January 13, 2013
Determining the Concentrations of Red Dye in Sodas
The use of red dye #40 is common in various soft drinks today. The labels on these beverages do not specify how much dye we are consuming. We did this experiment to find out which soda uses the most dye. Using a spectrophotometer, we measured how much light is absorbed by various known concentrations of red dye. After collecting this data, a standard curve was made that correlated the concentration of red dye #40 to its absorbance rate. Our results showed that the sample of strawberry crush had the highest concentration of red dye #40 when compared to grape soda, diet cherry, and big red. After doing this experiment, one knows how much red dye #40 he or she is consuming when drinking these products. Methods
Making a Standard Curve
In order to create a standard curve we created 5 dilutions of solutions containing red dye #40. Concentrations of .666 ug/mL, 1.667ug/mL, 3.333ug/mL, 13.333ug/mL, and 20.000 were measured in a spectrophotometer set to a wavelength of 504 nm to find the amount of light they absorbed. Using Microsoft Excel, we entered the absorbance values as the Y coordinates and the concentrations as the X coordinates to make a line of best fit and that was our standard curve. Measuring Red Dye #40 in Drinks
We then measured the absorbance of samples of grape soda, diet cherry, strawberry crush, and big red soda using the same spectrophotometer set at the same wavelength. Our standard curve correlating concentrations to absorbance values only went to an absorbance of 1 nm. So, for three of the four drinks, it was necessary to dilute the substance to get an absorbance rate within our standard curve. After the absorbance rates of these drinks were found, we used the standard curve to determine the concentration of red dye #40 in each drink. To do this, we looked to see which concentration matched with each measured absorbance.
... 1. Neutral red is a vital stain. It stains cells without quickly killing them. Many biological stains kill living cells.
2. Neutral red goes through an obvious color change, from red at about pH 6.8 to yellow at pH 8.0.
3. A 1% solution of sodium bicarbonate has a pH of about 8.5.
4. Yeast cells have an internal pH that is slightly acidic (about 5.5 to 6.0).
• Diffusion • Active transport
• Acid–base indicators • Selective permeability
Ammonia solution, NH3
, 0.01 M Beaker, 100-mL
Hydrochloric acid solution, HCl, 0.01 M Filter paper
Neutral red solution, 0.02% Funnel
Potassium hydroxide solution, KOH, 0.01 M Graduated cylinder, 25-mL
Sodium bicarbonate solution, NaHCO3
, 1% Pipets or droppers
Sodium hydroxide solution, NaOH, 0.01 M Test tubes, 13 × 100 mm
Yeast, suspended in 1% NaHCO3
solution Water bath
Dilute acids and bases are skin and eye irritants; they are slightly toxic by ingestion and inhalation. Wear chemical splash
goggles, chemical-resistant gloves, and a chemical-resistant apron. Please review current Material Safety Data Sheets for additional safety, handling, and disposal information.
The concentrations of solutions for this activity do not need to be precise in order for the lab to work. However, the recipes
provided do provide consistent results.
1. Sodium bicarbonate solution: Mix 1 g of sodium...
... Determining the concentration of reddye #40 in an unknown solution
Introduction: White light is composed of many different wavelengths of light combined together. A spectrophotometer is an instrument that shines a single wavelength of light of a known intensity into a solution and then measures the intensity of the light exiting the solution. If a solution contains any compound that absorbs light, the intensity of light exiting the solution will be less than what entered the solution. On the other hand, if none of the compounds in the solution absorb at that wavelength of light, then the intensity of the light exiting the solution will be the same as that entering.
The intensity of light that passes through an absorbing solution is dependent on the concentration of the absorbing compound in solution. In other words the more material in the solution absorbs the light, the less light will get through. This relationship is expressed by Beer’s Law
Procedure: Work with partners.
You and your partner will be assigned a unknown solution containing reddye #40. Your standard curve is to be prepared for this particular color of dye.
(1)Turn on the spectrophotometer before preparing the solutions since it...
...Determining the Concentration of a Solution: Beer’s Law
The purpose of the experiment is to determine the concentration and formula of an unknown cobalt nitrate solution by measuring absorbance.
A Colorimeter will be used to determine the concentration and formula of an unknown cobalt nitrate solution. The colorimeter sends blue light from the LED light source to pass through the solution and hit a photocell. A solution with a higher concentration will absorb more light and transmits less than s solution of lower concentration.
Five solutions with a known concentration of cobalt chloride hexahydrate will be used. Each solution will be put into a small cuvette which will ultimately be placed inside the colorimeter to find the amount of light that strikes the photocell; calculating the absorbance. When the absorbance to concentration information is graph it should be a direct relationship resulting in a linear relationship.
Three samples of unknown cobalt chloride hexahydrate will be obtained. The samples contain the same compound but different concentrations. By entering the absorbance on the relationship graph from part one, the concentration can be obtained.
All solutions were a pinkish color liquid. As the concentration increased, the concentration...
The purpose of this experiment is to use Volumetric Analysis to determine the concentration of acetic acid in white vinegar.
The concentration is a measurement of relative amounts of solute and solvent. There are many diverse ways of expressing concentration but the most accepted and widely used is molar concentration and regularly referred to as molarity which is defined in mole, the amount of solute dissolved in one litre of solution.
In this experiment there are solutions used with accurately known concentrations called standard solutions. The reaction of chemicals in the atmosphere and decomposition of them are the causes for many chemicals to be tainted or impure. This also means that common strong acids and bases cannot be made directly into standard solutions.
The amount of a certain type of substance, in mole that can be calculated accurately from their mass are called primary standards due its purity. Primary standards should be always readily obtainable in pure form. It also should also have a known formula and be simple to put away without deteriorating or reacting with the atmosphere. It is also preferable that the substance have a high molar mass in order to decrease the effect of errors in weighing. A primary standard can be used to prepare a standard solution by making up an accurately known volume of solution by means of dissolving an accurately...
...Name: Raj Bose
Partners: Sunniva & Bayu
Determining the concentration of glucose of 7UP
Glucose solutions prepared as follows:-
In each case 250.0 cm3 volumetric flasks used
Table: 1- Recording of concentration, volume, and qualitative observations of various solute/solvent/solution used during the experiment.
5 different types:
5.0 ± 0.1 ml
Potassium Permanganate (KMnO4)
1.00 ± 0.05 ml
Sulphuric Acid (H2SO4)
5.0 ± 0.1 ml
Table: 2- Shows the concentration of glucose solution (%) and the total time taken (s) by the solution to decolorize
Glucose Solution (%)
Time (± 1 s)
Trial 1 (Me)
Time (± 1 s)
Trial 2 (Sunniva)
Time (± 1 s)
Trial 3 (Bayu)
Table: 3- Shows the concentration of glucose solution (%) and the time after subtracting the lap time (s) took by the glucose solution to decolorize. Also the average for all three trials are calculated and shown below.
Glucose Solution (%)
Time (± 1 s)
...Biology Lab report #1
The uptake of neutral reddye in a yeast cell using different solutions
Every cell transports materials in and out throught something called a membrane. There are many different methods of transport in the cell Saccharomyces cerevisiae (Serrano, 1977) We want to know does adding higher concentrations of azide more effectively block dye transport? We tested the transport of dye in yeast cells with a metabolic inhibitor. When we did this we showed no difference in the absorbance between different azide solutions, and our control. From this we concluded that azide has no effect on the transport through a yeast cell membrane.
Every cell has a layer of protection called the cell membrane. This cell membrane has many functions. The Saccharomyces cerevisiae cell has a selectively permeabile membrane which means it allows certian materials to pass through its membrane more or less than others ( Campbell et al., 2008). In a certian process called active transport these cells need energy to move material across the membrane ( Campbell et al., 2008). This energy that is being used is called adenosine triphosphate or ATP (Campbell et al., 2008). The production of ATP, which helps cells maintain a cells pH, helps with the uptake of neutral reddye because neutral reddye cannot be absorbed if the pH of...
...Spectrophotometer; the finding of protein concentration of an unknown sample of BSA, and by using the standard curve.
A spectrophotometer’s purpose is to use colors of the light spectrum to determine the concentration of light absorbing molecules in a solution. (p.59) In this particular lab, our mission was to determine the protein concentration and the standard curve of the unknown sample of BSA. This, by preparing five dilutions of the unknown solution of BSA together with other known concentrations, and then experimenting by observing how the concentrations were passed through the spectrophotometer. The outcome resolved in the absorption levels being decreased, and this gave us an opportunity to plot the measured absorption levels and protein concentrations.
Absorption spectroscopy is a common method for finding the concentration of proteins or protein complexes in a solution. Proteins absorb light at specific wavelengths and can be defined by the equation A = log (I0/IT). These equations states that an absorbance at a specific wavelength, A, is equal to the log of the ratio of incident light intensity, I0, to transmitted light intensity. (p. 59-60) In this study, our purpose is, again, to develop a standard curve for Bovine Serum Albumin, and this is done by preparing at least five dilutions.
According to most research...
...Should RedDye #40 be banned in the United States?
Often, we don’t give much thought to the fact that much of what we consume is artificially colored. RedDye #40, also commonly called Red 40, is widely used in the foods and drugs that we consume. Red food coloring is the most commonly used dye in the U.S., according to Center for Science in the Public Interest (Carerra, 2013). In the food industry, red is a very appealing food color. The Food and Drug Administration approve it for use in candy, cereal, baked goods, gelatin powder, drugs and cosmetics. As consumers, we respond to those appealing visual cues in our food and the food industry recognizes that fact. The FDA has banned specific artificial colors in the past, but plenty remain approved and on the market, including Red 40. But is it safe to eat these artificially bright foods just because they look pretty?
Color dyes are used for much more than just painting Easter eggs. The ultimate reason that Red 40 is added to processed food is to make a food that would otherwise be an off colored mess look appealing. Nowadays, appeal is all that matters. “Food dyes are added simply for their color to make foods fun. They serve no health purpose whatsoever," says Michael Jacobson, director of the Center for Science in the Public Interest” (Fulton, 2011)....