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SEC PMMA Calibration Standards

Source: R/data.R
sec_pmma_standards.Rd

Poly(methyl methacrylate) narrow molecular weight standards for SEC/GPC calibration. A convenient subset of sec_calibration_standards containing only PMMA standards.

Usage

sec_pmma_standards

Format

A tibble with 10 rows and 12 columns:

standard_name

Character. Standard identifier (e.g., "PMMA-67700")

mp

Numeric. Peak molecular weight in Da

log_mp

Numeric. log10(Mp) for calibration curve fitting

retention_time

Numeric. Peak retention time in minutes

retention_volume

Numeric. Peak retention volume in mL

mn

Numeric. Number-average molecular weight in Da

mw

Numeric. Weight-average molecular weight in Da

dispersity

Numeric. Polydispersity index (Mw/Mn)

mp_uncertainty

Numeric. Relative uncertainty in Mp

k_value

Numeric. Mark-Houwink K constant (0.000128 mL/g)

a_value

Numeric. Mark-Houwink exponent (0.690)

dn_dc

Numeric. Refractive index increment (0.084 mL/g)

Source

Synthetic data based on typical commercial narrow PMMA standards.

Details

PMMA standards are useful for:

  • Calibrating for PMMA or acrylate samples

  • Validating universal calibration by comparing PS vs PMMA curves

  • Demonstrating polymer-specific hydrodynamic volume differences

At equivalent molecular weight, PMMA has a smaller hydrodynamic volume than PS in THF, so PMMA standards elute later than PS of the same MW. This demonstrates why conventional calibration is polymer-specific.

Universal Calibration Validation: When plotted as log(M * [eta]) vs retention time, PS and PMMA should fall on the same curve, confirming universal calibration is valid for the column.

See also

sec_calibration_standards for full dataset with PS sec_ps_standards for polystyrene standards step_sec_universal_cal for universal calibration

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

Other sec-calibration: load_sec_calibration(), save_sec_calibration(), sec_calibration_standards, sec_ps_standards, step_sec_broad_standard(), step_sec_conventional_cal(), step_sec_universal_cal()

Examples

data(sec_pmma_standards)
data(sec_ps_standards)

# Compare PS and PMMA calibration curves
if (requireNamespace("ggplot2", quietly = TRUE)) {
  library(ggplot2)
  library(dplyr)

  bind_rows(
    sec_ps_standards |> mutate(polymer = "PS"),
    sec_pmma_standards |> mutate(polymer = "PMMA")
  ) |>
    ggplot(aes(retention_time, log_mp, color = polymer)) +
    geom_point(size = 3) +
    geom_smooth(method = "lm", formula = y ~ poly(x, 3), se = FALSE) +
    labs(
      x = "Retention Time (min)",
      y = expression(log[10](M[p])),
      title = "PS vs PMMA Calibration Curves",
      subtitle = "PMMA elutes later at same MW (smaller hydrodynamic volume)"
    ) +
    theme_minimal()
}