Preparing Titration Samples

Accurate sample weighing for titration

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Jump to one of the following sections to explore and learn more:

  1. Application Workflow and Challenges
  2. METTLER TOLEDO Solutions
  3. FAQ's

 

Moisture Content Determination

Workflow of Preparing Titration Samples

Typical titrations require the titrant and analyte to be in a liquid form (solution). The solid samples are usually dissolved in water, but other solvents, such as glacial acetic acid or ethanol, may be used for specialized applications e.g. in petrochemistry.

 

Click Here to Read More on Typical Workflow: Quantitative Analysis of a Dissolvable Solid

In preparing for titration, the concentration of the titrant and the weight of the solid analyte must be accurately determined. It is important that all information and measurements are carefully logged, particularly when titrating multiple samples, to avoid any mix-ups between samples and incorrect calculations.

Preparation of the Sample

  • Place the titration beaker on the balance and tare
  • Weigh the substance under investigation into the beaker
  • Add the solvent to the desired quantity e.g. 50 mL

 

Titration

  • Transfer the beaker with the analyte to the titrator
  • The titrator adds the titrant to the analyte in an automated process
  • A sensor monitors the change in the measured potential of the solution and stops the titration when the end-point is reached
  • The titrator calculates the concentration of the analyte automatically

 



Sample Preparation for Titration Know-How
 

The table below provides information on the best techniques for preparing titration samples according to the characteristics of your sample.

Sample CharacteristicsPreparationSampling Technique
PowdersDissolved in solvent (organic/inorganic)Gravimetric, direct weighing
Pasty, creamy or sticky samplesDissolved in solvent (organic/inorganic)Gravimetric, direct weighing
Lubricants and oilsDissolved in solvent (organic/inorganic)Gravimetric, direct weighing
Meat, fishDigestion in acid solutionGravimetric, direct weighing
Water or other low viscosity solutionsBuffers if neededVolumetric

 

Preparing titration samples is a key part of many standard titration test methods such as those from United States Pharmacopoeia (USP), International Organization for Standardization (ISO), and American Society for testing and materials (ASTM). Most standards specify the required level of weighing accuracy.

For example, the ASTM D664 Standard Test Method for Acid Number (AN) of petroleum products includes recommended sample weights plus the required weighing accuracy:

Acid NumberMass of Test Portion (g)Accuracy of Weighing (g)
0.05 – < 1.020.0 +/- 2.00.10
1.0 – < 5.05.0 +/- 0.50.02
5 – < 201.0 +/- 0.10.005
20 – < 1000.25 +/- 0.020.001
100 – < 2600.1 +/- 0.010.0005


There are many more ASTM methods which use titration as a method for determination of different parameters, e.g. base number, bromine number. These methods specify sample size as a critical element of the standard. E.g. ASTM D974, D2896, D1159 and more.

 

 

Preparation of titration samples - expert



The Challenges of Accurate Sample Preparation for Titration

Sample and Data Handling

Titration is a common laboratory technique which is relatively straightforward to carry out. However, when working with several samples, which may be from the same analyte as well as from different analytes, sample and data handling can be challenging. It's vitally important to label samples and ensure all measurements are correctly logged against the correct sample.

Particular attention should be paid to:

  • The inherent risk of transcription errors in manual data recording processes
  • Correct and legible sample labelling to avoid sample mix-ups during the transfer of samples from the balance to the titrator
  • Correct input of weighing results from the balance to the titrator

Accuracy and Time

Obtaining accurate titration results is highly dependent on preparing titration samples accurately. With several standards specifying precise sample sizes and an associated weighing accuracy, it is critical that the balance used meets the needs of the titration application.

For small samples, the minimum net sample weight of the balance must be considered – weighing a sample below this weight cannot be trusted to be of the required level of accuracy. In a busy laboratory, in which many samples are tested every day, a robust balance that stabilizes quickly will ensure operators can keep working on tasks and are not kept waiting for the figures on the display to settle. Manual transcription of sample data, weight values and titration results is also time consuming and prone to error.

Cleaning

Keeping titration and weighing equipment thoroughly clean is important to prevent cross contamination. If samples are dirty and/or viscous, weighing and cleaning can become challenging.

 

METTLER TOLEDO Solutions for Preparing Titration Samples

Safe Weighing Guide

Software Solution for Secure Weighing and Titration Processes

Connect your METTLER TOLEDO Excellence analytical balance to LabX laboratory softwarefor the highest level of automated data handling and process security. The titration application is started directly from the balance touchscreen and users simply follow the onscreen instructions. LabX automatically takes care of all data and calculations, and all information is saved securely in a centralized database.

Simple Weighing

Excellence Balances connected to LabX have a dedicated entry point for titration tasks that re­quire weighing. Simply select the task and LabX provides step-by-step instructions on the balance to guide you through the sample weighing process. For improved productivity, you can even start your titration whilst weighing more samples.

Flexible Operation

Either start your analysis at the instrument or from the PC and have constant access to both your current sample analysis and the latest results. No matter where you are, the LabX Mail facility can send messages or results to you.

SmartCodes™

Fully automate the selection of the correct method and transcription of samples IDs with a barcode or SmartSample™ RFID tag. Thus, eliminate sample order errors by reading the sample information as you test it, as well as ensuring the right method is selected for each product.

Regulatory Compliance

The Regulation option of LabX server provides all the necessary tools to help you meet the FDA regulation (21 CFR Part 11) for data ma­nagement and storage. All rele­vant actions taken at the instru­ment or PC are recorded in the audit trail of LabX for full tracea­bility and flexibility, no matter where you work.

 

 

 

FAQs – Frequently Asked Questions on Preparing Titration Samples

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