Copolymer SEC Data for Composition Analysis

A synthetic dataset containing SEC chromatograms of styrene-acrylate copolymers with varying compositions, designed for demonstrating UV/RI ratio analysis for composition determination.

Usage

sec_copolymer

Format

A tibble with 4,206 rows and 8 columns:

sample_id

Character. Sample identifier (e.g., "Copoly-20S")

elution_time

Numeric. Elution time in minutes

ri_signal

Numeric. Refractive index detector signal

uv_254_signal

Numeric. UV detector signal at 254 nm

styrene_fraction

Numeric. Styrene content (0-1)

mw

Numeric. Weight-average molecular weight in Da

dispersity

Numeric. Polydispersity index (Mw/Mn)

description

Character. Sample description

Source

Synthetic data generated for package testing and examples.

Details

The dataset includes 6 samples spanning the full composition range:

• Pure polyacrylate (0% styrene) - no UV absorption

• 20%, 40%, 60%, 80% styrene copolymers

• Pure polystyrene (100% styrene) - strong UV absorption

UV/RI Ratio Analysis: The UV signal at 254 nm is selective for styrene units, while the RI signal responds to total mass. The UV/RI ratio across the chromatogram reveals composition as a function of molecular weight, enabling detection of compositional drift.

Typical Workflow:

1. Load data and convert to measure format

2. Apply step_sec_uv_ri_ratio to calculate ratios

3. Calibrate ratio to composition using homopolymer standards

4. Plot composition vs molecular weight

See also

Other sec-data: sec_branched, sec_calibration_standards, sec_pmma_standards, sec_protein, sec_ps_standards, sec_raw_multidetector, sec_raw_standards, sec_raw_unknowns, sec_system_suitability, sec_triple_detect

Examples

data(sec_copolymer)

# View composition range
unique(sec_copolymer[, c("sample_id", "styrene_fraction")])
#> # A tibble: 6 × 2
#>   sample_id  styrene_fraction
#>   <chr>                 <dbl>
#> 1 Copoly-20S              0.2
#> 2 Copoly-40S              0.4
#> 3 Copoly-60S              0.6
#> 4 Copoly-80S              0.8
#> 5 PS-Homo                 1  
#> 6 PA-Homo                 0  

# Plot RI vs UV for different compositions
if (requireNamespace("ggplot2", quietly = TRUE)) {
  library(ggplot2)
  ggplot(sec_copolymer, aes(elution_time)) +
    geom_line(aes(y = ri_signal, color = "RI")) +
    geom_line(aes(y = uv_254_signal, color = "UV 254nm")) +
    facet_wrap(~sample_id) +
    labs(x = "Elution Time (min)", y = "Signal", color = "Detector") +
    theme_minimal()
}