Chromatographic Integration Methods.

Chromatographic Integration Methods -- Contents -- Chapter 1 Measurements and Models -- 1 The Basic Measurements -- Measurements and Their Use -- 2 Quantitation -- Peak Area and Peak Height -- Peak 'Volume' -- Retention Time and Solute Identity -- Column Hold-up Time -- 3 Diagnostics and System Suitability Tests -- Baseline Noise -- Baseline Signal Level -- Peak Boundaries -- Peak Width and Column Efficiency -- Peak Asymmetry -- Peak Resolution -- Retention Time Stability -- 4 Results Assessment -- Correct Peak Measurements -- Total Peak Area -- Correct Number of Peaks -- Coefficient of Variation and Relative Standard Deviation -- Comparison Against Standards -- Trend Analysis -- 5 Performance Measurement -- Chromatograph Utilization -- Analyst Workload -- Cost per Analysis -- 6 Chromatographic Peak Models -- The Gaussian Function -- The Function -- Peak Height -- Ratio of Area/Height -- Calculation of Peak Width at Various Heights -- Gaussian Peak Shape Tests -- The Points of Inflection -- Fractional Peak Area Bounded by Various Widths -- Loss of Area from the Base of a Gaussian Peak -- Gaussian Peak Maximum as an Approximate Parabola -- The Exponentially Modified Gaussian Function -- The Function -- Practical Application of the EMG Function -- EMG Peak Shape Tests -- 7 Statistical Moments of a Chromatographic Peak -- Zeroeth Moment, m0 -- First Moment, m1 -- Second Moment, m2 -- Third Moment, m3 -- Fourth Moment, m4 -- Higher Odd Moments -- Higher Even Moments -- Measurement of Peak Moments -- Practical Disadvantages and Uses -- 8 Manual Peak Area Measurement -- Height X Width at Half Height -- The Condal-Bosch Area -- Peak Area by Triangulation -- Manual Measurement of Asymmetric (EMG) Peaks -- 9 References -- Chapter 2 Errors in Peak Area Measurement -- 1 Accuracy and Precision -- Accuracy -- Precision -- Inaccuracy and Uncertainty.

Repeatability -- Reproducibility -- Random Errors -- Systematic Errors -- Spurious Errors -- Causes of Imprecision -- Causes of Inaccuracy -- Precision of Integrator Measurements -- 2 Accurate Representation of the Solute Profile -- Additivity of Signals -- Negative Detector Signals -- Electronic Peak Distortion -- 3 Peak Area and Solute Quantity -- Mass and Flow Sensitive Detectors -- Flow Sensitive Detectors -- Mass Sensitive Detectors -- Detector Overload -- Linearity -- Detector Non-linearity -- Column Non-linearity -- Electronic Noise and Drift -- 4 Sources of Peak Measurement Error -- Hardware Errors -- Noise -- Noise and Frequency -- Short-term Noise -- Long-term Noise -- Drift -- Errors Created by Noise -- Signal-to-noise Ratio: The Smallest Measurable Peak -- Limits of Detection and Quantitation -- A 'Good Baseline' -- Errors Created by Baseline Drift -- Drifting Baseline and Peak Measurement -- Baseline Drift and Retention Time -- Reduced Detector Operating Range -- Some Preliminary Conclusions -- Errors of Incomplete Peak Resolution -- Height of a Fused Peak -- Perpendicular Separation -- Effect of Overlap on Area Measurement Accuracy -- Error Correction Strategies -- Error Propagation through Overlapping Groups -- Peak Overlap and Calibration -- Tangent Skim Errors -- Errors of Perpendicular/Tangent Transition -- Overlapping Peaks on Sloping Baselines -- Multiple Fused Peaks -- Mathematical Deconvolution of Overlapping Peaks -- The Isomer Test -- Errors from Peak Asymmetry -- Asymmetry and Peak Tailing -- Asymmetry and Base Broadening -- Asymmetry and Manual Peak Measurement -- Unequal Asymmetry -- The Achievement of Accuracy in Chromatographic Analyses -- Peak Area vs. Peak Height -- User Surveys -- 5 References -- Chapter 3 Manual Measurement of Peaks -- 1 Representation of the Detector Signal by Chart Recorder -- Slow Response Time.

Non-linear Signal Response -- Pen Head Damping -- Amplifier Noise -- Manual Measurement of Noise -- Dead Band -- Chart Motor Control -- Attenuator Accuracy -- 2 Measurement Strategies -- Counting Squares -- Cutting and Weighing -- Planimeters -- 3 Measurements based on a Peak Model -- Pencil and Rule Methods -- Measurement of Peak Height -- Height vs. Area Measurements -- Triangulation -- Peak Height X Width at Half Height -- Condal-Bosch Variation -- The Foley Variations -- Measurement of Overlapping Asymmetric Peaks -- Peak Shape Tests -- 4 Errors of Manual Measurement -- Optimum Peak Shape -- Advantages and Disadvantages of Manual Peak Measurement -- 5 References -- Chapter 4 Digital Integrators -- 1 A Brief History of Integrators -- Strip Chart Recorder Techniques -- Electromechanical Counters -- Electronic Integrators -- TTL Instruments - The First Electronic Integrators -- Microprocessor-based Integrators -- Integrators with Printer Plotters -- The Impact of the Microcomputer -- 2 Current Integrator Status -- Standard Integrator Specification -- Integrator Files -- Analysis Parameters for Peak Measurement -- Peak Width -- Slope Sensitivity or Detection Threshold -- Baseline Drift Tolerance -- Time to Double -- Minimum Area or Height Threshold -- Analysis Duration -- Integrate Inhibit -- Forcing Tangent or Perpendicular Separation -- Forcing Baseline Detection -- Horizontal Baseline Projection -- Inverting Negative Peaks -- Instrument Control and Communications -- Sample Management, Calculations and Calibrations -- Peak and Solute Identity -- Relative Retention Times -- Standard Calculations -- Area% or Normalization -- Internal Standard -- External Standard -- Sample Scheduling -- Calibration -- Report Preparation and Output -- Trends -- Report Distribution -- 3 Validation of Integrators -- The Integrator as a Diagnostic Tool.

Specification, Installation, Operational, Performance Qualification -- Integrator Specification and Selection (SQ) -- Installation Checks (IQ) -- Operational Qualification (OQ) -- Validation and Calibration: The Difference -- Records -- Performance Qualification (PQ): Regular Testing of the Integrator -- Logging Results -- Validation of Software -- 4 Standard Chromatograms -- Creation of Standard Chromatograms -- Computer-based Standard Chromatograms -- Specification of Standard Chromatograms -- Creation of Synthetic Chromatograms -- Baselines -- Baseline Noise -- Drift -- Traceability of Synthetic Chromatograms -- 5 References -- Chapter 5 Digital Measurement of Peak Areas -- 1 Signal Sampling -- Analogue to Digital Conversion -- Voltage to Frequency Conversion -- Dual Slope, Integrating A/D Conversion -- Resolution of A/D Converters -- Auto-ranging of A/D Converters -- Data Sampling Frequency -- Sampling Frequency and Integrator Manufacture -- Sampling Frequency and Data Processing Algorithms -- Data Bunching -- Baseline Bunching -- Estimating the A/D Sampling Frequency and Bunch Size -- Data Bunching and the Peak Width Parameter -- Peak Width Parameter and Analysis Reprocessing -- Peak Sampling Synchronization -- Rounding or Truncation Errors -- Aperture Time Jitter -- 2 Filtering and Smoothing the Chromatographic Signal -- Filtering -- Smoothing -- Electronic Filters -- Sampling Frequency and Mains Coupling -- Smoothing Techniques -- Digitizing and Integrating -- Bunching -- Moving Windows and Polynomial Curve Fitting -- Optimum Filtering -- Signal Subtraction -- Chromatogram Plotting -- Matched Filtering -- 3 Location and Measurement of Peaks -- Finding the Peaks -- Retention Time -- Peak Shape Test -- Properties of the Smoothed Data -- Data Integrals -- Baseline Fluctuations and Slope Sensitivity -- Programming Slope Sensitivity.

Slope Sensitivity and Representative Baseline -- Updating Peak Width and Slope Sensitivity during Analysis -- Location of the Limits of Integration -- Small Peak Filtering -- Location of Peak End -- Measurement of Peak Area -- Baseline Convention -- Measurement of Peak Height -- Measurement of Retention Time -- Measurement of Two Unresolved Peaks -- Measurement of Individual Peak Areas -- Peak Measurement Diagnostics -- Measurement of Fused Groups -- Shoulders -- Measurement of Tangent Peaks -- Tangent Skimmed Groups -- Small Peaks between Larger Ones -- Tangents on Tangents -- 4 Baselines, A More Detailed Discussion -- Baseline Drift Limit -- False Starts -- Formulating a Baseline Definition -- Mis-timing 'Start' and 'End' -- End of 'Integrate Inhibit' -- Forcing Baseline -- Incorrect Programming of Baseline Drift Tolerance -- Fused Tangent Measurement -- Single Peaks on a Rising Baseline -- Valleys Between Fully-resolved Peaks -- Negative Dips and Constructed Baselines -- Assigning Baseline Beneath the Whole Chromatogram -- Valley-Valley Skim -- 5 Conclusions -- 6 References -- Author Index -- Subject Index.