Chlorophyll A Extraction Concentration

Convert blank-corrected multiwavelength extract absorbances with caller method coefficients and path/dilution/sample-volume correction; negative estimates are retained and solvent-specific calibration is external.

Description

Pigment concentration can be estimated from blank-corrected extract absorbance at several wavelengths.

Pigment concentration can be estimated from blank-corrected extract absorbance at several wavelengths. Method coefficients, optical path and extraction volumes convert the result to the original water sample.^[1]

The tool returns extractChlorophyllMgPerLiter, waterChlorophyllMicrogramsPerLiter. The computation uses supplied observations and parameters rather than acquiring measurements.

When to use Chlorophyll A Extraction Concentration

Use this for the following task: Convert blank-corrected multiwavelength extract absorbances with caller method coefficients and path/dilution/sample-volume correction; negative estimates are retained and solvent-specific calibration is external. Prepare observations and calibration parameters on the same unit and reporting basis.

How to use Chlorophyll A Extraction Concentration and understand its results

Prepare the measured quantities and supplied model parameters. Match the units and align paired lists before calculating.
Enter spectralAbsorbances, blankAbsorbances, calibratedCoefficientsMgPerLiter, opticalPathCm, extractVolumeMl, filteredWaterVolumeMl, dilutionFactor according to the field table, then run the tool.
Read extractChlorophyllMgPerLiter, waterChlorophyllMicrogramsPerLiter. Use the calculation below to interpret the selected mean or the model’s signs, units and comparison flags.
Review the supplied assumptions and calibration before comparing or reporting the result.

Input field	Meaning	Value type and bounds	Requirement
spectralAbsorbances	Spectral absorbances	list of number	Required
blankAbsorbances	Blank absorbances	list of number	Required
calibratedCoefficientsMgPerLiter	Calibrated coefficients mg per liter	list of number	Required
opticalPathCm	Optical path cm	number	Required
extractVolumeMl	Extract volume ml	number	Required
filteredWaterVolumeMl	Filtered water volume ml	number	Required
dilutionFactor	Dilution factor	number	Required

Supply aligned nonnegative absorbances and blanks with signed calibration coefficients, and positive path, volumes and dilution factor. Apply the linear spectral combination and volume correction.

extract mg/L=dilutionFactor×Σ((absorbance−blank)×coefficient)/path; water µg/L=1000×extract×extractVolume/filteredWaterVolume

The symbols and boundary conditions refer to the supplied fields and the implementation described above.

Output field	Meaning	Value type
extractChlorophyllMgPerLiter	Extract chlorophyll mg per liter	number
waterChlorophyllMicrogramsPerLiter	Water chlorophyll micrograms per liter	number

json

{
  "input": {
    "spectralAbsorbances": [
      0.2,
      0.1,
      0.1
    ],
    "blankAbsorbances": [
      0.01,
      0.01,
      0.01
    ],
    "calibratedCoefficientsMgPerLiter": [
      10,
      -2,
      -1
    ],
    "opticalPathCm": 1,
    "extractVolumeMl": 10,
    "filteredWaterVolumeMl": 1000,
    "dilutionFactor": 1
  },
  "output": {
    "extractChlorophyllMgPerLiter": 1.63,
    "waterChlorophyllMicrogramsPerLiter": 16.3
  }
}

Limitations and assumptions

Negative calculated concentrations are preserved. Wavelength order, solvent-specific coefficients, extraction efficiency and sample quality must match the supplied method.

Numerical inputs must be finite. Input-shape and calculation checks do not establish measurement quality or the validity of a supplied calibration.

Alternative or Complementary methods

Choose Phaeophytin Absorbance Correction when you need its operation: Apply caller acid-correction convention Chl=k(Apre−Apost), phaeo=k(R·Apost−Apre); k must include method-specific acidification factors, and negative estimates are flagged rather than clamped. Choose Chlorophyll Phosphorus Regression Prediction for the complementary operation: Fit a log-power chlorophyll/phosphorus relation to caller observations with within-range median prediction; no mutable published regression or uncorrected arithmetic-mean claim.

Background reference: Method 446.0: chlorophylls and pheopigments by visible spectrophotometry.

References

Method 446.0: chlorophylls and pheopigments by visible spectrophotometry — Elizabeth J. Arar, U.S. Environmental Protection Agency

Similar or alternative tools

Phaeophytin Absorbance Correction
Apply caller acid-correction convention Chl=k(Apre−Apost), phaeo=k(R·Apost−Apre); k must include method-specific acidification factors, and negative estimates are flagged rather than clamped.
Chlorophyll Phosphorus Regression Prediction
Fit a log-power chlorophyll/phosphorus relation to caller observations with within-range median prediction; no mutable published regression or uncorrected arithmetic-mean claim.