MT-100 system for automated titration analysis

MT Series of Automated Environmental Titration and Multi-Parameter Analyzers

Rugged & Reliable

Whether your laboratory requires a simple pH system or a system with eight parameters, MANTECH will deliver. We realize each laboratory is unique and as a result, our systems are tailor configured with off-the-shelf modules to meet your requirements for sample volume, parameters and sample size. Each system is fully automated by easy to use software and robust robotics.

 

Benefits

  • Automates 26-400 samples in a single batch
  • Customizable user interface for simplified operation
  • IntelliRinse™ prevents cross contamination between samples
  • Eliminates potential for human error with automated pipetting using MANTECH’s Titrasip™
  • Non-destructive sample preparation allows for up to 5 parameters on a single sample

Applications

  • Water
  • Soil
  • Food & Beverage

Parameters

MANTECH is a leading manufacturer of automated titration and multi-parameter analysis systems. We can deliver analysis systems that perform the following functions: (click the links to view method abstracts)

We have purchased a MANTECH system to automate our suite of pH, Conductivity and Turbidity analysis. From industry feedback we knew that this suite is notoriously difficult to automate and the MANTECH system presented a new and viable solution to the problem. Camlab, the UK representatives have helped us from the very outset with the financial justification and there on with the development of our methods and engineering support. The staff, from product specialist to the engineers at Camlab have understood the constraints of our methodologies and have worked with us as a partnership to deliver the high performance we need.
I worked with three multi-parameter systems running applications such as pH, conductivity and alkalinity. It was wonderful being able to set up my run and then move on to other tasks around the lab. One of the systems often ran for ten hours straight (approximately 750 samples). The MANTECH systems were easy to use and very durable.
MANTECH instruments used by ALS have proven to be robust analytical solutions, generating accurate and precise results with a low per sample operating cost.
The support was excellent from all vendors but the software and hardware support teams for the MANTECH PC-Titrate system were local and are marketed and supported by the same company. The precision was superior on the PC-Titrate system as was the multi-valve cleaning system, which included more titrants, and purging of titrant lines. In conclusion the PC-Titrate system met our needs most closely and was the best long-term choice for our solutions analysis.

Models & Specifications

Model
MT-10
MT-30
MT-100
MT-30 Automated titration system for pH analysis
Capacity
26-400
28-400
30-400
DualProbe*
IntelliRinse™
Static and Dip Multiple Stations
Dynamic
Dynamic
SampleProtect™*
Temperature Compensation
Automated with Manual Temperature entry
Automated with Thermistor
Automated with Thermistor
PeCOD® COD Analyzer Add-on (10min COD and NOM)
BOD5 Day DUO Add-on
Food Applications, Total Acidity, Sulfite, Chloride
2 or more titration methods
In different sample cups
In different sample cups
From a single sample cup
125ml cups
50ml tubes
 ✓
 ✓
15ml tubes
 ✓
IntelliVOL™**
 ✓
 ✓
Automated Pipetting
RapidDuo™ e.g. alkalinity & hardness in 2 different vessels

*Available with AM122, AM197 and AM354 Autosamplers
**Aspiration of sample to a known volume via extraction pump. Accurate sample volume allows for titration directly in 125 mL cup or 50 mL tube

All of our systems can be customized to suit your needs. Contact us for more information.

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Frequently Asked Questions

Titration uses a solution of known concentration to determine the concentration of an unknown solution. The titrant (the solution with a known concentration) is added from a buret to a known quantity of the analyte (the solution with an unknown concentration) until the reaction is complete. Knowing the volume of titrant added allows the concentration of the unknown solution to be determined.

The potential of hydrogen (pH) is a measure of hydrogen ion (H+) concentration. Solutions with a high concentration of H+ ions have a low pH (acidic). Solutions with a low concentration of H+ ions have a high pH (alkaline). Read MANTECH’s pH method abstract here.

Conductivity, also known as electrical conductivity, is used to measure the concentration of dissolved solids which have been ionized in a polar solution such as water. Read MANTECH’s conductivity method abstract here.

Oxidation-reduction potential (ORP), also known as redox potential, refers to the capacity of a solution to oxidize (accept electrons) or reduce (donate electrons). ORP sensors work by measuring the voltage across a circuit formed between the indicator and reference electrodes. When an ORP electrode is placed in a solution containing oxidizing or reducing agents, electrons are transferred back and forth on the measuring surface, generating an electrical potential. Common applications for the ORP method include monitoring water chlorination processes for water disinfection, distinguishing between oxidizers and reducers present in wastewater, and metal screening. Read MANTECH’s redox potential method abstract here.

Ammonia is a colourless gas that is soluble in water and has a distinctive odour. It is a mild environmental hazard because of its toxicity and ability to remain active in the environment. Direct measurement of ammonia using a calibrated ion selective electrode (ISE) is a quick, accurate and precise way to easily determine ammonia levels. Read MANTECH’s ammonia method abstract here.

‘Hardness’ is defined as the total concentration of alkaline earth ions (Ca2+, Mg2+, Sr2+ and Ba2+) in water. The Ca2+ and Mg2+ ions dominate the alkaline earth ions. Therefore, one can refer to total hardness as the total concentration of the Ca2+ and Mg2+ ions in solution. Hardness is expressed as mg CaCO3/L water sample (ppm CaCO3). Read MANTECH’s hardness method abstract here.

Nitrates (NO3) are formed from the two most common elements on earth, nitrogen and oxygen. Their presence in soils comes from nitrogen-fixing bacteria in the soil, decay of organic matter, industrial effluents, human sewage, and livestock manure. Nitrates are a serious problem since they do not evaporate, and hence remain dissolved and accumulate in the groundwater. Read MANTECH’s nitrate method abstract here.

There are two types of salinity, absolute salinity and practical salinity. Absolute salinity is a ratio between the mass of dissolved material in seawater and the mass of the seawater. Practical salinity is the ratio of the electrical conductivity of a seawater sample to that of a standard potassium chloride (KCl) solution at the same temperature and pressure. Read MANTECH’s salinity method abstract here.

Turbidity is defined as the amount of suspended particles in a solution, measured in nephelometric turbidity units (NTU). It is used as a general indicator of the quality of water, along with colour and odour. The US EPA has a maximum contaminant level (MCL) of 5 NTU for drinking and wastewaters. Read MANTECH’s turbidity method abstract here.

Alkalinity refers to the capability of water to neutralize acid, also known as an expression of buffering capacity. A buffer is a solution to which an acid can be added without changing the concentration of available H+ ions (without changing the pH) appreciably. In other words, a buffer absorbs the excess H+ ions and protects the water body from fluctuations in pH. Read MANTECH’s alkalinity method abstract here.

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.  For more information on MANTECH’s method for automated alkalinity measurement and how the species of alkalinity are calculated, download the pdf.

Each of our AutoMax samplers are compatible with a variety of common sample cup and tube styles to accommodate up to 4 probes. To view available sample vessels and AutoMax sample capacities, read out technical bulletin here.

The standard method for measuring temperature is with a glass thermistor, and for certain specified applications, a stainless steel thermistor is used. Alternatively, when measuring conductivity, one can measure the temperature directly from the conductivity probe.

MANTECH has the ability to use any of these three 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.

 

As the temperature of a solution changes, the actual pH changes. This is not an error of the probe or meter being used, but is the actual pH of the solution at that particular temperature. The temperature effect on the pH value is 0.003 pH units per oC away from 25oC, per pH units away from pH 7. This effect can be either negative or positive, depending on if the temperature is above or below 25oC, and if the pH is above or below pH 7. At 25oC and pH 7, there is no change in the pH value.

The chart below shows how the actual pH changes with temperature and pH, which allows you to correct the pH reading to 25oC. As an example, if a sample measured pH 5 at a temperature of 5oC, the chart indicates this a negative effect, therefore the sample pH would be 5 – 0.12 = 4.88pH corrected to 25oC:

MANTECH software accounts for temperature by recording the temperature during calibration via a thermistor probe, then it corrects the pH reading at the time of measurement to account for the difference in measured temperature of the sample vs. the calibration buffers. The reported pH value is the corrected value @ the sample temperature. The equation below shows how the PC-Titrate software calculates pH:

pH equation

EMeas  =  Voltage measure by electrode at the time of titration (mV)

EInt  = Voltage of the Intercept value calculated from the calibration equation. (mV)

Slope = slope of the line calculated from the calibration equation. (mV)

TMeas = temperature measured at the time of pH measurement (K degrees)

TCal = temperature taken at the time of last calibration. (K degrees)

 

MANTECH also offers the option to report pH values corrected to a set temperature, such as 25°C. This is implemented in the software as an additional step after the sample pH is recorded. MANTECH offers this as a feature for new MT-Series systems, or as an upgrade to existing MANTECH systems.

For more information please follow this link or contact us at support@mantech-inc.com.

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.

Most MANTECH electrodes are connected to the Interface module via a BNC cable with a detachable S7 connection. This S7 connection is located at the electrode cable junction, allowing for easy detachment from the cable, and removal of the electrode while leaving the cable in place. This applies to all electrodes except the Ammonia Electrode and all Conductivity electrodes. See below for pictures of a pH electrode with the S7 connection attached, and detached.

If your titration standards are not reading the correct concentrations, for example, the alkalinity standard reading is low, first make sure the titrant has been standardized. Secondly, the precision of the results can indicate if this is a mechanical or chemical problem. If the results are precise, it is likely a chemical issue. Check your standards and titrant standardization. It is also possible that the sample volume may be incorrect.

NaOH is highly hygroscopic, meaning that it absorbs water from the air. Therefore, over time the titrant will become more dilute as it absorbs water. NaOH can be standardized by titrating into a sample of potassium hydrogen phthalate (KHP) of known concentration. For example, titrate 0.05 N KHP with 0.1 N NaOH to an endpoint, and using the volume of NaOH added, the precise concentration of NaOH can be calculated. For more information on standardizing NaOH titrant, please refer to Standard Methods 2310. To limit the amount of water being absorbed, a glass drying tube with a cotton ball inserted should be used to prevent moisture going into the tube.

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.

1:2 ratio (1 sample: 2 DI) is the acceptable dilution factor. This means that a sample volume as small as 2 ml can be diluted in 4 ml of Deionized water (DI) for a total of 6ml, when measured in a 50ml tube using the TitraPro3 pH electrode.  Note that since the sample is diluted, the pH should not be reported as the sample initial pH value.  Only undiluted samples should be measured and reported for initial pH. Dilutions factors that are greater, for example 1 part sample to 3 parts DI, were found to produce incorrect, lower alkalinity results.  It was also noted that on higher dilutions, the pH dropped below 7, indicating a change over to the acidic side.

Changes to slope at higher pHs

Alkaline Error or Sodium Error occurs when pH is very high (e.g. pH 12) because Na+ concentration is high (from NaOH used to raise pH) and H+ is very low.

Electrodes respond slightly to Na+ and give a false low reading.  This is related to the concept of selectivity coefficients where the electrode responds to many ions but is most selective for H+.  This problem occurs because Na+ is 10 orders of magnitude higher than H+ in the solution.

High pH electrodes use a 0-14 pH glass.  This electrode will read pH 14 (1 M NaOH) to be around pH 13.7 with a 0.3 pH sodium error.

A standard pH electrode uses a 0-12 pH glass.  The electrode will read pH 14 (1 M NaOH) to be around pH 12.4 with a 1.6 pH sodium error.

 

Alkaline error

The alkaline effect is the phenomenon where H+ ions in the gel layer of the pH-sensitive membrane are partly or completely replaced by alkali ions. This leads to a pH measurement which is too low in comparison with the number of H+ ions in the sample. Under extreme conditions where the H+ ion activity can be neglected the glass membrane only responds to sodium ions.  Even though the effect is called the alkaline error, it is only sodium or lithium ions which cause considerable disturbances. The effect increases with increasing temperature and pH value (pH > 9), and can be minimized by using a special pH membrane glass.

 

Sodium Ion Error

Although the pH glass measuring electrode responds very selectively to H+ ions, there is a small interference caused by similar ions such as lithium, sodium, and potassium. The amount of this interference decreases with increasing ion size. Since lithium ions are normally not in solutions, and potassium ions cause very little interference, Na+ ions present the most significant interference.

Sodium ion error, also referred to as alkaline error, is the result of alkali ions, particularly Na+ ions, penetrating the glass electrode silicon‐oxygen molecular structure and creating a potential difference between the outer and inner surfaces of the electrode. H+ ions are replaced with Na+ ions, decreasing the Hion activity, thereby artificially suppressing the true pH value. This is the reason pH is sometimes referred to as a measure of the H+ ion activity and not H+ ion concentration.

Na+ ion interference occurs when the H+ ion concentration is very low and the Na+ ion concentration is very high. Temperature also directly affects this error. As the temperature of the process increases, so does the Na+ ion error.

Depending on the exact glass formulation, Na+ ion interference may take effect at a higher or lower pH. There is no glass formulation currently available that has zero Na+ ion error. Since some error will always exist, it is important that the error be consistent and repeatable. With many glass formulations, this is not possible since the electrode becomes sensitized to the environment it was exposed to prior to experiencing high pH levels. For example, the exact point at which the Na+ ion error of an electrode occurs may be 11.50 pH, after immersion in tap water, but 12.50 pH after immersion in an alkaline solution.

Controlled molecular etching of special glass formulations can keep Na+ error consistent and repeatable.

This is accomplished by stripping away one molecular layer at a time. This special characteristic provides a consistent amount of lithium ions available for exchange with the hydrogen ions to produce a similar millivolt potential for a similar condition.

For water soluble contaminants, rinse probe in deionized (DI) water.  If ineffective, soak probe in warm DI water with household detergent for 15 – 30 minutes.

For oil-based contaminants, rinse probe in ethanol or acetone for short (5-minute) periods.

After cleaning, rinse probe in DI water to remove residual cleaning reagents.  Perform a meter calibration before proceeding with sample analysis.

MANTECH utilizes rapid dipping of conductivity probes into sample tubes to mix samples and ensure a stable analysis of conductivity from the probe. This style of mixing is applicable to systems featuring a 12mm conductivity probe dipping into 50mL sample tubes, and systems featuring a 5mm conductivity probe dipping into 15mL sample tubes.

For all other combinations of probe and sample vessel, a stirrer is required to ensure proper mixing is achieved.

A Method Detection Limit (MDL) is defined in slightly differring ways by the US EPA, and the APHA. The definitions are briefly described below:

MDL as per US EPA:
The method detection limit (MDL) is defined as the minimum measured concentration of a substance that can be reported with 99% confidence that the measured concentration is distinguishable from method blank results.

MDL as per APHA:
(MDL) is defined as the constituent concentration that, when processed through the entire method, produces signal that has a 99% probability of being different from the blank.

Standard Method 2130B (Nephelometric Method) specifies that a laboratory or process nephelometer should have a detector system with a spectral peak response of 400 to 600 nm. MANTECH’s T10 Turbidity meter and automated turbidity applications conform to this requirement.

MANTECH recommends the use of turbidity standards made with suspensions of microspheres of styrene-divinylbenzene copolymer for all turbidity applications. Standard Methods dictate that “Secondary standards made with suspensions of microspheres of styrene-divinylbenzene copolymer typically are as stable as concentrated formazin and are much more stable than diluted formazin.

The reason you may have negative conductivity values at the low end is that there is a PC-Titrate software calibration being applied on the raw conductivity values from the meter. They are not wrong and it means the value is zero (0). You see this often with DI water measurements. If you turned off the software calibration then you would get the exact same values as displayed on the conductivity meter.

Mantech Burets have a static IP address assigned to them. These addresses can be changed if there are communication issues between the Buret and the software.

If an IP address needs to be changed, then you can manually change it using the following steps:

1. Open the Network and Sharing Centre on your computer through the advanced network settings, or through searching on the Control Panel.

2. Open Command Prompt on your computer by searching it in your Windows Search Engine.

3. Extract this folder to your computer.

4. Plug in the burette. In the Network and Sharing Centre, find the active network for the buret (ethernet connection) and open the properties by selecting the blue “Ethernet”. Open the properties.

5.Internet Protocol Version 6 should be unselected, and Internet Version 4 should be selected. Click OK and open the Details for the ethernet status. The Value for IPv4 Address should be 192.168.1.1. If not, change the IP address in the Internet Protocol Version 4 properties.

6. In Command Prompt, type in ping and the IP address found on the back of the buret and then the enter key. For example, “ping 192.168.1.50” without the quotations and the enter key. The buret should reply.

 

 

 

 

 

7. Open the Buret_IP_Change folder now on your computer and open the application that is in the bin subfolder.

8. Type in the IP address and “Connect”. Click OK. Then type in the new IP address and select “Set IP”.

9. In Command Prompt again, ping the new IP address to ensure it works.

Specific notes:

  • If the IP address is not known, then in command prompt, type in “arp -a” without the quotes and the IP address for the buret will be given as the first line under the IPv4 Address Value. This can be done after Step 5.

  • If using PC-titrate, ensure that the version used is 889 or later. Previous versions do not support the ethernet Burets without an upgrade. Contact support@mantech-inc.com for the ethernet buret software upgrade.
  • If using Mantech Pro, you can find the IP address of the buret (if it is not the one already in the address line) in hardware configuration using the “Configure Adapter”. The software will find the IP address that works for that buret and can be used to test the ping as well for buret response.

Calibrations can be linear, logarithmic, single-line, and multi-line fit. 

The calibration method used depends on the method required.

pH and Color calibrations are linear, single-line fit calibrations.

Conductivity and Turbidity calibrations are multi-line, linear type calibrations.

ISE (Fluoride, Chloride, Ammonia, etc.) use a logarithmic multi-line calibration type.

A: The timing for analysis of different parameters depends on a few different factors, like the concentration of the sample and the equipment used.

Another factor is the total available sample volume in the vessel on the AutoMax Autosampler bed. With some combinations of parameters, larger sample volume allows for simultaneous measurements, resulting in faster total analysis time than sequential measurement.  A larger sample volume may require a larger sample cup, which decreases capacity on the same model Autosampler.  For example, an AM73 can accommodate 73x50ml tubes, or 30x125ml cups.  In some, the cases the same set of parameters can be analyzed in 2-5 minutes faster when using the 125ml cups vs 50ml tubes.

It is important to understand your customers’ requirements in terms of capacity and throughput speed, total batch capacity required and/or daily sample loads and if overnight, unattended analyses will be applicable.

Individual Parameters

Combined Parameters

MT-10 & MT-30 Models

* If alkalinity is combined with turbidity and/or colour an MT-100 System must be quoted

MT-100 Model

 

A: 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
  • Technical Specifications

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
  • Technical Specifications

Hot acidity is a variation of the standard Acidity titration using NaOH, with some pretreatment steps performed before the titration. It is outlined in Standard Methods SM2310B, officially called “hot peroxide treatment procedure for acidity determination”. This method is applicable to mine wastes and other samples containing large amounts of metals such as heavy industrial WW.

From SM2310B:

  • Use the hot peroxide procedure to pretreat samples known or suspected to contain hydrolysable metal ions or reduced forms of polyvalent cation, such as iron pickle liquors, acid mine drainage, and other industrial wastes.
  • Hot peroxide treatment acidity method:
    • Pipet sample volume into vessel
    • Measure pH
    • If pH > 4.0, add small increments of 0.02N H2SO4 to reduce pH to 4.0 or less
    • Remove samples from MANTECH system
    • Add 5 drops of 30% H2O2 and boil for 2 to 5 minutes
    • Cool to room temperature
    • Place samples back on MANTECH system and titrate with standard alkali (NaOH) to pH 8.3
  • The calculation for hot acidity is shown below:
    • Acidity = [((mL NaOH consumed)*(Normality of NaOH)) – ((mL H2SO4 consumed)*(Normality of H2SO4))*50,000]/Sample volume

MANTECH recommends storing pH and other electrodes immersed in a 1:10 dilution of pH 4 buffer in Tap Water (1 part pH 4, 9 parts Tap). Conductivity electrodes can be stored in air for system configurations that do not place it on the same holder as another electrode.

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