Weighing small amounts of samples is a typical operation in analytical laboratories. In the field of chemical analysis such as quantitative weight analysis, thermogravimetric analysis, or elemental analysis, accuracy plays a crucial role. When weighing a minimum sample volume with a laboratory balance, it is important to ensure that spillage does not fall directly into the sample container and affect the weighing result. Weight boats
are used when necessary.
Weighing sample volumes in the milligram range requires not only highly sensitive instruments but also expert operators. However, even a small amount of spillage can lead to measurement errors because of residual samples on the weighing dish
. Although the balance correctly displays the total amount of sample, not all of the sample is in fact in the weighing boat or crucible. This can lead to erroneous weighing results and negatively affect the analytical results.
If you need to weigh very small samples with laboratory balances and want to ensure that spills that do not fall directly into the sample container do not affect the weighing results, then we have a solution for you. ANTITECK weighing boats
are available for ultra-micro and micro balances. These balances offer ranges of up to 10 grams and 0.1 microgram readability. They have a minimized surface design with no sample residue on the weighing pan, which ensures reliable and highly accurate measurement results.
Analytical balances are a common piece of equipment found in research laboratories. These highly accurate instruments are capable of measuring down to 10,000ths of a gram or even 100,000ths of a gram. Three-beam balances use a counterweight on three beams to balance the sample in the tray. Modern analytical balances, on the other hand, use a complex system of electronic sensors to accurately weigh the substance.
Analytical balances are so sensitive that they often have a windshield to prevent air currents from interfering with the weighing. Weighing is done using weighing boats or aluminum weighing dishes to hold the substance and protect the weighing pan. Before weighing a substance, the weighing vessel or paper is placed in the tray and then re-zeroed. Zeroing is the process of returning the balance to a zero reading so that the substance can be accurately weighed. In addition to chemical substances, analytical balances can also weigh animals and insects, as well as centrifuge tubes in ultracentrifugation experiments.
The analytical balances used in modern laboratories are usually electronic analytical scales, which use the electromagnetic compensation method to determine the mass. It weighs on the principle that spring is replaced by a sinking force. The latter causes a pressure-measuring element to release a current to a signal processor, which indicates the mass. Modern analytical balances using this method can accurately measure the mass of an object. Analytical balances are very accurate instruments that can measure masses down to 10,000ths of a gram or even 100,000ths of a gram.
Analytical balances are made up of several important components. The weighing pan is where the sample is placed. It is the part of the balance that is attached to the beam or spring. The windshield, located above the balance, is a glass cover with a movable door that prevents drafts or dust from entering the weighing pan and affecting the accuracy of the weighing. Zeroing knob is used to zero the balance after placing the weighing dish (plastic weighing dish) or weighing boat (disposable weighing boats / reusable weigh boats) on the weighing pan.
Weighing dishes and weighing boats are used to hold the substances that need to be weighed by the balance. They prevent the weighing pan from being soiled or damaged by chemicals.
Weighing spoons are used to manipulate samples that need to be weighed. The choice is based on the type of substance and the amount needed. Micro medicine spoons are used to take small samples; large medicine spoons are used to take large samples.
a. Before using the analytical balance, press the zero button to make sure the balance is on. Open the windshield door, put in the weighing dish or paper, close the door and press the zero button again, the scale should read 0.0000g.
b. The choice between using a weighing dish (weighing boat)
or a weighing paper
depends on the amount of substance to be weighed. If it is a small amount, or if the substance to be weighed is to be transferred to a small test tube or a small centrifuge tube, then weighing paper is required. Weighing paper can be folded for easy handling. For larger amounts, weighing dishes are required.
c. Use a medicine spoon to place the sample on the weighing dish and avoid scattering it out. Wait for the reading to stabilize while weighing. If necessary, close the door of the windshield to ensure accurate readings. Do not allow your body to lean over the bench when using the analytical balance, as this will affect the reading.
d. When finished weighing, use a small brush to sweep up any excess sample scattered on the weighing pan
e. When using the analytical balance, remember to always wear gloves. This will prevent fingerprints from being left on the weighing pan.
f. Analytical balances are very sensitive and even fingerprints can affect the accuracy of their readings.
g. Keeping the windshield door closed while weighing samples avoids inaccurate readings caused by drafts.
When weighing hygroscopic samples that tend to absorb moisture from the air, act quickly because they will absorb moisture during the weighing process. When weighing frozen or refrigerated samples, be sure to bring them to room temperature first, also to prevent the chemicals from absorbing moisture. Chemical reagents are heavier at cold temperatures than at room temperature, which can also cause inaccurate weighing.
Be sure the balance is level at all times, which can be determined by observing whether the horizontal bubble is centered. If not, the balance is on a non-level operating surface and can be leveled by turning the balance's adjustable legs. In addition, the balance is usually placed on a vibration-cushioned base, which prevents damage to the electronics due to vibration.
Analytical balances are usually supplied with calibration weights to periodically calibrate your balance for correct readings. These standard weights are provided with precisely specified masses to check the accuracy of the balance. Calibration means adjusting the reading of the counter or balance to the known weight of the object.
Many different kinds of samples will need to be weighed in the laboratory. One application of analytical balances is to weigh liquids. This is very important for centrifugal experiments. One of the important factors is to make sure that the tubes of the ultracentrifuge have the same mass, otherwise, the rotor is not balanced and can cause big problems!
In addition to weighing liquids, a balance can also be used to weigh animals and even insects, such as fruit flies and mosquitoes. This allows the researcher to track the weight and food consumption of the animal during the experiment.
It is recommended that the product be left upright for a period of time (let it come to room temperature) so that the product is all concentrated at the bottom and easy to access. Especially for viscous substances, it can be tilted to 45 degrees from the vertical so that the product is concentrated at the bottom edge of the bottle.
When weighing powders or crystals, it is recommended to use the weighing boat and incremental weighing method. Place the weighing vessel on the balance first and then zero it. Then pour the product into the weighing vessel and read the weighing value.
When weighing viscous or liquid, it is recommended to use a syringe with a good seal and to weigh by reduction. Weigh the mass of the product plus the container first, and then weigh the remaining mass of the product plus the container after removing some of the product into the configuration container, the difference being the mass used in the configuration.
If there are substances stuck on the cap of the bottle, it can be weighed together with the cap when weighing by subtractive method, and be careful to use dry utensils when removing the product.