Grafiti LLC

Peak Fitting

The Fitting Functions and Features for PeakFit by Grafiti LLC are shown below:

Built-In Nonlinear Functions (83 total)

  • Spectroscopy (18): Gauss Amp, Gauss Area, Lorentz Amp, Lorentz Area, Voigt Amp, Voigt Area, Voigt Amp Approx, Voigt Amp G/L, Voigt Area G/l, Gauss Cnstr Amp, Gauss Cnstr Area, Pearson VII Amp, Pearson VII Area, Gauss+Lor Area, Gauss*Lor, Gamma Ray, Compton Edge
  • Chromatography (8): HVL, NLC, Giddings, EMG, GMG, EMG+GMG, GEMG, GEMG 5-parm
  • Statistical (31): Log Normal Amp, Log Normal Area, Logistic Amp, Logistic Area, Laplace Amp, Laplace Area, Extr Value Amp, Extr Value Area, Log Normal-4 Amp, Log Normal-4 Area, Eval4 Amp Tailed, Eval4 Area Tailed, Eval4 Amp Frtd, Eval4 Area Frtd, Gamma Amp, Gamma Area, Inv Gamma Amp, Inv Gamma Area, Weibull Amp, Weibull Area, Error Amp, Error Area, Chi-Sq Amp, Chi-Sq Area, Student t Amp, Student t Area, Beta Amp, Beta Area, F Variance Amp, F Variance Area, Pearson IV
  • General Peak (12): Erfc Pk, Pulse Pk, LDR Pk, Asym Lgstc Pk, Lgstc pow Pk, Pulse pow Pk, Pulse Wid2 Pk, Intermediate Pk, Sym Dbl Sigmoid, Sym Dbl GaussCum, Asym Dbl Sigmoid, Asym Dbl GaussCum
  • Transition (14): Sigmoid Asc, Sigmoid Desc, GaussCum Asc, GaussCum Desc, LorentzCum Asc, LorentzCum Desc, LgstcDose Rsp Asc, LgstcDoseRsp Desc, LogNormCum Asc, LogNormCum Desc, ExtrValCum Asc, ExtrValCum Desc, PulseCum Asc, PulseCum Desc
  • Transition (14): Sigmoid Asc, Sigmoid Desc, GaussCum Asc, GaussCum Desc, LorentzCum Asc, LorentzCum Desc, LgstcDose Rsp Asc, LgstcDoseRsp Desc, LogNormCum Asc, LogNormCum Desc, ExtrValCum Asc, ExtrValCum Desc, PulseCum Asc, PulseCum Desc

User Defined Functions

  • Up to 10 Parameters per function
  • Up to 15 UDF’s active during fit
  • Estimates can contain formulas and constraints
  • Extensive mathematical, statistical, Bessel, and logic functions

Baseline Fit and Subtract

  • Automatic detection of baseline points by constant second derivatives
  • Real-time Fitting in conjunction with data point selection, deselection
  • Background Functions (10): Constant, Linear, Progressive Linear, Quadratic, Cubic, Logarithmic, Exponential, Power, Hyperbolic and Non-Parametric

Graphical Review

  • Component and Sum Curve graphs
  • Residuals Graphs, including Distribution and Stabilized Normal Probability Plots
  • Confidence and Prediction Intervals
  • Peak Labels (Amplitude, Center, or Area)

Numerical Review

  • Peak Characterization data: Center, Amplitude, Integrated Area, Analytical Area, FWHM, FW10, FWBASE, Asymmetry at HM, Asymmetry at 10 percent, First and Second Moments, Column Efficiency and Resolution, Percentage Areas, Overlap Areas
  • Parameter Statistics: Parameter Values, Confidence Limits (90, 95, 99 percent), t-values, Standard Errors
  • Fit Statistics: Analysis of Variance, F-statistic, Overall Standard Error, r2 value
  • Data Statistics: Residual Values, Predicted Y-values, Confidence/Prediction Intervals
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