Meaning
Minimum concentrations of an analyte that can be determined quantitatively with acceptable precision and accuracy are established through laboratory testing. The limit of quantification LOQ defines the point where a measurement moves from simple detection to precise numerical calculation. This value is critical when testing plastics for restricted substances and heavy metals.
Detection Boundary
Establishing this limit requires statistical analysis of multiple blank samples to determine the noise level of the analytical instrument. The limit of quantification LOQ is typically set at ten times the standard deviation of the blank signal, ensuring high confidence in the reported concentrations. This boundary is much higher than the limit of detection, which only indicates the presence of the substance.
Method Validation
Analytical methods must be validated to confirm that the instrument can reliably measure at the specified limit. During validation, the limit of quantification LOQ is verified by analyzing spiked samples with known low concentrations of the target analyte. This process ensures that the laboratory can produce reproducible data during routine testing of incoming raw materials or finished molded products.
Compliance Assurance
For plastics used in sensitive applications, such as medical devices or food packaging, demonstrating that migrate substances remain below the limit of quantification LOQ is necessary for regulatory approval. This threshold ensures that potential contaminants are either absent or present only in such minute quantities that they pose no risk to human health, satisfying both legal mandates and safety requirements. By achieving a low and stable value for this limit, manufacturers can confidently verify compliance with global safety standards and provide documented assurance to their customers that their plastic parts are free of hazardous chemical residues.
