Quality Control and Compliance Key Points for Primers and Probes in In Vitro Diagnostic Reagents

Raw Material Acceptance and Critical Quality Attributes

In in vitro diagnostic reagents, primers and probes serve as core raw materials, and fluctuations in their quality can directly affect the sensitivity and specificity of the finished reagent. Manufacturers typically establish raw material quality standards to accept primers and probes based on appearance, molecular weight, purity, sequence correctness, and fluorescent labeling efficiency. For purity, it is generally required to remove truncated sequences and residual protecting groups by high-performance liquid chromatography (HPLC) or polyacrylamide gel electrophoresis (PAGE). Sequence correctness can be confirmed by mass spectrometry or sequencing. Fluorescent labeling efficiency needs to be estimated based on absorbance ratios, and acceptance criteria vary for different modification groups.

Batch-to-Batch Consistency and Process Stability

Batch-to-batch consistency of primers and probes is critical for in vitro diagnostic reagents. Coupling efficiency, deprotection conditions, purification methods, and lyophilization processes in the synthesis process can all contribute to batch differences. It is recommended to establish records of critical process parameters and perform functional verification for each batch of raw materials, such as amplification experiments using standard templates to observe Ct value fluctuations and fluorescence signal intensity. Generally, batch-to-batch differences of critical raw materials are required to be controlled within a certain range to reduce batch-to-batch differences in finished reagents. For multiplex detection systems, it is also necessary to pay attention to mutual interference and signal crosstalk among different primers and probes.

Stability Evaluation and Storage/Transport Requirements

The stability of primers and probes is affected by storage temperature, buffer pH, light exposure, and repeated freeze-thaw cycles. A conventional practice is to store dry powder or high-concentration stock solutions at -20°C or -80°C protected from light, avoiding frequent freeze-thaw cycles. Working solutions can be stored short-term at 4°C or used according to the product instructions. Stability evaluation typically includes real-time stability, accelerated stability, and transport stability, requiring observation of fluorescence signal retention rate, amplification sensitivity, and probe integrity. The transport process should be validated for tolerance under cold chain or ambient conditions to ensure that the quality upon arrival at the customer meets requirements.

In vitro diagnostic reagent manufacturers should incorporate primers and probes into supplier management and quality systems, ensuring the reproducibility of test results through continuous stability monitoring and change control.