Sexy Little Things

All girls love perfume. This is one of our favourites, Victoria's Secret, Heartbreaker.
Got interested in what does it contain while using it one morning, and guess what we found in this?
It actually contain propylene glycol!
Did a brief research on it and found out that there are people who are allergy to Propylene Glycol.
Hence, we decided to find out an effective way to detect the presence of Propylene Glycol in Cosmetic Products.

Propylene Glycol

Melting Point: -59°C

Density: 1.04g/cm³

Formula: C3H8O2
Boiling point: 188.2°C
Molar mass: 76.09 g/mol

IUPAC ID: Propane-1,2-diol

What is Propylene Glycol?

Propylene glycol (also known as 1,2-propanediol or propane-1,2-diol) is an organic compound. It is a colorless, nearly odorless liquid that is miscible with acetone, water and chloroform. Propylene glycol molecule itself is chemically inert (not chemically reactive), and because of this special feature propylene glycol becomes an idealistic compound when seeking to combine contrasting chemical elements to form a single, homogenous fluid. It act as an emulsifier that connects and stabilizes active ingredients that is insoluble with one another (would not mix) and create a stable homogenous fluids that will allow the intended final project. This inert feature of propylene glycol also allows it to develop an ability to attract water/moisture. Hence, propylene glycol is one of the most widely used ingredients in cosmetic product as it can help to hold and dissolves active ingredients equally in a medium (e.g. perfume, shower foam, lipstick) and act as a moisturizer in cosmetic formulas (e.g. facial cream, toner)

Some examples of the cosmetic products that contain propylene glycol are…

Personal care: Facial Cleanser, Shaving Foams, Lipsticks, Perfumes, Antiperspirant deodorants

Skin Care: Hand, Body and Facial Moisturizer, sunscreen products

Hair Care: Styling Gels, Shampoo, Conditioners

Oral Care: Mouthwashes, toothpaste

Baby care: Baby wipes, antiseptics

So is propylene glycol safe??

Propylene glycol can enter the bloodstream by inhaling air containing mists or vapors from this compound or through skin via direct contact with it. Consumption of propylene glycol can also be a way for the compound to enter the bloodstream. Propylene glycol will be broken down by the body within 48hours.

According to the FDA (Food and Drug Administration), Propylene glycol is GRAS (generally recognized as safe). Base on the results of human irritation and sensitization test, it the CIR Expert panel concluded that Propylene Glycol is safe to be used in cosmetic products at concentration up to 50%.  However, it was also noted that patients with diseased skin (e.g. eczema) may be susceptible to developing irritation/sensitization reaction to Propylene Glycol.

In 2003, the National Toxicology Program’s Centre for the Evaluation of Risk to Human Reproduction (CERHR) Expert Panel reviewed the reproductive and developmental effect of Propylene Glycol and concluded that there is “negligible concern for reproductive or developmental toxicity to humans.” 
Studies were also conducted on dogs and rats, which were fed doses of PG ranging from 2 to 5 grams per kg of body weight per day. The results showed that there is no links of Propylene Glycol to cancer. Hence, Cosmetic Ingredient Review Expert Panel concluded that there was no carcinogenic risk with low levels of ingestion of PG.

So what is the big fuss about PG found in cosmetic products all about??

A study was conducted by a dermatologist from the North American Contact Dermatitis Group (NACDG) and the results shown that repeated exposures to propylene glycol for a short time may cause irritation and allergies. Using the database, they analyzed the number of products containing allergens. According to Table 1, Propylene glycol is found to be the second most commonly present allergen in deodorants and antiperspirants. It is found in 47% of the deodorants and antiperspirants of the database, at a concentration of 2 to 5% of the product weight. This low concentration of propylene glycol is unable to elicit the irritation for patients with Propylene glycol allergy. However, it is recommended to avoid deodorant and antiperspirant with Propylene Glycol, as exposure over time may change the elicitation threshold, and thus causing dermatitis.

Though cancer might not be a concern (according to the Cosmetic Ingredient Review Expert Panel), it was found that Propylene Glycol can provoked allergic reactions in patients with eczema and other skin allergies, even in formulations of much less than 50%.

In addition, the Material Safety Data Sheet (MSDS) cites skin, liver and kidney damage that can result from contact with PG, and it gives safe handling instructions, calling it a hazardous substance. Though not specified, this is for the more concentrated industrial grade.

On the other hand, studies done in vitro tests on mammalian cells revealed that some cells underwent mutation when contact repeatedly with PG.
In Europe, where the authorities are much more cautious about what is allowable in cosmetics and foods, propylene glycol is limited to mostly non-food uses. 

Method to detect Propylene Glycol in Cosmetic

A wide range of ingredients in found in Cosmetic, for example, in a simple Victoria secret perfume, the ingredients found are...

Since propylene glycol is a liquid, Gas Chromatography-Mass Spectrometry is one of the method to detect propylene glycol. Analyte: Propylene Glycol

Gas Chromatography-Mass Spectrometry

An analytical method that combine features of gas-liquid chromatography and mass spectrometry to identity different known substances within a test sample and identify trace elements in materials that were previously thought to have disintegrated beyond identification.

High-Performance Liquid Chromatography (HPLC)

A technique in analytic chemistry used to separate the components in a mixture to identify and quantify each component.  It relies on pumps to pass a pressurized liquid solvent containing the sample mixture through a column filled with a solid absorbent material. Each component in the sample would then interacts slightly differently with the adsorbent material, causing different flow rates for the different components and hence leading to the separation of the components as they elute out the column.

MATERIALS

Chemical and Reagents:
- GC Grade Nitrogen, hydrogen and air.
- Propylene glycol (CAS 57-55-6), Reagent grade
- Methanol (CAS 67-56-1)
- Sample

Instruments and Apparatus:
- 4ml Vials with Teflon-lined caps
- Gas Chromatograph equipped with Flame Ionization Detector (FID)
- Electronic integrator
- 10µl syringe
- Pipettes
- Volumetric flasks
- Electronic Balance

Gas Chromatography Conditions:

Injection size:	1 µL
Flow rates (mL/min)
Nitrogen (make-up):	30
Hydrogen (carrier):	2
Hydrogen (detector):	40
Air:	420
Temperatures (°C)
Injector:	200
Detector:	275
Column:	40 isothermal

METHOD

Standard Preparation:
1) Weight a quantity of propylene .
2) Dilute it with methanol.
(Concentration approximately 150.0mg/ml) Dilute to 74.9 to 1497.8µg/ml

Sample Preparation:
Sample collected using a sampling pump and OVS-7 tubes.
1) Front and back section of each sample tube are placed in separate 4ml Vials.
2) Desorbed with 2ml of methanol.
3) Seal vials and desorb for one hour on mechanical rotator.
4) Transfer to smaller vials for autosampler.

1. Inject 1µl of standard in separate runs. Dry tips before injection.
2. Wash syringe after each injection. Dry tip before taking the next sample.
3. Inject 1µl of the analyte that contain many compounds.
4. Record retention times of peaks. Compare the retention time of the analyte with the standards to identify the presence of Propylene Glycol. (Tentative identification)
5. For spiking: Using a dropper, add in additional drops of unknown sample into suspected standard.
    Mix. Inject 1µl of the mixutre into the GLC.
6. Peak enhancement occurs, unknown contain suspected standard.

RESULTS

Figure 3.5.1 Chromatogram at the target concentration.

*Peak areas measured by integrator or other suitable means

Figure 3.6.2 Mass spectra of propylene glycol.

GC-mass spectrometer is used to confirm the identity and purity of analyte peak.

Calibration curve made from 4 standards of different concentrations bracketing the samples.
Concentration of samples can be obtained from the calibration curve.

Risk Assessment

	Reagent used in the experiment
Chemicals/ Reagents	Potential risks to remember	Use of this chemical	Source of this reagent	How will you protect yourself?	First aid
Propylene Glycol	·         Slightly combustible liquid. ·         Hazardous in case of ingestion. ·         Slightly hazardous in case of skin contact (irritant, permeator), of eye contact (irritant), of Inhalation. ·         Do not handle near heat, sparks, or open flame. ·         May cause minor eye irritation. ·         High aerosol Concentrations ·         May cause mild irritation of the nose and throat as well as central nervous system depression.	Research and development	Chemical synthesized	Handle with gloves, lab coat, and safety googles. Avoid eye, mouth and skin contact.	Eye Contact:  Remove any contact lenses. Immediately flush eyes with running water for at least 15 minutes, keeping eyelids open. Seek medical attention. Skin Contact: In case of contact, immediately flush skin with plenty of water. Cover the irritated skin with an emollient. Remove contaminated Clothing and shoes. Cold water may be. Wash clothing and shoes before reuse. Get medical attention. Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek immediate medical attention. Inhalation: If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention. Ingestion: Do NOT induce vomiting unless directed to do so by medical personnel. Never give anything by mouth to an unconscious person. If large quantities of this material are swallowed, call a physician immediately. Loosen tight clothing such as a collar, tie, belt or waistband.
Methanol	·         Hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation. ·         Slightly hazardous in case of skin contact (permeator). ·         Severe over-exposure can result in death ·         Slightly hazardous in case of skin contact (sensitizer). ·         Mutagenic for mammalian somatic cells. Mutagenic for bacteria and/or yeast. ·         The substance is toxic to eyes. The substance may be toxic to blood, kidneys, liver, brain, peripheral nervous system, upper respiratory tract, skin, central nervous system (CNS), optic nerve. ·         Repeated or prolonged exposure to the substance can produce target organs damage. ·          Repeated exposure to a highly toxic material may produce general deterioration of health by an accumulation in one or many human organs.	Research and development	Chemically synthesize	Handle with gloves, lab coat, and safety googles. Avoid eye, mouth and skin contact.	Eye Contact: Check for and remove any contact lenses. Immediately flush eyes with running water for at least 15 minutes, keeping eyelids open. Seek medical attention. Skin Contact: In case of contact, immediately flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Cover the irritated skin with an emollient. Wash clothing and shoes before reuse. Get medical attention immediately. Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek immediate medical Attention. Inhalation: If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention immediately. Serious Inhalation: Evacuate the victim to a safe area as soon as possible. Loosen tight clothing such as a collar, tie, belt or waistband. If breathing is difficult, administer oxygen. If the victim is not breathing, perform mouth-to-mouth resuscitation. (WARNING: It may be hazardous to the person providing aid to give mouth-to-mouth resuscitation when the inhaled material is toxic, infectious or corrosive.) Seek immediate medical attention. Ingestion: If swallowed, do not induce vomiting unless directed to do so by medical personnel. Never give anything by mouth to an unconscious person. Loosen tight clothing

CONCLUSION

Detecting the presence of propylene glycol in cosmetic products is for safety purposes. Many are allergy to this compound and have irritation from exposure to it. Using this GC method is a good way to determine whether the product contain propylene glycol and therefore, suggest customers that have allergy to avoid using it. This analytical method has high sensitivity, reproducibility and precision for detection of Propylene glycol in cosmetic products, hence, it is a favorable method for this analysis.

However, this method does not aid in differentiating particulate matter and vapor. Therefore, more research has to be done to find a more effective method to differentiate it and to detect propylene glycol; also on the effects of propylene glycol on different individuals.