This document describes a study that used a palm-sized near-infrared spectroscopy instrument to rapidly and non-destructively detect contaminated cosmetic raw materials and products. Six reference products and test samples were analyzed. The instrument could detect contamination within seconds by comparing the near-infrared spectra of the reference and test samples. Two products showed differences in water content, while the remaining four products showed various types of contamination detectable in their spectral differences. The method provides a fast, non-destructive way to detect contaminated cosmetics.

1. On-Spot detection of contaminated cosmetics using palm-sized near-infrared spectroscopy
Jordan Thomas, Sulaf Assi and David Osselton
Faculty of Science and Technology, Bournemouth University, Talbot Campus, Bournemouth, BH12 5BB, UK.
Introduction
Contaminated cosmetics often results in unwanted side
effects such as irritation and flushing. Contamination can
be encountered at any stage of the product preparation
or even during storage. Handheld near-infrared (NIR)
spectroscopy offer the advantage of non-destructive and
rapid detection of the physicochemical properties of raw
materials and products.
Therefore, this work aims at the development of a rapid
and non-destructive method for detection of
contaminated cosmetic raw material s and products using
handheld NIRS.
Experimental
A total of six products which included both raw materials
and cosmetic products alongside their references were
used in this work (Table 1).
Results and Discussion
NIR could detect within seconds any difference between the
reference and test products (Figure 2).
Conclusion
Handheld NIRS offered a rapid and non-destructive
method for detection of contaminated cosmetic
products.
Table 1. Details of the products used in this work.
Figure 1. The palm-sized
JDSU MicroNIR
spectrometer
Figure 3. NIR spectra of
reference (blue) and test
(magenta) blue corn
powder.
Instrument
Products were measured in their original bottles or during
manufacturing process at Hampshire Cosmetics Ltd, using the
JDSU MicroNIR equipped with 128-pixel uncooled InGaAs
photodiode array detector (Figure 1). Ten spectra were taken
per products, such that each spectrum was the sum of 50
scans over the wavelength range of 700 -1900 nm.
P: Product, L: Liquid, P:Powder. For products P1 to P5 one reference
and one tests sample was measured. For P6 one reference and two
test samples were measured.
Figure 2 . MSC-D1 treated NIR spectra of (a) P1, (b) P2, (c) P3, (d) P4, (e)
P5 and (f) P6 respectively.
Acknowledgements
Hampshire Cosmetics Ltd for the samples and access to
facilities..
Scimed for the palm-sized near-infrared instruments
In this respect, P2 (blue corn powder) and P4
(hyaluronic acid) showed differences in the water
content at around 1400 nm. Apart from the water
content, there was no significant difference between
P2 and P4 reference and test products. However, all
blue corn powder and hyaluronic acid products
showed false positive results against each other (r>
0.98) (Figure 3).
The remaining four products (P1, P3, P5 and P6)
showed variable type of contamination which could be
attributed to physicochemical differences among the
sample (Figure 2). The spectra of each of the test
products gave a low match against its reference
product (Figure 4). Moreover, P6T2 (peppermint oil)
showed a false positive result (r = 0.98) against P5
(Soothex). This could be because products contained
linalool as a major ingredient.
Figure 4. Correlation map of the MSC-D1 NIR spectra reference
and test products of P1, P2, P3, P4, P5 and P6 respectively..
Spectral Treatment
Spectral pre-treatment and treatment were made using
multiplicative scatter correction-second derivative (MSC-D1)
and correlation in wavelength space (CWS) method
respectively. For CWS method, the threshold for correlation
coefficient (r) value was 0.95.