Purpose

Define user requirements for a standalone FUZKK utility that accepts laboratory CSV data, evaluates the records using limits embedded in code, and produces LabWare-compatible JSON.

Scope

The utility is intended for preliminary QC/QA review, integration testing, LIMS/LabWare flow and evidence-trail preparation. Final release decisions remain under the laboratory's validated procedure and responsible personnel.

Users

QC analyst, QA reviewer, CSV/validation engineer, LIMS/LabWare integration engineer, responsible laboratory specialist.

User requirements

1. The utility shall run without arguments and print its self-description, a built-in input.csv example from GetDemoData(), and demo evaluation for the embedded records.
2. The utility shall run with two arguments: input.csv output.json.
3. The utility shall not read input.csv and shall not write output.json when started without arguments.
4. CSV numeric values shall be parsed using CultureInfo.InvariantCulture.
5. Output shall be generated as LabWare-compatible JSON with Header, Samples, Results, Status, StatusCode, ErrorMessage, Description and DescriptionEN.
6. For PASS records, ErrorMessage shall be an empty string.
7. Embedded limits shall follow this priority: Ph. Eur. → British Pharmacopoeia / UK implementation → EAEU / regional requirements → EMA/ICH/EU guidance → USP fallback.
8. If an exact monograph is not known, strict standard API limits are used where applicable: assay 98–102%, total impurities ≤1.0%, individual impurity ≤0.5%.
9. For biologics and mAb-like products, aggregation, sterility and endotoxin checks shall be included where relevant to the utility purpose.
10. If a parameter may arrive in different units, the unit shall be represented as a separate input field or explicitly reflected in the input.csv field name.

Input CSV

BatchNumber,ProductName,Z_Average_nm,PDI,Peak1_Size_nm,Peak1_Percent,Zeta_Potential_mV,Intercept,Temperature_C,Measurements_Count
LNP-SIZE-2026-001,mRNA-LNP Vaccine,95.5,0.12,92.0,98.5,-15.0,0.95,25.0,3
LNP-SIZE-2026-002,mRNA-LNP Booster,110.0,0.18,108.0,95.0,-12.0,0.92,25.0,3
LNP-SIZE-2026-003,mRNA-LNP Therapeutic,150.0,0.35,145.0,80.0,-5.0,0.85,25.0,3

input.csv fields

Utility description

LNP Particle Size & PDI Monitor — LNP Particle Size and Polydispersity Monitor

LNP Particle Size & PDI Monitor — LNP Particle Size and Polydispersity Monitor

ℹ️ Utility analyzes Dynamic Light Scattering (DLS) data:
• Mean size (Z-Average) 80-120 nm
• Polydispersity Index (PDI ≤0.2)
• Zeta potential (stability)
• Size distribution (Main Peak %)

⚠️ CRITICAL: High PDI indicates formulation instability!
Particle size affects cellular uptake and organ distribution.

Usage:
LNPParticleSizePDIMonitor.exe → demo mode (console output)
LNPParticleSizePDIMonitor.exe input.csv output.json → evaluate your data

Input format:
BatchNumber,ProductName,Z_Average_nm,PDI,Peak1_Size_nm,Peak1_Percent,Zeta_Potential_mV,Intercept,Temperature_C,Measurements_Count

Example:
LNP-SIZE-2026-001,mRNA-LNP Vaccine,95.5,0.12,92.0,98.5,-15.0,0.95,25.0,3

— WHY IS THIS NEEDED?
Physical parameter control is critical for LNPs (Moderna, BioNTech, Novartis):
• Particle size (80-100 nm) is optimal for endocytosis and avoiding rapid clearance
• Low PDI (<0.2) ensures population homogeneity and predictable pharmacokinetics
• Zeta potential reflects colloidal stability and aggregation risk
• Size change during storage is an early marker of lipid degradation or particle fusion

⚠️ CRITICAL:
• Z-Average 80-120 nm — target range for most mRNA vaccines
• PDI ≤0.2 — indicator of high monodispersity
• Main peak ≥90% — absence of large aggregates
• Correlation intercept 0.8-1.0 — guarantee of DLS measurement quality
• Stable zeta potential prevents particle clumping

Key features:
• DLS and electrophoretic light scattering data analysis
• Aggregation risk assessment via PDI and distribution
• Measurement quality control (Intercept)
• Size stability monitoring over time

Critical parameters:
• Z-Average: 80–120 nm
• PDI: ≤0.2
• Main peak: ≥90%
• Intercept: 0.8–1.0

💡 Usage tips:
1. Dilute samples to optimal scattering intensity (kHz)
2. Use 0.22 μm filters for buffers to avoid background noise
3. Perform at least 3 replicates per sample
4. Compare size before and after freeze-thaw cycles
5. High PDI may indicate issues with microfluidic mixing during production

⚠️ Note: LNPs are soft particles, their size depends on temperature and medium viscosity. The utility accounts for these factors and helps distinguish real aggregation from measurement artifacts.

Traceability and limitations

• The URS is used as the source document for functional specification, CSV review and later validation work.
• This document does not replace an approved pharmacopoeial monograph, validated analytical method or internal product specification.
• For product-specific limits, the approved customer specification takes priority.

The functional specification describes the behaviour of the standalone FUZKK console utility, input-data format, evaluation algorithm and output JSON structure.

Functional flow

1. Main() checks the number of arguments.
2. If no arguments are provided: PrintHello() prints the description and built-in input.csv example, then RunDemoEvaluation() executes Evaluate() over GetDemoData() and prints demo JSON.
3. If two arguments are provided: RunWithFiles(input.csv, output.json) reads CSV, evaluates each record and writes LabWare-compatible JSON.
4. LoadData() uses CultureInfo.InvariantCulture and shall not be called in no-arguments mode.
5. Evaluate() returns a named tuple with BatchNumber, ProductName, Parameters, CriticalFailCount, WarningCount, Recommendation and RecommendationEN.
6. GetIssues() builds messages for ErrorMessage in WARNING/FAIL cases.

Evaluation rules

• PASS: CriticalFailCount = 0 and WarningCount = 0.
• WARNING: CriticalFailCount = 0 and WarningCount > 0.
• FAIL: CriticalFailCount > 0.
• ERROR: exception during reading or processing.
• ErrorMessage remains empty for PASS.
• Limits are embedded in Program.cs; no external limit configuration is required.

Input and fields

BatchNumber,ProductName,Z_Average_nm,PDI,Peak1_Size_nm,Peak1_Percent,Zeta_Potential_mV,Intercept,Temperature_C,Measurements_Count
LNP-SIZE-2026-001,mRNA-LNP Vaccine,95.5,0.12,92.0,98.5,-15.0,0.95,25.0,3
LNP-SIZE-2026-002,mRNA-LNP Booster,110.0,0.18,108.0,95.0,-12.0,0.92,25.0,3
LNP-SIZE-2026-003,mRNA-LNP Therapeutic,150.0,0.35,145.0,80.0,-5.0,0.85,25.0,3

Output JSON

{
  "Header": {
    "UtilityName": "LNP_ParticleSize_PDI_Monitor",
    "Version": "1.0.0",
    "Timestamp": "UTC",
    "InstrumentID": "FUZKK-QC-WORKSTATION",
    "OperatorID": "Admin"
  },
  "Samples": [
    {
      "SampleID": "from BatchNumber",
      "BatchNumber": "from CSV",
      "ProductName": "from CSV",
      "TestName": "utility-specific test",
      "AnalysisCode": "utility-specific code",
      "Status": "PASS | WARNING | FAIL | ERROR",
      "StatusCode": "1 | 2 | 0 | -1",
      "ErrorMessage": "",
      "Description": "Russian recommendation",
      "DescriptionEN": "English recommendation",
      "Results": [
        {
          "ParameterName": "parameter",
          "ResultValue": 0.0,
          "UnitOfMeasure": "unit",
          "SpecificationLimit": "limit",
          "IsWithinSpec": true
        }
      ]
    }
  ]
}