Leici SCH-02B Automatic Sample Changer

Overview

The Leici SCH-02B Automatic Sample Changer is an integrated electrochemical sample handling module engineered for high-throughput, reproducible operation in regulated laboratory environments. Designed explicitly for compatibility with Leici’s ZDJ-5B series automatic titrators, L-series benchtop electrochemical analyzers, and T-series intelligent instruments, the SCH-02B functions as a precision motion control platform that automates sample positioning, electrode conditioning, solution aspiration, waste evacuation, and in-situ stirring—eliminating manual intervention between measurements. Its operational principle relies on programmable stepper-motor-driven dual-tower architecture, enabling precise angular indexing of removable sample trays and synchronized actuation of peristaltic and diaphragm pumps for controlled fluid handling. This architecture supports both sequential multi-sample analysis and repeated single-sample validation—critical for method verification, calibration stability checks, and QC batch processing under GLP/GMP-aligned workflows.

Key Features

• Dual-tower modular design with detachable upper turret, allowing rapid reconfiguration for varying sample vessel geometries and volumes
• Three interchangeable sample trays: 30-position 50 mL tray, 24-position 100 mL tray, and 18-position 200 mL tray—each calibrated for positional repeatability within ±0.1°
• Bi-directional stirring capability: user-selectable top-mounted magnetic stirrer or bottom-mounted probe stirrer, with 45-step speed adjustment (0–1000 rpm equivalent range)
• Dual-pump cleaning system: PUMP-1 (chemically resistant diaphragm pump) handles high-pressure spray rinse of electrodes and sensor surfaces; PUMP-2 (precision peristaltic pump) manages low-shear aspiration of spent electrolyte and residual sample from cups
• Automated self-diagnostics at power-on and prior to each sequence, including motor homing verification, pump priming status, and interface handshake validation
• Dual communication interfaces (USB 2.0 and RS232) ensure seamless command-and-control integration with host instruments via standardized ASCII protocol—fully compliant with Leici’s instrument command set (LICS v3.2)

Sample Compatibility & Compliance

The SCH-02B accommodates standard cylindrical polypropylene or glass sample cups conforming to ISO 8573-1 dimensional tolerances for 50 mL, 100 mL, and 200 mL formats. Its mechanical design complies with IEC 61010-1:2010 safety requirements for electrical equipment used in measurement, control, and laboratory use. All wetted components—including tubing, pump heads, and rinse nozzles—are constructed from PTFE, EPDM, and 316 stainless steel to resist corrosion from common titrants (e.g., HCl, NaOH, AgNO₃), buffers (e.g., pH 4/7/10), and organic solvents (e.g., ethanol, acetonitrile). The unit supports audit-trail-capable operation when paired with Leici ZDJ-5B instruments configured for FDA 21 CFR Part 11 compliance, including electronic signature enforcement and immutable sequence logging.

Software & Data Management

The SCH-02B operates exclusively as a peripheral device—no embedded operating system or local data storage is present. All method sequencing, timing parameters, stir speed profiles, and rinse cycles are defined and executed by the host instrument’s firmware. Sequence files (.seq) generated on ZDJ-5B or L-series platforms include timestamped metadata, pump activation timestamps, position confirmation codes, and error flags—exportable in CSV or XML format for LIMS integration. Firmware updates are delivered via USB flash drive using Leici’s certified update utility (LUF v2.4), requiring cryptographic signature verification prior to installation.

Applications

• High-volume acid-base, redox, precipitation, and complexometric titrations in water quality labs (ASTM D129, ISO 9297)
• Electrochemical endpoint detection in pharmaceutical assay validation (USP , EP 2.2.43)
• Multi-point pH and ion-selective electrode calibration across concentration gradients
• Repeatability studies for sensor drift assessment under ISO/IEC 17025 clause 7.7
• Unattended overnight analysis of environmental extracts (e.g., soil leachates, wastewater influents)

FAQ

Is the SCH-02B compatible with non-Leici instruments?
No—the device uses proprietary mechanical coupling and ASCII-based command syntax optimized exclusively for Leici ZDJ-5B, L-series, and T-series platforms. Third-party integration requires custom firmware adaptation and is not supported.
Can the SCH-02B perform dilution or reagent addition?
No—it lacks volumetric dispensing hardware. It supports only sample positioning, stirring, rinsing, and waste removal. Reagent delivery must be handled by the host titrator or external dosing module.
What maintenance intervals are recommended?
Pump tubing replacement every 6 months under continuous use; annual inspection of stepper motor gear backlash and optical position encoder alignment; quarterly verification of rinse nozzle flow rate consistency using gravimetric measurement.
Does the unit support temperature-controlled sample staging?
No—ambient temperature operation only (0–40 °C). Integration with external chillers or heating blocks requires third-party mechanical adaptation and is outside the validated operational envelope.
How is positional accuracy verified during routine operation?
Each sample cycle initiates a homing routine referencing an optical zero mark on the lower turret. Positional confirmation is logged in the host instrument’s audit trail as “POS_OK” or “POS_ERR” with corresponding encoder pulse count deviation.