Detection Methods for Benzoic Acid
I. Chromatographic Analysis (High-precision quantification)
High-Performance Liquid Chromatography (HPLC)
- Principle: Samples are extracted, purified, separated via reversed-phase column, and quantified by UV detector (wavelength: 230–254 nm).
- Advantages: High sensitivity (LOD: 0.01 mg/kg), strong anti-interference capability; ideal for complex matrices (e.g., condiments, dairy products).
- Procedure: Sample pretreatment (defatting/deproteinization) → Chromatographic separation (mobile phase: methanol-water or methanol-ammonium acetate) → Quantification by external standard method.
Gas Chromatography (GC) & GC-Mass Spectrometry (GC-MS)
- Principle: After acidification, benzoic acid is extracted with ethyl ether, separated by chromatography, and quantified via FID or MS detection.
- Advantages: GC-MS enables simultaneous detection of benzoic acid derivatives; high sensitivity (suitable for trace analysis).
- Applications: Soy sauce, fruit juices, oils, etc.
II. Spectroscopic & Rapid Screening Methods (Convenient screening)
UV-Vis Spectrophotometry
- Principle: Quantification based on absorbance at specific wavelengths (e.g., 225 nm).
- Advantages: Simple operation, low cost; suitable for batch screening (e.g., beverages, candies).
- Limitations: Susceptible to impurity interference; requires pretreatment.
Rapid Test Strips
- Principle: Color development via antigen-antibody binding; results interpreted by Test line (T)/Control line (C) color comparison.
- Advantages: Results in 5 minutes; instrument-free; ideal for on-site screening (e.g., production line sampling).
III. Other Methods
- Ion Chromatography (IC): High specificity and anti-interference; suitable for complex matrices (e.g., dairy).
- Acid-Base Titration: Measures purity in industrial-grade benzoic acid (e.g., titration with NaOH standard solution).
- Melting Point Determination: Assesses purity (pure benzoic acid melts at 122.4°C).
Method Selection Guide
| Scenario |
Recommended Method |
Detection Limit/Features |
| High-precision quant (food) |
HPLC, GC-MS |
0.01–1 mg/kg |
| On-site rapid screening |
UV-Vis, Test strips |
Results in 5–10 min |
| Complex matrices (e.g., oils) |
GC-MS, IC |
Strong anti-interference |
| Industrial purity testing |
Titration, MP analysis |
Low cost, simple operation |
Note: Method selection depends on sample properties and accuracy requirements. Laboratory standards: HPLC/GC; Rapid screening priorities: Test strips/UV-Vis.
Source: Web content.
DATE：[2025-06-20] |
