Molecular Devices CMax Plus Absorbance-Only Microplate Reader

Overview

The Molecular Devices CMax Plus Absorbance-Only Microplate Reader is a dedicated, high-performance absorbance detection system engineered for precision and reproducibility in life science laboratories. Based on photometric measurement principles—where light attenuation through sample-containing wells is quantified via Beer-Lambert law—the CMax Plus delivers reliable optical density (OD) data across the visible spectrum (400–750 nm). Designed exclusively for absorbance-based assays, it eliminates spectral interference from fluorescence or luminescence pathways, ensuring optimal signal-to-noise ratio and assay specificity. Its compact footprint, robust mechanical architecture, and integrated 8-channel detection system enable rapid, parallel acquisition from standard 96-well microplates—compatible with both flat-bottom and round-bottom configurations—without cross-well crosstalk. The instrument features real-time lamp health monitoring and automatic pre-read source calibration to maintain long-term photometric stability, critical for longitudinal studies and multi-user lab environments.

Key Features

• Fully automated operation with intuitive touchscreen interface and hardware-initiated startup sequence
• Integrated 8-position filter wheel (6 filters standard, 2 user-upgradable), supporting customizable wavelength selection for diverse assay chemistries
• Tungsten-halogen light source with embedded lifetime tracking and auto-compensation for intensity drift
• High-speed photometric acquisition: ≤8 seconds per single-wavelength read; ≤15 seconds for dual-wavelength subtraction
• Three programmable orbital shaking intensities (low/medium/high) optimized for cell-based and immunoassay protocols
• Onboard memory and USB export capability for immediate data backup and offline analysis
• Compliance-ready design with audit trail support and user-access logging when paired with validated CMax Pro software configurations

Sample Compatibility & Compliance

The CMax Plus accommodates standard ANSI/SLAS-compliant 96-well microplates—including clear, white, and black polystyrene plates—as well as specialized formats such as UV-transparent plates for nucleic acid quantification at lower wavelengths. It supports endpoint and kinetic absorbance measurements required by widely adopted regulatory methods, including USP (LAL endotoxin testing), CLSI EP10-A3 (precision evaluation), and ISO 15197:2013 (in vitro diagnostic performance standards). When deployed under controlled conditions and operated with documented SOPs, the system meets foundational requirements for GLP-compliant data generation. Optional IQ/OQ documentation packages are available to support laboratory validation workflows aligned with FDA 21 CFR Part 11 expectations for electronic records and signatures.

Software & Data Management

CMax Pro software serves as both instrument control platform and analytical engine, providing a unified environment for protocol definition, real-time monitoring, and post-acquisition processing. Its modular architecture supports flexible plate mapping, dynamic well grouping, and conditional logic for threshold-based pass/fail classification. Curve-fitting algorithms include linear regression, semi-logarithmic transformation, log-log plotting, and four-parameter logistic (4-PL) modeling—essential for ELISA standard curve analysis and IC₅₀/EC₅₀ determination. Kinetic data are stored in time-stamped, version-controlled datasets with built-in interpolation and derivative calculation tools. All results export natively to Microsoft Excel (.xlsx) without third-party converters; raw absorbance values, fitted parameters, and metadata (including timestamp, operator ID, and instrument serial number) are preserved. Software updates follow a documented change-control process, and installation qualification reports are provided upon request.

Applications

• Enzyme-linked immunosorbent assays (ELISA) for cytokine, hormone, and antibody quantification
• Total protein determination using Bradford, Lowry, or BCA methodologies
• Cell viability and cytotoxicity assessment via MTT, XTT, WST-1, and resazurin reduction assays
• Endotoxin detection using chromogenic Limulus Amebocyte Lysate (LAL) methods
• Phosphatase and kinase activity profiling using pNPP or ADP-Glo™-coupled chemistries
• Reporter gene assays (e.g., β-galactosidase, SEAP) requiring precise endpoint OD measurement
• Platelet aggregation kinetics monitored via turbidimetric absorbance changes
• Pesticide residue screening in agricultural samples via colorimetric enzymatic inhibition

FAQ

Does the CMax Plus support wavelength scanning or spectral acquisition?
No. The CMax Plus is a fixed-wavelength, filter-based absorbance reader. It does not perform continuous spectral scans or monochromator-based wavelength selection.
Can I upgrade the CMax Plus to include fluorescence or luminescence detection?
No. As a dedicated absorbance-only platform, the CMax Plus lacks optical components necessary for fluorescence excitation/emission or luminescent signal capture. For multimodal capability, consider the SpectraMax i3x or Paradigm systems.
Is CMax Pro software compatible with Windows 11 and 64-bit architectures?
Yes. CMax Pro v6.2 and later versions are validated for Windows 10 and Windows 11 (64-bit), with full support for high-DPI displays and modern security policies.
What level of traceability does the system provide for regulatory submissions?
When configured with enabled audit trails, electronic signatures, and secure user authentication, CMax Pro complies with core elements of 21 CFR Part 11. Full compliance requires site-specific validation, including risk assessment and documented procedures.
How often must the halogen lamp be replaced, and how is replacement tracked?
Lamp lifetime is typically ≥2,000 hours. The instrument continuously monitors operational hours and luminous output decay; alerts appear in the status bar and CMax Pro event log when replacement is recommended.