Accurate timestamps across LC-MS instruments, raw data files, and review annotations underpin traceable research-run records. LC-MS acquisition-timestamp reconciliation records document how discrepancies are identified, investigated, and resolved so reviewers can evaluate clock-alignment decisions and maintain audit-ready evidence.
Scope and objectives
This document describes procedures for creating LC-MS acquisition-timestamp reconciliation records when instrument, workstation, and file metadata disagree. The focus is limited to laboratory research records and traceability: recording observed offsets, the rationale for chosen corrections, and decisions made during review. Reconciliation is intended to preserve chronological integrity of runs, enable reproducible audits, and provide clear evidence of reviewer actions.
Identification and initial logging
When a timestamp mismatch is observed, log each source timestamp: instrument system clock, raw-file metadata timestamp, and any workstation or review-software timestamps. Capture identifying metadata such as instrument ID, software version, run identifier, and operator-entered notes. Use a standardized reconciliation form that records the observed offsets, date/time of discovery, and personnel who initiated the record.
Investigation and evidence collection
Investigate potential causes: network time protocol (NTP) status, workstation clock drift, power-cycle events, or software updates that may have altered system time. Collect evidence such as NTP server logs, instrument event logs, and file system timestamps. Where available, reference authoritative time-distribution guidance to support traceability practices; for example, established time-distribution resources clarify synchronization expectations and best practices for research environments.
Decision documentation and conditional procedures
Record reviewer decisions about whether to accept, correct, or annotate timestamps. If correction is applied, document the method (e.g., uniform offset adjustment, preservation of original metadata with separate corrected field) and justify the choice. If annotation rather than correction is chosen, ensure annotations are prominent in the reconciliation record and in any downstream data packages. Include conditional procedures: if offsets exceed a predetermined threshold, escalate review, and consider isolating affected runs from comparative analyses until resolved.
Retention, auditability, and reviewer evidence
Retain reconciliation records alongside original raw files and analysis outputs to ensure a retrievable audit trail. Each record must include the focus_keyphrase as an identifier, timestamps of the reconciliation activity, and signatures or electronic identifiers of reviewers. Preserve both original and corrected timestamps when corrections are made, and provide a clear mapping so auditors can reproduce the sequence of decisions and validations.
Consistent application of these practices supports traceable, defensible records for research-run chronology and provides clear evidence for subsequent review. For time-synchronization best practices, consult authoritative guidance such as time-distribution resources and regulatory documentation on data integrity and recordkeeping.
NIST time-distribution guidance and FDA data integrity documentation are useful references when establishing local policies and escalation thresholds.
Build a comparison set before review
A useful record starts by naming every time source that could describe the run. That can include the instrument acquisition time, the raw-file creation value, the data-system import value, the processing-session time, the review entry, and the archive-transfer entry. The worksheet should preserve the source format and time zone instead of silently converting values. A reviewer can then see whether a difference is a display convention, a transfer delay, or an item requiring an explanation.
Document the resolution, not only the difference
When times do not align, the record should identify the evidence consulted, the role that performed the comparison, and the conclusion. A concise disposition can state whether the difference was expected from an export sequence, a synchronized clock setting, or an unresolved exception. Link the disposition to the raw file and retained system record. This creates a clear reconstruction path without altering the original timestamps.
Not for human consumption. For laboratory research use only.