Pepkio Standard Curve & Concentration Calculator

Call the Pepkio absorbance-curve-calculator REST API from Python to fit standard curves and return dilution-corrected sample concentrations with QC flags.

What It Does

Plate-reader exports for BCA, Bradford, or ELISA assays need blank subtraction, curve model selection, interpolation, and dilution correction before concentrations can be reported. Rebuilding that workflow in a spreadsheet for each plate is slow and error-prone.

This package submits 96-well absorbance data, well layout, standard concentrations, and dilution factors to the same Pepkio Tools engine as the hosted web calculator. It returns fitted model parameters, side-by-side R² comparisons, per-sample concentrations with formula paths, and QC flags for high replicate CV or out-of-range ODs.

Programmatic runs require a network connection and a Pepkio API key. Calculations are not bundled for offline use.

Features

• Assay types: BCA, Bradford, sandwich ELISA, competitive ELISA
• Blank subtraction and assay-aware default models (linear for protein assays, 4PL for ELISA)
• Model comparison: linear, quadratic, 4PL, inverted 4PL with R²
• Optional model_override and excluded_wells
• Dilution correction with formula path in output
• QC flags: replicate CV > 20%, out-of-range ODs, R² thresholds
• Manifest examples: bca_linear, sandwich_elisa_4pl, competitive_elisa_4pl, blocking_few_standards
• CLI: pepkio-absorbance-curve-calculator manifest and run
• Configuration via PEPKIO_API_KEY and PEPKIO_API_BASE_URL

Installation

pip install pepkio-absorbance-curve-calculator

Set an API key with tools:run scope before calling run():

export PEPKIO_API_KEY="your-key"

Create a key in your Pepkio account API keys settings.

Quick Example

from pepkio_absorbance_curve_calculator import PepkioClient

with PepkioClient() as client:
    inp = client.get_example_input("bca_linear")
    result = client.run(inp)
    for sample in result.result["samples"]:
        print(sample["sample_id"], sample["corrected_conc"], sample.get("formula_path"))

CLI:

pepkio-absorbance-curve-calculator run --example bca_linear

Manifest inspection does not require an API key.

Typical Use Cases

• BCA protein assay standard curve from 96-well absorbance data
• ELISA sample concentration back-calculation with dilution factors
• Comparing linear vs 4PL fit for Bradford or ELISA data
• Automated reanalysis of plate-reader exports in notebooks or CI
• QC screening for R², replicate CV, and out-of-range samples before reporting

Scientific Background

Blank wells are averaged and subtracted before fitting. BCA and Bradford default to linear regression; ELISA defaults to 4PL (sandwich) or inverted 4PL (competitive). Corrected concentration = interpolated concentration × dilution factor. The engine flags R² below 0.98 (linear) or 0.995 (4PL), replicate CV above 20%, and ODs outside the standard range.

Web Application

For researchers who prefer a graphical interface, an interactive Standard Curve Calculator is available in the browser.

The web interface adds paste-from-Excel grid entry, one-click well exclusion with audit logging, CSV/PDF export with curve plots, and reload of recent runs.

Documentation and Resources

Source code and issue tracking: github.com/pepkio/pepkio-absorbance-curve-calculator

Web application: https://www.pepkio.com/tools/absorbance-curve-calculator

About Pepkio

Pepkio develops software tools and provides bioinformatics analysis services for life science research. See https://www.pepkio.com for additional tools and services.

Keywords

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