Table 2. The recoveries of seven internal standards (ISs) for neonicotinoid pesticides from brown rice, grape, and peanuts obtained by the proposed method with two different addition timings of ISs.
| ISs | Brown rice | Grape | Peanuts | |||
|---|---|---|---|---|---|---|
| BEa) | SAb) | BEa) | SAb) | BEa) | SAb) | |
| Acetamiprid-d3 | 105±1.6 | 105±1.6 | 100±2.3 | 93.1±7.5 | 106±1.0 | 103±2.4 |
| Clothianidin-d3 | 106±1.8 | 110±4.4 | 116±2.8 | 110±5.5 | 84.0±7.2 | 84.5±3.3 |
| Dinotefuran-d3 | 101±2.5 | 102±2.6 | 93.5±2.3 | 91.0±7.2 | 92.5±1.1 | 92.1±1.5 |
| Imidacloprid-d4 | 119±0.6 | 119±0.4 | 115±2.0 | 105±8.4 | 120±1.3 | 119±0.6 |
| Nitenpyram-d3 | 91.4±5.9 | 86.4±5.4 | 81.6±3.0 | 76.0±8.3 | 91.1±4.2 | 88.4±3.3 |
| Thiamethoxam-d3 | 105±2.0 | 105±0.7 | 107±1.9 | 102±7.2 | 84.0±4.9 | 82.5±2.7 |
| Thiacloprid-d4 | 102±1.6 | 101±1.1 | 97.2±1.3 | 91.4±7.2 | 102±1.7 | 98.8±2.3 |
a) Before extraction, b) Spike into aliquot. Values are average recoveries±relative standard deviations (%).