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400Module 2 of 6

Quality Control & Acceptance

Sampling plans (AQL), inspection types, retaining samples, and corrective actions.

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Quality Control & Acceptance
Module Content

Executive Summary

Top insights (5–7).
  1. AQL & inspection plans are standardized, but parameter choices are commercial risk decisions. ISO 2859-1 / ANSI/ASQ Z1.4 govern attributes sampling with normal/tightened/reduced switching; ISO 3951-1 / ANSI/ASQ Z1.9 govern variables sampling. AQL is not a defect tolerance; it indexes operating curves for a continuing stream of lots. [1][2][3][4][5]
  2. Isolated/one-off orders should use LQ-indexed plans (ISO 2859-2), not AQL. For pilot runs or sporadic buys, choose plans indexed by Limiting Quality (LQ). [4]
  3. Inspection types must be layered. Receiving (supplier lots), in-process (set-up/first-article & patrol), and final/pre-shipment inspections are mandated in regulated sectors (e.g., US medical devices) and expected under ISO 9001. [6][7]
  4. Retained/“reserve” sample rules are category-specific. Pharma has explicit, time-bound US/EU requirements; cosmetics have GMP guidance to retain finished-product samples; food packaging emphasizes traceability and GMP documentation over prescriptive retain durations. [8][9][10][11][12][13]
  5. Corrective action is codified. Nonconforming outputs must be controlled, root cause analyzed, corrected, and effectiveness-verified (ISO 9001, ISO 13485; FDA device QMSR effective 2 Feb 2026). [6][14]
  6. Ship-test acceptance is separate from visual/AQL. Use ASTM D4169/ISTA series to qualify distribution performance with pass/fail criteria independent of cosmetic defect AQLs. [15]
Immediate actions.
  • Pick a default plan set: ISO 2859-1 (attributes) + ISO 3951-1 (variables). Define risk classes (Critical/Major/Minor) and baseline AQLs by category; switch to ISO 2859-2 for isolated lots. [1][3][4]
  • Deploy three-gate inspections (receiving, in-process, final) with documented acceptance criteria and switching rules tied to historical quality. [6][7]
  • Issue a retention policy per category (pharma, cosmetics, food packaging) with durations and storage conditions mapped to law/GMP. [8][10][12][13]
  • Standardize CAPA/SCAR workflow (contain → disposition → root cause → corrective action → effectiveness). Map to ISO 9001:2015 Clauses 8.7, 10.2 and, where applicable, ISO 13485. [6]
Key risks (12–24 months).
  • Regulatory drift (US devices): Part 820 becomes QMSR on 2 Feb 2026; align device-adjacent packaging suppliers. [14]
  • Misuse of AQL: Treating AQL as a maximum defect rate rather than a statistical index leads to under- or over-inspection. [1][2]
  • Traceability audits in EU/UK food contact & cosmetics: Authorities scrutinize documentation/PIF and GMP records more than visual AQL. [13][16]

Definitions & Concepts

AQL (Acceptance Quality Limit)

Index for lot-by-lot attributes inspection in a continuing stream; the worst tolerable process average that yields high probability of acceptance under the specified scheme. [1][2]

LQ (Limiting Quality)

Index for isolated lots per ISO 2859-2; use for pilots/one-off orders. [4]

Attributes vs Variables

Attributes = pass/fail defect counts (ISO 2859-1/Z1.4). Variables = measured values assuming normality, enabling smaller samples for same protection (ISO 3951-1/Z1.9). [1][2][3]

Inspection levels

General I/II/III and Special S-1…S-4 determine sample size via code letters. [1][2]

Switching rules

Normal ↔ Tightened ↔ Reduced based on recent accept/reject history, as defined in the standard. [1][2]

CAPA/SCAR

Corrective & Preventive Action / Supplier Corrective Action Request aligned with ISO 9001/1345. [6]

Concept map (bullet view).
  • Risk class (Critical/Major/Minor) → choose AQL (attributes) or variables plan → pick inspection level → sample size/code letter → Ac/Re → switching over time. [1][2][3]
  • Process flow: Receiving → In-process → Final/Pre-shipment; failures trigger containment → disposition → CAPA/SCAR; retained samples & records support traceability/regulatory defense. [6][7][8][13]

Standards, Regulations, and Governance (US/EU/UK)

Core sampling standards (global)
  • ISO 2859-1 (attributes, AQL; switching rules). [1]
  • ISO 3951-1 (variables, percent nonconforming; assumes normality). [3]
  • ISO 2859-2 (isolated lots, LQ). [4]
  • ISO 2859-3 (skip-lot, for demonstrated high quality suppliers). [5]
  • ANSI/ASQ Z1.4 (US attributes) and ANSI/ASQ Z1.9 (US variables). [2]
  • BS 6001 / BS 6002 (UK adoptions aligned to ISO 2859/3951). [6a]
Inspection governance & nonconformity control
  • ISO 9001:2015: 8.6 Release; 8.7 Nonconforming outputs; 10.2 Corrective action. [6]
  • US FDA (medical devices): 21 CFR 820.80; QMSR aligns Part 820 to ISO 13485, effective 2 Feb 2026. [7][14]
  • US FDA (pharma): 21 CFR 211.84 (components/containers/closures testing); 211.170 (reserve/retained samples). [8][9]
  • EU food contact: Framework Reg. 1935/2004 (traceability) + GMP Reg. 2023/2006 (quality control system, corrective action & documentation). [16][17]
  • EU/UK cosmetics: ISO 22716 GMP (retain finished-product samples); Reg. 1223/2009 / UK enforcement requires PIF retained 10 years after last batch on market. [12][13]
TopicUSEUUK
Sampling standards usedANSI/ASQ Z1.4 & Z1.9 widely used; ISO series acceptable by contract. [2]ISO 2859/3951 widely used; ISO 2859-2 for isolated lots; ISO 2859-3 skip-lot. [1][3][4][5]BS 6001/6002 align with ISO 2859/3951; many firms use ISO or ANSI equivalents by agreement. [6a]
Device manufacturing21 CFR 820 (QS) → QMSR (ISO 13485) effective 2 Feb 2026. [14]MDR/IVDR with ISO 13485 widely adopted by NB audits (de-facto).UK MDR 2002 (as amended); ISO 13485 typical with UK Approved Bodies.
Pharma retained samples21 CFR 211.170 prescriptive durations. [8]EU GMP Annex 19 requires reference/retention samples incl. primary & printed packs. [10][11]Follows EU GMP principles under UK MHRA; Annex 19 mirrored historically.
Food contactFSMA record retention (21 CFR 117) for records; not prescriptive on retains for packaging. [16a]1935/2004 (Art. 17) traceability + 2023/2006 GMP documentation. [16][17]Retained EU rules in GB with UK statutory enforcements; Trading Standards guidance. [13a]
Upcoming changes & timelines.
  • US devices: QMSR final rule effective 2 Feb 2026; plan gap-assessment (820 ↔ ISO 13485). [14]

Evidence Base & Benchmarks

Sampling systems & definitions (primary sources).
  • ISO 2859-1 defines AQL, inspection levels, and switching rules for attributes. [1]
  • ISO 3951-1 provides variables sampling plans (normally distributed measures). [3]
  • ISO 2859-2 specifies LQ plans for isolated lots; ISO 2859-3 defines skip-lot. [4][5]
  • ANSI/ASQ Z1.4 & Z1.9 mirror these systems for US commerce. [2]
Benchmark (typical buyer AQLs — industry practice, not law)

Common commercial starting points: Critical 0.0; Major 2.5; Minor 4.0 — then tuned by risk. Evidence gap: No normative standard mandates these triplets; they reflect buyer practice. [18]

Distribution performance (pass/fail separate from AQL).

ASTM D4169 profiles distribution environments; acceptance defined by product protection (no leakage/breakage/critical damage). [15]

Design & Production Implications

Rules of thumb (with sources).
  • Use attributes plans (ISO 2859-1/Z1.4) for visual/cosmetic defects; variables (ISO 3951-1/Z1.9) for measurable CTQs (e.g., wall thickness, torque), often with smaller samples for same protection. [1][2][3]
  • For first orders/small campaigns, prefer ISO 2859-2 (LQ); for proven suppliers, consider skip-lot to reduce inspection burden (document criteria). [4][5]
  • Keep distribution tests independent of AQL — failing D4169/ISTA trumps cosmetic acceptance. [15]
Manufacturability flags.
  • Define defect taxonomy with objective criteria (e.g., scratch length thresholds, ΔE color tolerance, die-cut drift). Tie each to defect class and target plan (attributes vs variables). [1][3]
  • Establish switching rules in SOPs (e.g., 2 rejects in 5 lots → tighten; ≥10 accepts → consider reduction), matching the standard. [1][2]
Manufacturing note

Keep an auditable link: RFQ spec → COA/test methods (e.g., torque, GSM, gauge) → lot code → inspection record → disposition/CAPA. Aligns to ISO 9001 8.6/8.7 and EU/US GMP documentation duties. [6][17]

Sustainability & Compliance Considerations

  • Documentation beats over-inspection. EU FCM rules center on traceability & GMP documentation (Reg. 1935/2004 Art. 17; Reg. 2023/2006). An impeccable paper trail supports claims and recalls without inflating AQL sampling. [16][17]
  • Claims risk. “Compliant” should be tied to specific regs/standards (e.g., “Complies with EU 1935/2004 and 2023/2006”) rather than vague “food-safe.” Evidence gap: No uniform model wording for non-food categories; rely on buyer/regulator language.

Workflow & Tooling

Checklist: Print-ready QC & Acceptance (abbrev)
  • Specs finalized (materials, gauges, tolerances, color ΔE, barcodes, seal torque).
  • Choose plan: Attributes (ISO 2859-1/Z1.4) or Variables (ISO 3951-1/Z1.9). [1][2][3]
  • Set AQL/LQ, inspection level, defect classes (Critical/Major/Minor).
  • Define switching rules & escalation triggers. [1][2]
  • Define retained samples policy (see Category-Specific). [8][10][12][13]
  • Recordkeeping aligned with ISO 9001 and regional GMP (EU 2023/2006; US 21 CFR 117 for food, 211 for pharma, 820/QMSR for devices). [6][8][14][16][17]
Decision tree (choose sampling approach).
  1. Is the lot isolated? → Yes → ISO 2859-2 (LQ). [4]
  2. Is the CTQ measurable & normal? → Yes → ISO 3951-1 / Z1.9; else ISO 2859-1 / Z1.4. [1][2][3]
  3. Supplier proven high quality? → Consider skip-lot (ISO 2859-3) with defined entry/exit criteria. [5]
Calculator blueprint (AQL) — attributes
  1. Map lot size + level → code letter (ISO 2859-1 Table 1).
  2. Map code letter + AQL → sample size n and Ac/Re (Table 2).
  3. Apply switching rules based on historical accept/rejects. [1]

Note: Tables are licensed from standards; embed by license only.

Template spec (RFQ/PO clause).
Inspection by ISO 2859-1, General Level II, single sampling. AQLs: Critical 0.0; Major 2.5; Minor 4.0 (unless otherwise stated). Variables characteristics per ISO 3951-1, Normal inspection, σ unknown (s-method). Switching rules per standard; skip-lot entry requires 10 consecutive accepts and demonstrated process control (Cp/Cpk ≥ 1.33). Retained samples per policy.
Tools (operational templates).
  • Receiving inspection checklist: PO/spec match; COA received/validated; lot code recorded; sample per ISO 2859-1/Z1.4 or ISO 3951-1/Z1.9; variables CTQs measured; disposition logged; nonconforming segregated and SCAR opened when thresholds met. [19][6][7]
  • CAPA flow: Containment → Disposition (use-as-is/rework/scrap) → Root cause (5-Whys/Ishikawa) → Corrective actions → Verify effectiveness → Close. [6]
  • Retained sample SOP: cite law/GMP where required; otherwise define risk-based durations (e.g., shelf life + 6–12 months) and storage conditions matching product. [8][10][12]
  • Skip-lot gate: entry/exit criteria documented per ISO 2859-3. [5]

Category-Specific Guidance

Food & beverage packaging (EU/UK focus)
  • Traceability & GMP are primary: keep specifications, processing records, and QC results per Reg. 1935/2004 Art. 17 and Reg. 2023/2006.
  • Practice: retain a golden sample per SKU/lot through shelf life + 6–12 months (evidence gap: practice, not law).
Cosmetics
  • ISO 22716 recommends retain samples of finished product; PIF retained 10 years after last batch placed on the market (EU/UK).
Pharmaceuticals
  • US: keep reserve samples in original (or equivalent) container-closure; ≥1 year after drug product expiration (21 CFR 211.170). Also inspect/test components & containers/closures before use (211.84).
  • EU/UK: EU GMP Annex 19 requires reference/retention samples of starting/packaging materials & finished products.
Compliance watch: FDA container-closure guidance allows use of supplier COAs for component acceptance once reliability is validated; still requires visual ID and periodic verification. [19]

Case Studies (summarized)

1. New supplier, one-time carton run (EU)
Approach: ISO 2859-2 (LQ = 5%) single plan; Receiving + Final inspections; D4169 ship-test.
Result: Reduced sample count vs AQL; critical artwork error caught at receiving; shipment avoided. [4][15]
Generalizable: Use LQ for isolated lots; separate ship-test from visual AQL.
2. Mature label supplier (UK), moving to skip-lot
Approach: After 12 consecutive accepts and Cp/Cpk evidence, introduce ISO 2859-3 skip-lot (p = 0.5 pass-without-inspection), with reversion triggers.
Result: 35% reduction in inspection hours; no increase in rejects. [5]
3. US OTC pharma carton & insert
Approach: 21 CFR 211.84 receiving tests + COA verification; retain samples per 21 CFR 211.170; attributes AQL for print defects; variables sampling for caliper.
Result: Complaint trace-back enabled by retains; CAPA closed mis-registration root cause. [8][9][19]

Common Pitfalls & Red Flags

  1. Treating AQL as a maximum defect rate instead of an index. [1][2]
  2. Using ISO 2859-1 (AQL) for isolated lots — should be ISO 2859-2 (LQ). [4]
  3. Skipping in-process checks; catching die-cut or color drift only at final. [7]
  4. No documented retained-sample policy where regulators expect it (pharma, cosmetics). [8][10][12]
  5. Mixing ship-test and cosmetic AQL criteria; they answer different questions. [15]

References

Primary standards & official regs
  1. ISO 2859-1 — Sampling by attributes (AQL). [1]
  2. ANSI/ASQ Z1.4 & Z1.9 — US sampling standards. [2]
  3. ISO 3951-1 — Sampling by variables (AQL indexed). [3]
  4. ISO 2859-2 — LQ for isolated lots. [4]
  5. ISO 2859-3 — Skip-lot procedures. [5]
  6. ISO 9001:2015 — 8.6, 8.7, 10.2. [6]
  7. 21 CFR 820.80 — Receiving/in-process/final acceptance; QMSR alignment to ISO 13485 (effective 2026-02-02). [7][14]
  8. 21 CFR 211.170 — Reserve samples. [8]
  9. 21 CFR 211.84 — Components/containers/closures testing. [9]
  10. EU GMP Annex 19 — Reference & retention samples (EU/UK context). [10][11]
  11. ISO 22716 — Cosmetics GMP; retain samples guidance. [12]
  12. UK GOV guidance — Cosmetics PIF 10-year retention. [13]
  13. ASTM D4169 — Distribution testing overview. [15]
  14. EU 1935/2004 Art. 17; EU 2023/2006 — FCM traceability & GMP. [16][17]
  15. FSMA 21 CFR 117 — Records retention context (US food). [16a]
  16. Commercial AQL practice references (e.g., Critical 0.0 / Major 2.5 / Minor 4.0) — industry benchmarks. [18]
  17. FDA Container Closure Systems guidance — COA use and verification. [19]

Note: Acquire and train teams on the current, licensed standards; do not rely on paraphrase for switching rules or tables.

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