The Determination of Metals in Cosmetics

APPLICATION NOTE

ICP-Mass Spectrometry

Authors Zoe Grosser, Ph.D. Lee Davidowski, Ph.D. Laura Thompson PerkinElmer, Inc. Shelton, CT 06484 USA

Introduction The Determination of Cosmetics of one form or another have been used since the beginning of time. Metals in Cosmetics The U.S. Food and Drug Administration (FDA) defines today’s cosmetics as:

“1. articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body or any part thereof for cleansing, beautifying, promoting attractiveness, or altering the appearance, and 2. articles intended for use as a component of any such articles; except that such term shall not include soap.” 1

The U.S. FDA has not regulated metals in cosmetics except in the case that zirconium is prohibited in aerosol preparations and mercury can only be used (generally as a preservative) when no other alternative is possible. They do have the authority to protect consumers against contamination deemed to be deleterious to health. Proposition 65 in California requires notice when concentrations in a product may cause exposure to hazardous components exceeding a prudent level. A letter from the Attorney General of the State of California discusses the level of concern and calculates that based on documented lipstick use, a concentration of 5 mg/kg would be the level of concern requiring listing.2 The regulations in Canada include statements about heavy metals, and although low concentrations may be difficult to avoid, concentrations above the levels listed in Table 1 (Page 2) require special scrutiny. Measurements in this work are performed using ICP-MS. Table 1. Canadian metal concentrations of concern in Elements chosen for examination are commonly considered cosmetics.3 to be toxic, although there are others that might be consid- Metal Concentration (mg/kg) ered hazardous as well, such as antimony, included on the Lead 10 Canadian list. Arsenic 3 Cadmium 3 Experimental Mercury 3 Samples of a variety of commercially available lipsticks (Figures 1 and 2), nail polishes, and skin creams (for evening Antimony 5 tone, lightening age spots) were purchased and prepared in duplicate. Nail polishes were painted onto tared weighing The European Union (EU) has also developed a list of more paper and allowed to dry before weighing into the digestion than 1000 compounds that are banned for use in cosmetic vessel (Figures 3 and 4). Microwave digestion was used manufacturing. They further limit the amount of these (Multiwave™ 3000, PerkinElmer®, Shelton, CT USA) to obtain compounds that may be found naturally-occurring in the clear solutions. Six mL of nitric and 0.5 mL of hydrofluoric product. For example, strontium peroxide may be found in acid (GFS Chemical™, Columbus, OH USA) were added to rinse-off hair care preparations, but is limited to containing PTFE vessels with approximately 0.3-0.5 g of sample and the less than 4.5% as strontium in the ready-to-use product.4 digestion program shown in Table 2 applied. The samples were ® Examining the notices of recall in the U.S. for products then transferred and diluted to 50 mL with ASTM Type I manufactured in various parts of the world show that a water. The samples were fairly homogeneous and in number of items which have been recalled are cosmetics. a form that allowed a representative sample to be easily For example, skin whitening cream from several Caribbean taken. If the samples were solids, grinding, blending or other countries was put on an import alert because the level of procedures might be necessary to ensure a more homogeneous mercury measured in the product was 8%.5 Another alert sample to be measured. Preparing replicate samples will allow was issued for eye colors including Kohl, Kajal, or Surma. us to evaluate if our homogeneity assumption is accurate. In addition to being an unapproved coloring agent, the material was found to contain lead (Pb). There has also been Table 2. Microwave digestion program. recent concern about lead in lipstick, uncovered through Step Power Ramp Hold Fan 6 testing. The U.S. FDA has not recalled lipstick and states 1 750 10:00 10:00 1 they will do further testing.7 The guidance mentioned for 2 1200 10:00 10:00 1 lead relates to the limited guidance available for food, where a letter stating that 0.1 mg/kg of Pb in candy is the 3 0 15:00 3 maximum tolerable limit for acceptable children’s exposure. An ELAN® DRC-e ICP-MS (PerkinElmer, Shelton, CT USA) This application note will evaluate the levels of several was used for measurement of chromium, cadmium, lead, heavy metals in lipstick, nail polish and skin cream. Based mercury, arsenic, selenium, and antimony. The instrumental on candy guidance in the U.S. and the limits set in Canada, conditions are shown in Table 3 (Page 3). Mercury was also either graphite furnace atomic absorption (GFAA), inductively measured using the SMS 100 Mercury Analyzer (PerkinElmer, coupled plasma optical emission spectroscopy (ICP-OES), Shelton, CT USA) which uses a combustion system, requiring or inductively coupled plasma mass spectrometry (ICP-MS) no sample preparation and generating no waste. Instrumental would be appropriate, based on the amount of sample conditions are shown in Table 4 (Page 3). taken for digestion and the final volume of solution.

Figure 1. A variety of commercially- Figure 2. Lipstick was weighed prior Figure 3. Nail polish was dried on Figure 4. The nail polish and tared available lipsticks were analyzed. to microwave digestion. tared paper before digestion. paper were weighed into the digestion vessel.

2 Table 3. ICP-MS instrumental conditions. Table 4. Mercury system instrumental conditions. Nebulizer Quartz Concentric Parameter Spray Chamber Quartz Cyclonic Dry 400 °C for 200 s RF Power 1500 W Decomposition 800 °C for 350 s Integration time 1000 ms (per analyte) Catalyst 600 °C Replicates 3 Catalyst wait period 60 s

Reaction Gas for arsenic O2 = 0.6 mL/min Gold trap 600 °C for 30 s RPq for arsenic as 91 AsO 0.5 Measurement 100 s Oxidant gas flow 350 mL/min Arsenic analysis employed cell technology to remove the chloride interference arising from either natural chlorine Results and Discussion content, salt added to a supplement material or hydrochloric acid used in sample preparation, which can degrade the Sample preparation is an important contributor to the detection limit. This cell allows a gas to react with the results, especially when it influences the consistency and sample, and under controlled conditions, the interference is information provided by the results. An article by several chemically separated from the analyte. Figure 5 shows how researchers, including the U.S. FDA, discussed the need the Dynamic Reaction Cell™ (DRC™) operates. Detection for a small amount of hydrofluoric acid (HF) in the digest limits are improved compared to other approaches and the to ensure better consistency and recovery of all the metal, precision in varying matrices is more consistent. An instrument including that which might be protected from other acid detection limit for arsenic measured in 1000 mg/L NaCl was attack by a silica particle.9 The question always becomes: shown to be 2.3 ng/L, comparing favorably to detection is it better to report the total metal content or the portion limits of 0.6-1.8 ng/L, measured in 1% nitric acid solution, that might be bioavailable? Even if lipstick is consumed and using this technique.8 exposed to hydrochloric acid in the digestion process, lead enclosed in silica particles will not be released and is therefore unable to cause harm. The digestion here used HF and therefore reports a total metal value with more confidence, although it may not be all bioavailable.

Several performance criteria were evaluated to ensure the method was operating as expected and the sample preparation had been performed correctly. Table 5 (Page 4) shows the results for NIST® reference material Typical Diet (1548a) digested at the same time as the cosmetics, using the same conditions and acids. Although Typical Diet is not a cosmetic matrix, it has some of the same components. The fat content may not be comparable to all of the skin cream or lipstick Figure 5. Dynamic reaction cell (DRC) operates with the PerkinElmer ELAN® ICP-MS to react and remove interferences without allowing types, depending on their formulation. competing reactions to add other interferences.

The mass for selenium measurement was chosen to avoid interference from calcium, which may be present in cosmetics.

Since this work was completed, the NexION® 300 ICP-MS has been introduced by PerkinElmer, Inc. and performance is expected to be the same or better than the ELAN DRC-e ICP-MS.

3 Table 5. NIST® 1548a Typical Diet certified reference material. Element and Mass 1548a – 1 (mg/kg) 1548a – 2 (mg/kg) Average (mg/kg) Certificate Value % Rec Cr 52 0.135 0.118 0.127 – Cd 111 0.036 0.038 0.037 0.035 106 Hg 202 < DL < DL 0.005* Pb 208+207+206 0.045 0.046 0.046 0.044 104 Se 82 0.231 0.251 0.241 0.245 98.4 AsO 91 0.183 0.192 0.188 0.20 93.8 Prepared at the same time as the cosmetics, using the same procedure. * Informational value, not certified.

Recoveries of the certified values were within ±20%, indicating acceptable performance. Table 6. Estimated detection limits in the solid cosmetic. Element and Mass µg/g Detection limits were estimated from digested blanks run Cr 52 0.044 during the analysis. The standard deviation was multiplied by three and adjusted by the dilution of the solid during Cd 111 0.00069 digestion to give an estimate in the original cosmetic material. Hg 202 0.0037 Estimated detection limits calculated for the solid cosmetic Pb 208 0.0096 material are well below the current compliance limits, allowing Se 82 0.082 confidence when measurements are made near the compliance limits. AsO 91 0.014

The duplicate digestions were run and average values reported in Table 7 for the lipsticks. It is interesting to note that although several have more than 1 µg/g of lead (which caused a controversy when results were reported in the Poison Kiss document10), it is below the regulated limit in Canada. Other elements that may be of concern are also seen in some samples, such as Cr and Se.

Table 7. Lipstick results (ug/g). Element Lip-1 Lip-2 Lip-3 Lip-4 Lip-5 Lip-6 Lip-7 Lip-8 Lip-9 Lip-10 Lip-11 Lip-12 and Mass Cr 52 7.41 7.05 93.3 0.226 18.7 0.858 7.94 5.27 0.645 0.520 1.46 1.46 Cd 111 0.0293 0.0179 0.139 0.0353 0.0264 0.00860 0.0398 0.144 0.0288 0.00897 0.0159 0.00595 Hg 202 0.00944 0.00794 < DL < DL 0.00977 0.0125 0.0107 < DL 0.00707 0.00422 < DL < DL Pb 208 1.38 0.545 0.273 0.0407 0.611 1.12 0.591 0.397 0.321 0.943 0.489 0.700 Se 82 0.211 < DL < DL < DL 0.329 0.162 < DL 0.708 1.91 105 0.166 0.108 AsO 91 0.828 0.250 0.411 0.481 0.073 0.123 0.209 0.242 0.0571 0.0586 0.0976 0.0969

Table 8 shows the individual results for two sample Table 8. Precision and agreement of duplicate samples (µg/g). digestions for Lipstick 3 and standard deviation and relative percent difference (RPD) between Element and Mass Lip-3 A Lip-3 B Average SD RPD the two measured concentrations. The RPD is less Cr 52 94.4 92.2 93.3 01.52 2.30 than 5%, which shows good agreement between Cd 111 0.138 0.140 0.139 0.00129 1.31 the duplicate digestions. Hg 202 < DL < DL < DL – Pb 208 0.271 0.275 0.273 0.00221 1.15 Se 82 < DL < DL < DL – AsO 91 0.421 0.401 0.411 0.0142 4.90

4 The lipsticks covered a range of colors, from black to pink, red, purple and brown. The results for the elements measured Table 10. Skin cream results (µg/g) and post-digestion spike varied quite a bit between the various brands and colors. recovery. The black lipstick (Lip-4) was made in China and was one of Element Cream-1 the lipsticks lowest in lead and the other metals measured. and Spike In no case was the Canadian limit or the limit suggested in Mass Cream-1 Cream-2 Cream-3 Recovery (%) California for Proposition 65 compliance exceeded. Cr 52 0.0318 0.0800 0.00867 109 Cd 111 0.00318 0.00122 0.00194 87.6 Several of the lipsticks measured in the Poison Kiss publication10 were also purchased for this work. The result obtained here Hg 202 < DL < DL < DL 111 for lead on Lipstick 5 was 0.611 µg/g and in the report on Pb 208 < DL 0.168 0.0180 97.2 two separate tubes of lipsticks they measured 0.65 and Se 82 0.0198 0.168 0.187 – 0.50 µg/g. The measurements in the publication were also AsO 91 < DL 0.0128 < DL 86.4 performed using ICP-MS, but the digestion used contained Sb 121 0.00187 0.00483 0.0120 92.4 nitric and sulfuric acid and no HF. Therefore, the results may be low or may have less precision for duplicate measurements. Spike levels in solution: 4 µg/L, except mercury 0.5 µg/L

Another cosmetic with a different kind of matrix is nail polish Post-digestion spike recoveries show that the matrix is not and a variety of colored nail polishes of different brands unduly influencing the accuracy of the result. were measured for the same elements and the results are shown in Table 9. Colors ranged from blue to pink and Lead was measured on two separate days, at least a week red. Again, small amounts of metals are present in most of apart, to ensure the results could be replicated (Table 11). the polishes and may cause exposure if nails are bitten or The lead results were present at several different concentration chewed and the polish ingested. levels in the skin cream and showed good agreement over the two days. Table 9. Nail polish results (µg/g). Element NP-1 NP-2 NP-3 NP-4 NP-5 NP-6 Table 11. Lead results on separate days (µg/g). and Mass Cream-1 Cream-2 Cream-3 Cr 52 6.58 0.999 2.95 0.800 10.9 1.96 Day 1 < DL 0.168 0.0180 Cd 111 0.0364 0.0290 0.0193 0.0160 0.0832 0.0110 Day 2 < DL 0.161 0.0214 Hg 202 < DL < DL 0.00965 < DL 0.192 0.00826 Pb 208 0.863 0.947 2.12 0.204 6.03 1.82 Skin cream has been the subject of a U.S. FDA Import Alert because high mercury content was found in potential import Se 82 62.2 128 161 61.7 0.0477 0.397 samples. Mercury measurements were confirmed for the AsO 91 0.147 < DL 0.266 0.0690 1.91 0.510 skin creams measured in this work using a dedicated mercury system (Table 12). The detection limit is lower than with The third type of cosmetic examined was skin cream. This digestion because dilution is less and low concentrations of type of skin cream was intended to lighten the skin to remove mercury were confirmed. Small samples can be used and age spots or even skin tone. Three types were digested and rapid screening performed because the system requires no measured for the elements of interest. Antimony was added sample preparation and generates no waste. Figure 5 shows as an analyte for this determination to show that it can be the autosampler for the mercury system and the sample incorporated into the multielement run for Canadian compli- measured into small boats. ance. The results are shown in Table 10. Table 12. Mercury results using mercury system. Conc. (µg/g) SD Cream-1 < DL Cream-2 0.00240 0.00008 Cream-3 0.00824 0.000044 Three replicate analyses averaged Detection limit: 0.02 ng/g in the skin cream

Figure 5. Skin cream samples measured into small boats for analysis.

5 Conclusions References Cosmetics contain a variety of components that can be 1. Food, Drug, and Cosmetic Act, as amended through 2004, challenging to digest, including fats and silica-based compounds. Chapter II, Definitions 21USC 321, http://www.fda.gov/ Digestion using a microwave with the addition of HF to digest opacom/laws/fdcact/fdcact1.htm. siliceous materials may be necessary. Sensitivity to the resulting decisions to be made with the information, such as the need 2. Letter from Edmund G. Brown, Attorney General, State of for bioavailability information, may influence the sample California, to two law groups in reference to Proposition preparation acids chosen. Microwave digestion also provides 65 Claims Concerning Lead in Lipstick, http://ag.ca.gov/ a clean digestion and retains mercury so that a full suite of prop65/pdfs/Lipstick_Letter-a.pdf (accessed 1-24-2011). elements may be easily examined. 3. Draft Guidance on Heavy Metals in Cosmetics, Health ICP-MS is a good choice for determination of low concentrations Canada, http://www.hc-sc.gc.ca/cps-spc/legislation/consul- of analytes, allowing evaluation of toxic and potentially toxic tation/_cosmet/metal-metaux-consult-eng.php (accessed components in cosmetics. More sophisticated interference 1-24-2011). correction, such as DRC, can remove molecular interferences 4. Cosmetic Products Regulation, EU Regulation 1223/2009 at the mass of interest, allowing the lowest detection limit to (accessed 1-24-2011). be achieved. 5. Import Alerts, http://www.fda.gov/ForIndustry/Color This application note has demonstrated the successful analysis of Additives/ComplianceEnforcement/EnforcementNews/ three types of cosmetics for toxic elements and shown good ucm123909.htm (accessed 1-24-2011). results through replicate analyses and spiked samples. Analysis of a reference material helped to ensure that the digestion 6. Lead in Lipstick http://www.safecosmetics.org/article. step and instrumental analysis were under control. php?id=223 (accessed 1-24-2011).

Acknowledgement 7. FDA Q&A, http://www.fda.gov/Cosmetics/ResourcesFor You/Consumers/CosmeticsQA/default.htm (accessed 1-24- The authors would like to thank Lindsay Drennan for the 2011). confirmatory data on mercury in skin cream measured with the SMS 100 Mercury Analyzer. 8. Ruth Wolf and Ken Neubauer, Determination of Arsenic in Chloride Matrices, PerkinElmer, (2002).

9. N.M. Hepp, W.R. Mindak, and J. Cheng, J. Cosmet. Sci., 60, 405–414 (July/August 2009).

10. A Poison Kiss: The Problem of Lead in Lipstick, The Campaign for Safe Cosmetics, October 2007 http://www. safecosmetics.org/downloads/A%20Poison%20Kiss_report. pdf (accessed 1-24-2011).

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