1.0 PURPOSE
This Standard Operating Procedure
(SOP) outlines the process for the procurement, handling, and intermediate
checks of Certified Reference Materials (CRMs) used in chemical testing
laboratories, specifically for the quantification of residues and metals in
food and related products.
2.0 SCOPE
2.1 This SOP applies to all personnel
involved in the handling and use of CRMs for chemical testing in food and
related product laboratories.
3.0 RESPONSIBILITY
3.1 Analyst:
Responsible for procuring, handling, maintaining, and performing intermediate
checks of CRMs.
3.2 Quality Assurance (QA): Responsible for maintaining the SOP
‘Master Copy’ and ensuring that it is approved through the Quality Manager.
3.3 User Departments: Ensure that a 'Control Copy' of the
SOP is available with the user department.
4.0 DISTRIBUTION
4.1 The QA department will
ensure that the approved SOP is distributed to all relevant departments.
4.2 Each department should keep the ‘Control Copy’ for reference.
5.0 ABBREVIATIONS
- SOP: Standard
Operating Procedure
- CRM: Certified
Reference Material
- COA: Certificate
of Analysis
- RPD: Relative
Percent Difference
- ID:
Identification
- R: Response
- WS: Working
Standards
- NIST: National
Institute of Standards and Technology
6.0 PROCEDURE
6.1 Procurement of Certified Reference
Materials
6.1.1 CRMs must be procured
from approved manufacturers or suppliers.
6.1.2 The procurement of CRMs should meet the following requirements:
- A
current and valid Certificate of Analysis (COA) with
traceability with ISO 17034.
- An
expiration date that is current.
- NIST
traceability should be ensured wherever possible during procurement.
6.2 Receipt of Certified Reference Materials
6.2.1 Upon receipt, each CRM
shall be assigned a unique identification
code for
tracking, from the neat standard to the final dilution.
6.2.2 Documentation of the receipt should include the following details:
- Name
of the CRM
- Unique
identification code
- Purity
- Lot
number
- Quantity
received
- Gross
weight
- Date
received
- Expiration
date
6.2.3 The receipt and traceability of each CRM must be documented and retained
in the laboratory records.
6.3 Storage of Certified Reference Materials
6.3.1 CRMs should be stored at the
temperature specified in the Certificate
of Analysis (COA).
6.3.2 Stock standards and dilutions, including mixed standards, should be
stored in refrigerators or freezers to prevent contamination or in the specific condition if required.
6.3.3 Access to the storage areas should be controlled.
6.3.4 The following records must be maintained for storage:
- Temperature
readings of refrigerators and freezers, recorded daily.
- Details
of the standards used (e.g., standard name, volume, solvent, lot number,
purity, final concentration, storage location).
6.3.5 CRMs should be used within 12 months of preparation or
before expiration, whichever is earlier.
6.4 Preparation of Intermediate Dilutions
6.4.1 Intermediate dilutions,
including mixed standards, should be prepared in a clean, controlled
environment.
6.4.2 Each dilution should be labelled with the following information:
- Name
of CRM
- Concentration
- Solvent
used
- Date
of preparation
- Initials
of the preparer
- Expiration
date
6.4.3 Documentation should include:
- Amount
of stock standard used
- Solvent
used
- Volume
made up
- Date
of preparation
- Final
concentration
- Expiration
date
6.5 Standard Intermediate Checking
6.5.1 Intermediate checks
must be performed to ensure the integrity of dilutions and their
concentrations.
6.5. Two working standards, labeled as WS1 and WS2, should be prepared separately. One standard (WS1) is
made from the stock solution, and the other (WS2) is made from the intermediate
dilution. Both standards should then be analyzed using the appropriate
equipment to measure their respective responses (R1 for WS1 and R2 for WS2). These
responses are used to check the consistency and accuracy of the standards.
6.5.3 The Relative Percent Difference (RPD) between the responses should be
calculated as follows:
6.5.4 Acceptance Criteria: The RPD should not exceed 10%
6.5.5 Any discrepancies
should be investigated, and corrective actions should be taken.
6.6 Documentation of Intermediate Checks
6.6.1 All intermediate checks
must be documented in the logbooks to ensure traceability and compliance
with the SOP.
6.6.2 The logbook must include:
- Date
and time of check
- Identification
code of CRM used
- Responses
obtained (R1 and R2)
- RPD
calculation and results
- Any
corrective actions taken, if applicable.
7.0 RECORDS
- Certificate
of Analysis (COA) for each CRM
- Logbooks for
intermediate checks and preparation of dilutions
- Temperature
logs
for storage units (refrigerators/freezers)
- Procurement
records
for each CRM
8.0 REVISION HISTORY
- Version 1.0 – As per the
lab policy
