Preservatives_Combo_QC

URS & FS — User Requirements and Functional Specification

This document describes the controlled interface, user requirements and functional behaviour of Preservatives_Combo_QC. The utility is intended for automated verification of laboratory, pharmacopoeial, analytical or manufacturing QC parameters using input.csv and producing a structured output.json result.

Domain limits and critical parameters

• • Sodium Benzoate: 90–110% of Label Claim
• • Potassium Sorbate: 90–110% of Label Claim
• • Methylparaben: 90–110% of Label Claim
• • Propylparaben: 90–110% of Label Claim
• • Solution pH: 4.0–6.0 (Optimal range)
• • Benzoates and sorbates are active mainly against yeasts and molds in acidic media.
• • Parabens are active against bacteria and fungi in a wider pH range.
• • Synergistic effect allows reducing the concentration of each component.
• • HPLC allows simultaneous quantification of all components in one analysis.
• • pH control is mandatory as it determines the fraction of undissociated (active) acid form.
• • pH must be maintained in the range 4.0–5.5 for maximum efficacy of benzoates/sorbates.
• • Parabens may hydrolyze at extreme pH values.
• • Total preservative concentration must not exceed safe limits (toxicity).
• • Check compatibility of preservatives with other excipients (e.g., PEG may bind parabens).
• • Simultaneous control of 4 popular preservatives.
• • Assessment of pH criticality for antimicrobial activity.

URS — User Requirements Specification

input.csv contract

BatchNumber,Benzoate%,Sorbate%,MethylPar%,PropylPar%,pH
PRES-COMBO-2026-001,0.10,0.10,0.05,0.05,5.0
PRES-COMBO-2026-002,0.09,0.09,0.045,0.045,4.8
PRES-FAIL-PH-003,0.10,0.10,0.05,0.05,7.2

FS — Functional Specification

Example output.json

{
  "utilityId": "preservatives-combo-qc",
  "utilityName": "Preservatives_Combo_QC",
  "overallStatus": "PASS|WARNING|FAIL",
  "sourceFile": "input.csv",
  "checks": [
    {
      "parameter": "BatchNumber",
      "value": "PRES-COMBO-2026-001",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "Benzoate%",
      "value": "0.10",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "Sorbate%",
      "value": "0.10",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "MethylPar%",
      "value": "0.05",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "PropylPar%",
      "value": "0.05",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "pH",
      "value": "5.0",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    }
  ],
  "criticalFindings": [],
  "warnings": [],
  "generatedFor": "QA/QC review and LIMS integration"
}

Traceability matrix

OQ/PQ test scenarios

QA/QC and change control

• Do not rename columns without updating the validator, documentation and test set.
• Retain input.csv, output.json, executable version, documentation and checksum.
• Before production use, perform IQ/OQ/PQ or equivalent CSV/CSA verification.
• Critical limits must be verified against the approved specification, local SOPs and registration dossier.