| Product Identity | Confirm that the material is L-carnitine rather than L-carnitine L-tartrate, acetyl-L-carnitine, or another derivative. | CAS 541-15-1; molecular formula C7H15NO3; molecular weight approximately 161.20 g/mol for L-carnitine base. | Identity test by FTIR, HPLC, or another validated method, supported by the agreed product specification. | Critical |
| Assay and Potency | Review the quantitative content of L-carnitine and confirm whether the result is reported on an as-is or dry basis. | Use the contracted specification; a commonly used commercial target is approximately 97.0%–103.0% for L-carnitine base, subject to the test method and product form. | Batch-specific certificate of analysis with method reference, result, unit, basis, and laboratory approval. | Critical |
| Moisture and Water | Excess moisture can affect flowability, stability, packaging performance, and the calculated active content. | Set a moisture limit according to the validated product specification; Karl Fischer testing is preferred when water content must be measured accurately. | Karl Fischer or validated loss-on-drying result, including the test date and sample identification. | High |
| Impurity Profile | Check related substances, residual starting materials, degradation products, and inorganic residues. | Limits should be established through a risk assessment and agreed specification rather than relying only on a general appearance check. | Validated HPLC or equivalent impurity report with individual and total impurity results. | Critical |
| Heavy Metals and Elemental Impurities | Evaluate lead, arsenic, cadmium, mercury, and other elements relevant to the raw-material process and intended market. | Apply the limits required by the destination market and product category; use risk-based elemental-impurity controls instead of an unspecified “heavy metals pass” statement. | ICP-MS or ICP-OES report, laboratory accreditation details, and an elemental-impurity risk assessment. | Critical |
| Microbiological Quality | Confirm total aerobic microbial count, total yeast and mold count, and absence or limits for specified pathogens. | Limits should match the final application, such as food, dietary supplement, or pharmaceutical use, and the destination-market requirements. | Microbiology certificate of analysis with sampling plan, methods, results, and specification limits. | Critical |
| Residual Solvents | Determine whether solvents are used in the manufacturing or purification process and whether any may remain in the finished powder. | Control residual solvents according to the applicable ICH Q3C or market-specific requirements when relevant to the process. | Residual-solvent analysis by gas chromatography or a documented justification for not testing. | High |
| Physical Appearance | Inspect color, odor, visible contamination, agglomeration, and powder uniformity. | Uniform white to off-white powder is commonly specified for L-carnitine products; the exact description must be agreed in advance. | Approved visual standard, retained sample comparison, and batch inspection record. | High |
| Particle Size and Flow | Particle-size distribution affects blending, filling, dust generation, dissolution, and automated handling. | Define a sieve or laser-diffraction range based on the buyer's process rather than using a generic particle-size claim. | Particle-size distribution report, bulk density, tapped density, and flowability data where applicable. | High |
| Solubility and Performance | Verify that the powder dissolves consistently in the intended formulation and does not create unacceptable haze or sediment. | Use a buyer-approved test concentration, solvent, temperature, mixing time, and visual or instrumental endpoint. | Application-specific performance test and a signed technical specification. | High |
| Traceability | Every shipment should be traceable to raw materials, production records, testing, packaging, and release decisions. | Unique lot number, manufacturing date, retest or expiry date, production record, and retained sample for each batch. | Batch record summary, traceability statement, and documented change-control procedure. | Critical |
| Quality Management System | Assess whether the facility maintains controlled procedures for deviations, complaints, recalls, corrective actions, and changes. | Documented GMP-based quality procedures appropriate to the intended use and destination market. | Current audit report, quality manual summary, deviation and CAPA process, and relevant third-party certification where applicable. | Critical |
| Packaging and Storage | Protect the powder from moisture, contamination, heat, light, and damage during bulk transport. | Food- or pharmaceutical-contact packaging as applicable, intact seals, clear lot labeling, and storage conditions supported by stability data. | Packaging specification, container-closure information, transport requirements, and stability or retest documentation. | High |
| Stability and Shelf Life | Confirm that assay, moisture, appearance, and microbiological quality remain within specification throughout the stated shelf life. | Shelf life should be supported by real-time or appropriately designed stability data under defined storage conditions. | Stability protocol, time-point results, retest rationale, and recommended storage statement. | High |
| Regulatory and Market Fit | Check whether the product, labeling, documentation, and manufacturing controls meet the rules of the importing country and final application. | Specification and dossier should be aligned with the product category, such as food ingredient, dietary supplement, or pharmaceutical raw material. | Regulatory statement, allergen and GMO declarations where relevant, product specification, SDS, and export documentation. | Critical |
