Particle Sizing Systems AccuSizer A7000 APS Automated Optical Particle Counter

Overview

The Particle Sizing Systems AccuSizer A7000 APS is a fully automated optical particle counter engineered for high-fidelity quantification of particle size distribution and absolute particle concentration in liquid dispersions. It employs Single Particle Optical Sensing (SPOS), a direct-counting methodology that detects and sizes individual particles as they pass through a precisely defined optical sensing zone. Unlike ensemble-averaging techniques such as laser diffraction or dynamic light scattering, SPOS delivers statistically robust number-based distributions—critical for applications where low-abundance, large-diameter particles (“tail-end” outliers) dictate product safety, stability, or regulatory compliance. The A7000 APS integrates light extinction (LE) and light scattering (LS) detection within a single sensor architecture, enabling extended lower detection limits (down to 0.5 µm) while preserving full resolution across the 0.5–400 µm range. Its dual-stage automated dilution system allows accurate analysis of highly concentrated samples (up to 10¹¹ particles/mL) without manual intervention, eliminating operator-induced variability and ensuring reproducible, traceable data generation under cGMP conditions.

Key Features

• 512-channel logarithmic resolution across the full 0.5–400 µm measurement range—enabling precise discrimination of closely spaced particle populations (e.g., 0.7 µm vs. 0.8 µm) and faithful representation of multimodal distributions.
• Dual-mode SPOS detection: Simultaneous LE and LS signal acquisition improves sensitivity at sub-2 µm sizes while maintaining accuracy for larger particles, independent of refractive index or sample matrix.
• Two-step automated dilution: First-stage static dilution in a 30 mL quartz chamber, followed by second-stage dynamic dilution via precision ceramic piston pump—achieving total dilution factors from 20× to 144,060× with programmable repeatability.
• Regulatory-compliant software platform compliant with 21 CFR Part 11, including full audit trail, user authentication, electronic signatures, and secure data backup—validated for pharmaceutical quality control and GLP environments.
• Modular hardware design: Interchangeable sensors (e.g., LE400-05, LE1000-2), selectable syringes (0.5–5 mL), and configurable sample loops (0.5–10 mL) support method development and cross-application flexibility.
• Integrated cleaning protocol with Micro-90 flow cell cleaning kit and 0.2 µm Millipore-certified diluent filtration ensures minimal background interference and long-term sensor stability.

Sample Compatibility & Compliance

The AccuSizer A7000 APS accommodates both aqueous and organic-phase suspensions—including drug nanosuspensions, CMP slurries, inkjet inks, pigment dispersions, and lipid emulsions—without requiring solvent-specific recalibration. Its PFA-wetted fluid path and high-purity quartz flow cell minimize adsorption, leaching, or particle generation during analysis. The instrument meets pharmacopeial requirements for subvisible particle testing: it is explicitly referenced in Chinese Pharmacopoeia (CP) 2015 for PFAT5 (Percent Fat Above 5 µm) determination in injectable emulsions and conforms to USP for fat globule size analysis. All operational parameters—including dilution factor, flow rate, injection volume, and sensor gain—are electronically logged and immutable post-acquisition, satisfying FDA expectations for data integrity in regulated manufacturing environments.

Software & Data Management

The AccuSizer regulatory software provides a validated, closed-system environment for particle characterization workflows. It supports customizable reporting templates aligned with internal SOPs or external standards (e.g., ISO 21501-4, ASTM F2174). Raw pulse data, calibrated channel assignments, and dilution-corrected concentration values are stored in encrypted binary format with SHA-256 hashing. Audit trails record every user action—including parameter changes, report generation, and calibration events—with timestamps and operator IDs. Role-based permissions enforce separation of duties: analysts may acquire data, supervisors approve reports, and QA personnel review audit logs. The software exports ASCII-compatible CSV files and supports direct integration with enterprise LIMS via standardized ODBC drivers—ensuring seamless alignment with digital quality management systems.

Applications

The A7000 APS addresses critical quality attributes in industries where particle heterogeneity directly impacts performance or safety. In biopharmaceutical manufacturing, it quantifies oversized particles in monoclonal antibody formulations and liposomal drug products—supporting ICH Q5A and Q5C assessments of aggregation propensity. For semiconductor fabrication, it characterizes silica- and ceria-based CMP slurries, detecting agglomerates >30 µm that cause wafer scratching—where sensitivity exceeds laser diffraction by up to 25,000×. In advanced materials R&D, it validates dispersion stability of quantum dots, metal oxides, and conductive nanomaterials. Inkjet ink developers rely on its ability to resolve sub-micron pigment clusters before nozzle clogging occurs, while vaccine manufacturers use it to monitor adjuvant particle integrity during lyophilization cycles.

FAQ

How does SPOS differ from laser diffraction for tail-end particle detection?
SPOS counts and sizes each particle individually, yielding true number-weighted distributions; laser diffraction infers size from ensemble scattering patterns and often overestimates large-particle presence due to signal bias toward larger scatterers.
Can the A7000 APS analyze viscous or non-aqueous samples?
Yes—its adjustable flow rate (60–180 mL/min), chemically resistant PFA fluidics, and optional mechanical stirring accommodate solvents like DMSO, ethanol, and propylene glycol, provided viscosity remains below 50 cP.
Is sensor recalibration required between sample types?
No—NIST-traceable polystyrene latex (PSL) standards enable rapid in-situ verification; full recalibration is only needed annually or after sensor replacement, per IQ/OQ protocols.
What validation documentation is provided?
PSS supplies a comprehensive Validation Support Package including Installation Qualification (IQ), Operational Qualification (OQ), Performance Qualification (PQ) protocols, and 21 CFR Part 11 readiness assessment reports.
Does the system support unattended batch analysis?
Yes—the autosampler accepts up to 96 vials, and method sequences—including rinse cycles, dilution steps, and data export—execute automatically with real-time status monitoring via Ethernet-connected HMI.