All around us there is mass, from the paper we write on to the computer keyboard we use. Even the air we breathe has mass.

People weigh stuff all the time using balances. But if you went to the moon or to Jupiter, your weight would change, but not your mass. This is because mass is not affected by gravity, whereas weight is.

Units of Measurement

A system of measurement is a set of units used to quantify quantities like length, mass and time. Different systems of measurement have been used over the centuries, but as science progressed a need arose for a universal system. This led to the development of the International System of Units or SI (from the French, “Le Système d’unités”).

The seven base units of the SI are the kilogram, the meter, the second, the ampere, the kelvin, the mole and the candela. Three of these, the mole and candela, depend on the definition of the kilogram.

In the past, a physical artifact was used to define these and other base units, but scientists have discovered that it is possible to use constants of nature to provide more stable and consistent definitions of units. For example, the new definition of the kilogram uses a value for Planck’s constant and the Avogadro constant instead of the actual kilogram artifact in Paris.

Methods of Measurement

Mass measurement is a key part of chemistry labs. In general, it is measured using a balance scale, which works by measuring the force of gravity acting on an unknown sample. The scale is then calibrated and displayed in units of mass.

Another common instrument for measuring mass is the spring scale, which measures the amount of force exerted on an object by the elasticity of a calibrated spring. This type of scale is often used in households.

For liquids or materials that cannot be weighed on standard balances, transducers are often used to measure mass properties. These devices send a signal to a processor, which makes the mass calculations and displays them on an indicator.

NIST scientists are developing methods for direct mass measurement that use quantities proportional to the mass-to-charge ratio of ions, either in their time-of-flight through a Penning trap (SPEG at GANIL) or their cyclotron frequency in an ISOLTRAP storage ring or a magnetic spectrometer (TOFI at LANL). These techniques may allow us to extend the known mass table far beyond the proton drip line.

Instruments

In the field of measurement, instruments are used to acquire and compare physical quantities. The process of measurement gives a number relating the item under study to an established standard object or event. Measuring instruments can range from simple objects like rulers to complex equipment such as electron microscopes.

For mass measurements, the most common instruments are balances and scales. The scale is the most common example; a person stands on the device and it obtains a person’s body weight, using Newton’s second law of motion which states that force equals mass times acceleration.

A more precise instrument is a beam balance. This device has two pans and a sliding weight on a beam. By placing a known weight in one pan and the unknown object in the other, the balance determines the difference in weight and therefore the mass of the object. Other instruments that measure mass include spring balances and electronic balances. These devices use different methods for measuring, ranging from measuring the length of an object to determining a pressure reading.

Applications

Whether one buys groceries, takes medication, designs a bridge or space shuttle, or trades commodities across borders, mass measurements play a critical role in our daily lives. Since the dawn of humankind, we have relied on balances and weight standards to measure mass to ensure equity and equivalence in commerce.

Unlike traditional measuring tools like rulers and tape measures, which infer mass from other physical properties of the object or sample, mass photometry directly measures true molecular mass. This enables you to study protein oligomerisation and aggregation, characterise samples in terms of stability or heterogeneity, determine stoichiometry of biochemical reactions, and much more.

From macro scale vibration frequency sensing via spring balances, to micro and nanoscale resonator devices used in mass spectrometry, the technology is advancing rapidly to meet the needs of a wide range of applications. Check out our application page on optomechanical mass sensing for more information.

When it comes to automated weighing, successful implementation requires careful planning. This helps businesses to avoid costly mistakes, reduce waste, and ensures that all processes meet strict quality standards.

Process weighing can involve monitoring level or inventory, discharging material by weight, batch blending, and more. However, it is important to remember that any balance must be “exercised” before taking a reading.

Direct Weighing

Weighing a substance directly on the balance pan is straightforward and quick, making it an ideal solution when precision is not a priority. The lack of additional steps, such as taring the container, also reduces operational costs.

With this method, you first weigh the exact mass of the weighing bottle and then subtract it from the actual drug’s mass on the balance to get the precise measurement you need. This eliminates the need for a tared container and prevents tare errors from affecting subsequent readings.

This method is ideal for pharmaceuticals and chemicals, where accurate measurements are critical, and jewellery and gemology, where even the slightest discrepancy could affect value. However, this process is not foolproof and should be supplemented with protocols for checking results and recording data. In addition, automation does not negate the need for staff training. It’s crucial that employees have the skills to operate the system, so you should establish a smooth onboarding process.

Pre-Weighing

The pre-weighing process is essential for many manufacturing sectors. It helps ensure the right quantity of each ingredient is available and can help in predicting any shortages or overages. It’s particularly important in industries where accurate measurements are paramount, such as food and pharmaceuticals, where a single mistake can lead to costly product recalls and health risks for consumers.

The use of advanced batching control systems that are designed for precision, accuracy and streamlined inventory management can simplify the pre-weighing process. This eliminates manual interventions and reduces the risk of error, helping to maintain the integrity of each batch.

Automated weighing systems can also help to improve the onboarding process for new staff, as they reduce the traditional learning curve and can be used by anyone with minimal training. This helps to speed up the hiring process and reduce time to productivity.

Balance Validation

Using balance validation to cross-check data during period-end close and to comply with financial regulations is an important task that can help make more informed business decisions. Specifically, it can verify that G/L account balances don’t deviate too far from the comparison period and ensure that depreciation is less than original cost of assets and that open-item-managed G/L accounts have zero unapplied transaction balances.

Regular balance testing is an essential part of the weighing process and can reduce human error in your laboratory. In addition to verifying the repeatability of a balance’s weighing results, routine testing can help improve cornerload, linearity, and span. For example, testing for cornerload ensures that your scale displays the same results no matter where you place an object on the pan for weighing purposes. Similarly, testing for linearity helps ensure that your scale reads the correct value throughout its entire range, such as from zero to half capacity, when using two calibration weights.

Automated Weighing

Many manufacturing tasks require the use of a scale to ensure accuracy. These systems are often automated to reduce labor costs, improve efficiency and decrease errors. Whether used for quality control, dispensing, or inventory monitoring, these systems help your business complete essential tasks without a human touch. This helps save your company money in worker wages, regulatory fees, and customer refunds. Automated systems are able to process high volumes of items quickly, providing real-time data without a delay.

For example, an automated system might monitor the weight of containers as they move through your production line and trigger alarms when a container exceeds or falls below an established range. This could prevent product recalls and minimize material waste. Additionally, these systems are often designed to integrate with your existing information systems to streamline data collection and monitoring. This supports better inventory management, improved workflows, and ensures compliance with industry standards and regulations.