A salting out-acetonitrile homogeneous extraction coupled with gas chromatography–mass spectrometry method for the simultaneous determination of thirteen N -nitrosamines in skin care cosmetics

Simultaneous determination of sixteen phthalic acid esters (PAEs) in soil and evaluation of matrix effect using a QuEChERS/GC/MS-internal standard method

Phthalic acid esters (PAEs) are emerging pollutants that need to be analyzed precisely. Chromatography-based determination of PAE content in soils are frequently affected by matrix effect, which may limit the quantification of different kinds of PAEs from different types of soil. Here we optimized a QuEChERS protocol combined with gas chromatography-mass spectrometry (GC-MS) for simultaneous determination of 16 PAEs in different soils. PAEs in different type of soils (fluvo-aquic soil, red soil, and black soil) were extracted with acetonitrile followed by GC-MS detection based on quantitative ion internal standard method. All 16 PAEs showed excellent linear relationships with mass peak areas (R2 > 0.99). The limits of detection (LOD) and limits of quantitation (LOQ) of all the samples were in the range of 0.91-66.97 µg/kg and 2.7-200.9 µg/kg, respectively. The accurate test at 0.5, 0.1, and 1.0 mg/kg spiking level recorded recovery rate between 80.11% and 100.99% with relative standard deviations (RSDs) ranging from 0.37 to 8.50% in tested matrices. No significant matrix effect was observed for most tested PAEs. This is a simple method with high sensitivity and strong stability, which is suitable and reproducible for quantifying large number of PAEs in different types of soil.

Rapid and Simultaneous Determination of Anabolic Andro-Genic Steroids in Livestock and Poultry Meat Using One-Step Solid-Phase Extraction Coupled with UHPLC-MS/MS

Anabolic androgenic steroids (AASs) are usually illegally added to animal feed because they can significantly promote animal growth and increase carcasses' leanness, which threatens the safety of animal-derived foods and indirectly hazards human health. This study aimed to establish an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the simultaneous detection of twelve AAS residues in livestock and poultry meat. The homogenized samples were extracted with acetonitrile containing 1% acetic acid (v/v) and purified using the one-step extraction column. After concentration using nitrogen, the residues were redissolved in acetonitrile and then quantified with an external standard method using UHPLC-MS/MS. The results showed that the above-mentioned method had a satisfactory linear correlation (R2 ≥ 0.9903) with a concentration range of 1-100 μg/L, and the limits of detection (LODs) and quantification (LOQs) were 0.03-0.33 μg/kg and 0.09-0.90 μg/kg, respectively. With the intraday and interday precision less than 15%, the average recoveries of pork, beef, lamb, and chicken, at different spiked levels, ranged from 68.3 to 93.3%, 68.0 to 99.4%, 71.6 to 109.8%, and 70.5 to 97.7%, respectively. Overall, the established method is validated, precise, and capable of the high-throughput determination of the residues of twelve AASs in livestock and poultry meat.

Development and validation of a deep eutectic solvent-assisted liquid-liquid extraction method for simultaneous quantification of six steroid hormones in serum by liquid chromatography-tandem mass spectrometry

Steroid hormones have been reported to be associated with endocrine system diseases. This paper proposes a novel procedure of deep eutectic solvent (DES)-assisted liquid-liquid extraction (LLE) to extract six steroid hormones (including cortisone, cortisol, androstenedione, testosterone, 17-hydroxyprogesterone, and progesterone) from serum coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of five types of L-proline, choline chloride, and citric acid-based DESs were tailored; the DES from L-proline and ethylene glycol at a molar ratio of 1:4 with 20 % acetonitrile was selected as the best-fit assisted solvent for the six steroid hormones compared with other DESs. The parameters for extraction by selected DES were optimized using Box-Behnken design (BBD), and the optimal extraction conditions are 200 µL of acetonitrile, 100 µL of the sample, and 80 µL of DES. Under optimum conditions, the method has good linear calibration ranges (between 0.07 ng mL-1 and 600 ng mL-1), correlation coefficients of determination (r2>0.99), and low limits of quantification (between 0.02 and 0.60 ng mL-1). The extraction recoveries were in the range of 81.84-114.43 %, and the intra-day and inter-day relative standard deviations (RSDs) were less than 10 %.In general, the DES-LC-MS/MS method is a simple and environmentally-friendly method, which can be complementary to the presently available methods for determining steroid hormones in serum.

A Novel Method for Monitoring N-Nitrosamines Impurities Using NH2-MIL-101(Fe) Mediated Dispersive Micro-Solid Phase Extraction Coupled with LC-MS/MS in Biopharmaceuticals

A highly efficient and convenient method for the simultaneous determination of 12 N-nitrosamines (NAs) has been developed using an amine-functionalized metal-organic framework (NH2-MIL-101(Fe)) as sorbent for dispersive micro-solid phase extraction (D-μSPE) coupled with LC-MS/MS in biopharmaceuticals. The experimental variables involved in the extraction process (i.e., amount of the sorbent, extraction time, desorption time, ionic strength, desorption solvent and volume) were optimized to achieve the best extraction efficiency of the target analytes. Under the optimum conditions, the method was successfully validated, showing good linearity in the range of 0.5-3.0 μg/L with determination coefficients (R2) higher than 0.990, repeatability (RSD ≤ 10.0%, spiked level at 2.0 μg/L) and precision (RSD ≤ 8.2%). The limit of detection (LOD) and limit of quantitation (LOQ) were in the range of 0.005-0.025 μg/L and 0.010-0.250 μg/L, respectively. Satisfactory recoveries ranging from 82.4 to 116.8% were obtained by spiking standards at three different concentrations (0.5 μg/L, 2.0 μg/L and 3.0 μg/L). Other validation parameters, including specificity, stability, and robustness, met the validation criteria. More importantly, the plausible adsorption mechanism on NH2-MIL-101(Fe) was proposed by Fourier-transform infrared (FTIR) spectra technique. Finally, this method was successfully applied to detect trace nitrosamines in biopharmaceuticals.

N-nitrosamines in Qingdao dried aquatic products and dietary risk assessment

N-nitrosamines are human carcinogens commonly present in dried aquatic products. A method of gas chromatography - mass spectrometry combined with steam distillation was developed for the determination of 9 N-nitrosamines in dried aquatic products in Qingdao, China, with which 300 samples of fish, squid, shrimp and sea cucumber collected from Qingdao were analysed. A health risk assessment was conducted based on determined levels of N-nitrosamines by using estimated daily intake and slope factors. Results showed that fish products was the category with the highest content of N-nitrosamines, whereas squid and shrimp products were the categories with the highest frequency of presence of N-nitrosamines. The average estimated cancer risk of N-nitrosamines in dried aquatic products in Qingdao ranged from 3.57 × 10^-8 to 3.53 × 10^-5. Nitrosodimethylamine, N-Nitrosodiethylamine and N-Nitrosodibutylamine could be considered to pose a potential cancer risk to residents in Qingdao.

Determination of nine prohibited N-nitrosamines in cosmetic products by vortex-assisted dispersive liquid-liquid microextraction prior to gas chromatography-mass spectrometry

An analytical method for the simultaneous determination of nine prohibited N-nitrosamines in cosmetic products is presented. N-nitrosamines are banned compounds in cosmetic products due to their harmful effects. Therefore, these compounds are not intentionally added to these products but, however, small amounts of them may be present due to unintentional causes, and thus sensitive methods for their analytical control are required. The proposed method is based on vortex-assisted dispersive liquid-liquid microextraction (VA-DLLME) to extract and preconcentrate the analytes, followed by gas chromatography-mass spectrometry (GC-MS) for their determination. The variables involved in the VA-DLLME process were optimized by using a Box-Behnken design and, due to the different polarity of the N-nitrosamines studied, several approaches for sample treatment were compared to achieve the best results. The method was successfully validated, showing a good linearity at least up to 20 ng mL^-1, enrichment factors from 2 to 100 depending on the target analyte, limits of detection and quantification at the low μg kg^-1 level, and good repeatability values (<13%). Finally, the proposed analytical method was applied to the determination of N-nitrosamines in commercial cosmetic samples of different nature, avoiding the matrix effect by means of standard addition calibration. Significant amounts of some of the N-nitrosamines, even exceeding the established regulatory limit, were found in the samples. The resulting method is fast, simple, and affordable to carry out the quality control of cosmetic products to ensure consumer safety for most laboratories.

Rapid and selective determination of 9 nitrosamines in biological samples using ultra-high performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry

A sensitive, selective and convenient method for the simultaneous determination of 9 nitrosamines (NAs) in biological samples was developed using isotope dilution ultra-high performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry (UPLC-QTRAP-MS). Multiple reaction monitoring-information dependent acquisition-enhanced product ion (MRM-IDA-EPI) scan mode was performed to eliminate false positive results, and the whole detection procedure was characterized by less time consuming and simple sample preparation. 9 NAs were separated through a T3 column with the gradient elution of acetonitrile and water, and detected by UPLC-QTRAP-MS with an atmospheric pressure chemical ionization (APCI) source in the positive mode. The quantitative analysis was carried out via the isotope internal standard method with a matrix calibration curve. Under the optimized conditions, good linearity for the 9 NAs was achieved in the range of 0.2-20 μg L^-1 with correlation coefficients (r) higher than ≥0.9991, and the limits of detection and limits of quantitation were 0.02-0.1 μg L^-1 (S/N = 3) and 0.06-0.3 μg L^-1 (S/N = 10), respectively. Satisfactory recoveries ranging from 79.4% to 108.0% were obtained, and the precision of the proposed method, indicated by the relative standard deviations (RSDs), was 2.3-12.9%. The matrix effect study showed that NDMA, NMOR and NMEA presented a matrix suppression effect, NDPHA displayed a matrix enhancement effect, and the matrix effects of the other 5 analytes could be ignored. Real application of the developed method in 13 urine and 24 plasma samples demonstrated that NDBA, NPIP and NPYR occurred in both urine and plasma samples with the concentration of 0.038-0.60 μg L^-1, while other NAs were not detected. Such a method was sensitive and selective, and could be applied to the rapid qualitative and quantitative analysis of the 9 NAs in biological samples.

A Full Evaporation Static Headspace Gas Chromatography Method with Nitrogen Phosphorous Detection for Ultrasensitive Analysis of Semi-volatile Nitrosamines in Pharmaceutical Products

The recent detection of potent carcinogenic nitrosamine impurities in several human medicines has triggered product recalls and interrupted the supply of critical medications for hundreds of millions of patients, illuminating the need for increased testing of nitrosamines in pharmaceutical products. However, the development of analytical methods for nitrosamine detection is challenging due to high sensitivity requirements, complex matrices, and the large number and variety of samples requiring testing. Herein, we report an analytical method for the analysis of a common nitrosamine, N-nitrosodimethylamine (NDMA), in pharmaceutical products using full evaporation static headspace gas chromatography with nitrogen phosphorous detection (FE-SHSGC-NPD). This method is sensitive, specific, accurate, and precise and has the potential to serve as a universal method for testing all semi-volatile nitrosamines across different drug products. Through elimination of the detrimental headspace-liquid partition, a quantitation limit of 0.25 ppb is achieved for NDMA, a significant improvement upon traditional LC-MS methods. The extraction of nitrosamines directly from solid sample not only simplifies the sample preparation procedure but also enables the method to be used for different products as is or with minor modifications, as demonstrated by the analysis of NDMA in 10+ pharmaceutical products. The in situ nitrosation that is commonly observed in GC methods for nitrosamine analysis was completely inhibited by the addition of a small volume solvent containing pyrogallol, phosphoric acid, and isopropanol. Employing simple procedures and low-cost instrumentation, this method can be implemented in any analytical laboratory for routine nitrosamine analysis, ensuring patient safety and uninterrupted supply of critical medications.

High-Resolution Mass Spectrometry Screening of Emerging Organophosphate Esters (OPEs) in Wild Fish: Occurrence, Species-Specific Difference, and Tissue-Specific Distribution

There is a dearth of information regarding the pollution status of emerging organophosphate esters (OPEs) in wild fish. Here, we optimized and validated a quick, easy, cheap, effective, rugged, and safe (QuEChERS) pretreatment method, which was further applied for target, suspect, and nontarget screening of OPEs in n = 48 samples of wild fishes from Taihu Lake (eastern China). This integrated technique allows us to fully identify 20 OPEs, and 9 out of them are emerging OPEs detected in wild fish for the first time. Importantly, some of the emerging OPEs, i.e., tris(2,4-di-tert-butylphenyl) phosphate (TDtBPP), 4-tert-butylphenyl diphenyl phosphate (BPDP), and 2-isopropylphenyl diphenyl phosphate (IPDP), exhibited greater or at least comparable contamination levels as compared to traditional ones. There were no statistically significant interspecies (n = 6) differences regarding OPE concentrations. However, we observed significant differences on OPE concentrations among different tissues of silver carp (Hypophthalmichthys molitrix), for which the intestine has the highest OPE mean concentration (46.5 ng/g wet weight (ww)), followed by the liver (20.1 ng/g ww) ≈ brain (20.0 ng/g ww) > gill (14.8 ng/g ww) > muscle (11.4 ng/g ww). An interesting exception is IPDP, which presents an unexpectedly high concentration in the brain (0.510 ng/g ww). Collectively, this study expands our understanding of OPE contamination in wild fish and clearly shows that emerging TDtBPP, IPDP, and BPDP could play an equally important role as traditional OPEs in contribution of OPE pollution in wild fish samples.

High level nitrosamines in rat faeces with colorectal cancer determined by a sensitive GC-MS method

N-nitrosamines (NAs) are common toxic substances that have a strong correlation with many human diseases, such as liver damage and cancer. However, there is a lack of studies on methods involving the detection of NAs in biological samples, possibly owing to the interference of complex biological matrices and the influence of endogenous NAs. In this work, solid-phase extraction with mixed solid phases and adsorption sedimentation were used to successfully establish a gas chromatography-mass spectrometry (GC-MS) method for detecting eight NAs in rat faeces. Chromatographic separation of analytes was performed with Agilent VF-WAXms (30 m × 0.25 mm, 0.25 µm) GC columns. The LLOQs of eight NAs were set to the concentration of 0.5 ng/g and the obtained standard curves were linear, and correlation coefficients (r) were ≥ 0.99 for samples with concentration ranges of 0.5-500 ng/g. The inter and intra-assay precisions were< 15% for all analytes in the quality control samples, and the accuracies ranged from 88.67% to 108.33%. The extraction recoveries were above 78.56% for seven NAs, and a significant matrix effect was not observed. The application of this method revealed that the levels of NAS in the faeces of rats with colorectal cancer were higher than those of normal rats. Additionally, the effect of a high nitrite diet on NAs in faeces was analysed; the results confirmed that a high nitrite diet might contribute to an abnormal increase in NAs. Our work provides an analytical method for further in vivo study of NAs. Furthermore, a pilot study on the relationship between NAs and colorectal cancer was completed.

On-line solid phase extraction-ultra-high performance liquid chromatography coupled to tandem mass spectrometry for the determination of N-nitrosodiethanolamine in baby shampoo

N-nitrosodiethanolamine (NDELA) is a carcinogenic contaminant of concern in the cosmetics industry. Contaminated raw material, degradation, reactions of ingredients of the formulation, or migration of packaging material can be responsible for the presence of NDELA in the final product. Liquid chromatography coupled to tandem mass spectrometry is the most widely accepted technique for the quantitation of NDELA in cosmetic products. Still, there is no consensus regarding the sample preparation procedure. The aim of this work was to evaluate the performance of two-dimensional liquid chromatography coupled with tandem mass spectrometry for the determination of NDELA in shampoo. In the first dimension an Oasis HLB SPE-column was used and in the second dimension a CSH C18 column. NDELA-d₈ was used as an internal standard. The 2D-LC parameters were optimized by a central composite multivariate design. However, before quantitation, a sample preparation step using solid-phase extraction was necessary to eliminate compounds present in the formulation, especially surfactants that were not compatible with the chromatographic columns. Moreover, the complex matrices and singular compositions of shampoo from different manufacturers required adjustments of the sample preparation procedure for each sample. The limit of quantitation of the method for the determination of NDELA in shampoo was in the range of 5-10 ng g^-1. The accuracy of the method at the LOQ (10 ng g^-1) was 114 % and the inter-day precision of 15.3 % (n = 9). One sample out of 12 presented an NDELA concentration of 54 ng g^-1.

Progress in the pretreatment and analysis of N-nitrosamines: an update since 2010

As highly toxic substances, N-nitrosamines (NAs) have been proved to cause carcinogenesis and mutagenesis in humans. Therefore, to carefully monitor safety and preserve human health, the development of rapid, accurate, and high-sensitivity determination methods of NAs is of substantial importance. This review provides a current-status comprehensive summary of the pretreatment and determination methods of NAs in various samples since 2010. Common pretreatment methods that have been used to extract and purify targets include solid-phase extraction, liquid-liquid extraction and various microextraction methods, such as solid-phase microextraction and liquid-phase microextraction, among others. Determination methods include liquid chromatography, gas chromatography, supercritical fluid chromatography and electrochemical methods, among others. In addition, we discuss and compare the advantages and disadvantages of various pretreatment and analytical methods and examine the prospects in this area.

Acetonitrile wastewater treatment enhanced by a hybrid membrane-aerated bioreactor containing aerated and non-aerated zones

Acetonitrile (ACN) is a very volatile, toxic and nitrogen-rich organic compound. To enhance ACN wastewater treatment, a novel hybrid membrane-aerated bioreactor (MAB) containing aerated and non-aerated zones was established. A polypropylene hollow fiber membrane module (HF) and a silicone rubber membrane module (SR) were separately used as the bubble-free aeration diffuser and the biofilm carrier, and the non-aerated zones of these two types of reactors were packed with ceramsite. When the influent ACN loading was 1.200 kg/m³·d, under aeration pressures of 20 kPa in the HF-MAB and 40 kPa in the SR-MAB, ACN removal loadings of 1.116 kg/m³·d and 1.004 kg/m³·d, respectively, were achieved, and the TN (total nitrogen) removal loadings were 0.267 kg/m³·d and 0.246 kg/m³·d, respectively. In the MABs, different stratified biofilm structures of the two zones and the diffusion and counter-diffusion of oxygen synergistically promoted ACN degradation, nitrification and denitrification.

Electrochemical sensor for facile detection of trace N-nitrosodiphenylamine based on poly(diallyldimethylammonium chloride)-stabilized graphene/platinum nanoparticles

A simple and sensitive electrochemical sensor for the detection of trace N-nitrosodiphenylamine was constructed based on PDDA-stabilized graphene/platinum nanoparticles.

Analytical Method for Measurement of Tobacco-Specific Nitrosamines in E-Cigarette Liquid and Aerosol

An experimental method was developed and validated for the collection and analysis of tobacco-specific nitrosamines (TSNAs) that are present in electronic cigarette (EC) liquid or are released from aerosol samples using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system. As part of this study, the relative recovery of four target TSNAs was assessed by spiking standards in a mixture of propylene glycol and vegetable glycerin. Recovery was assessed against two major variables: (1) the chemical media (solution) selected for sample dilution (acetonitrile [ACN] vs. ammonium acetate [AA]) and (2) the type of sampling filter used (Cambridge filter pad [CFP] vs. quartz wool [QW] tube). The average recovery of TSNAs in terms of variable 1 was 134 ± 22.1% for ACN and 92.6 ± 8.27% for AA. The average recovery in terms of variable 2 was 83.4 ± 7.33% for QW and 58.5 ± 12.9% for CFP. Based on these conditions, the detection limits of N′-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N′-nitrosoanatabine (NAT), and N′-nitrosoanabasine (NAB) were calculated as 4.40, 4.47, 3.71, and 3.28 ng mL−1, respectively. The concentration of TSNAs in liquid and aerosol samples of six commercial EC solutions was measured as below the detection limit.

Rapid determination of hexavalent chromium in textiles by a novel ammonium pyrrolidine dithiocarbamate derivatization combined with UHPLC-MS/MS

Hexavalent chromium is mainly determined by traditional spectrophotometry, atomic absorption spectrometry, and ion chromatography methods. In the present work, a reliable ultra high performance liquid chromatography with tandem mass spectrometry method was firstly developed for the determination of hexavalent chromium in textiles. The sample was extracted by acetic acid/sodium acetate buffer solution and followed by derivatization with ammonium pyrrolidine dithiocarbamate. The resulting derivative product was extracted by ethyl acetate, separated on a C18 column, and detected through electrospray ionization source in the positive mode with multiple reaction monitoring conditions. The derivatization reaction conditions were investigated and optimized. The developed method was validated in terms of the sensitivity, linearity range, matrix effects, recovery, accuracy, intra- and interday precision. Results showed that the calibration curves of pure solvent and matrix were linear over the selected concentration ranges of 0.1-20.0 μg/L. The achieved instrument and method limit of quantification were 0.1 and 40.0 μg/kg, respectively. Recoveries were calculated at three spiked concentrations and the values were between 92.2 and 103% with relative standard deviation values of 2.7-4.9% for intra-day precision and 6.1% for inter-day precision. Successful analysis of hexavalent chromium in practical textiles indicated that there was hexavalent chromium contamination in textiles.

Determination of halquinol residual levels in animal-derived food products using liquid chromatography-tandem mass spectrometry

A reliable and highly sensitive detection method based on liquid chromatography coupled with triple quadrupole electrospray tandem mass spectrometry (LC-MS/MS) analysis has been developed for determination and quantification of halquinol, including 5,7-dichloroquinolin-8-ol and 5-chloroquinolin-8-ol. The target analytes were extracted from porcine muscle, egg, milk, eel, flatfish and shrimp using a mixture of acetonitrile and ethyl acetate followed by liquid-liquid purification with n-hexane. The analytes were separated on an Agilent Eclipse XDB-C₁₈ reversed-phase analytical column using 0.05% formic acid in distilled water and acetonitrile as mobile phases. Good linearity from six-point matrix-matched calibration was obtained with correlation coefficients (R² ) ≥ 0.9904. Recoveries from three spiking levels (5, 10 and 20 μg/kg) ranged between 70.6 and 101.7% in various matrices with relative standard deviations ≤8.6%. Samples acquired from markets located in Seoul, Republic of Korea, tested negative for the target analytes. In conclusion, the proposed method is versatile and precise for the routine detection of halquinol residual levels in animal-derived food products intended for human consumption.

Risk assessment of N-nitrosodiethylamine (NDEA) and N-nitrosodiethanolamine (NDELA) in cosmetics

N-nitrosamines and their precursors found in cosmetics may be carcinogenic in humans. Thus the aim of this study was to carry out risk assessment for N-nitrosamines (N-nitrosodiethanolamine [NDELA], N-nitrosodiethylamine [NDEA]) and amines (triethanolamine [TEA], diethanolamine [DEA]) levels in cosmetics determined using validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) procedures. NDELA and NDEA concentrations were present at levels of "not detected" (N.D.) to 596.5 μg/kg and N.D. to 40.9 μg/kg, respectively. TEA and DEA concentrations ranged from N.D. to 860 μg/kg and N.D. to 26.22 μg/kg, respectively. The nitrite concentration (3-2250 mg/l), number of nitrosating agents to a maximum 5, and pH (3.93-10.09) were also assessed. The impact of N-nitrosamine formation on the levels of TEA, DEA, nitrite, and other nitrosating agents was also examined. N-nitrosamine concentrations correlated with the number of nitrosating agents and nitrite concentrations. Data demonstrated that higher nitrite concentrations and a greater number of nitrosating agents increased NDELA and NDEA yields. Further, the presence of TEA and DEA exerted a significant influence on N-nitrosamine formation. Risk assessments, including the margin of exposure (MOE) and lifetime cancer risk (LCR) for N-nitrosamines and margin of safety (MOS) for amines, were calculated using product type, use pattern, and concentrations. Exposure to maximum amounts of NDELA and NDEA resulted in MOE > 10,000 (based upon the benchmark dose lower confidence limit 10%) and LCR <1 × 10^-5, respectively. In addition, TEA and DEA concentrations in cosmetic samples resulted in MOS values >100. Therefore, no apparent safety concerns were associated with cosmetic products containing NDELA, NDEA, TEA, and DEA in this study. However, since amines and nitrosating agents produce carcinogenic nitrosamines, their use in cosmetics needs to be minimized to levels as low as technically feasible.

Solid phase extraction with high polarity Carb/PSA as composite fillers prior to UPLC-MS/MS to determine six bisphenols and alkylphenols in trace level hotpot seasoning

The present study reports an ultra high-performance liquid chromatography tandem mass spectrometry method for the simultaneous determination of six bisphenols (bisphenol A, bisphenol B and bisphenol F) and alkylphenols (4-nonylphenol, 4-n-nonylphenol and octylphenol) in hotpot seasoning. Samples were dispersed in n-hexane after addition of internal standards bisphenol A-d₄ and 4-n-nonylphenol-d₄. Sample solutions were then centrifuged, and the supernatants purified using solid phase extraction with high polarity Carb/PSA composite fillers. Six target analytes were separated on a Waters ACQUITY BEH C18 column by gradient elution with methanol and 0.05% ammonium hydroxide in water as the mobile phase, and determined under multiple reactions monitoring mode. The limits of detection and quantitation, matrix effect, recovery and precision of the method were investigated. Results were linear in the concentration range 0.1-250 µg/L for all compounds of interest, with R² > 0.9950. Limits of detection were in the range 0.1-0.4 μg/kg, and limits of quantitation were between 0.5 μg/kg and 1.0 μg/kg. The mean recoveries for negative samples at three spiked concentrations were in the range 87.9%-102.4%, and the intra-day precision and inter-day precision were in the ranges 2.1-8.2% and 4.8-11.2%, respectively. This method is accurate and sensitive, and had good clean-up characteristics, which might apply to screening and quantitation of target bisphenols and alkylphenols in hotpot seasoning.

Formation and inhibition of N-nitrosodiethanolamine in cosmetics under pH, temperature, and fluorescent, ultraviolet, and visual light

N-nitrosodiethanolamine (NDELA), a type of nitrosamine, is a possible human carcinogen that may form in cosmetic products. The aim of this study was to examine the formation and inhibition of NDELA through chemical reactions of secondary amines including mono-ethanolamine, di-ethanolamine (DEA), and tri-ethanolamine (TEA), and sodium nitrite (SN) under varying conditions such as pH, temperature, and fluorescent, ultraviolet (UV), and visual light (VIS) using liquid chromatography-mass spectroscopy. In a mixture of TEA and SN under acidic conditions pH 2, residual NDELA concentrations rose significantly under various storage conditions in the following order: 50°C > 40°C > UV (2 W/m²) > VIS (4000 lux) > fluorescent light > 25°C > 10°C. In a mixture of DEA and SN under the same acidic pH 2 conditions, NDELA formation was significantly elevated in the following order: UV (2 W/m²) > VIS (4000 lux) > 50°C > 40°C > fluorescent light > 25°C > 10°C. Inhibition of NDELA formation by d-mannitol, vitamin C (Vit C), or vitamin E (Vit E) was determined under varying conditions of pH, temperature, and fluorescent, UV, and VIS. At high concentrations of 100 or 1000 µg/ml, Vit E significantly decreased residual NDELA compared with control levels under acidic pH 2, but not under basic pH 6. Among various antioxidants, Vit E reacted more effectively with many nitrosating agents such as nitrate and nitrite found in cosmetic products. Therefore, to reduce NDELA, it is recommended that cosmetics be stored under cool/amber conditions and that Vit E or Vit C inhibitors of nitrosation be optimally added to cosmetic formulations at concentrations between 100 and 1000 µg/ml.

Current trends in sample preparation for cosmetic analysis

The widespread applications of cosmetics in modern life make their analysis particularly important from a safety point of view. There is a wide variety of restricted ingredients and prohibited substances that primarily influence the safety of cosmetics. Sample preparation for cosmetic analysis is a crucial step as the complex matrices may seriously interfere with the determination of target analytes. In this review, some new developments (2010-2016) in sample preparation techniques for cosmetic analysis, including liquid-phase microextraction, solid-phase microextraction, matrix solid-phase dispersion, pressurized liquid extraction, cloud point extraction, ultrasound-assisted extraction, and microwave digestion, are presented. Furthermore, the research and progress in sample preparation techniques and their applications in the separation and purification of allowed ingredients and prohibited substances are reviewed.

Solid-phase extraction coupled with ultra performance liquid chromatography tandem mass spectrometry to determine seven halogenated salicylanilides in cosmetics

A solid-phase extraction (SPE) purification coupled with ultra performance liquid chromatography tandem mass spectrometry (SPE-UPLC-MS/MS) method was developed for simultaneous determination of seven halogenated salicylanilides in cosmetics.