1. Sample Preparation
The candidate of reference material was prepared by biological zymolysis methods and purify by preparative chromatography technique.
Compound | Molecular formula | CAS |
Patulin (PAT) | C7H6O4 | 149-29-1 |
2 . Traceability and Characterization Method
Candidate material was characterized by UV spectroscopy, melting point method, and nuclear magnetic resonance. Mass balance and qNMR methods was used to assign value of the RM. In mass balance, high performance liquid chromatography with diode array detector (HPLC-PDA) was used to determine the main component. Water was determined by Karl-fisher method. Total non-volatiles/inorganics were determined by ICP-MS and TGA method. Volatile solvents were determined by qNMR and GC-ECD methods.
3. Certified values and uncertainties
The property values and expanded uncertainty of the present CRM are as follows：
No. | Reference material | Certified Value (%) | U (%) k=2 |
GBE10257 | Patulin (PAT) | 99.7 | 0.2 |
The uncertainty given is the expanded combined uncertainty and represent an estimated standard division equal to the positive square root of the total variance of the uncertainty of components. Expanded factor k (k=2) is the coverage factor at the 95% confidence level. The uncertainty evaluation considered sources from characterization, between-unit homogeneity and stability.
4 . Homogeneity and Stability Testing
According to national technical specification of JJF1343 (equivalent to ISO Guide 35), homogeneity and stability study for this certified reference material were carried out through random sampling of subpackaged samples followed by UPLC-PDA method. The results demonstrated good homogeneity and stability of this CRM.
The minimum sample amount is 1.0 mg.
The F-test method was used for homogeneities testing and no statistically significant differences among bottles were observed.
Random sampling at regular intervals was made to test the stability of the certified reference material. The period of validity of this RM is 36 months since the date of certification. The stability of the CRM is regularly monitored by NIM. Any change of the certified values during this period will be informed to the customer just-in-less-time.
The period of validity of this CRM is 5 years since the date of certification. The stability of this CRM is regularly monitored by NIM, during this period the customer will be informed of any change of the certified values just-in-less-time.