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mRNA Raman Calibrator.

Build a PLS calibration from Raman spectra and known mRNA concentrations, then predict unknowns with 95% prediction intervals and outlier diagnostics. Runs entirely in your browser.

PrivateData stays in your browser
LiveNo sign-up required
Validated2026-04-25
CitableMethods and citation included

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Try it out

Load example mRNA Raman data to see the full workflow

1

Calibration spectra

Drop SPC, JCAMP-DX, or two-column CSV/TSV files and enter the known concentration for each.

2

Build model

Pipeline: Savitzky–Golay smoothing → baseline correction (AsLS) → SNV → optional SG 1st derivative → PLS regression with leave-one-out CV.

3

Predict unknowns

Drop spectrum files of unknown concentration. Each prediction includes a 95% interval and an outlier flag based on Hotelling's T² and Q-residuals.

When to use

  • Quantifying mRNA concentration in IVT reactions or LNP formulations from Raman spectra
  • Building a per-instrument calibration when reference standards span the working concentration range
  • Routine QC where you score dozens to hundreds of unknowns against a fixed calibration set
  • Replacing a univariate peak-height assay with a multivariate model that uses the whole spectrum

Do not use for

  • No vetted calibration set — the tool is honest about uncertainty, but only if your standards are honest
  • Single-spectrum prediction with no reference samples (use a published shipped model instead)
  • Hyperspectral imaging cubes — the tool is sized for ≤ 200 spectra of ≤ 4000 wavenumbers each

Span the working range with your standards

PLS extrapolates poorly. If you expect to measure 0.1–2 mg/mL, your calibration set should bracket that range. The 95% PI inflates outside the calibration centroid; the outlier flag warns you when an unknown is too far out.

Watch the LV vs RMSECV elbow

The tool picks the LV count using a one-standard-error rule on RMSECV — the smallest LV count whose CV error is within 1 SE of the global minimum. If RMSECV keeps falling with more LVs, you're fitting noise. Two to four LVs is typical for clean Raman data.

Treat outlier flags as veto, not advisory

An out-of-distribution score (high T²) means the spectrum sits in a part of latent-variable space the model didn't see. A high Q means there's structure in the spectrum the model can't explain. Either way, the prediction is an extrapolation.

1

Method

PLS1 regression by NIPALS with leave-one-out cross-validation for latent-variable selection (one-standard-error rule). Preprocessing pipeline: Savitzky–Golay smoothing → asymmetric-least-squares baseline correction (λ = 10⁵, p = 0.01) → standard normal variate normalization → optional SG 1st derivative. Prediction interval at 95% from CV residual standard deviation, t-distributed with n−1 degrees of freedom, inflated by sample-specific Hotelling T². Outlier limits use the F-distribution-based Hotelling T² 95% bound and a max+2σ Q-residual bound calibrated on the training set.

2

Validated

Last validated 2026-04-25. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.

3

How to cite

How to Cite

ConductScience. (2026). mRNA Raman Calibrator (v1.0) [Web tool]. https://conductscience.com/tools/mrna-raman-calibrator

Wold S, Sjöström M, Eriksson L. PLS-regression: a basic tool of chemometrics. Chemometrics and Intelligent Laboratory Systems. 2001;58:109–130. doi:10.1016/S0169-7439(01)00155-1

Eilers PHC, Boelens HFM. Baseline correction with asymmetric least squares smoothing. Leiden University Medical Centre Report. 2005.

Savitzky A, Golay MJE. Smoothing and differentiation of data by simplified least squares procedures. Analytical Chemistry. 1964;36:1627–1639. doi:10.1021/ac60214a047

Raman quantification of mRNA

Raman spectra of mRNA in aqueous solution are dominated by a small number of vibrational bands.

Diagnostic regions: - ~785 cm⁻¹ — uracil ring breathing - ~1080 cm⁻¹ — phosphate-backbone symmetric PO₂⁻ stretch - ~1240 cm⁻¹ — uracil + cytosine in-plane bending - ~1485 cm⁻¹ — guanine + adenine ring stretches - ~1660 cm⁻¹ — amide I / carbonyl stretching of pyrimidines

Intensity at the phosphate band (~1080) tracks total nucleic acid concentration well over the 0.05–5 mg/mL range typical of IVT and LNP work. Combining several bands in a multivariate model (PLS) outperforms univariate calibration, especially when buffers contribute background bands.

How PLS regression works

Partial Least Squares regression solves the same problem as linear regression — predicting concentration from spectrum — but copes with the fact that adjacent wavenumbers are highly correlated.

The algorithm (NIPALS): 1. Find the direction in spectral space (a 'latent variable') that is most correlated with concentration 2. Project all spectra onto that direction to get scores 3. Subtract the explained variation from spectra and concentrations 4. Repeat for the next latent variable
Choosing latent variables: too few = under-fit, too many = over-fit. Leave-one-out cross-validation picks the LV count that minimizes the prediction error on samples the model hasn't seen — usually 2–6 LVs for Raman calibration.
Diagnostics to check: - R²cv (Q²): how well predictions match held-out truth. > 0.9 is good for routine assays - RMSECV: average prediction error in concentration units - T² and Q residuals: detect when an unknown spectrum doesn't look like the training set

Preprocessing rationale

Savitzky–Golay smoothing fits a low-order polynomial to a sliding window and replaces the centre point with the polynomial's value. Removes shot noise without flattening narrow Raman peaks. Window 11, polynomial 2 is a safe default for typical 1–4 cm⁻¹ resolution data.
AsLS baseline correction (Eilers & Boelens 2005) estimates a smooth baseline by penalized least squares with asymmetric weights — points above the current estimate are downweighted, so the baseline tracks the bottom envelope of the spectrum. λ = 10⁵, p = 0.01 works well for fluorescent biological matrices.
SNV (Standard Normal Variate) subtracts the per-spectrum mean and divides by the per-spectrum standard deviation. Removes multiplicative scatter effects from path-length and density variations between samples.
SG 1st derivative (optional) takes the local slope rather than the smoothed value. Strips residual broad backgrounds completely, at the cost of amplifying high-frequency noise.

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