Gran analysis is an effective alternative method for endpoint and pKa detection. Using a series of mathematical manipulations, standard titration curves are transformed into linear data called ‘Gran functions’. Endpoints and pKa’s are determined by performing a linear regression on these functions. In many cases, Gran analysis provides a more accurate endpoint, or identifies endpoints not evaluated in Standard Methods.

The main compounds of alkalinity are: hydroxides (OH–), carbonates (CO32-), and bicarbonates (HCO3–). The alkalinity, or buffering capacity, of a solution depends on the absorption of positively charged hydrogen ions by negatively charged bicarbonate and carbonate molecules. When bicarbonate and carbonate molecules absorb hydrogen ions, there is a shift in equilibrium without a significant shift in pH. A sample with high buffering capacity will have high bicarbonate and/or carbonate content, and a greater resistance to changes in pH.

Conductivity is a temperature dependent measurement. All substances have a conductivity coefficient which varies from 1% per °C to 3% per °C for most commonly occurring substances. The automatic temperature compensation on the MANTECH Conductivity meter defaults to 1.91% per °C, this being adequate for most routine determinations.

Temperature-corrected Conductivity is calculated by:

1. Subtract the current temperature of your standard from 25°C (or whichever reference temperature applies).
2. Multiply the result by 1.91% which is your default temperature coefficient.
3. Multiply the result by the uncorrected conductivity value.
4. Add the result to the uncorrected conductivity value. If the sample temperature is higher than the reference temperature, the result of step 1, 2, and 3 are negative numbers so it is a subtraction from the uncorrected conductivity value.
5. The result is the corrected conductivity value.

Example: Uncorrected conductivity value is 1200uS, current temperature is 21.4°C, reference temperature is 25°C, default correction factor of 1.91%

1. 25.0 – 21.4 = 3.6
2. 3.6 * 0.0191 = 0.06876
3. 0.06876 * 1200 = 82.51
4. 1200 + 82.51 = 1282.51uS <— Temperature Corrected Value for Reference Temperature 25°C

Conductivity readings varying with temperature may be due to the substances under test having a coefficient other than the typical value of 1.91% per °C. To eliminate this variation it is necessary to maintain all samples at the reference temperature by use of a thermostatic water bath or equivalent.

Adjustment may be made by entering the 4510 conductivity meter SETUP menu and selecting COEFF. The reading can then be adjusted to the required value (0.00 to 4.00) by using the keypad. A setting of 0.00 will mean that there is no temperature compensation being applied.

When using 50mL sample tubes, the minimum total volume can be as small as 6 ml using the TitraPro4 pH electrode and the MANTECH 5mm conductivity probe. This is due to the lower immersion depth of these electrodes and precise autosampler coordinate specifications. When using 125mL sample cups, the minimum total volume can be as small as 15mL.

IntelliRinse™ is beneficial because it uses real-time measurement to provide confirmation that your probes are 100% clean, eliminating chances of cross-contamination.
Active IntelliRinse™ systems allows users to set user-defined values (e.g. rinse to a specific conductivity value) or to adjust the rinse intensity based on previous sample concentrations before moving to the next sample. This is beneficial as it improves the rinsing of probes/electrodes to ensure that cross-contamination does not occur even with particularly dirty or high-strength samples. There is also the option to have the final value measured during rinsing shown in a column on the results report, for a visual confirmation directly with sample results.

MANTECH systems utilize one of two dissolved oxygen probes from YSI for automated dissolved oxygen determination. The measuring ranges of both probes are listed below, along with a link to the complete specification sheets.

YSI FDO 4410 IDS Sensor

• Dissolved Oxygen Range: 0 to 20 mg/L
• Air Saturation Range: 0 to 200%
• Temperature Measurement Range: 0 to 50°C

YSI ProOBOD Sensor

• Dissolved Oxygen Range: 0 to 50 mg/L
• Air Saturation Range: 0 to 500%
• Temperature Measurement Range: Ambient 10 to 40°C; Compensation -5 to 50°C

The measurements listed below are based on standard MT-Series systems. Measurements and pictures include the MANTECH System Organizer (MSO), where applicable. System controllers and computer monitors are not included in the dimensions described below.

AM400 Only Configuration (No MSO):

The tubing used in MANTECH peristaltic and metering pumps is compatible with many types of chemicals. The following is a list of chemicals that are not recommended to be used with MANTECH tubing/pumps.

*Chemicals without listed concentrations are assumed to be 100% concentrations/the maximum percent solubility in water.

The standard method for measuring temperature is with a USB-connected stainless steel thermistor probe. The specifications for this probe are below:

• Communication: USB controlled by MANTECH Pro Software
• Sheath Material: Super OMEGACLAD XL/ Stainless Steel/Inconel
• Temp Range: 0 to 1038 Degree C.
• Diameter: 0.062in
• Length: 6 inch
• Measurement to 3 decimal places
• Autocalibration feature in MANTECH Pro software

Alternatively, when measuring conductivity, one can measure the temperature directly from the conductivity probe. This temperature is also displayed directly on the conductivity meter screen.

MANTECH has the ability to use either of these measurement methods for pH temperature compensation, depending on customer preference and system configuration.

MANTECH temperature sensors are available in both PT1000 and 10kNTC styles. PT1000 sensors have a linear positive-slope relationship between resistance and temperature with a resistance of 1000 ohms at 0°C, and 10kNTC sensors have a curved negative-slope relationship between resistance and temperature with a resistance of 10,000 ohms at 25°C. Both these models of temperature sensor perform well and comparably within the 0-100°C temperature range that liquid samples exist in. If you require a specific type of temperature sensor, please feel free to let MANTECH know and we will accommodate.