Skip to contents

Right-Angle Light Scattering Processing for SEC

Source: R/step_sec_rals.R
step_sec_rals.Rd

step_sec_rals() creates a specification of a recipe step that processes right-angle light scattering (RALS) signals for absolute molecular weight.

Usage

step_sec_rals(
  recipe,
  measures = NULL,
  concentration_col = NULL,
  angle = 90,
  laser_wavelength = 670,
  dn_dc = NULL,
  solvent_ri = 1.333,
  optical_constant = NULL,
  calibration_constant = NULL,
  output_mw = "mw_rals",
  min_signal = 0.01,
  role = NA,
  trained = FALSE,
  skip = FALSE,
  id = recipes::rand_id("sec_rals")
)

Arguments

recipe

A recipe object.

measures

Character vector of RALS measure columns. If NULL, the step searches for measure columns containing "rals".

concentration_col

Name of the concentration measure column (from step_sec_concentration() or similar).

angle

Detection angle in degrees. Default is 90.

laser_wavelength

Laser wavelength in nm.

dn_dc

Refractive index increment (mL/g). Required unless optical_constant is provided.

solvent_ri

Solvent refractive index. Default is 1.333 (water).

optical_constant

Optional optical constant K; overrides dn/dc.

calibration_constant

RALS instrument calibration constant. If NULL, results are in relative units.

output_mw

Name for the molecular weight output column.

min_signal

Minimum signal threshold (as fraction of max) below which MW is set to NA.

role

Role for generated columns.

trained

Logical indicating if the step has been trained.

skip

Logical. Should the step be skipped when baking?

id

Unique step identifier.

Value

An updated recipe with the new step added.

Details

RALS provides absolute MW using a 90-degree detector. It is most accurate for smaller molecules where angular dependence is minimal (Rg << lambda/20).

See also

Other sec-detectors: step_sec_concentration(), step_sec_dad(), step_sec_dls(), step_sec_intrinsic_visc(), step_sec_lals(), step_sec_mals(), step_sec_ri(), step_sec_uv(), step_sec_viscometer()

Examples

if (FALSE) { # \dontrun{
library(recipes)
library(measure)

rec <- recipe(~., data = sec_triple_detect) |>
  step_measure_input_long(ri_signal, location = vars(elution_time), col_name = "ri") |>
  step_measure_input_long(rals_signal, location = vars(elution_time), col_name = "rals") |>
  step_sec_concentration(detector = "ri", injection_mass = 0.2, flow_rate = 1.0) |>
  step_sec_rals(measures = "rals", concentration_col = "ri", dn_dc = 0.185) |>
  prep()
} # }