TOC Systems, Inc.

- Model AP-1001 - Alkalinity/Direct Process Analyzer



Standard Methods use nomographs for estimating CO2 concentrations based on total alkalinity titrations. Alkalinity/Direct actually measures the CO2 Concentrations derived from analysis of Total Inorganic Carbon, using interference-free infrared technology. Both methods are compatible, since each uses the same stochiometric relationships. For convenience in relating the technologies, phenolphthalein alkalinity is determined.

The Alkalinity/Direct Method overcomes the limitations of traditional alkalinity tests involving multiple endpoint determinations by titration and colorimetric measurements. Burettes, multiple standards, complicated and troublesome rotary valves dispensing metered volumes, etc. are all avoided. This method uses direct analysis of CO2 and continuously measures the following:

  • Total Alkalinity, mg/Las CaCO3
  • Hydroxide Alkalinity, mg/L as CaCO3
  • Carbonate Alkalinity, mg/L as CaCO3
  • Bicarbonate Alkalinity, mg/L as CaCO3
  • Free Carbon Dioxide, mg/L as CO2

The sample is delivered into a reaction chamber and mixed with acid to lower the pH to 2 – 3, at which point the species listed above are converted to CO2. The CO2 is measured by the non-dispersive Infrared Analyzer and displayed as Total Alkalinity and Phenolphthalein Alkalinity.


  • Range: 1 to 1000 mg/L as CaCO3
  • Sample Temperature: 5 to 50oC
  • Grab Sample Volume: 10 mL minimum
  • Sample Flow Rate: 10 mL/min (minimum)
  • Sample Pressure: Atmospheric +0 – psi (max)


  • Response Time: Less than 4 minutes
  • Repeatability: Better than 2% of reading or +/- 0.6 mg/L
  • Accuracy: Better than +/- 5% of reading or +/- 1.0 mg/L

  • Cooling Towers
  • Boilers/Steam Generators
  • Chemical Process
  • Drinking Water
  • Waste Water
  • Foods & Beverages

  • Alkalinity/Direct Method
  • Avoids Titrimetric/ ColorimetricProcedures
  • Reports Total & Phenolphthalein Alkalinity
  • Requires No Probes
  • Integrates with StarTOC Onboard Computer
  • Interference – Free Analysis
  • Completely Automatic
  • Rapid Response  (3 - 4 Minutes)

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