Chen et al. 2022 — Multi-element concentrations in Chinese peanuts by ICP-MS
This study measured 19 elements including toxic metals (As, Pb, Cd, Cr), micro-nutrients (Ni, Al, Fe, Zn, Cu, Mn, Mo, Se, Co, Sr, V), and macro-elements (K, Ca, Mg, Na) in 66 peanut samples from six major Chinese provinces using ICP-MS with microwave digestion. The primary aim was geographical characterization via linear discriminant analysis (LDA), which correctly classified 97.0% of samples by origin. Toxic element concentrations were all below Chinese regulatory limits (GB2762-2017), with Cd noted as the main risk point due to peanuts’ underground growth and extended soil contact.
Key numbers
Toxic element concentrations by province (mg/kg fresh weight):
| Element | Jilin | Liaoning | Henan | Hebei | Guangxi | Guangdong |
|---|---|---|---|---|---|---|
| Cd | 0.110 ± 0.049 | 0.204 ± 0.131 | 0.147 ± 0.080 | 0.047 ± 0.040 | 0.168 ± 0.063 | 0.121 ± 0.096 |
| Pb | 0.025 ± 0.045 | 0.060 ± 0.020 | 0.018 ± 0.045 | ND | 0.024 ± 0.041 | 0.007 ± 0.044 |
| As | 0.015 ± 0.007 | 0.020 ± 0.008 | 0.020 ± 0.012 | 0.016 ± 0.004 | 0.009 ± 0.0008 | 0.014 ± 0.003 |
| Cr | 0.278 ± 0.092 | 0.234 ± 0.099 | 0.293 ± 0.126 | 0.268 ± 0.069 | 0.280 ± 0.041 | 0.262 ± 0.072 |
Nickel concentrations (mg/kg): Jilin 3.08 ± 1.21, Liaoning 7.53 ± 1.17, Henan 5.87 ± 6.11, Hebei 1.34 ± 1.49, Guangxi 8.73 ± 1.77, Guangdong 8.33 ± 3.70.
Aluminum concentrations (mg/kg): range 64.5–119 across provinces (no significant regional difference, p = 0.222).
Regulatory context: China ML for Cd in peanuts = 0.5 mg/kg (GB2762-2017); Australia similarly revised to 0.5 mg/kg in 2009. ML for Cr = 1 mg/kg. All samples within limits.
LOD values: Al 0.036 mg/kg, As 0.0007 mg/kg, Cd 0.0001 mg/kg, Cr 0.001 mg/kg, Ni 0.005 mg/kg, Pb 0.003 mg/kg. LOQ values: Cd 0.0003 mg/kg, Pb 0.009 mg/kg.
Methods (brief)
ICP-MS (iCAP Q, Thermo) with microwave digestion (HNO3 + H2O2). Kinetic energy discrimination mode. CRM: GBW10013 (soybean); recoveries 91.4–109.1%. R² > 0.9993 for all calibrations. Values on fresh weight basis. Paper does not speciate arsenic (tAs reported).
Implications
Certification: Provides peanut-specific Cd, Pb, Cr, Ni, Al, and As concentrations from Chinese production regions. Cd is the highest-concern toxic metal; maximum observed (0.204 mg/kg in Liaoning) is well below EU ML (0.20 mg/kg for peanuts — note: EU ML coincides with highest observed here). Pb and As are very low relative to regulatory limits. Ni concentrations are high (1.3–8.7 mg/kg range), relevant for HMT&C Ni standards.
Courses: Illustrates geographical origin as a driver of heavy-metal variation in nuts; soil pH and type (acidic red soils in southern provinces) affect uptake patterns. Useful case study for supply-chain screening guidance.
App: Provides concentration ranges for peanuts ingredient page. Note: As not speciated (total arsenic only); iAs fraction would be lower.