The Science of Spectrophotometry

Do you wonder how chemists quantify chemical concentration in a sample, match colour on the production line, or identify hidden substances in forensic analysis? Behind this uncomfortable-looking process lies a strong and effective scientific process: spectrophotometry. From the fundamental principles of light interaction with matter, spectrophotometry is the basis of modern scientific and industrial use.

In this article, we will discuss the subject of spectrophotometry, exploring why it is unique among its counterparts and how it operates.

Spectrophotometry

Spectrophotometry is a technique used to study the substance's response to light, or the degree to which it transmits or absorbs light, by sending a beam known as a wavelength, typically ultraviolet, visible, or near-infrared, through a sample and measuring the amount of light that passes through on the other side. 

It is non-destructive and is highly useful where the integrity of the sample must be maintained. Spectrophotometry is also used in the measurement of the concentration of enzymes, DNA, and proteins in Biochemistry. It is used in the paint, plastic, and textile industries to ensure that their products are of the same material and color properties.

Spectrometry

Spectrometry is a broader term applied to the measurement of any property of electromagnetic radiation or particles. While spectrophotometry is the interaction of light in particular, spectrometry is an array of techniques, like mass spectrometry, analysing molecules by analysing the mass-to-electric charge ratio.

Spectrometry finds application in nearly all branches of science. From chemical sample analysis in a laboratory to the examination of celestial bodies in astronomy or unknown chemicals in forensic science, its applications are boundless. 

Besides optical measurements, spectrometry also involves particles or invisible radiation. Some examples of such techniques include X-ray spectrometry and ion mobility spectrometry, which extend their application to analysis of atomic structures, materials, as well as environmental analysis.

Spectroscopy 

Spectroscopy is the umbrella term that encompasses a broad class of techniques that examine the interaction between matter and radiation. It encompasses numerous categories such as:

1. Ultraviolet-Visible (UV-Vis) Spectroscopy

2. Infrared (IR) Spectroscopy

3. Raman Spectroscopy

4. Nuclear Magnetic Resonance (NMR) Spectroscopy

5. X-ray Spectroscopy

Although frequently interchangeably used, spectrophotometry, spectrometry, and spectroscopy are all names for different scientific procedures, each providing different information about the interaction of energy with matter.

In essence:

Spectroscopy questions: What occurs when matter is exposed to light?

Spectrometry questions: What is it, and how much is there?

Spectrophotometry questions: How much light is absorbed or transmitted by the sample?

Spectrophotometric Analysis

Spectrophotometric analysis is a simple type of chemistry analysis and quality assurance. It includes calibration of the blank, proper wavelength, and sample.  Spectrophotometry is applied in the food and drinks sector to track color and transparency of fluids for product quality and brand reputation. Spectrophotometry is applied in the hospital laboratory to track the concentration of the drug or the level of blood sugar. Spectrophotometers such as those provided by ThreeNH provide full-range analysis from 360–780 nm, and there is a dual-optical-path system with a resolution greater than 10 nm. This enables SCI and SCE to be measured simultaneously, providing extremely accurate and reliable measurement of color.

What Does a Spectrophotometer Measure?

A spectrophotometer is used to measure:

(a) Absorbance 

(b) Transmittance 

(c) Reflectance

They are employed for concentration measurement, that is, measurement of impurities, measurement of color, and measurement of material properties. They are offered as absorbance spectra, a fingerprint per material.

Spectrophotometers of Color Science and Industrial Use

Spectrophotometers today are not limited to quality control and measurement of color, but also for the accurate determination of material concentration in chemistry. The motor vehicle, textile, plastic, food, and printing industries are extremely reliant on spectrophotometers in a bid to guarantee color consistency, identify material mismatch, and ensure product appearance from batch to batch. Greater precision and conformity demands have turned spectrophotometers into a key instrument in industrial quality control systems. ThreeNH offers instruments tailored for industrial needs, such as the NS800/NS810 series, designed for textile and paint industries with high inter-instrument agreement (<0.2 ΔE), or the TS8560, which uses a dual-array CMOS sensor for ultra-precise colorimetric analysis in plastics and automotive components.

How Does a Spectrophotometer Work?

A spectrophotometer is a small laboratory device, but what you find inside its box is an advanced setup to convert the light a material takes in. Effectively, the device does this by taking measurements of the light intensity formed before and after it travels through a specimen, providing valuable information regarding the content and concentration of the specimen.

This is the division of its main working parts:

Illumination System (Light Source)

The method starts with a constant source of light, a deuterium source of UV light, or a halogen for visible light. It's a general-purpose, broad-spectrum light and analytical base.

Wavelength Selector (Monochromator)

Light needs to be purified to a single wavelength before it's applied to the sample. It is achieved using a monochromator, which may be a prism or a diffraction grating. It simply allows us to pass the wavelength that we desire to give us proper readings.

Sample Chamber (Cuvette Holder)

The chosen light also passes through a cuvette, an optically transparent tube containing the sample, a solution in most situations. The cuvette is made of glass or quartz, depending on the wavelength utilized.

Discovery System (Photodetector)

As the light passes through the sample, it is detected by a sensor. The instrument converts the light remaining (the reflected or transmitted) into an electrical signal that indicates the amount of light absorbed in the sample.

Software & Display Processing Unit

The instrument's electronic circuitry converts the signal into quantifiable data, typically in the form of absorbance or transmittance. The outcome is the light absorbed by the sample and is proportional to its concentration.

Commercial Spectrophotometers in Action

High-end spectrophotometers like ThreeNH have precision engineering and user-friendly interfaces. Their devices, like the NH310 or YS30 series, come with high-end features like high-speed scanning, multi-angle color measurement, and non-contact measurement—ideal for utilization in textile, automotive, paint, and plastic industries. The machines are Bluetooth, handheld, and have highly accurate calibration modes so that experts can conduct high-precision color matching and reflectance analysis along production lines or R&D labs. Such heavy machinery aids industries in delivering quality assurance and regulatory compliance with minimal user effort.

Mass Spectrometry in Forensics

Mass spectrometry is a very sensitive analytical technique and is employed most frequently in forensic analysis. It permits differentiation of chemical compounds on the basis of molecular weight and structural characteristics exactly. When combined with spectrophotometry, trace evidence identification and material analysis is a class in itself.

Applications in forensic include

1.  Identification and detection of drugs

2. Screening for toxicology

3. Chemical warfare and explosives

4. Analysis of biological samples

What is Non-Contact Spectrophotometry?

Non-contact spectrophotometry uses non-contact spectrophotometric probes that do not have to be in contact with samples. Instead of putting a sample into a cuvette, light is shone onto the surface, and information on reflected or scattered light is measured quantitatively. This is worth the thought where sample shape, cleanliness, or integrity keeps contact forms unavailable.

Advantages of Non-Contact Spectrophotometry

The non-contact sensors have several benefits:

1. It is hygienic 

To use a substance in food, medicine, or biomedicine where the degree of contamination has to be extremely low.

2. It is Effective

Used in mass production lines with little or no human intervention.

3. It is Adaptable

Envelops firm, curved, moving, or irregular samples.

4. Maintains Integrity

It can be applied to art, clothes, and cultural objects without destroying them. With each new technology, the hardware becomes smaller, more precise, and cheaper.

Non-Contact Measuring Instruments in Industry

Multiple non-contact measurement instruments are being used in:

1. Motor car manufacturing: colour matching of paint and fault finding

2. Tablet and coating production: drugs

3. Food and drink: to test texture and colour

4. Packaging: for the control of film and ink quality. 

Non-contact Desktop Spectrophotometer YL4560

The unique and innovative design of YL4560 by threenh can not only provide non-contact measurement solutions directly from the production line, but can also ensure stable and high-precision measurement results.

Beginning Your Spectrometry Career?

 A spectrometry or spectrophotometry career is an exciting combination of professional satisfaction and scientific challenge. Here is how you can build your career in it:

1. Build a Strong Academic Base

Start with a bachelor's in one of the sciences of the field—chemistry, physics, biology, or materials science. These sciences provide one with the theoretical basis to understand analytical methods.

2. Gain First-Hand Laboratory Exposure 

Volunteer in laboratories where spectrophotometers, chromatographs, and mass spectrometers are used daily. You require practical experience to gain technical knowledge and equipment know-how.

3. Get Professional Certifications

 Obtain your analytical chemistry, lab instrumentation, or regulatory compliance certification. Professional certifications will elevate your career, especially in regulated industries.

4. Specialize in a Segment

Specialize your expertise by entering a niche application area, pharmaceuticals, forensic, environment, food, or clinical diagnostics. Specialization enables you to gain niche knowledge in demand.

Unlock the power of light and matter, explore spectrophotometry to elevate your scientific precision and analytical expertise! Spectrophotometry is at the forefront of accuracy in industry and science.