ISO 24465:2023

Surface chemical analysis — Determination of the minimum detectability of surface plasmon resonance device

This document describes a method for determining the minimum detectability of surface plasmon resonance device. This document is applicable to surface plasmon resonance devices of the white-light illumination type and the laser illumination type with the angle scanning capability.

Titre manque

General Information

• Status: Published
• Publication Date: 09-Jan-2023
• ICS: 71.040.40 - Chemical analysis
• Technical Committee: ISO/TC 201 - Surface chemical analysis
• Drafting Committee: ISO/TC 201/WG 5 - Optical interface analysis
• Current Stage: 6060 - International Standard published
• Start Date: 10-Jan-2023
• Due Date: 10-Oct-2022
• Completion Date: 10-Jan-2023

Overview

ISO 24465:2023 specifies a standardized method to determine the minimum detectability (limit of detection) of surface plasmon resonance (SPR) devices. Applicable to both white‑light illumination and laser illumination SPR systems with angle‑scanning capability, the standard defines sample preparation, instrument conditions, data acquisition and a statistical protocol to quantify the lowest reliably measurable response.

Key topics and requirements

• Scope: Method for measuring the lowest detectable SPR signal for white‑light and laser angle‑scanning devices (Kretschmann geometry).
• Measurement principle: Monitor changes in reflected light (spectral dip or resonant angle) caused by analyte‑induced changes in dielectric constant; responses recorded as a sensorgram (response units, RU) using CCD or photodetectors.
• Statistical approach: Uses the 3‑sigma rule to define the lower limit of detectability (signal-to-noise ≈ 1); series measurements across concentrations yield SD and detection limit.
• Standard sample: Recommends single neutral solutes (e.g., ethylene glycol or sucrose in DI water) to avoid complex surface chemistry; prepare multiple concentration points (minimum five) for statistical accuracy.
• Instrument conditions: Control and document optics alignment, cleanness of optics, temperature, and flow rate (typical suggested range 5 μl/min to 100 μl/min).
• Sensor chip: Use a bare metal (gold) sensor chip for absolute device characterization; typical gold film thickness is around 100 nm.
• Data recording: Detailed acquisition and recording procedures are specified to ensure reproducible RU measurements and derivation of the limit of detection.

Applications and practical value

• Characterizing and validating the sensitivity performance of SPR instruments during manufacturing, acceptance testing, or routine quality control.
• Establishing traceable limit of detection (LOD) for research labs performing label‑free biomolecular binding studies.
• Supporting procurement decisions and performance comparisons between SPR platforms (white‑light vs. laser systems).
• Providing non‑expert operators with a simple, reproducible protocol using neutral analytes for baseline device capability assessment.

Who should use this standard

• SPR instrument manufacturers and calibration labs
• Analytical chemists and surface scientists
• QA/QC personnel in biotechnology and pharmaceuticals
• Research groups deploying label‑free biosensing or surface chemical analysis

Related guidance

• Prepared by ISO/TC 201 (Surface chemical analysis). This document contains no normative references; users may consult other ISO surface chemical analysis standards and manufacturer manuals for complementary procedures.

Keywords: ISO 24465:2023, surface plasmon resonance, SPR, minimum detectability, limit of detection, 3‑sigma rule, white‑light illumination, laser illumination, Kretschmann geometry, sensor chip, response unit.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 24465
First edition
2023-01
Surface chemical analysis —
Determination of the minimum
detectability of surface plasmon
resonance device
Reference number
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 1
4 General information . 1
4.1 Overview . 1
4.2 White light excitation type . 2
4.3 Laser illumination type . 3
5 Outline of proposed method .3
6 Instrument of operation conditions . 4
6.1 General . 4
6.2 Alignment of optics including incident light . 4
6.3 Sensor chip . 4
6.4 Cleanness of optics . 5
6.5 Temperature . 5
6.6 Flow rate . 5
7 Standard sample preparation . 5
8 Data acquisition .6
8.1 Data collection and analysis . 6
8.2 Recording of the data . . 8
Bibliography . 9
iii
Foreword
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This document was prepared by Technical Committee ISO/TC 201, Surface chemical analysis.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv
Introduction
The surface plasmon resonance (SPR) is the term used for the real time chemical contents analysing
device. The chemical ingredient dissolved in buffer solvent causes the dielectric constant change
compared to the buffer solvent. Changes in the dielectric constant of the solution modify the resonance
condition of the surface plasmon coupling at the interface between metal (mostly gold or functionalized
gold) and solution channel. So the reflection from the interface has the dip corresponding to the surface
plasmon components which is evanescent. The change of the reflection spectrum is analysed by a
charge coupled device (CCD) and the change of the spectrum dip represents the absolute amount of
the surface existing chemical component at the interface. The determination of the dynamic range of
the chemical analysis depends on the upper limit and lower limit of the detectability of the SPR device.
The objective of this document is to provide the standardized definition of lower limit of detection and
experimental protocol of measuring the lowest detectability of the SPR device. To avoid the complex
and unwanted chemical interaction between the metal surface and the analyte, a single chemical
solute method is presented, suitable for use by non-expert operators. That provides users with the
fundamental capability of the SPR device.
v
INTERNATIONAL STANDARD ISO 24465:2023(E)
Surface chemical analysis — Determination of the
minimum detectability of surface plasmon resonance
device
1 Scope
This document describes a method for determining the minimum detectability of surface plasmon
resonance device. This document is applicable to surface plasmon resonance devices of the white-light
illumination type and the laser illumination type with the angle scanning capability.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1.1
sensorgram
graph of responses versus time in surface plasmon resonance studies
3.2 Abbreviated terms
SPR surface plasmon resonance
RU response unit
CCD charge coupled device
SD standard deviation
DI deionized
4 General information
4.1 Overview
Surface plasmon is the light-matter interaction due to the collective longitudinal coupling between the
surface electrons and the excitation light at the metal/dielectric interface. The dispersion relation of
surface plasmon mainly depends on the dielectric functions of metal and dielectric materials, thus the
change of the dielectric constant of the dielectric material can change the resonant coupling of surface
plasmon in different wavelength ranges. The coupled surface plasmon is basically an evanescent wave,
so it does not propagate into the far field. Finally, spectral analysis of the reflected light reveals the
wavelength range which the surface plasmon is coupled resonantly. The most widely-used geometry
of the SPR is known as Kretschmann geometry. In the white light illumination type, the position of the
dip tells the changes of the dielectric constant; and in the case of laser illumination, the reflected laser
intensity or the resonant angle is changed by dielectric constant of the analyte. Both measurements
provide with the dielectric constant changes of the targeted analyte. For example, the Kretschmann
geometry is composed of a metal-coated prism as shown in Figure 1.
Key
1 light source
2 molecular layer
3 glass prism
4 photodiode
5 metal film
a
Incidence angle.
NOTE Kretschmann gemeotry with total internal reflection in the glass prism. The evanescent field on the
metal film interacts with the molecular layer via surface plasmon coupling.
Figure 1 — Schematic diagram of Kretschmann geometry
The excitation light is incident on the side surface of the prism and totally reflected at the interface
be
...