Three-phase hollow-fiber liquid-phase microextraction combined with HPLC-UV for the determination of isothiazolinone biocides in adhesives used for food packaging materials

Quantification of Methylisothiazolinone and Methylchloroisothiazolinone Preservatives by High-Performance Liquid Chromatography

Isothiazolinone preservatives (methylisothiazolinone (MIT) and methylchloroisothiazolinone (CMIT) are commonly used in cosmetics, industrial and household products. However, these isothiazolinone derivatives are known to cause allergic contact dermatitis. Hence, a sensitive, accurate, and reliable method for the detection of these compounds is thus warranted. The study aims to analyze concentrations of MIT and CMIT by high performance liquid chromatography. The analytical method used for quantification of MIT and CMIT in cosmetic products (leave-on-baby wet wipes) complies with the validation acceptance criteria (international standards ISO 5725, EU25 European Union for cosmetic regulations). MIT and CMIT were extracted and analyzed in leave-on baby wet-wipes collected from different stores in Riyadh city. Extraction was performed by ultrasonication of the samples, solid-phase extraction, and liquid-liquid extraction. Ten (10) µL of the sample was injected into the HPLC system and samples were analyzed with a mixture of acetic acid and methanol (80:20 v/v) in an isocratic mode. The flow rate was maintained at 1 mL/min. UV detection was performed at 274 nm. The results demonstrated recoveries between 90 and 106%, measurement uncertainty of C +/- 0.4% for methylisothiazolinone and C +/- 0.03% for methylchloroisothiazolinone, repeatability limit (r = 0.2%) and intermediate precision limit; R = 2% and R² of 0.9996.

3D Printed SERS-Active Thin-Film Substrates Used to Quantify Levels of the Genotoxic Isothiazolinone

Several reports present methods to fabricate thin-film substrates capable of surface-enhanced Raman scattering (SERS). Substrates synthesized by displacing silver onto copper using facile synthesis methods such as galvanic displacement can generate high levels of SERS enhancement rivaling commercially available substrates manufactured by lithographic methods. Here, we describe the optimization of a novel set of SERS-active thin-film substrates synthesized via the electroless displacement of Ag onto the surface of three-dimensional (3D) printed disks composed of the copper/polymer (PLA) composite filament. The effect of AgNO₃ concentration on the deposition, morphology, and overall SERS activity of the substrates has been carefully studied. Two commonly used Raman reporters, 4-mercaptobenzoic acid (MBA) and malachite green isothiocyanate (MGITC), were used to measure the SERS output of the substrates. Good SERS signal reproducibility (RSD ∼16.8%) was measured across the surface of replicate substrates and high-sensitivity detection of MBA was achieved (10^-12 M). To test the real-world application of our substrates, we opted to detect 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT), which is a genotoxic, biocide common in many household products, known to leach into water supplies. Our newly developed SERS-active substrates could detect CMIT down to 10 ppm when spiked in simulated lake water samples, which is well within current agency standards.

The detection and elucidation of oligomers migrating from biodegradable multilayer teacups using liquid chromatography coupled to ion mobility time-of-flight mass spectrometry and gas chromatography-mass spectrometry

Biodegradable materials are increasingly being used in manufacturing processes due to their environmental benefits. In this work, a study has been performed to assess the migration of compounds from biodegradable multilayer teacups to a tea solution. Liquid chromatography in conjunction with ion-mobility quadrupole time-of-flight mass spectrometry has been used for the elucidation of non-volatile compounds. An orthogonal projection to latent structures-discriminant analysis has been carried out to compare the tea after migration against untreated tea used as blank. Headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry has been optimised to analyse the migration of volatile compounds. Eight migrants were identified in the tea, six of which were non-intentionally added oligomers. The degree of migration for hot tea ranged from 0.05 and 4.68 mg/kg, exceeding the specific migration limit. Nevertheless, the migration to cold tea was an order of magnitude lower (between 0.003 and 0.56 mg/kg).

Simultaneous Determination of Isothiazolinones and Parabens in Cosmetic Products Using Solid-Phase Extraction and Ultra-High Performance Liquid Chromatography/Diode Array Detector

Isothiazolinones methylisothiazolinone (MI) and methylchloroisothiazolinone (MCI), and parabens methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) are the most common synthetic preservatives. They are all known to be potential skin allergens that lead to contact dermatitis. Thus, the identification of these unsafe chemicals in cosmetic products is of high importance. In the present study, solid-phase extraction (SPE) based on HyperSep reversed-phase C8/benzene sulfonic acid ion exchanger (HyperSep C8/BSAIE) and Sep-Pak C18 sorbents, and ultra-high performance liquid chromatography/diode array detector (UHPLC/DAD) were optimized for the simultaneous determination of MI, MCI, MP, EP, PP and BP in cosmetic products. HyperSep C8/BSAIE and UHPLC/DAD with the eluting solvent mixture (acetonitrile/methanol, 2:1, v/v) and detection wavelength (255 nm) were found to be the optimal conditions, respectively. The method illustrates the excellent linearity range (0.008–20 μg/mL) with coefficient of determination (R², 0.997–0.999), limits of detection (LOD, 0.001–0.002 μg/mL), precision in terms of relative standard deviation (RSD < 3%, intra-day and <6%, inter-day) when examining a standard mixture at low (0.07 µg/mL), medium (3 µg/mL) and high (15 µg/mL) concentrations. A total of 31 cosmetic samples were studied, achieving concentrations (MI, not detected (nd)-0.89 µg/g), (MCI, nd-0.62 µg/g), (MP, nd-6.53 µg/g), (EP, nd-0.90 µg/g), (PP, nd-9.69 µg/g) and (BP, nd-17.80 µg/g). Recovery values ranged from 92.33 to 101.43% depending on the types of sample. To our knowledge, this is the first specific method which covers the theme and describes background amounts of such preservatives in cosmetics.

Isothiazolinone Biocides: Chemistry, Biological, and Toxicity Profiles

The importance of isothiazole and of compounds containing the isothiazole nucleus has been growing over the last few years. Isothiazolinones are used in cosmetic and as chemical additives for occupational and industrial usage due to their bacteriostatic and fungiostatic activity. Despite their effectiveness as biocides, isothiazolinones are strong sensitizers, producing skin irritations and allergies and may pose ecotoxicological hazards. Therefore, their use is restricted by EU legislation. Considering the relevance and importance of isothiazolinone biocides, the present review describes the state-of-the-art knowledge regarding their synthesis, antibacterial components, toxicity (including structure–activity–toxicity relationships) outlines, and (photo)chemical stability. Due to the increasing prevalence and impact of isothiazolinones in consumer’s health, analytical methods for the identification and determination of this type of biocides were also discussed.

Simultaneous Quantitative Analysis of Six Isothiazolinones in Water-Based Adhesive Used for Food Contact Materials by High-Performance Liquid Chromatography-Tandem Mass Spectrometry (HPLC-MS/MS)

In this study, a target analytical approach using high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) was developed to simultaneously determine six isothiazolinones containing 2-Methylisothiazol-3(2H)-one (MI), 5-Chloro-2-methyl-4-isothiazolin-3-one (CMI), 1,2-benzisothiazolin-3-one (BIT), 2-Octyl-3(2H)-isothiazolinone (OIT), Dichlorooctylisothiazolinone (DCOIT), and 2-methyl-1,2-benzisothiazolin-3-one (MBIT) in water-based adhesive used for food contact materials. The main factors affecting extraction efficiency such as extraction method, extraction time, extraction solvent, and solid–liquid ratio have been evaluated by using real adhesive samples. Multiple-reaction monitoring (MRM) was used for the qualitative and quantitative analyses of targeted isothiazolinones. This method was demonstrated as an effective and reliable technique for detecting multiple isothiazolinones with satisfactory recoveries (81.5~107.3%), and the limits of detection (LOD) and quantification (LOQ) were obtained at a low level. This method was validated and applied to the determination of six isothiazolinones in commercial water-based adhesives. The present results revealed that these adhesives contained a combination of isothiazolinones (BIT, MI, CMI, and MBIT) with the concentration ranging from 2.27 to 123.5 mg/kg. To our knowledge, it is the first time it has been reported that MBIT was detected in water-based adhesives used for food contact materials, which requires a further investigation for its migration to food and the risk to human health.

Isothiazolinone Content of US Consumer Adhesives: Ultrahigh-Performance Liquid Chromatographic Mass Spectrometry Analysis

BACKGROUND

There are limited data regarding the prevalence and concentration of isothiazolinone preservatives in consumer adhesives.

OBJECTIVES

The aim of this study was to determine the prevalence and concentration of 5 specific isothiazolinones (methylisothiazolinone [MI], methylchloroisothiazolinone [MCI], benzisothiazolinone [BIT], butyl BIT, and octylisothiazolinone) in US adhesives.

METHODS

Thirty-eight consumer adhesives were analyzed using ultrahigh-performance liquid chromatographic-mass spectrometry. Fisher exact tests were used to test for isothiazolinone content and: 1) glue format (2) application purpose and 3) extraction method.

RESULTS

Nineteen adhesives (50%) had at least 1 isothiazolinone, and 15 contained 2 isothiazolinones. Frequencies and concentrations were as follows: MI (44.7%; 4-133 ppm), MCI (31.6%; 7-27 ppm), BIT (15.8%; 10-86 ppm), and octylisothiazolinone (2.6%; 1 ppm). Butyl BIT was not detected in any of the adhesives. Format (stick vs liquid) was not statistically associated with isothiazolinone presence. At least half of adhesives in the following application purposes had at least 1 isothiazolinone: shoe, craft, fabric, and school. All-purpose glues had a statistically significant lower concentration of MI and MCI, whereas craft glues were associated with higher concentrations of MI and MCI. Compared with other glues, fabric adhesives were associated with a higher risk of containing BIT.

CONCLUSIONS

Half of the tested adhesives contained at least 1 isothiazolinone. Methylisothiazolinone and MCI were the most common. Consumers and dermatologists should be aware of adhesives as a source of isothiazolinones.

Occurrence and concentrations of isothiazolinones in detergents and cosmetics in Switzerland

BACKGROUND

In recent years, the frequency of contact allergy to isothiazolinones has increased alarmingly in Europe, but only limited data are available on concentrations of isothiazolinones in consumer products.

OBJECTIVES

To examine the current frequency of isothiazolinones [methylisothiazolinone (MI), methylchloroisothiazolinone (MCI), benzisothiazolinone (BIT), and octylisothiazolinone (OIT)] in a wide array of detergents and cosmetics relevant for the Swiss population.

METHODS

By means of a market survey, the occurrence of isothiazolinones was investigated in 1948 consumer products. Of these, 88 products were analysed by liquid chromatography-high-resolution mass spectrometry after ultrasonic extraction.

RESULTS

Only 7.6% of all cosmetics contained isothiazolinones, but the prevalence in detergents was much higher (42.9%). The measured concentration ranges in detergents were 4.3–10, 3.5–279, 3.8–186 and 7.9 ppm (one product only) for MCI, MI, BIT, and OIT, respectively [corrected]. For cosmetics, these were 1.3-133 and 4.8 ppm (one product only) for MI and MCI, respectively.

CONCLUSIONS

Our study has shown that high concentrations of isothiazolinones (including MI) can be found in a large variety of products, in particular in detergents. Therefore, the safe use of these preservatives should be re-evaluated by including detergents in the exposure assessment.

Hollow-fiber solvent bar microextraction with gas chromatography and electron capture detection determination of disinfection byproducts in water samples

A liquid-phase microextraction method that uses a hollow-fiber solvent bar microextraction technique was developed by combining gas chromatography with electron capture detection for the analysis of four trihalomethanes (chloroform, dichlorobromomethane, chlorodibromomethane, and bromoform) in drinking water. In the microextraction process, 1-octanol was used as the solvent. The technique operates in a two-phase mode with a 5 min extraction time, a 700 rpm stirring speed, a 30°C extraction temperature, and NaCl concentration of 20%. After microextraction, one edge of the membrane was cut, and 1 μL of solvent was collected from the membrane using a 10 μL syringe. The solvent sample was directly injected into the gas chromatograph. The analytical characteristics of the developed method were as follows: detection limits, 0.017-0.037 ng mL^-1 ; linear working range, 10-900 ng mL^-1 ; recovery, 74 ± 9-91 ± 2; relative standard deviation, 5.7-10.3; and enrichment factor, 330-455. A simple, fast, economic, selective, and efficient method with big possibilities for automation was developed with a potential use to apply with other matrices and analytes.