Zhiyunda ST-1/LAS Anionic Synthetic Detergent Analyzer
| Brand | Zhiyunda |
|---|---|
| Origin | Beijing, China |
| Manufacturer Type | Authorized Distributor |
| Country of Origin | China |
| Model | ST-1/LAS |
| Pricing | Available Upon Request |
Overview
The Zhiyunda ST-1/LAS Anionic Synthetic Detergent Analyzer is a compact, single-parameter photometric analyzer engineered for rapid, field-deployable quantification of linear alkylbenzene sulfonates (LAS) and other anionic surfactants in aqueous matrices. It operates on the principle of colorimetric detection via methylene blue active substances (MBAS) methodology—standardized in ISO 7875-2, ASTM D2330, and GB/T 5750.4–2023—where anionic surfactants form ion-pair complexes with methylene blue dye under controlled pH and ionic strength conditions. These complexes are extracted into chloroform, and absorbance is measured at 652 nm using a precision LED-based optical system. The instrument integrates factory-calibrated MBAS standard curves directly into firmware, enabling direct concentration readout in mg/L LAS equivalents without manual calibration or external software intervention.
Key Features
- Pre-programmed MBAS method compliant with international and national standards (ISO 7875-2, ASTM D2330, GB/T 5750.4)
- Stabilized LED light source with automatic optical self-check and drift compensation for long-term photometric stability
- Palm-sized ergonomic housing (142 × 78 × 42 mm), weighing ≤280 g with battery, optimized for handheld operation in field or mobile lab environments
- Backlit monochrome LCD display with intuitive Chinese-language interface (character-based, 128 × 64 resolution), supporting real-time measurement, unit toggle (mg/L or ppm), and status prompts
- Onboard data logging capacity for up to 500 measurement records, including timestamp, sample ID (user-defined), and result; data export via USB-C to CSV-compatible devices
- Integrated rechargeable lithium-ion battery (3.7 V / 2200 mAh) supporting ≥12 hours of continuous operation or ~3,000 measurements per full charge under typical ambient conditions (20–25°C)
- Dual power mode: battery-only operation for field use or AC adapter (5 V / 1 A) for benchtop continuity
Sample Compatibility & Compliance
The ST-1/LAS is validated for use with clarified, low-turbidity water samples—including raw and treated drinking water, wastewater effluents, surface water, boiler feedwater, cooling tower water, and agricultural runoff—provided turbidity remains below 5 NTU and free chlorine concentration is ≤0.5 mg/L (dechlorination recommended if exceeded). Interference from high concentrations of cationic surfactants, humic acids (>10 mg/L DOC), or heavy metals (e.g., Fe³⁺ > 0.3 mg/L) may require matrix-specific spike recovery validation. The analyzer meets CE marking requirements for electromagnetic compatibility (EN 61326-1) and safety (EN 61010-1). While not certified under FDA 21 CFR Part 11, its audit-ready data log structure—including immutable timestamps and non-editable result fields—supports GLP-aligned documentation practices in environmental testing laboratories.
Software & Data Management
No proprietary desktop software is required for basic operation. All calibration, measurement, and data retrieval occur within the embedded firmware. Measurement records are stored in a non-volatile memory partition with write-protection logic: entries cannot be deleted or modified post-acquisition. When connected via USB-C, the device emulates a mass-storage device, allowing drag-and-drop transfer of timestamped CSV files containing Sample ID, Date/Time, Absorbance (mAU), Concentration (mg/L), and QC flag status (e.g., “Low Signal”, “Out-of-Range”). Firmware updates are delivered as signed binary packages via Zhiyunda’s secure technical portal (accessible to registered distributors only) and applied through the same USB interface.
Applications
- Regulatory compliance monitoring of LAS discharge limits in municipal wastewater treatment plants (per local environmental protection bureau mandates)
- Routine surveillance of surfactant residuals in potable water distribution systems and point-of-use filtration verification
- Process control in detergent manufacturing facilities during effluent pretreatment
- Field assessment of surfactant contamination in rivers, lakes, and irrigation canals following industrial spill events
- Educational laboratory exercises in environmental chemistry and water quality analysis curricula
- QA/QC screening for cleaning validation in pharmaceutical cleanroom utilities (as supplementary tool alongside TOC or conductivity methods)
FAQ
What reagents are required for operation?
The ST-1/LAS requires Zhiyunda-certified MBAS assay kits (Cat. No. LAS-KIT-ST1), containing methylene blue solution, chloroform, buffer tablets, and extraction funnels. Use of non-certified reagents voids method compliance claims.
Is the instrument suitable for seawater samples?
Direct analysis of undiluted seawater is not recommended due to high chloride interference and salinity-induced phase separation issues; dilution (1:10) with deionized water and matrix-matched calibration is required for semi-quantitative estimation.
How often does the instrument require recalibration?
Factory calibration remains valid for 12 months under normal storage and usage conditions; annual verification against NIST-traceable LAS reference standards (e.g., Sigma-Aldrich 439205) is advised prior to critical reporting cycles.
Can the device store custom calibration curves?
No—only the preloaded MBAS curve is supported. Custom curve loading is intentionally disabled to maintain regulatory traceability and method integrity.
What is the detection range and LOD?
Based on standard MBAS protocol, the effective linear range is 0.05–2.0 mg/L LAS; limit of detection (3σ) is approximately 0.02 mg/L when using 10 mL sample volume and optimized extraction efficiency.
