Single Particle Optical Sensing (SPOS) Analytical Service

Single Particle Optical Sensing (SPOS) Analytical Service refers to the quantitative measurement of individual particles in liquid samples using optical detection principles, providing both particle counts and size distributions across submicron to micron ranges. MtoZ Biolabs provides a professional Single Particle Optical Sensing (SPOS) Analytical Service designed to characterize visible and subvisible particles in drug formulations, protein therapeutics, and colloidal suspensions.

 

Particulate matter is a critical quality attribute in pharmaceuticals, biopharmaceuticals, and other liquid-based formulations. The presence, size, and number of particles can directly affect safety, efficacy, and stability. In injectable drugs and protein-based therapeutics, particles may induce immunogenicity, impact therapeutic performance, or compromise regulatory compliance. Many regulatory agencies require stringent particle characterization to ensure patient safety and product consistency. Our Single Particle Optical Sensing (SPOS) Analytical Service offers a robust solution by detecting and measuring each particle as it passes through a sensing zone, generating highly accurate size and count data.

 

Technical Principles

SPOS is based on the detection of light intensity changes as particles individually pass through a focused optical beam. Two main sensing methods are commonly employed:

🔸Light Extinction (Light Obscuration)

As a particle passes through the sensing zone, it blocks or scatters a portion of the light beam. The reduction in light intensity is proportional to the particle's cross-sectional area, enabling calculation of particle diameter.

 

🔸Light Scattering

Smaller particles scatter light at different angles, and the intensity of scattered light is analyzed to provide size information. This method complements extinction detection by extending the measurement range into the submicron domain.

 

By combining these principles, SPOS can reliably measure particles ranging from approximately 0.5 microns to several hundred microns in diameter. Each particle is measured individually, ensuring accurate particle counts, size distributions.

 

The following table summarizes the main strengths and limitations of Single Particle Optical Sensing (SPOS) technology:



  

Service at MtoZ Biolabs

MtoZ Biolabs' Single Particle Optical Sensing (SPOS) Analytical Service supports precise particle characterization in diverse liquid samples, including injectable suspensions, ophthalmic solutions, industrial oils, slurries, and dilute process or waste water. With this technology, we can measure particle size distributions on both a number-weighted and volume-weighted basis, identify specific size ranges when required, and determine particle concentrations in particles per milliliter. These capabilities enable comprehensive assessment of both visible and subvisible particles, helping clients address critical needs in product development, stability evaluation, and regulatory compliance.

 



 

Amidi, M. et al. J Liposome Res. 2010.

Figure 1. Microscopy and SPOS Analysis of Particle Size Distribution of Liposomes Formed by Rehydrating Freeze-Dried Liposomes with IVTT Mix, FDG, and pIVEXem-LacZ (5 nM) and After 3 Hours of Incubation at 30°C

 

Service Advantages

MtoZ Biolabs is dedicated to delivering high-quality analytical services that empower clients across the life sciences and pharmaceutical industries. By choosing our Single Particle Optical Sensing (SPOS) Analytical Service, you benefit from:

☑️Advanced SPOS instrumentation with validated calibration standards.

☑️Expertise in handling a wide range of liquid formulations, including injectables and protein therapeutics.

☑️Customized workflows tailored to client-specific needs.

☑️Rigorous quality control for reproducible and defensible results.

☑️Comprehensive data packages suitable for regulatory and research applications.

☑️Dedicated scientific support for interpreting results and guiding next steps.

 

Applications

The Single Particle Optical Sensing (SPOS) Analytical Service is widely applied in pharmaceuticals, biotechnology, and other fields where particle characterization in liquids is essential. Key applications include:

1. Injectable Drug Products

Detection and quantification of visible and subvisible particles in parenteral formulations, ensuring compliance with related pharmacopoeial standards.

 

2. Protein-Based Therapeutics

Analysis of subvisible particles in monoclonal antibodies, fusion proteins, and other biologics. SPOS supports the evaluation of protein aggregation, stability, and immunogenicity risk.

 

3. Biopharmaceutical Development

Particle analysis during formulation optimization, stability studies, and manufacturing process validation.

 

4. Quality Control of Raw Materials

Screening of excipients and buffer solutions for particulate contamination.

 

5. Nanotechnology and Advanced Materials

Measurement of particles in colloidal dispersions, nanoparticle suspensions, and specialty chemical formulations.

 

6. Regulatory Compliance

SPOS data support regulatory submissions by providing validated particle counts and size distributions.

 

Sample Submission Suggestions

1. Sample Types

Injectable drug products, protein formulations, colloidal suspensions, and other liquid samples requiring particle characterization.

 

2. Sample Volume

If the sample contains a large number of visible particles, approximately 100 mL may be required, whereas nearly transparent samples may need at least 250 mL to ensure adequate particle detection.

 

Note: If you have special sample types or require additional guidance, please contact us for personalized support before sample preparation.