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Separate a powder into particle-size fractions with calibrated sieves while controlling sample mass, agitation, blinding, attrition, weighing and the limits of a two-dimensional opening
Read FDA’s final September 2010 Q4B Annex 12 through analytical sieving, sieve selection, aperture verification, sample preparation, dry and wet methods, agitation, endpoint, retained mass, cumulative distribution, mass balance, investigation and lifecycle control.
Powder that looks uniform can contain coarse particles, fine particles and agglomerates that behave differently during blending, flow, compression and dissolution. Analytical sieving turns that hidden distribution into mass fractions.
FDA lists Q4B Annex 12, Analytical Sieving General Chapter, as final guidance dated September 2010, with docket FDA-2009-D-0579 and CDER and CBER as issuing offices.
Did you know? A sieve classifies particles by whether they pass an opening in a particular orientation. It does not directly measure a unique three-dimensional particle diameter.
For students, a sieve stack is a staircase for particles: each screen catches a different size range, and the final pattern works only if mass balance, aperture condition and agitation remain trustworthy.
Chapter index
Chapters 1–9: final September 2010 Q4B Annex 12
- 1. Annex 12 owns the harmonised analytical-sieving pharmacopoeial intent
- 2. FDA lists Annex 12 as final guidance from September 2010
- 3. Sieving reports mass by aperture interval
- 4. Particle shape affects whether a particle passes
- 5. Sieve selection brackets the useful distribution
- 6. Aperture condition and verification protect classification
- 7. Representative sampling comes before precise weighing
- 8. Sample preparation avoids changing the particles
- 9. Dry sieving uses reproducible mechanical agitation
Chapters 10–17: analytical sieving, particle-size distribution, sieve apertures, agitation, mass balance and investigation
- 10. Wet sieving can help when particles agglomerate or blind screens
- 11. Sieve loading affects passage and blinding
- 12. The endpoint separates sufficient classification from attrition
- 13. Each fraction keeps its identity through weighing
- 14. Mass balance checks the completeness of recovery
- 15. Cumulative percentages answer specification questions
- 16. Orthogonal sizing methods may answer different questions
- 17. A complete Annex 12 receipt reconstructs the sieve analysis
CHAPTER 1 OF 17 · See the particle-size question
1. Annex 12 owns the harmonised analytical-sieving pharmacopoeial intent
The annex evaluates selected analytical-sieving general chapters for interchangeable use under stated regional conditions. Product specifications and validated procedures still define the particle-size ranges and decisions for a particular material.
The scientific value of annex 12 owns the harmonised analytical-sieving pharmacopoeial intent appears when the observation, method and quality decision remain connected. The annex evaluates selected analytical-sieving general chapters for interchangeable use under stated regional conditions. Product specifications and validated procedures still define the particle-size ranges and decisions for a particular material. Keep this boundary visible: A sieve opening is an operational classifier rather than a unique particle diameter.
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Build an evidence receipt for annex 12 owns the harmonised analytical-sieving pharmacopoeial intent. Trace annex 12 owns the harmonised analytical-sieving pharmacopoeial intent from bulk sampling through every sieve fraction and cumulative result. Add the source version, equipment identity and acceptance rule. Keep this limit: A sieve opening is an operational classifier rather than a unique particle diameter.
A strong science note separates observation from interpretation. Trace annex 12 owns the harmonised analytical-sieving pharmacopoeial intent from bulk sampling through every sieve fraction and cumulative result. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Trace annex 12 owns the harmonised analytical-sieving pharmacopoeial intent from bulk sampling through every sieve fraction and cumulative result. Keep this boundary visible: A sieve opening is an operational classifier rather than a unique particle diameter.
CHAPTER 2 OF 17 · See the particle-size question
2. FDA lists Annex 12 as final guidance from September 2010
The official page identifies final status, docket FDA-2009-D-0579 and CDER and CBER as issuing offices. The evidence receipt records the annex, chapter edition, material specification and regional implementation.
For fda lists annex 12 as final guidance from september 2010, a reliable result depends on both the material and the controlled measurement system. The official page identifies final status, docket FDA-2009-D-0579 and CDER and CBER as issuing offices. The evidence receipt records the annex, chapter edition, material specification and regional implementation. Preserve this guardrail: Overloading, blinding and attrition can reshape the apparent distribution.
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Challenge the assumptions behind fda lists annex 12 as final guidance from september 2010. Challenge aperture condition, loading, agitation, endpoint and mass recovery behind fda lists annex 12 as final guidance from september 2010. Test one realistic failure mode and record what changes. Respect this boundary: Overloading, blinding and attrition can reshape the apparent distribution.
A strong science note separates observation from interpretation. Challenge aperture condition, loading, agitation, endpoint and mass recovery behind fda lists annex 12 as final guidance from september 2010. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Challenge aperture condition, loading, agitation, endpoint and mass recovery behind fda lists annex 12 as final guidance from september 2010. Keep this boundary visible: Overloading, blinding and attrition can reshape the apparent distribution.
CHAPTER 3 OF 17 · See the particle-size question
3. Sieving reports mass by aperture interval
A weighed sample passes through progressively smaller openings. Material retained on each sieve is weighed and expressed as a fraction of the recovered mass or starting mass under the defined calculation.
A trustworthy account of sieving reports mass by aperture interval keeps preparation, apparatus, timing, calculation and review in one traceable route. A weighed sample passes through progressively smaller openings. Material retained on each sieve is weighed and expressed as a fraction of the recovered mass or starting mass under the defined calculation. Remember: Representative sampling is essential because powders segregate.
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Audit the evidence route for sieving reports mass by aperture interval. Recalculate sieving reports mass by aperture interval from original tare and retained masses without premature rounding. Mark every handoff where identity, consent, time, contamination, bias or units could be lost. Preserve this caution: Representative sampling is essential because powders segregate.
A strong science note separates observation from interpretation. Recalculate sieving reports mass by aperture interval from original tare and retained masses without premature rounding. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Recalculate sieving reports mass by aperture interval from original tare and retained masses without premature rounding. Keep this boundary visible: Representative sampling is essential because powders segregate.
CHAPTER 4 OF 17 · See the particle-size question
4. Particle shape affects whether a particle passes
Elongated, plate-like or irregular particles can orient differently at an opening. Sieve data are operational size classes, not a direct image-based or volume-equivalent diameter for every particle.
The scientific value of particle shape affects whether a particle passes appears when the observation, method and quality decision remain connected. Elongated, plate-like or irregular particles can orient differently at an opening. Sieve data are operational size classes, not a direct image-based or volume-equivalent diameter for every particle. Keep this boundary visible: Mass balance must support the reported fractions.
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Build an evidence receipt for particle shape affects whether a particle passes. Reassess particle shape affects whether a particle passes after a milling, granulation, drying, supplier or sieve change. Add the source version, equipment identity and acceptance rule. Keep this limit: Mass balance must support the reported fractions.
A strong science note separates observation from interpretation. Reassess particle shape affects whether a particle passes after a milling, granulation, drying, supplier or sieve change. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Reassess particle shape affects whether a particle passes after a milling, granulation, drying, supplier or sieve change. Keep this boundary visible: Mass balance must support the reported fractions.
CHAPTER 5 OF 17 · Control the sieve stack
5. Sieve selection brackets the useful distribution
Aperture sizes span the expected material range without producing too many empty or overloaded fractions. Stack order, lid and receiver are documented before the sample is introduced.
For sieve selection brackets the useful distribution, a reliable result depends on both the material and the controlled measurement system. Aperture sizes span the expected material range without producing too many empty or overloaded fractions. Stack order, lid and receiver are documented before the sample is introduced. Preserve this guardrail: A sieve opening is an operational classifier rather than a unique particle diameter.
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Challenge the assumptions behind sieve selection brackets the useful distribution. Trace sieve selection brackets the useful distribution from bulk sampling through every sieve fraction and cumulative result. Test one realistic failure mode and record what changes. Respect this boundary: A sieve opening is an operational classifier rather than a unique particle diameter.
A strong science note separates observation from interpretation. Trace sieve selection brackets the useful distribution from bulk sampling through every sieve fraction and cumulative result. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Trace sieve selection brackets the useful distribution from bulk sampling through every sieve fraction and cumulative result. Keep this boundary visible: A sieve opening is an operational classifier rather than a unique particle diameter.
CHAPTER 6 OF 17 · Control the sieve stack
6. Aperture condition and verification protect classification
Woven wire can deform, wear, clog or corrode. Sieve identity, nominal aperture, certification or verification and visual inspection remain traceable. Damaged meshes are removed from use.
A trustworthy account of aperture condition and verification protect classification keeps preparation, apparatus, timing, calculation and review in one traceable route. Woven wire can deform, wear, clog or corrode. Sieve identity, nominal aperture, certification or verification and visual inspection remain traceable. Damaged meshes are removed from use. Remember: Overloading, blinding and attrition can reshape the apparent distribution.
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Audit the evidence route for aperture condition and verification protect classification. Challenge aperture condition, loading, agitation, endpoint and mass recovery behind aperture condition and verification protect classification. Mark every handoff where identity, consent, time, contamination, bias or units could be lost. Preserve this caution: Overloading, blinding and attrition can reshape the apparent distribution.
A strong science note separates observation from interpretation. Challenge aperture condition, loading, agitation, endpoint and mass recovery behind aperture condition and verification protect classification. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Challenge aperture condition, loading, agitation, endpoint and mass recovery behind aperture condition and verification protect classification. Keep this boundary visible: Overloading, blinding and attrition can reshape the apparent distribution.
CHAPTER 7 OF 17 · Control the sieve stack
7. Representative sampling comes before precise weighing
Segregation can enrich coarse or fine fractions during transfer. The sampling approach, quantity and subdivision technique preserve the material distribution rather than creating a convenient laboratory portion.
The scientific value of representative sampling comes before precise weighing appears when the observation, method and quality decision remain connected. Segregation can enrich coarse or fine fractions during transfer. The sampling approach, quantity and subdivision technique preserve the material distribution rather than creating a convenient laboratory portion. Keep this boundary visible: Representative sampling is essential because powders segregate.
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Build an evidence receipt for representative sampling comes before precise weighing. Recalculate representative sampling comes before precise weighing from original tare and retained masses without premature rounding. Add the source version, equipment identity and acceptance rule. Keep this limit: Representative sampling is essential because powders segregate.
A strong science note separates observation from interpretation. Recalculate representative sampling comes before precise weighing from original tare and retained masses without premature rounding. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Recalculate representative sampling comes before precise weighing from original tare and retained masses without premature rounding. Keep this boundary visible: Representative sampling is essential because powders segregate.
CHAPTER 8 OF 17 · Control the sieve stack
8. Sample preparation avoids changing the particles
Drying, dispersion and removal of obvious agglomerates follow the procedure without grinding fragile material into fines. Moisture and static can alter flow and adhesion, so relevant conditions are controlled.
For sample preparation avoids changing the particles, a reliable result depends on both the material and the controlled measurement system. Drying, dispersion and removal of obvious agglomerates follow the procedure without grinding fragile material into fines. Moisture and static can alter flow and adhesion, so relevant conditions are controlled. Preserve this guardrail: Mass balance must support the reported fractions.
Try this
Challenge the assumptions behind sample preparation avoids changing the particles. Reassess sample preparation avoids changing the particles after a milling, granulation, drying, supplier or sieve change. Test one realistic failure mode and record what changes. Respect this boundary: Mass balance must support the reported fractions.
A strong science note separates observation from interpretation. Reassess sample preparation avoids changing the particles after a milling, granulation, drying, supplier or sieve change. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Reassess sample preparation avoids changing the particles after a milling, granulation, drying, supplier or sieve change. Keep this boundary visible: Mass balance must support the reported fractions.
CHAPTER 9 OF 17 · Calculate the distribution
9. Dry sieving uses reproducible mechanical agitation
A shaker supplies controlled motion for a defined time or endpoint. Amplitude, tapping, duration, load and instrument identity affect passage. Hand sieving needs equally disciplined technique where permitted.
A trustworthy account of dry sieving uses reproducible mechanical agitation keeps preparation, apparatus, timing, calculation and review in one traceable route. A shaker supplies controlled motion for a defined time or endpoint. Amplitude, tapping, duration, load and instrument identity affect passage. Hand sieving needs equally disciplined technique where permitted. Remember: A sieve opening is an operational classifier rather than a unique particle diameter.
Try this
Audit the evidence route for dry sieving uses reproducible mechanical agitation. Trace dry sieving uses reproducible mechanical agitation from bulk sampling through every sieve fraction and cumulative result. Mark every handoff where identity, consent, time, contamination, bias or units could be lost. Preserve this caution: A sieve opening is an operational classifier rather than a unique particle diameter.
A strong science note separates observation from interpretation. Trace dry sieving uses reproducible mechanical agitation from bulk sampling through every sieve fraction and cumulative result. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Trace dry sieving uses reproducible mechanical agitation from bulk sampling through every sieve fraction and cumulative result. Keep this boundary visible: A sieve opening is an operational classifier rather than a unique particle diameter.
CHAPTER 10 OF 17 · Calculate the distribution
10. Wet sieving can help when particles agglomerate or blind screens
A suitable liquid carries fines through the mesh while preserving the material and aperture. Compatibility, dispersion, flow, drying and recovery are controlled because the liquid can dissolve, swell or transform particles.
The scientific value of wet sieving can help when particles agglomerate or blind screens appears when the observation, method and quality decision remain connected. A suitable liquid carries fines through the mesh while preserving the material and aperture. Compatibility, dispersion, flow, drying and recovery are controlled because the liquid can dissolve, swell or transform particles. Keep this boundary visible: Overloading, blinding and attrition can reshape the apparent distribution.
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Build an evidence receipt for wet sieving can help when particles agglomerate or blind screens. Challenge aperture condition, loading, agitation, endpoint and mass recovery behind wet sieving can help when particles agglomerate or blind screens. Add the source version, equipment identity and acceptance rule. Keep this limit: Overloading, blinding and attrition can reshape the apparent distribution.
A strong science note separates observation from interpretation. Challenge aperture condition, loading, agitation, endpoint and mass recovery behind wet sieving can help when particles agglomerate or blind screens. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Challenge aperture condition, loading, agitation, endpoint and mass recovery behind wet sieving can help when particles agglomerate or blind screens. Keep this boundary visible: Overloading, blinding and attrition can reshape the apparent distribution.
CHAPTER 11 OF 17 · Calculate the distribution
11. Sieve loading affects passage and blinding
Too much material forms a bed that prevents smaller particles from reaching openings. The procedure limits load per sieve and may divide a sample into portions. Persistent blinding is recorded rather than hidden by excessive brushing.
For sieve loading affects passage and blinding, a reliable result depends on both the material and the controlled measurement system. Too much material forms a bed that prevents smaller particles from reaching openings. The procedure limits load per sieve and may divide a sample into portions. Persistent blinding is recorded rather than hidden by excessive brushing. Preserve this guardrail: Representative sampling is essential because powders segregate.
Try this
Challenge the assumptions behind sieve loading affects passage and blinding. Recalculate sieve loading affects passage and blinding from original tare and retained masses without premature rounding. Test one realistic failure mode and record what changes. Respect this boundary: Representative sampling is essential because powders segregate.
A strong science note separates observation from interpretation. Recalculate sieve loading affects passage and blinding from original tare and retained masses without premature rounding. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Recalculate sieve loading affects passage and blinding from original tare and retained masses without premature rounding. Keep this boundary visible: Representative sampling is essential because powders segregate.
CHAPTER 12 OF 17 · Calculate the distribution
12. The endpoint separates sufficient classification from attrition
Sieving continues until additional agitation produces little further passage under the procedure. Excessive time can abrade friable particles and create fines, changing the property being measured.
A trustworthy account of the endpoint separates sufficient classification from attrition keeps preparation, apparatus, timing, calculation and review in one traceable route. Sieving continues until additional agitation produces little further passage under the procedure. Excessive time can abrade friable particles and create fines, changing the property being measured. Remember: Mass balance must support the reported fractions.
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Audit the evidence route for the endpoint separates sufficient classification from attrition. Reassess the endpoint separates sufficient classification from attrition after a milling, granulation, drying, supplier or sieve change. Mark every handoff where identity, consent, time, contamination, bias or units could be lost. Preserve this caution: Mass balance must support the reported fractions.
A strong science note separates observation from interpretation. Reassess the endpoint separates sufficient classification from attrition after a milling, granulation, drying, supplier or sieve change. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Reassess the endpoint separates sufficient classification from attrition after a milling, granulation, drying, supplier or sieve change. Keep this boundary visible: Mass balance must support the reported fractions.
CHAPTER 13 OF 17 · Use the result wisely
13. Each fraction keeps its identity through weighing
Retained material is recovered carefully from each sieve and the receiver. Tare values, balance resolution, transfer losses and labels support a one-to-one route from stack position to mass result.
The scientific value of each fraction keeps its identity through weighing appears when the observation, method and quality decision remain connected. Retained material is recovered carefully from each sieve and the receiver. Tare values, balance resolution, transfer losses and labels support a one-to-one route from stack position to mass result. Keep this boundary visible: A sieve opening is an operational classifier rather than a unique particle diameter.
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Build an evidence receipt for each fraction keeps its identity through weighing. Trace each fraction keeps its identity through weighing from bulk sampling through every sieve fraction and cumulative result. Add the source version, equipment identity and acceptance rule. Keep this limit: A sieve opening is an operational classifier rather than a unique particle diameter.
A strong science note separates observation from interpretation. Trace each fraction keeps its identity through weighing from bulk sampling through every sieve fraction and cumulative result. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Trace each fraction keeps its identity through weighing from bulk sampling through every sieve fraction and cumulative result. Keep this boundary visible: A sieve opening is an operational classifier rather than a unique particle diameter.
CHAPTER 14 OF 17 · Use the result wisely
14. Mass balance checks the completeness of recovery
The sum of retained fractions is compared with the initial sample mass. A poor recovery can signal dust loss, static, adhesion, spill, dissolution or transcription error and limits confidence in the distribution.
For mass balance checks the completeness of recovery, a reliable result depends on both the material and the controlled measurement system. The sum of retained fractions is compared with the initial sample mass. A poor recovery can signal dust loss, static, adhesion, spill, dissolution or transcription error and limits confidence in the distribution. Preserve this guardrail: Overloading, blinding and attrition can reshape the apparent distribution.
Try this
Challenge the assumptions behind mass balance checks the completeness of recovery. Challenge aperture condition, loading, agitation, endpoint and mass recovery behind mass balance checks the completeness of recovery. Test one realistic failure mode and record what changes. Respect this boundary: Overloading, blinding and attrition can reshape the apparent distribution.
A strong science note separates observation from interpretation. Challenge aperture condition, loading, agitation, endpoint and mass recovery behind mass balance checks the completeness of recovery. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Challenge aperture condition, loading, agitation, endpoint and mass recovery behind mass balance checks the completeness of recovery. Keep this boundary visible: Overloading, blinding and attrition can reshape the apparent distribution.
CHAPTER 15 OF 17 · Use the result wisely
15. Cumulative percentages answer specification questions
Percent retained and percent passing are calculated from unrounded masses using the defined denominator. Cumulative curves or tables make cut points visible without inventing precision beyond the aperture series.
A trustworthy account of cumulative percentages answer specification questions keeps preparation, apparatus, timing, calculation and review in one traceable route. Percent retained and percent passing are calculated from unrounded masses using the defined denominator. Cumulative curves or tables make cut points visible without inventing precision beyond the aperture series. Remember: Representative sampling is essential because powders segregate.
Try this
Audit the evidence route for cumulative percentages answer specification questions. Recalculate cumulative percentages answer specification questions from original tare and retained masses without premature rounding. Mark every handoff where identity, consent, time, contamination, bias or units could be lost. Preserve this caution: Representative sampling is essential because powders segregate.
A strong science note separates observation from interpretation. Recalculate cumulative percentages answer specification questions from original tare and retained masses without premature rounding. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Recalculate cumulative percentages answer specification questions from original tare and retained masses without premature rounding. Keep this boundary visible: Representative sampling is essential because powders segregate.
CHAPTER 16 OF 17 · Use the result wisely
16. Orthogonal sizing methods may answer different questions
Laser diffraction, microscopy and dynamic imaging use different measurement principles. Agreement is not assumed; method selection follows the property linked to manufacturing or product performance.
The scientific value of orthogonal sizing methods may answer different questions appears when the observation, method and quality decision remain connected. Laser diffraction, microscopy and dynamic imaging use different measurement principles. Agreement is not assumed; method selection follows the property linked to manufacturing or product performance. Keep this boundary visible: Mass balance must support the reported fractions.
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Build an evidence receipt for orthogonal sizing methods may answer different questions. Reassess orthogonal sizing methods may answer different questions after a milling, granulation, drying, supplier or sieve change. Add the source version, equipment identity and acceptance rule. Keep this limit: Mass balance must support the reported fractions.
A strong science note separates observation from interpretation. Reassess orthogonal sizing methods may answer different questions after a milling, granulation, drying, supplier or sieve change. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Reassess orthogonal sizing methods may answer different questions after a milling, granulation, drying, supplier or sieve change. Keep this boundary visible: Mass balance must support the reported fractions.
CHAPTER 17 OF 17 · Use the result wisely
17. A complete Annex 12 receipt reconstructs the sieve analysis
The record includes annex and chapter versions, material and lot, sampling, sample mass and preparation, moisture or environment, sieve identities and verification, stack order, dry or wet method, shaker settings, time and endpoint, retained masses, recovery, calculations, observations, deviations, investigation and approval.
For a complete annex 12 receipt reconstructs the sieve analysis, a reliable result depends on both the material and the controlled measurement system. The record includes annex and chapter versions, material and lot, sampling, sample mass and preparation, moisture or environment, sieve identities and verification, stack order, dry or wet method, shaker settings, time and endpoint, retained masses, recovery, calculations, observations, deviations, investigation and approval. Preserve this guardrail: A sieve opening is an operational classifier rather than a unique particle diameter.
Try this
Challenge the assumptions behind a complete annex 12 receipt reconstructs the sieve analysis. Trace a complete annex 12 receipt reconstructs the sieve analysis from bulk sampling through every sieve fraction and cumulative result. Test one realistic failure mode and record what changes. Respect this boundary: A sieve opening is an operational classifier rather than a unique particle diameter.
A strong science note separates observation from interpretation. Trace a complete annex 12 receipt reconstructs the sieve analysis from bulk sampling through every sieve fraction and cumulative result. Record the source, version or date, population or device context, method, result and one uncertainty. If the official record does not show a field, write “not shown” instead of filling the gap from memory.
Evidence checkpoint
Trace a complete annex 12 receipt reconstructs the sieve analysis from bulk sampling through every sieve fraction and cumulative result. Keep this boundary visible: A sieve opening is an operational classifier rather than a unique particle diameter.
Analytical-sieving evidence map
| Question | Evidence to capture | Boundary to retain |
|---|---|---|
| What is classified? | Representative powder sample | Control segregation |
| What defines the classes? | Verified sieve apertures | Preserve stack identity |
| What moves particles? | Specified agitation or wet flow | Avoid blinding and attrition |
| What validates the result? | Mass balance and transparent calculation | Keep recovery visible |
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Annex 12 turns a pile of powder into a readable size distribution. When sampling, screens, motion and mass balance are kept honest, each retained fraction becomes useful evidence about how the material may flow, blend and perform.
Primary sources and verification date
Source status checked 26 October 2026. FDA guidance describes the agency’s current thinking and does not replace applicable statutes, regulations or product-specific communication with FDA.
- FDA: Q4B Annex 12 Analytical Sieving — Final guidance, September 2010; checked 26 October 2026.
- ICH: Quality Guidelines — Official Q4B annex index and harmonisation context.
- FDA: Q4B Core Guidance — Final Q4B process guidance, February 2008.