Raw Multi-Detector SEC Data

A dataset containing raw SEC chromatograms with RI, UV, and MALS detector signals that have NOT been corrected for inter-detector delay. Designed for teaching triple detection workflows from raw data.

Usage

sec_raw_multidetector

Format

A tibble with approximately 48,000 rows and 12 columns:

sample_id

Character. Sample identifier

description

Character. Sample description

mw

Numeric. Known weight-average MW in Da

dispersity

Numeric. Known dispersity

dn_dc

Numeric. Refractive index increment in mL/g

ext_coef

Numeric. UV extinction coefficient

time_min

Numeric. Elution time in minutes

ri_mv

Numeric. RI detector signal in millivolts

uv_au

Numeric. UV detector signal in absorbance units

mals_mv

Numeric. MALS detector signal in millivolts

delay_uv_ml

Numeric. True UV detector delay in mL (negative = before RI)

delay_mals_ml

Numeric. True MALS detector delay in mL (positive = after RI)

Source

Synthetic data generated for package tutorials.

Details

This dataset simulates raw multi-detector SEC data before inter-detector delay correction. The detectors are physically separated in the flow path, so peaks appear at different times in each detector.

Detector Configuration:

• UV detector is 0.08 mL BEFORE RI (peaks appear earlier)

• MALS detector is 0.18 mL AFTER RI (peaks appear later)

• RI is the reference detector (delay = 0)

Samples Included:

• PS-DelayStd: Narrow PS standard for determining delays

• Sample-1: PS sample with strong UV absorption

• Sample-2: PMMA sample with weak UV

• Sample-3: Copolymer sample

Tutorial Workflow:

1. Load raw multi-detector data

2. Use delay standard to determine inter-detector offsets

3. Apply step_sec_detector_delay to align signals

4. Process with step_sec_mals for absolute MW

See also

step_sec_detector_delay for delay correction step_sec_mals for MALS processing sec_triple_detect for pre-processed multi-detector data

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

Other sec-raw: sec_raw_standards, sec_raw_unknowns

Examples

data(sec_raw_multidetector)

# View sample information
unique(sec_raw_multidetector[, c("sample_id", "description", "mw")])
#> # A tibble: 4 × 3
#>   sample_id   description                           mw
#>   <chr>       <chr>                              <dbl>
#> 1 PS-DelayStd Narrow PS for delay determination 100000
#> 2 Sample-1    PS sample with UV absorption       75000
#> 3 Sample-2    PMMA sample (weak UV)             150000
#> 4 Sample-3    Copolymer sample                   45000

# Plot delay standard showing detector offset (peaks not aligned)
if (requireNamespace("ggplot2", quietly = TRUE)) {
  library(ggplot2)
  library(dplyr)
  library(tidyr)

  sec_raw_multidetector |>
    filter(sample_id == "PS-DelayStd") |>
    select(time_min, ri_mv, uv_au, mals_mv) |>
    # Normalize for comparison
    mutate(
      ri_norm = ri_mv / max(ri_mv),
      uv_norm = uv_au / max(uv_au),
      mals_norm = mals_mv / max(mals_mv)
    ) |>
    select(time_min, RI = ri_norm, UV = uv_norm, MALS = mals_norm) |>
    pivot_longer(-time_min, names_to = "detector", values_to = "signal") |>
    ggplot(aes(time_min, signal, color = detector)) +
    geom_line() +
    labs(
      x = "Time (min)",
      y = "Normalized Signal",
      title = "Raw Multi-Detector Data (Before Delay Correction)",
      subtitle = "Note: Peaks are NOT aligned - UV leads, MALS lags"
    ) +
    theme_minimal()
}