ATAGO PAL-22S Portable Digital Honey Moisture Refractometer
| Brand | ATAGO |
|---|---|
| Origin | Japan |
| Model | PAL-22S |
| Product Type | Handheld Refractometer |
| Temperature Compensation | Automatic (ATC, 10–40°C) |
| Display | Digital LCD |
| Measurement Range | 12.0–30.0% w/w moisture |
| Accuracy | ±0.2% |
| Resolution | 0.1% |
| Power | 2 × AAA batteries |
| IP Rating | IP65 |
| Dimensions | 5.5 × 3.1 × 10.9 cm |
| Weight | 100 g (instrument only) |
Overview
The ATAGO PAL-22S is a compact, field-deployable digital refractometer engineered specifically for the rapid, non-destructive quantification of moisture content in honey. It operates on the principle of critical-angle refractometry: incident light passes through a honey sample placed on the sapphire prism surface, and the resulting refraction angle—directly correlated to the solution’s refractive index—is converted into moisture concentration (%) using a pre-calibrated algorithm traceable to international honey standards (e.g., Codex Alimentarius STAN 12-1981, EU Directive 2001/110/EC). Unlike generic Brix refractometers, the PAL-22S applies a proprietary temperature-compensated conversion curve optimized for the unique sucrose–glucose–fructose–water matrix of natural honey, eliminating systematic bias caused by invert sugar hydrolysis or thermal drift. Its optical architecture features a high-stability LED light source, precision-ground sapphire prism (Mohs hardness 9), and solid-state photodiode array—ensuring long-term calibration stability without mechanical moving parts.
Key Features
- Optimized optical calibration for honey-specific moisture determination—validated against reference oven-drying (AOAC 950.46) and Karl Fischer titration (ISO 5725-2)
- Automatic Temperature Compensation (ATC) across 10–40°C ambient range, enabling reliable field use without external thermostating
- Digital LCD display with 0.1% resolution and real-time measurement stabilization indicator
- IP65-rated enclosure—dust-tight and protected against low-pressure water jets—suitable for apiary, warehouse, and market inspection environments
- Lightweight (100 g) ergonomic design with one-handed operation and intuitive single-button interface
- No reagents, no consumables, no sample preparation—measurements completed in <3 seconds per sample
Sample Compatibility & Compliance
The PAL-22S accepts viscous, opaque, and particulate-containing honey samples—including raw, filtered, creamed, and comb honey—without clogging or prism fouling. Its sapphire prism resists scratching from crystalline glucose deposits and cleaning abrasives. The instrument complies with ISO 2173:2003 (fruit juice refractometry) as adapted for honey matrices, and supports GLP documentation workflows via optional RS-232 output (with compatible data logger). While not FDA 21 CFR Part 11 certified as a standalone device, its measurement traceability aligns with HACCP prerequisite programs and EU Regulation (EC) No 852/2004 for food hygiene control. Calibration verification is performed using distilled water (0.0%) and standardized sucrose solutions traceable to NIST SRM 84g.
Software & Data Management
The PAL-22S operates as a self-contained measurement unit with no embedded firmware update capability or onboard memory. However, it supports analog data export via optional RS-232 serial interface (cable sold separately), enabling integration with laboratory information management systems (LIMS), Excel-based QA logs, or custom QC dashboards. When paired with ATAGO’s free PAL-PC software (Windows-compatible), users can generate time-stamped measurement reports, apply batch-level statistical process control (SPC) charts (X̄–R), and archive calibration history—fulfilling audit requirements for ISO/IEC 17025-accredited honey testing laboratories. All measurement outputs are unit-consistent (w/w % moisture) and exclude Brix or density conversions.
Applications
- On-site honey grading and compliance screening at apiaries, cooperatives, and collection centers
- Quality assurance during bottling and packaging—verifying adherence to national moisture limits (e.g., ≤18.6% in USA, ≤20% in EU, ≤23% in China GB 14963)
- Monitoring honey ripening during hive storage and post-harvest maturation
- Pre-shipment inspection to prevent fermentation risk associated with elevated water activity (aw > 0.60)
- Educational use in food science curricula for demonstrating colligative property relationships in supersaturated solutions
- Research applications in apiculture studies evaluating varietal, climatic, and processing effects on honey hygroscopicity
FAQ
What standard does the PAL-22S calibration follow?
It uses a honey-specific refractive index–moisture correlation derived from empirical data sets validated against AOAC 950.46 reference method and harmonized with Codex Alimentarius honey specifications.
Can the PAL-22S measure other viscous liquids like maple syrup or jam?
No—it is factory-calibrated exclusively for honey; using it on other matrices introduces unquantified systematic error due to differing sugar composition and refractive dispersion profiles.
How often should calibration verification be performed?
Daily verification with distilled water (0.0%) is recommended before first use; full recalibration by an authorized ATAGO service center is advised annually or after physical impact.
Does the instrument require prism cleaning between samples?
Yes—wipe gently with lens tissue and distilled water after each measurement to prevent cross-contamination and residue buildup; avoid alcohol or acetone, which may degrade the prism adhesive.
Is temperature-controlled sample equilibration necessary?
No—the built-in ATC compensates for sample temperature within 10–40°C; however, measurements outside this range require manual correction or retesting at ambient equilibrium.
