Technical Solution for Method 2342: Determination of Plant Growth Regulator Residues in the Chinese Pharmacopoeia 2025 Edition

This newly established method (2342) in the 2025 Chinese Pharmacopoeia (ChP) is designed for detecting synthetic plant growth regulator (PGR) residues in herbal materials, decoction pieces, plant extracts, and preparations. It covers 65 regulators with liquid chromatography-tandem mass spectrometry (LC-MS/MS) as the primary analytical technique.

Scope of Application

• Target Matrices: Herbal medicines, decoction pieces, plant extracts, and preparations.
• Key Analytes:
  Gibberellin (GA₃), Forchlorfenuron (CPPU), Paclobutrazol (PAC), Indole-3-acetic acid (IAA), Naphthaleneacetic acid (NAA), and emerging regulators (e.g., Trinexapac-ethyl, Prohexadione calcium).

Analytical Methods

1. LC-MS/MS (Primary Method)
   • Principle: Multi-reaction monitoring (MRM) for enhanced selectivity/sensitivity.
   • Conditions:
     • Column: C18 (2.1 mm × 100 mm, 1.7 μm)
     • Mobile Phase: 0.1% formic acid (A) / acetonitrile (B), gradient elution
     • Ion Source: ESI± (±3.5 kV)
   • Advantages: Simultaneous detection of >20 regulators; LOD: 0.001 mg/kg.
2. GC-MS
   • For volatile or derivatized regulators (e.g., Chlormequat, Daminozide) using BSTFA derivatization.
3. HPLC-UV/DAD
   • Alternative for single/few regulators (e.g., Gibberellin) in resource-limited labs.

Regulatory Significance

This standard combats PGR misuse in herbal cultivation by setting residue limits (e.g., PAC limit in Ophiopogonis Radix). The 2025 ChP further strengthens quality control with expanded standards for exogenous contaminants (pesticides, heavy metals).