19 ± 0.27a | 1.20 ± 0.061ab | Mt/Mz = 46.1t0.20 | 1.47 |
| 3:3 | 81.4 ± 0.81a | 39.1 ± 0.39a | 7.35 ± 0.23a | 1.16 ± 0.013ab | Mt/Mz = 55.9t0.17 | 0.51 |
| 2:4 | 82.2 ± 0.79ab | 39.5 ± 0.38ab | 7.05 ± 0.19a | 1.18 ± 0.027b | Mt/Mz = 65.8t0.13 | 0.14 |
| 1:5 | 81.1 ± 0.70a | 39.0 ± 0.34a | 6.97 ± 0.31a | 1.17 ± 0.042ab | Mt/Mz = 72.3t0.13 | 0.060 |
| D: gelatin concentration (%) | ||||||
| 0 | 84.5 ± 0.67c | 40.6 ± 0.32c | 7.19 ± 0.27a | 1.13 ± 0.023a | Mt/Mz = 30.5t0.29 | 5.45 |
| 0.5 | 80.7 ± 1.29b | 38.8 ± 0.62b | 7.26 ± 0.31a | 1.14 ± 0.049ab | Mt/Mz = 10.3t0.40 | 53.7 |
| 2.5 | 75.8 ± 0.95a | 36.4 ± 0.42a | 7.45 ± 0.27a | 1.21 ± 0.025b | Mt/Mz = 7.60t0.39 | 129 |
| 4.5 | 74.2 ± 0.81a | 35.7 ± 0.39a | 7.65 ± 0.26a | 1.18 ± 0.015b | Mt/Mz = 4.51t0.45 | 212 |
Note: (a): Contents of SP + EM determined by HPLC. (b): Contents of SP + EM determined by spectrophotometer. “Mt/Mz” and “t” represent cumulative quantity of insecticides release (%) and release time (d), respectively. T 50 represents the time (d) when cumulative insecticides release reached 50%. Kinetic equations of insecticides release for condition A to D and T 50 were calculated based on data in Fig. 1A to D, respectively. Correlation coefficients for two fitted equations were higher than 0.99. Different letters (such as a, b, and c) in a same column represents significant difference (t-test, P ≤ 0.05).