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Calculate LOD and LOQ Together

Source: R/lod-loq.R
measure_lod_loq.Rd

Convenience function to calculate both LOD and LOQ using the same method.

Usage

measure_lod_loq(
  data,
  response_col,
  method = c("blank_sd", "calibration", "sn", "precision"),
  conc_col = "nominal_conc",
  sample_type_col = "sample_type",
  calibration = NULL,
  k_lod = NULL,
  k_loq = 10,
  ...
)

Arguments

data

A data frame containing the measurement data.

response_col

Name of the response column.

method

Method for LOD calculation:

  • "blank_sd": 3 * SD of blank samples (requires sample_type == "blank")

  • "calibration": 3.3 * sigma / slope from calibration curve

  • "sn": Signal-to-noise ratio method (requires sn_col or noise estimate)

  • "precision": Based on acceptable precision at low concentrations

conc_col

Name of concentration column (for calibration method).

sample_type_col

Name of sample type column. Default is "sample_type".

calibration

Optional measure_calibration object for calibration method.

k_lod

Multiplier for LOD (default 3 or 3.3 for calibration).

k_loq

Multiplier for LOQ (default 10).

...

Additional arguments passed to method-specific calculations.

Value

A list with components lod and loq, each being the respective limit object.

See also

measure_lod(), measure_loq().

Examples

data <- data.frame(
  sample_type = c(rep("blank", 10), rep("standard", 5)),
  response = c(rnorm(10, mean = 0.5, sd = 0.1),
               c(5, 15, 35, 70, 150)),
  nominal_conc = c(rep(0, 10), c(10, 25, 50, 100, 200))
)

limits <- measure_lod_loq(data, "response", method = "blank_sd")
limits$lod
#> <measure_lod>
#>   Value: 0.752
#>   Method: blank_sd
#>   k: 3
#>   Uncertainty: 0.06627
#>   Parameters:
#>     blank_mean: 0.5424
#>     blank_sd: 0.06986
#>     n_blanks: 10
limits$loq
#> <measure_loq>
#>   Value: 1.241
#>   Method: blank_sd
#>   k: 10
#>   Uncertainty: 0.2209
#>   Parameters:
#>     blank_mean: 0.5424
#>     blank_sd: 0.06986
#>     n_blanks: 10