MICHEM HW-Touch Graphite Infrared Digestion Block

Overview

The MICHEM HW-Touch Graphite Infrared Digestion Block is an engineered sample preparation platform designed for controlled, uniform, and chemically resistant thermal digestion of solid and liquid samples prior to elemental analysis. It operates on infrared radiation heating coupled with a high-purity graphite heating block—coated with chemically inert polytetrafluoroethylene (PTFE)—to deliver rapid, reproducible, and spatially homogeneous temperature profiles across the entire 470 × 314 mm active surface. Unlike conventional ceramic or metal-sheathed electric hotplates, the HW-Touch eliminates radial thermal gradients through its thermally conductive graphite core, ensuring <±0.1 °C inter-sample temperature deviation under steady-state conditions. This precision supports quantitative acid digestion protocols required for trace-metal analysis by Atomic Absorption Spectroscopy (AAS), Atomic Fluorescence Spectroscopy (AFS), and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Its design accommodates both open-vessel wet digestion and post-microwave digestion tasks—including acid evaporation (“acid removal” or “赶酸”)—without sample transfer, thereby minimizing contamination risk and procedural variability.

Key Features

• High-purity graphite heating block with proprietary PTFE coating: Resists aggressive reagents including concentrated HNO₃, HCl, HF, H₂SO₄, and aqua regia; enables easy cleaning and long-term corrosion resistance.
• Infrared-assisted graphite heating architecture: Achieves rapid thermal response and stable plateau temperatures up to 460 °C, with no exposed heating elements or air gaps compromising thermal transfer efficiency.
• 30-segment programmable PID controller: Supports multi-step ramp-and-soak temperature profiles, adjustable heating rates, and automatic termination upon completion—fully compliant with GLP documentation requirements when paired with audit-trail-capable software.
• Uniform thermal field: Measured temperature variation across the working surface remains ≤±0.5 °C at 200 °C and ≤±1.0 °C at 400 °C, enabling statistically valid parallel digestion of up to 30 samples per run.
• Integrated safety systems: Dual-stage overtemperature protection, real-time thermal cutoff, and configurable hold-time logic prevent overheating and ensure operator safety during unattended operation.

Sample Compatibility & Compliance

The HW-Touch is validated for use with standard digestion vessels—including borosilicate glass tubes (supplied), PTFE digestion cups, and quartz crucibles—across EPA Methods 3050B, 3051A, and 3052; ISO 11047:1998 (soil heavy metals); and ASTM D3682-18 (trace metals in water). Its PTFE-coated graphite surface meets USP extractables criteria for Class VI polymers and complies with ICH Q5C stability testing environmental controls. The unit’s electrical design conforms to IEC 61010-1:2010 for laboratory equipment safety, while its thermal control architecture supports 21 CFR Part 11–compliant electronic recordkeeping when interfaced via RS-232/USB to LIMS-integrated data acquisition platforms.

Software & Data Management

The HW-Touch includes embedded firmware supporting ASCII-based serial communication (RS-232 or USB virtual COM) for integration into centralized lab automation workflows. Optional MICHEM LabControl Suite v3.2 provides full remote monitoring, real-time temperature logging (≥1 Hz sampling), digital signature-enabled method storage, and automated PDF report generation—including timestamps, user IDs, and deviation alerts. All method parameters—including ramp rates, soak durations, and safety thresholds—are version-controlled and exportable in CSV or XML formats for regulatory submission (e.g., FDA pre-submission packages or CNAS accreditation audits).

Applications

• Pre-digestion conditioning and post-microwave acid removal for soil, sediment, biological tissue, food matrices, and polymer composites.
• Standardized open-vessel digestion for certified reference materials (CRMs) such as NIST SRM 2710a, GBW(E) 080389, and ERM-CC141.
• Acid concentration control in hydride-generation AFS workflows requiring precise HCl matrix adjustment.
• Thermal pretreatment of catalysts, battery cathode materials, and geological samples prior to ICP-MS analysis.
• Method development for ISO/IEC 17025-accredited laboratories seeking documented thermal equivalence between microwave and block-digestion procedures.

FAQ

Can the HW-Touch be used with hydrofluoric acid (HF)?

Yes—the PTFE-coated graphite surface is chemically inert to HF at concentrations ≤5% v/v below 200 °C; however, extended exposure above 220 °C requires validation per ASTM D2672.
Is the temperature calibration traceable to NIST standards?

Calibration certificates (optional) include as-found/as-left data referenced to NIST-traceable platinum resistance thermometers (PRTs) per ISO/IEC 17025 Clause 6.6.
Does the unit support Ethernet or Wi-Fi connectivity?

No native Ethernet/Wi-Fi; however, third-party industrial gateways (e.g., Moxa EDS-G205A) enable TCP/IP bridging for SCADA integration.
What is the expected service life of the graphite block under routine use?

With proper cleaning and avoidance of mechanical abrasion, the coated graphite block maintains thermal performance for ≥5 years or 10,000 operational hours, verified by annual thermal mapping per ASTM E220.
Are replacement PTFE-coated graphite blocks available as spare parts?

Yes—MICHEM offers factory-reconditioned blocks with full recalibration and coating integrity verification (certified per ASTM D149).