Moisture Content Determination

Moisture Content Determination

Using a moisture analyzer or a drying oven

What is the drying oven method?

The drying oven method is a thermogravimetric method (loss on drying) in which the sample is dried for a defined period of time at constant temperature. The moisture content is determined by weighing the sample before and after drying and determining the difference.

How are samples heated in the drying oven and in the moisture analyzer?

In the drying oven, samples are heated by convection. This means the samples are at the same temperature as the drying oven. When using a moisture analyzer, the sample heats up and dries by absorbing infrared radiation from the heating element. The sample's temperature and drying time depends on its absorption characteristics.

Isn't moisture the same as water?

This is a common misconception. Everything which evaporates upon heating is named moisture. Water may be a part of this but there may be other substances which also evaporate, such as alcohol or solvents.

I have many different samples (liquid, pasty, solid, powder). Which method should I use for moisture content determination?

In general, all kinds of samples are suitable for both the drying oven and the halogen moisture analyzer. Which method is best for you, depends on how fast you need the result or if you need the result using an official method. Sometimes, for example, in goods-in or final product quality control, moisture analyzers are used in parallel with a drying oven. Fast analysis with the moisture analyzer is done to optimize processes and the drying oven is used for official documentation purposes.

We have to use the standard method with the drying oven but using a moisture analyzer would really speed up our processes. Is it possible?

Many industry regulations require manufacturers to follow a standard method. However, it is acceptable to use a moisture analyzer if you can prove its results are the same as those from the drying oven procedure and are of the same level of accuracy. This requires developing a drying method for the moisture analyzer and cross-validating it against the drying oven through a series of analyses. METTLER TOLEDO's application database contains over 100 free ready-to-use cross-validated drying methods. Contact us if you don't find what you need.

How can I put the batch number on the printout from my moisture analysis?

You can do this either through the ID management functionality on our moisture analyzers or in the differential weighing application on our balances. If your batch number is a barcode, you can even connect a barcode reader to scan it, or any other ID.

I am using the drying oven procedure. How can I avoid errors when I'm recording results and doing calculations?

Manual processes are more prone to error so it's best to use the built-in balance application or a software solution (LabX) with a balance to capture all the results and do the calculations automatically. It's not only much faster but it's error-free too. Results can be printed out for your lab journal or saved on a USB stick to be saved electronically. LabX saves everything in a secure database so you can be sure your data is safe. The LabX report generator enables you to create elegant reports with charts which can be printed out or saved electronically.

How can I avoid my crucibles getting mixed up in the drying oven?

Good labelling is key. Using barcode labels uniquely identifies each sample. A barcode reader attached to the balance ensures that no mix-ups occur and weighing results are correctly logged against each sample. Use of a barcode reader is fully supported by the differential weighing application on the balance and by LabX.

What is the difference between moisture content, dry content and ATRO moisture?

Moisture content is the amount of moisture in the sample given as a percentage of the sample's original (wet) weight. Dry content is the amount of solids which are left after drying given as a percentage of the sample's original (wet) weight. ATRO moisture (AM) is the amount of moisture in the sample given as a percentage of the sample's final (dry) weight. Different industries use different units e.g. in wood or pulp, ATRO is commonly used.

What do TS and DC stand for?

The loss on drying procedure can be used to determine moisture content (MC) or, alternatively, dry content (DC). A sample may undergo extensive drying to remove all the moisture. The dry content remaining may be termed the total solids (TS).

Is there a difference between dry content (DC) and total solids (TS)?

Dry content and total solids mean the same thing. They describe the amount of material remaining after all the moisture has been evaporated.

Moisture Content Determination Using a Drying Oven and a Balance

 


 Moisture AnalyzerDrying Oven and Balance
Analysis methodDirectDirect
Official standard methodNo. Must be referenced to drying ovenYes. Typically the official method for moisture content determination
Typical measurement time3-15 min
240-480 min
PrecisionHigh
High
HandlingOne step, direct measurement
Many steps, differential weighing
MaintenanceLow
Low
CalculationAutomatic (result given in % MC, % DC or other units)
Manual or with help of balance
Result documentationEasy and direct with printer
Manual or with help of balance and printer
Applicable moisture range0-100%
0-100%
Multiple samples at the same time
No
Yes
Typical area of useGoods-in control (raw material delivery), In-Process Control, Final Quality Control
Final Quality Control

 

Application Food Segment Chips
Moisture AnalyzerDrying Oven and Balance
  • Fast results
    A moisture analyzer is perfect whenever it is important that the moisture content result must be available quickly. A fast result enables any required action to be taken rapidly and avoids lengthy delays. For example, to reduce waiting time until unloading raw materials in Goods-In Inspection or to enable fast intervention in the production process following an In-Process Control check.
  • Official method
    For some substances, the drying oven method is the official reference method to determine moisture content. As the official reference method, the drying oven is used for cross-referencing alternative methods such as the moisture analyzer.
  • Simple operation
    When you need a seamless process with few manual steps. Suitable even for untrained operators.
  • No time pressure
    The drying oven can be used when it is not necessary to have a fast result.
  • Minimized errors
    The simple process and the automatic results calculation minimize errors.
  • Multiple samples
    The drying oven is perfect when you want to process many samples simultaneously, particularly if there is no time pressure for the results.
  • Alternative to official method
    By demonstrating that moisture analyzer results are comparable with results from the drying oven, the moisture analyzer can be used instead of the official drying oven method.
  • Very inhomogeneous samples
    For very inhomogeneous substances, it is necessary to use a large sample size (e.g. 500 g). This is only possible with a drying oven.

 

Moisture Content Determination

Moisture Content Determination Using a Drying Oven and a Balance

Software Solution for Moisture Content Determination

C30S
Thermogravimetric Analysis

 

 

FAQs - Frequently Asked Questions on Moisture Content Determination

Publication

  • Publications

Related Products

 
 
 
 
 
 
 
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