Calculate Peak Asymmetry Factor

Calculates the asymmetry factor (As) or tailing factor (Tf) for a chromatographic peak.

Usage

measure_sec_asymmetry(leading, tailing, method = c("usp", "ep"))

Arguments

leading

Width of the leading (front) half of the peak at the measurement height.

tailing

Width of the tailing (back) half of the peak at the measurement height.

method

Asymmetry calculation method:

• "usp" (default): Tailing factor at 5% height

• "ep": Asymmetry factor at 10% height

Value

Numeric asymmetry value. Values > 1 indicate tailing, < 1 indicate fronting. Ideal value is 1.0.

Details

Peak asymmetry indicates deviation from ideal Gaussian peak shape:

USP Tailing Factor (at 5% height): $$T_f = \frac{W_{0.05}}{2f}$$

where W_0.05 is the width at 5% height and f is the leading half-width.

EP Asymmetry Factor (at 10% height): $$A_s = \frac{b}{a}$$

where b is the tailing half-width and a is the leading half-width.

Interpretation:

• As = 1.0: Symmetric (ideal)

• As < 0.9 or > 1.2: Slight asymmetry (acceptable)

• As < 0.8 or > 1.5: Significant asymmetry (investigate)

• As > 2.0: Severe tailing (column/sample issue)

See also

Other sec-qc: measure_sec_column_performance(), measure_sec_plate_count(), measure_sec_recovery(), measure_sec_resolution(), measure_sec_suitability()

Examples

# Calculate USP tailing factor
measure_sec_asymmetry(
  leading = 0.12,
  tailing = 0.15,
  method = "usp"
)
#> [1] 1.125