Table 3.

Comparison of advantages and disadvantages of pretreatment methods.

Pretreatment methods	Advantages	Disadvantages
SPE	Sample enrichment and purification can be completed at the same time, simple operation	High cost, limited enrichment capacity, poor repeatability
SPME	No need for organic solvents, low environmental pollution; simple instrumentation and easy to operate	Poor repeatability, low accuracy of quantitative detection, few types of commercially available polymers
QuEChERS	Rapid and simple operation, good sensitivity and accuracy, wide application range, less environment pollution	Impurities can be only partially removed, susceptible to matrix effects