---
title: Module 2. What are IHCalibrators®?
description: "## Physical Characteristics BCS IHCalibrators, which enable IHC Calibration, are described below. (Figure 1) - 15 small round spots pre-printed on a microscope slide. - The spots are glass microbeads covalently coated with a biomarker. - Each bead has a…"
url: "https://bostoncellstandards.com/learning-center/documentation/metric-calibration-tutorial/what-are-ihcalibrators/"
updated: "2026-09-01"
category: Metric Calibration Tutorial
---

# Module 2. What are IHCalibrators®?

## Physical Characteristics

BCS IHCalibrators, which enable IHC Calibration, are described below. (Figure 1)

- 15 small round spots pre-printed on a microscope slide.
- The spots are glass microbeads covalently coated with a biomarker.
- Each bead has a defined concentration of biomarker traceable to a primary NIST standard.
- The numbers provide an orientation to the sequence of increasing biomarker concentrations.
- A certificate of analysis provides the exact concentration for each level.

 

 ![](https://bostoncellstandards.com/wp-content/uploads/2026/09/calibratorslide.png)

*Figure 1. IHCalibrators*

##

## Schematic Representation and Photomicrographs

Figure 2 below provides a schematic representation of Calibrator levels 1-10 (Panel A) and photomicrographs of the stained microbeads (Panel B). The actual LOD is likely at a concentration between levels 4 and 5.

- Identify the lowest concentration level that is still stained.
- In these examples, level 5 is the lowest that still has sufficient color intensity to consider positive.
- Look at the Certificate of Analysis for the calibrator and correlate it with the actual concentration.
- The actual Lower Limit of Detection (LOD) is likely at a concentration between levels 4 and 5.
- Metric calculates the precise LOD.

 ![](https://bostoncellstandards.com/wp-content/uploads/2026/09/SchematicRepresentation.png)

*Figure 2.**Schematic Representations of Calibrator Levels and Photomicrographs*