21 CFR § 866.4540 - Immunonephelometer equipment.

---
identifier: "/us/cfr/t21/s866.4540"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 866.4540 - Immunonephelometer equipment."
title_number: 21
title_name: "Food and Drugs"
section_number: "866.4540"
section_name: "Immunonephelometer equipment."
chapter_name: "FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "H"
subchapter_name: "MEDICAL DEVICES"
part_number: "866"
part_name: "IMMUNOLOGY AND MICROBIOLOGY DEVICES"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "21 U.S.C. 351, 360, 360c, 360e, 360j, 360 371."
regulatory_source: "47 FR 50823, Nov. 9, 1982, unless otherwise noted."
cfr_part: "866"
---


# 866.4540 Immunonephelometer equipment.

(a) *Identification.* Immunonephelometer equipment for clinical use with its electrical power supply is a device that measures light scattering from antigen-antibody complexes. The concentration of these complexes may be measured by means of reflected light. A beam of light passed through a solution is scattered by the particles in suspension. The amount of light is detected by a photodetector, which converts light energy into electrical energy. The amount of electrical energy registers on a readout system such as a digital voltmeter or a recording chart. This electrical readout is called the light-scattering value and is used to measure the concentration of antigen-antibody complexes. This generic type of device includes devices with various kinds of light sources, such as laser equipment.

(b) *Classification.* Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 866.9.

[47 FR 50823, Nov. 9, 1982, as amended at 54 FR 25047, June 12, 1989; 66 FR 38792, July 25, 2001]