Rigaku Micro-Z Benchtop Wavelength Dispersive X-Ray Fluorescence Spectrometer

Overview

The Rigaku Micro-Z is a benchtop wavelength dispersive X-ray fluorescence (WDXRF) spectrometer engineered for high-precision, routine elemental quantification—specifically optimized for total sulfur determination in liquid hydrocarbon matrices such as gasoline, diesel, jet fuel, and lubricants. Unlike energy dispersive XRF (EDXRF), the Micro-Z employs Bragg diffraction from precisely aligned analyzing crystals to isolate characteristic X-ray lines with superior spectral resolution, enabling accurate peak-to-background discrimination critical for low-level sulfur detection. Its fixed-channel optical architecture eliminates mechanical scanning, delivering exceptional long-term stability and measurement reproducibility without recalibration drift. Designed for industrial laboratories and refinery QC environments, the instrument operates under ambient conditions—requiring no vacuum pumps, helium purge gas, liquid nitrogen, or external cooling water—making it significantly more robust and lower in operational overhead than conventional WDXRF systems.

Key Features

• Patented monochromator optics dedicated to S Kα (2.307 keV) detection, minimizing spectral interferences from Cl, Ca, and transition metals commonly present in fuel matrices
• Air-cooled X-ray tube and detector assembly—eliminates dependency on chiller units, helium gas supplies, or cryogenic coolers
• Direct analysis of neat liquid samples: no digestion, dilution, or chemical derivatization required; compatible with sealed sample cups or standard vials
• Touchscreen-integrated user interface with guided workflows—designed for operators with minimal spectroscopic training
• Compliance with regulatory test methods: fully validated against ASTM D2622 (Standard Test Method for Sulfur in Petroleum Products by Wavelength Dispersive XRF), ISO 20884 (Petroleum products — Determination of sulfur content — Wavelength dispersive X-ray fluorescence spectrometry), and JIS K 2541-7 (Testing methods for petroleum products — Determination of sulfur content — X-ray fluorescence method)
• Real-time background correction algorithm based on dual-point (peak + adjacent background) acquisition per ISO 20884 protocol

Sample Compatibility & Compliance

The Micro-Z accepts liquid samples in volumes ranging from 1–10 mL, including volatile distillates, viscous residual fuels, and biodiesel blends. Solid samples (e.g., catalysts, particulates on filters) may be analyzed using pressed pellets or fused beads—though its primary design emphasis remains on rapid, unprepared liquid analysis. All measurement protocols adhere strictly to GLP-aligned data integrity requirements: audit trails record operator ID, timestamp, calibration status, and raw intensity values for each analysis. Instrument qualification documentation supports FDA 21 CFR Part 11 readiness when deployed in regulated manufacturing environments (e.g., API-grade fuel production). Full traceability to NIST-traceable sulfur reference standards (e.g., SRM 2722, SRM 1634c) is maintained through factory-installed calibration curves.

Software & Data Management

Rigaku’s proprietary QuantExpress software provides method setup, calibration curve generation, and automated report export in PDF and CSV formats. Each analysis session logs full spectral metadata—including tube voltage/current, crystal selection, dwell time, and dead-time corrected intensities—enabling retrospective reprocessing and uncertainty propagation modeling. The system supports LIMS integration via ASTM E1384-compliant ASCII output and optional OPC UA connectivity. Software validation packages include IQ/OQ documentation templates aligned with ISO/IEC 17025 laboratory accreditation requirements.

Applications

• Regulatory sulfur compliance testing for ultra-low-sulfur diesel (ULSD), gasoline (Tier 3), and marine fuels (IMO 2020)
• In-process monitoring of hydrotreating unit efficiency in refineries
• Quality control of biofuels and synthetic hydrocarbons where combustion-based methods (e.g., UV fluorescence) suffer from matrix quenching
• Research applications requiring interference-free quantification of sulfur speciation proxies in catalyst studies
• Third-party verification labs performing contract testing per EPA, EN, or GB standards

FAQ

Does the Micro-Z require helium or vacuum operation?
No. It operates under atmospheric air using a sealed X-ray path and air-cooled detector—no gas purge or vacuum pump is needed.
Can it analyze solid samples such as catalyst powders?
Yes, though optimal performance is achieved with liquids. Solids require homogenization and pelletization; detection limits degrade approximately 3–5× compared to liquid analysis.
Is method validation support available for ISO 20884 implementation?
Yes. Rigaku provides application notes, certified reference material recommendations, and on-site IQ/OQ assistance for method transfer and regulatory submission.
What maintenance is required beyond routine cleaning?
Annual X-ray tube output verification and crystal alignment check are recommended; no consumables (e.g., detector windows, gas counters) require replacement.
How does its detection limit compare to EDXRF instruments for sulfur in fuels?
Typical MDL is 0.5–1.0 ppm for diesel at 100 s counting time—approximately 5–10× lower than comparable benchtop EDXRF systems due to superior peak-to-background ratio from wavelength dispersion.