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Through forensic spectrophotometry, analysts can intensely study crime scene evidence using the power of electromagnetic imaging. Spectrophotometry is the process of scientifically and objectively measuring color and radio wavelengths. It is more dependable than using human eyes, and it provides reproducible results on an easy-to-understand scale. With spectrophotometry, forensic examiners can distinguish between the chemical composition, material and even brand of a piece of evidence all by examining how the sample reflects wavelengths. 

Spectrophotometry is a preferred method of forensic analysis due to its non-destructive analytical abilities. This process is versatile enough to analyze fibers, hairs and forensic materials such as bodily fluids, drugs and fingerprints. Spectrophotometers also have the advantage of not requiring sample preparation before a material can be analyzed. 

What Is Spectrophotometry?

Spectrophotometry refers to the process of analyzing samples using electromagnetic waves. To test a sample, spectrophotometers test how the light refracts and reflects off a particular material and analyze its color, infrared and ultraviolet properties and more. Using spectrophotometry, you can tell the difference between similar samples of hairs, fibers, drugs, bodily fluids and fingerprints. 

Spectrophotometry works by taking a sample and measuring the intensity of light when a beam passes through it. Since each compound transmits and absorbs light differently, it is possible to identify the true nature of a substance by analyzing this wavelength. Depending on the nature of the sample, it can be studied using either a UV-visible or infrared range spectrophotometer. 

Color surrounds us every moment of our lives and affects our emotions, behaviors and beliefs in large and small, conscious and unconscious ways. Color can set a mood, warn us of danger, give us critical information and even bring us joy. Despite the universal presence of color, describing it remains elusive, in part due to variations in color perception from person to person and in part due to a lack of descriptors for each of the millions of shades seen by the human eye.

Instrumental color measurement moves beyond the limits of human perception and vocabulary and allows us to capture color information as objective data, creating a common language of color that is essential for communication within and between industries around the world, ranging from food and beverage to pharmaceuticals. The two most advanced color measurement instrument types are colorimeters and spectrophotometers, both of which use sophisticated technologies to accurately and precisely quantify and define color.

While closely related, these instruments have unique qualities that may make one more suitable than the other for a particular type of measurement. Understanding the characteristics of a colorimeter vs. spectrophotometer can help you select the best tool for your application.

What Is a Colorimeter?

A colorimeter is designed to perform a type of psychophysical sample analysis, which means its measurements correlate to human perception. In other words, it is designed to see color the way we do.

Its results are direct and read as tristimulus values. A tristimulus value is one that identifies a color with characters that represent different dimensions of its visual appearance. A tristimulus value may contain values like X, Y and Z or L, a and b. The “gold standard” for tristimulus colors is the CIE Color System, developed by the International Commission on Illumination — the CIE in the title stands for the French version of their name.

There are a few unique components involved in a colorimeter.

• Illuminant: The illuminant represents a specific light source, such as daylight or incandescent light, to project consistent brightness onto the object. In a colorimeter, an illuminant is fixed.
• Observer: The standard observer offers a specific field of view with which to analyze the colors. A colorimeter usually uses a 2-Degree Standard Observer, which is suitable for color evaluation and quality control.
• Tristimulus absorption filter: The absorption filter isolates specific wavelengths to be applied to the sample.

How Does a Colorimeter Work

A colorimeter’s usage is often based on the Beer-Lambert law, which tells us that the concentration of a solute is proportional to its absorbance. The colorimeter starts with a simple light source. With the help of a lens and tristimulus absorption filters, the beam of light becomes a single, focused wavelength which then moves through to the sample solution. On the other side of the solution is a photocell detector that identifies how much of the wavelength got absorbed. The detector is connected to a processor and digital display that offers a readable output of the results.

As consumers look for healthy alternatives to carbonated soft drinks, apple juice is making a splash. Image Source: Pexels user Jeshoots

The fact that soda isn’t the most healthy beverage isn’t news. Historically, sugar content was the quality of soda that consumers considered to be “bad for you” and diet soda was presented as a healthier alternative. Part of this perception was driven by marketing campaigns that playing up their lack of calories. That much-feared word that has become synonymous with weight gain. But in recent years, we have increasingly begun to examine the health impact of diet sodas and, more specifically, the artificial sweeteners they contain. The results have been startling. Last week a study by researchers at George Washington found that sucralose consumption is linked to weight gain; the very phenomenon so many diet soda enthusiasts are seeking to avoid.1So what are health-conscious consumers to do? For a growing number of consumers, fruit juices offer a perfect solution. According to global market intelligence company Transparency Market Research, “the global juice market is [now] the most competitive segment in the beverage industry” and it’s expected to grow significantly in coming years.2 While some juice producers are responding to consumer demand for healthy alternatives to carbonated soft drinks by introducing exotic products, others are introducing organic and low-calorie alternatives to traditional juices. Chief among these is apple juice, an old favorite that is taking on new life in the rapidly changing fruit juice market. In Norway, for example, apple juice sales have nearly doubled in the past 5 years.3

But increasing global interest in apple juice doesn’t mean juice producers can rest on their laurels. As demand for healthier beverages has grown, so too has the desire for high quality and aesthetically pleasing products. For apple juice producers, this translates to juices of the right color and clarity, making apple juice color and haze measurement more important than ever before.

Seasonal color analysis enables fashion-conscious consumers to find clothing that’s most complementary to their features and skin tones through color psychology and color wheel analysis. Seasonal color analysis depends on color theory, which is used as a practical guide for analyzing how color works in the fashion, design and art fields.

Humans have intensely studied color since Sir Isaac Newton first learned how light refracted in the 18th century, and color theory has since evolved into a critical component of our daily lives. Today, the fashion industry still uses Carole Jackson’s seasonal color theory to create unforgettable looks and color palettes. 

What Is Seasonal Color Analysis?

Seasonal color analysis refers to the process of examining a person’s skin tone, eyes, hair and lips to create a color palette that compliments them best. The practice gained popularity in the 1980s when American color theorist Suzanne Caygill combined color psychology with seasonal palette theory.

Caygill’s model became immensely popular among color professionals and inspired psychologist Carole Jackson to write the book “Color Me Beautiful.” By creating seasonal palettes that matched her clients’ features and skin tones, Jackson inspired fashion-forward individuals to create curated wardrobes. 

In astronomy, a star’s color tells its story. Measuring the color of a star gives astronomers immense insights into its temperature, age and composition even from hundreds of thousands of miles away. By measuring stars’ wavelengths, you can determine their elemental makeup and main components.

What Is Astronomical Spectrophotometry?

Spectrophotometry refers to the process of measuring a sample’s electromagnetic wavelengths to determine information such as color, chemical composition and age. Every element in a star emits a unique wavelength of electromagnetic radiation, which allows spectrophotometry to examine the percentage of hydrogen, helium and trace elements in a star. Astronomical spectrophotometry uses Planck’s curve to examine a star’s peak wavelength and understand components of its makeup, which are impossible to judge from Earth.

Since stars are powered by nuclear fusion at their core, they maintain a steady dynamic equilibrium throughout their life and display their life cycle position using color. Due to this uniform time and color cycle, you can determine a star’s age by its hue. Though all stars appear white due to their peak wavelength on the color spectrum, many are blue, yellow, red and green. The following star colors correspond with the listed heat levels in Kelvins: 

• Blue stars: 10,000-50,000 K
• Yellow stars: 5,500 K
• Bright red stars: 3,500 K
• Dark red stars: 2,500 K

A liquid’s appearance and appeal to consumers are based on optical qualities like turbidity. Learn more about the meaning of turbidity and our turbidity test procedure with a spectrophotometer.

What Is Turbidity?

Turbidity is the measure of the clarity of a liquid to indicate the presence of suspended particles. It’s a visual feature that can be seen with the naked eye and calculated with turbidity measurement methods. Highly turbid liquid has an opaque, cloudy appearance, and low-turbid liquid is clear and transparent.

What Causes Turbidity?

Turbidity is caused by materials like:

• Microscopic organisms
• Minerals
• Sand
• Clay
• Algae
• Proteins
• Dissolved colored organic compounds
• Silt
• Oils
• Microscopic organic and inorganic matter
• Bacteria
• Plankton
• Dirt

When a body of water has low flow, it is clear and has low turbidity. Movement through water, such as a rainstorm, washes particles from the land into it. The flow speed also stirs up material from the bed. As a result, this water is cloudy and highly turbid.

A food dye is a chemical substance that uses artificial color to enhance the appearance of food. Though dye may make drinks, candy and other food look better, many are concerned about adverse side effects. Learn more about why we color food and how it impacts health.

The History of Food Coloring

Food coloring has been around for centuries. It was first developed around 1500 B.C. using saffron or wine. The early Romans used these natural options as well as mulberries, flowers, carrots, beets and pomegranates. The first artificial food coloring was made from coal tar in 1856. Food dyes are petroleum-based today.

Why Do We Color Food?

Food dye changes the food’s color and appearance to look more appealing to the consumer. Some food processing can remove food’s natural color. Dye adds it back so the food looks as expected. Food manufacturers typically prefer artificial food dye to natural options because it has more vibrant colors, longer shelf life and a lower production cost.

The Health Effects of Food Coloring

The safety of food coloring is a long-debated topic due to the concern about negative health effects. Out of the hundreds of developed food dyes, a select few are deemed safe for consumption because they have been tested for toxicity in animals. Yellow 5, Red 40 and Yellow 6 are the most common.

Food dye safety can be confusing because different countries have different laws about the same food coloring. For example, The Food and Drug Administration (FDA) in the United States and the European Food Safety Authority (EFSA) agree that food coloring is not harmful. However, there are food dyes approved by the FDA but banned by the EFSA, and vice versa.