Loss on Drying Test Service

The moisture in pharmaceutical materials such as excipients, drug formulations and packaging films are critical factors in determining their storage, shelf-life, stability, processing and delivery performance. Loss on drying (LOD) test is a common analytical method used to determine the content of moisture or volatile substances in tablets, capsules or bulk materials. The sample was weighed before and after treatment to measure the weight difference. BOC Sciences offers state-of-the-art loss on drying test services designed to meet the stringent standards of the pharmaceutical industry, ensuring accurate and reliable results that help our customers maintain the highest quality of their products and comply with regulatory requirements.

Loss on drying definition

The loss on drying of a drug refers to the weight lost after drying under specified conditions of the drug to be tested, usually expressed as a percentage. The lost components are mainly the water lost under specified conditions of the drug under test, and may also include other volatile substances such as solvating components or residual solvents.

The principle of loss on drying measurement method is relatively simple, that is, under normal pressure or pressure reduction, after heating or normal temperature drying for a certain time, so that the volatile substances in the drug such as water, other volatile substances volatilize, measure the constant weight of the test (drug) before and after drying, you can calculate the weight loss percentage (%) of the test (drug).

W1: Sample weight (g)

W2: Weight of empty weighing bottle after constant weight (g)

W3: Total weight of sample + weighing bottle after constant weight (g)

Loss on drying test services

Our loss on drying test services cover a wide range of dosage forms from APIs to formulations, including tablets, capsules, granules, powders and more. We offer comprehensive test solutions to meet the needs of our customers at different stages of development.

Loss on drying test for APIs: Loss on drying test for APIs helps customers understand the stability of raw materials and provides basic data for formulation.

Loss on drying test of preparations: Loss on drying test of different types of preparations is performed to assess the stability of preparations during storage and use, and to optimize packaging and storage conditions.

Loss on drying test in stability studies: In long-term stability studies, the drying loss of samples is regularly tested to provide a scientific basis for determining the expiration date of the product.

Loss on drying test in process optimization: During the optimization of drug production process, the influence of different process conditions on product quality is assessed by loss on drying test.

Loss on drying test methods

Constant temperature and atmospheric pressure drying method: Suitable for heat stable samples. Such as acetaminophen, vitamin B1, etc. Put the test product in a flat weighing bottle that has been dried to constant weight under the same conditions, weigh it accurately, and dry it to constant weight in the oven at the specified temperature (generally 105℃). The drying weight of the test product is calculated from the weight lost and the sample amount.

Constant temperature and vacuum drying method: Suitable for drugs with low melting point, unstable heat or difficult to remove water, such as racanisodamine, ciprofloxacin, ibuprofen, epinephrine, etc. The test product is dried in the vacuum drying oven at the specified temperature to constant weight or to the specified time, that is, the vacuum heating drying method.

Desiccant drying method: Put the test product in the dryer, use the desiccant in the dryer to absorb water, dry to constant weight, and calculate the drying weight of the test product from the weight loss and sampling amount. Commonly used desiccant silica gel, sulfuric acid and phosphorus pentoxide, etc., water absorption is phosphorus pentoxide > silica gel > sulfuric acid, of which silica gel is the most commonly used.

Thermogravimetry analysis(TGA): A dynamic measurement method that can simultaneously measure the relationship between mass change and temperature. Terbinafine hydrochloride was taken as an example to test its drying weight loss. Take about 5-15mg terbinafine hydrochloride, place the sample in a tray, put it on a thermobalance, and accurately weigh it. Under the condition of nitrogen flow rate of 45 mL/min, heat it up at a heating rate of 20℃/min to 220℃, record the thermal analysis curve, and record the baseline under the same conditions. Calculate the weight loss of the sample at room temperature to 125℃, which should not exceed 0.5%.

Loss on drying test procedure

• Dry the shallow weighing bottle with glass stopper in the dryer for about 30 minutes;
• Cool to room temperature and weigh the tare, place the sample in the bottle, and weigh the initial sample;
• Shake gently to evenly distribute the sample in the bottle;
• Remove the glue plug, place the bottle in a drying chamber and culture at high temperature;
• After high temperature treatment, the bottle is immediately sealed, cooled to room temperature in a dryer, and then the differential weight is measured.

Advanced experimental equipment

Highly accurate moisture meter: Using advanced infrared heating and gravimetric analysis technology, it can accurately determine the drying loss of the sample in a short time, while ensuring the repeatability and accuracy of the test results.

Automated drying weight loss analyzer: This equipment integrates an automated control system and an accurate data acquisition system, which can automatically complete the sample drying, weighing and data analysis process, greatly improving the test efficiency.

Thermogravimetric analyzer: An instrument that uses thermogravimetric analysis to detect the temperature-mass relationship of a substance. Thermogravimetric method is to measure the weight of the sample and the change of weight with temperature under a certain atmosphere. When the sample under test sublimates, vaporizes, breaks down gas, or loses crystal water during heating, the quality of the sample under test will change. In this case, the thermogravimetric curve is not a straight line but a decline. By analyzing the thermogravimetric curve, it is possible to know at what degree the measured substance changes, and according to the weight loss, it is possible to calculate how much substance is lost.

Environmental control laboratory: Our laboratory is equipped with an advanced environmental control system, which can accurately control environmental factors such as temperature and humidity to ensure the consistency of test conditions.

Data management system: Advanced data management software is used to collect, process and analyze test data in real time, and generate detailed test reports for customer tracking and comparison.

Our service process

• Confirm customer order, send samples
• After receiving the sample, determine the specific test project and test plan
• Lab quote
• Sign a confidentiality agreement, run the test
• Complete the test and confirm the test report
• Post-technical service

FAQ

1. What details do you pay attention to during the loss on drying test services?

• Ensure that the temperature of the drying oven is constant before placing the test product to be dried.
• When using a glass dryer to decompress, it is advisable to wrap the dryer with a thicker cloth or add a suitable jacket to prevent breakage.
• The sample should be laid flat in a flat weighing bottle with a thickness of no more than 5mm, or no more than 10mm if it is loose material.
• When multiple samples are measured in parallel, the appropriate method should be used to first symmetrically code the bottle.
• Pay attention to the control of ambient temperature and humidity, and be quick when weighing.

2. What if the sample melts during the drying process?

If the sample melts at the drying temperature, a film is formed on the surface of the sample, so that the water contained in it is not easy to continue to volatilize, such test products should be dried at a temperature below the melting temperature of 5-10 °C until most of the water is removed, and then dried according to the specified conditions.

3. How are the test results interpreted?

The percentage of dry weight loss reflects the amount of water and volatile substances in the sample. Results should be compared with product specifications or relevant standards to determine conformity.

4. What if the test product is hygroscopic?

If the test product has wettability, and the drying weight loss data is used for content determination calculation, it is best to conduct the content determination at the same time as the drying weight loss sampling to reduce errors.