Chinese Journal of Chromatography

2022, Vol. 40, No. 12
Online: 08 December 2022

CN 21-1185/O6
ISSN 1000-8713
Editors-in-Chief: Prof. Yukui Zhang
For Selected: Toggle Thumbnails
Adsorption characteristics of six bisphenol compounds on magnetic three-dimensional nitrogen-doped carbon nanomaterials and their use in effervescent reaction-assisted dispersive microextraction
LIU Tingting, WANG Qi, YE Hanzhang, KONG Jia, LI Yuhao, GU Jingjing, DING Yongli, ZHANG Zhan’en, WANG Xuedong
2022, 40 (12):  1049-1063.  DOI: 10.3724/SP.J.1123.2022.03041
Abstract ( 26 )   HTML ( 7 )   PDF (7525KB) ( 8 )  

Herein, we successfully prepared magnetic Co/Ni-based N-doped 3D carbon nanotubes and graphene nanocomposites (CoNi@NGC) using a simple high-temperature calcination method. The CoNi@NGC nanocomposites were used as adsorbents to study their adsorption performances and underlying kinetic mechanisms for six types of bisphenol compounds (BPs) in water. They were also used as extractants, and acid-base effervescent tablets were used to enhance extractant dispersion with the aid of vigorous CO2 bubbling. Thus, a novel pretreatment method was developed, denoted effervescent reaction-assisted dispersive solid-phase microextraction (ER-DSM), which was combined with high performance liquid chromatography-fluorescence detection (HPLC-FLD) to rapidly quantify trace-level BPs in several drinks. The morphology and structure of the CoNi@NGC adsorbent were characterized in detail using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption and desorption (BET-BJH), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). The CoNi@NGC nanocomposites were successfully doped with N and exhibited large specific surface areas (109.42 m2/g), abundant pores, and strong magnetic properties (17.98 emu/g).
Key parameters were rigorously optimized to maximize the adsorption performance of CoNi@NGC, including adsorbent dosage, solution pH, temperature, and time. Under the constant conditions of pH=7, 5 mg of CoNi@NGC, initial BP concentrations of 5 mg/L, and 5 min of shaking at 298 K, the adsorption percentages of bisphenol M (BPM) and bisphenol A (BPA) reached respective maxima of 99.01% and 98.21%. Remarkably, those of bisphenol Z (BPZ), BPA, and BPM reached almost 100% after 90 min. The adsorption between the BPs and CoNi@NGC was mainly governed by hydrogen bonds, electrostatic interactions, and π-π conjugation. The entire adsorption process was consistent with Freundlich adsorption and a quasi-second-order kinetic equation, representing spontaneous adsorption. Via integration with HPLC-FLD, ER-DSM was used to rapidly extract and analyze trace-level BPs in six types of boxed drinks. Critical factors were optimized individually, including the type of eluent and elution time and volume, which influenced the enrichment effect. Under the optimized extraction conditions (pH=7, 5 mg CoNi@NGC, elution with 2 mL acetone for 6 min), the limits of detection and quantification of the novel extraction method were 0.06-0.20 and 0.20-0.66 μg/L, respectively. The intra- and inter-day precisions spanned the ranges 1.44%-4.76% and 1.69%-5.36%, respectively, and the recoveries in the actual samples were in the range 82.4%-103.7%. Moreover, the respective residual levels of BPA and BPB in peach juice samples were 2.09 and 1.37 μg/L. Regeneration studies revealed that the CoNi@NGC adsorbent could be reused at least five times, which significantly reduced the cost of evaluation. In summary, compared to other methods, this method displays the advantages of a high sensitivity, rapid extraction, and environmental friendliness, thereby exhibiting considerable potential for use in conventional monitoring of trace-level BPs in food matrices.

Determination of 107 typical pesticides and metabolites in raw water and drinking water by online-solid phase extraction coupled with ultra performance liquid chromatography-triple quadrupole mass spectrometry
CHEN Yongyan, LÜ Jia, ZHANG Lan, YE Bixiong, JIN Ning
2022, 40 (12):  1064-1075.  DOI: 10.3724/SP.J.1123.2022.07011
Abstract ( 20 )   HTML ( 8 )   PDF (2232KB) ( 8 )  

In order to monitor the risk of pesticide pollutants in drinking water, an analytical method based on online-solid phase extraction coupled with ultra performance liquid chromatography-triple quadrupole mass spectrometry (online-SPE-UPLC-MS/MS) was established for the simultaneous rapid screening and determination of 107 pesticides and metabolites (organophosphorus, organic nitrogen, organic heterocycle, carbamate, amide, benzoyl urea, neonicotinoid, etc.) in raw water and drinking water. Different injection volumes (5, 10, and 15 mL) were compared. The detection response increased with an increase in the injection volume, but the matrix effect also became more pronounced. Under the premise of ensuring the sensitivity of the method and meeting the detection requirements, the injection volume was selected as 5 mL. Accordingly, the samples were filtered through a 0.22-μm hydrophilic polytetrafluoroethylene filter, and then, 5 mL samples were injected into the online-SPE system by the automatic sampler. After adsorption on an X Bridge C18 online-SPE column, the samples were washed with pure water and eluted by gradient elution using acetonitrile and 0.1% formic acid aqueous solution as the mobile phases, with separation on an ACQUITY HSS T3 column. The samples were detected by multiple reaction monitoring with electrospray ionization in positive and negative ion modes, and quantified by an external standard method. Using raw water and drinking water as the sample matrices, the accuracy and precision of the method were verified. The 107 pesticides and metabolites showed good linear relationships in different ranges with correlation coefficients (r2)>0.995. The limits of detection (LODs, S/N=3) of the method were 0.03-1.5 ng/L, and the limits of quantification (LOQs, S/N=10) were 0.1-5.0 ng/L. The target pesticides were spiked at concentration levels of 1, 20, and 50 ng/L. The spiked recoveries of the 107 targets in raw water and drinking water samples were 60.6%-119.8% and 61.2%-119.0%, respectively. The corresponding relative standard deviations (RSDs, n=6) were 0.3%-18.6% and 0.4%-17.1%. The pesticide residues in raw water and drinking water were determined by this method. Amide herbicides, triazine herbicides, triazole insecticides, carbamate insecticides, and neonicotinoid insecticides had high detection rates. The detected concentrations ranged from 0.1 to 97.1 ng/L in raw water and from 0.1 to 93.6 ng/L in drinking water. The sample consumption of online-SPE method was lower than that in the traditional off-line SPE methods, which greatly improved the convenience of sample collection, storage, and transportation. The samples only need to be filtered before injection and analysis. The method is simple to operate and shows good reproducibility. With this online-SPE method, only 23 min were required from online enrichment to detection completion. The developed method has the advantages of high analytical speed and high sensitivity. The method is suitable for the trace analysis and determination of 107 typical pesticides in raw water and drinking water, which effectively improves the detection efficiency of pesticides in water and has high potential for practical application. It can extend technical support for the pollution-level analysis of typical pesticides and metabolites in drinking water and provide an objective basis for human health risk assessment.

Determination of multi-veterinary drug residues in complementary foods for infants and young children by ultra performance liquid chromatography-tandem mass spectrometry
LUO Ruilian, WU Zhengshuang, LIANG Chiqiong, LUO Liting
2022, 40 (12):  1076-1086.  DOI: 10.3724/SP.J.1123.2022.03039
Abstract ( 43 )   HTML ( 6 )   PDF (2482KB) ( 24 )  

Special attention must be paid to children and infants because health issues stemming from a poor immunologic system and low weight make them a vulnerable risk group. Complementary foods for infants and young children, which are a class of special dietary foods, are essential transitional foods for infants from lactation to adaptation to ordinary food. Some complementary foods for infants and young children are of animal origin such as fish, meat, and the liver, which may contain veterinary drug residues. Veterinary drugs are usually small-molecular-weight chemicals that are essential for treating infections, increasing production, and improving animal husbandry. However, abuse of these substances can provoke transfer to the food chain, leading to negative consequences for humans, especially infants and young children. For a more comprehensive safety supervision of infant supplementary foods, a method based on ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed and used for the determination of 50 antibiotics and antivirals (grouped into six categories: fluoroquinolones, sulfonamides, macrolides, nitroimidazoles, chloramphenicols, and antivirals) in complementary foods for infants and young children. The matrix of complementary foods for infants and young children is complex and contains a large number of proteins and lipids, which poses a serious challenge for sample pretreatment. The Captiva EMR-Lipid solid-phase extraction (SPE) column is a new type of product that allows for selective and efficient lipid/matrix removal without negatively affecting the recovery of the analyte. In this study, samples were extracted with acidified acetonitrile and then purified using a Captiva EMR-Lipid SPE column. The target analytes were separated on a BEH C18 column by gradient elution using acetonitrile and water containing 0.1% (v/v) formic acid as the mobile phases. MS detection was performed with an electrospray source in the positive and negative modes in the multireaction monitoring (MRM) mode. The ion spray voltages were set at 5500 V and -4500 V in the positive and negative modes, respectively. The source temperature for both the ionization modes was set to 500 ℃. Instrumental parameters such as collision energy and declustering potential were optimized. The samples were quantified using the external standard method with matrix calibration curves to reduce the influence of the matrix effect on the quantitative results.
The results showed that the 50 veterinary drug residues had good linear relationships in the range of 0.5 to 50 μg/L, with correlation coefficients higher than 0.995. The limits of detection (LODs) and quantification (LOQs) were in the range of 0.03-0.70 μg/kg and 0.09-2.33 μg/kg, respectively. The average recoveries for all the compounds under different matrices ranged from 64.37% to 119.3% at spiked levels of 5 μg/kg and 50 μg/kg, with relative standard deviations of less than 15%. Compared to QuEChERS, this method has a better purification effect. The recoveries of the 50 veterinary drugs extracted by this method were also much higher than those in the case of QuEChERS. This method was applied to the detection of 14 domestic and six imported infant supplementary foods. Sulfaquinoxaline, sulfamethazine, and tilmicosin were detected in one imported meat-based baby food. With its simple operation, high sensitivity and accuracy, and low sample quantity consumption, this method is suitable for the determination of multiveterinary drug residues in complementary foods for infants and young children. This study provides an effective analysis method for risk monitoring and troubleshooting of complementary foods for infants and young children, which is of great significance in ensuring the healthy growth of the next generation.

Determination of paraquat and diquat residues in urine samples based on solid-phase extraction and ultra performance liquid chromatography-high resolution mass spectrometry
PAN Shengdong, WANG Li, QIU Qiaoli, HE Qian
2022, 40 (12):  1087-1094.  DOI: 10.3724/SP.J.1123.2022.02012
Abstract ( 67 )   HTML ( 10 )   PDF (1320KB) ( 40 )  

Determining the presence of paraquat (PQ) and diquat (DQ) in urine samples through physical and chemical testing is challenging. As PQ and DQ have characteristics such as high molecular polarity and good water solubility, they are difficult to be retained by conventional reversed-phase columns. Most of the methods in the literature use hydrophilic interaction chromatography (HILIC) for the retention of PQ and DQ, but they often require high concentrations of buffer salts as the mobile phase, which increase the contamination of the mass spectrometer. In view of the above problems, a rapid and accurate analysis method was developed for the determination of PQ and DQ residuals in urine samples based on weak cation exchange (WCX) solid-phase extraction (SPE) and ultra performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS) in this study. Urine samples were first diluted with phosphate buffer (pH=6.86) and pretreated using the WCX SPE method. Chromatographic separation was performed on a Syncronis HILIC column (100 mm×2.1 mm, 1.7 μm). An electrospray ion source in the positive (ESI+) mode and full mass-data dependent MS2 (full mass-ddMS2) mode was used for quantification by matrix-matched external standard method. In this study, the concentration of ammonium formate in the mobile phase in the HILIC mode was effectively reduced to 10 mmol/L by the continuous optimization of the chromatographic conditions. MS optimization results indicated that the molecular ion (M) of PQ and DQ had the strongest response. In addition, sample pretreatment conditions were also optimized. The obtained results indicated that the hydrophobic polytetrafluoroethylene (PTFE) filter membrane, acetonitrile-water (1∶1, v/v) as a fixing solution, and polypropylene vials were suitable for PQ and DQ analysis. Under the optimal conditions, the linearity of PQ and DQ was good with correlation coefficients (r2) greater than 0.998. The limits of detection (LODs, S/N≥3) and limits of quantification (LOQs, S/N≥10) were 0.2 μg/L and 0.6 μg/L, respectively. Mean spiked recoveries of PQ and DQ at the four spiked levels (1.0, 20.0, 100.0, and 200.0 μg/L) were in the range of 85.8%-101% and 80.3%-86.9%, with the RSDs of 0.8%-5.1% and 0.9%-4.2%. The established method was employed for the analysis and confirmation of PQ and DQ for clinical poisoning cases. In one case, a 23-year-old male who had taken approximately 20 mL of pesticide orally was confirmed as DQ poisoning by the developed method. DQ concentration monitoring of the urine samples was conducted for this case during the clinical treatment process. The patient was successfully discharged from the hospital after five times of blood perfusion and other treatments until the DQ concentration was low in the urine samples. In conclusion, the method developed in this study based on WCX SPE-UPLC-HRMS can be used for the confirmation of poisoning cases and concentration monitoring during clinical treatment, providing strong technical support for clinical precision treatment. The method is rapid, simple, sensitive, and accurate, and it is suitable for the detection of PQ and DQ in urine samples.

Simultaneous determination of three components of sodium nitrophenolate in foodstuffs of animal origin by high performance liquid chromatography-tandem mass spectrometry using atmospheric pressure chemical ionization
ZOU You, SHAO Linzhi, LAN Cao, CHEN Simin
2022, 40 (12):  1095-1101.  DOI: 10.3724/SP.J.1123.2022.03006
Abstract ( 22 )   HTML ( 3 )   PDF (1089KB) ( 5 )  

Sodium nitrophenolate (SNP) is a widely used universal growth regulator consisting of 5-nitroguaiacol sodium (5NG), 4-nitrophenol sodium (PNP), and 2-nitrophenol sodium (ONP). SNP has a positive influence on plants and animals as a feed additive that accelerates growth but is potentially hazardous to humans. SNP has been reported to be cytotoxic and mutagenic, which may increase the risk of cancer and pose a great threat to food safety. There are neither mature detection nor standard methods for the trace analysis of SNP in animal food. Therefore, the development of an accurate and precise analytical method is imperative. This innovative method has theoretical and practical significance for the control of SNP residues, offering advantages such as cost-effectiveness and time efficiency. It will be beneficial for the establishment of detection standards and management measures in foodstuffs of animal origin.
In this study, a reliable method for the simultaneous determination of SNP residues in animal food (porcine muscle, chicken tissue, fish, and liver) was developed. For realizing the perfect limit of quantification, the application of back extraction coupled with high performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (HPLC-APCI-MS/MS) was proposed to combine high sensitivity and high selectivity. The optimal method was as follows. First, 2.0 g samples were extracted with 10 mL 0.5 mol/L sodium hydroxide solution, followed by adjustment of the pH to acidity with 3 mol/L hydrochloric acid and the addition of sodium chloride (5.0 g) to saturate the inorganic phase. After back-extraction twice with 16 mL acetonitrile, the solution was merged and again saturated with 5 mL of sodium chloride solution. Second, the merged organic phase was cleaned up with 10 mL of n-hexane for defatting. The middle acetonitrile layer was then concentrated to nearly 1.5 mL at 40 ℃ in a N2 stream before dilution with the mobile phase to a volume of 3.0 mL and filtered. Finally, the analytes were separated on a C18 column (100 mm×4.6 mm, 3 μm) and subjected to gradient elution with a mixed solution of methanol and water. Mass spectrometric analysis, which was quantified using the external standard method, was carried out with an atmospheric pressure chemical ionization negative ion source and based on multiple reaction monitoring (MRM) mode. The key parameters, such as the extraction solvent, extraction steps, and purification method, were optimized.
The calibration curves were linear in the ranges of 0.5-10 (5NG), 1.0-20 (PNP), and 2.5-50 μg/L (ONP) with correlation coefficients greater than 0.9999. The limit of quantification (LOQ) for 5NG was 1.0 μg/kg, double for PNP, and five times for ONP. The recoveries of the three different concentration levels in all the four matrices were in the range of 81.5%-98.4%, 81.5%-102%, and 81.4%-95.1%. The repeatability, expressed as the relative standard deviations (RSDs) of the three compounds, ranged from 1.51% to 5.98%, 1.10% to 8.85% and 0.91% to 8.61% (n=6). The developed method is characterized by an excellent purification effect, sensitivity, and accuracy. This method is suitable for the simultaneous and quantitative determination of SNP residues in foodstuffs of animal origin.

Quality evaluation of Fufang Jinqiancao granules based on ultra performance liquid chromatography-ultraviolet detection quantitative fingerprint combined with chemical pattern recognition
LU Shaoming, XU Xin, XUE Qianqian, XIAO Liujun, YU Wenyi, WEI Tong, JIN Hongli, LIU Yanfang, LIANG Xinmiao
2022, 40 (12):  1102-1110.  DOI: 10.3724/SP.J.1123.2022.07021
Abstract ( 10 )   HTML ( 4 )   PDF (3043KB) ( 2 )  

Fufang Jinqiancao granules have a large market demand due to the fact that they contain diuretics, inhibit urinary calculi formation, and exhibit both anti-inflammatory and antioxidant effects. In the current study, a fast and efficient quantitative ultra performance liquid chromatography-ultraviolet detection (UPLC-UV) fingerprinting method was established to analyze the Fufang Jinqiancao granules, while a chemical pattern recognition technology was used to evaluate the quality of the granules over different years. More specifically, the UPLC-UV system consisted of a Waters Acquity UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm), acetonitrile (mobile phase A), and a 0.1% formic acid aqueous solution (mobile phase B), wherein a gradient elution protocol was followed. Ultra performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS, Agilent Infinity Ⅱ 1290-6545) was used in combination with reference substances and literature comparisons to identify the common peaks present in the quantitative fingerprint. The fingerprints of 35 batches of Fufang Jinqiancao granules were established by means of the quantitative UPLC-UV fingerprinting method, and the fingerprint data obtained for these samples were further analyzed by chemical pattern recognition techniques, including hierarchical cluster analysis (HCA) and principal component analysis (PCA). The quality difference markers, namely mangiferin and isomangiferin, were screened, and their contents were determined. It was found that 12 common peaks existed in the fingerprint of the Fufang Jinqiancao granules, and the similarities of all 35 batches of samples were greater than 0.952. In addition, for the purpose of HCA, the 35 batches were divided into two categories, of which sample years 2018 and 2019 belonged to one category, and sample years 2020 and 2021 belonged to another category. Notably, PCA gave the same clustering trends as HCA. Based on the obtained results, the mangiferin and isomangiferin components responsible for the differences between the 2018, 2019 and 2020, 2021 samples were further screened by orthogonal partial least squares discriminant analysis (OPLS-DA). Moreover, the contents of the 35 batches of samples were determined using the two differential markers mangiferin and isomangiferin as indicators. The obtained results indicated that the chromatographic peaks of all 35 batches had acceptable resolutions, with mangiferin exhibiting a good linear relationship in the range of 5.3291-133.2276 mg/L, and isomangiferin exhibiting a similar linear relationship in the range of 4.1847-104.6170 mg/L. The average recovery of mangiferin was 101.7%-105.6%, with a relative standard deviation (RSD) of 0.63%-1.43%, while that of isomangiferin was 103.4%-105.5%, with an RSD of 0.60%-1.18%. Importantly, all RSD values were less than 1.43%, thereby indicating that our method meets the requirements of the Chinese Pharmacopoeia (2020 Edition). Among the 35 batches of samples, the contents of mangiferin and isomangiferin were higher in the 2020 and 2021 samples, and the content fluctuation range was smaller. Overall, the development of an accurate and reliable quality control method for Fufang Jinqiancao granules, and a reasonable and effective quality evaluation of Fufang Jinqiancao granule samples from different years was realized. We therefore expect that this study will provide a reference for establishing a more systematic and comprehensive quality control system.

Determination of 16 particle-phase polycyclic aromatic hydrocarbons in herbal incense by ultrasonic extraction-gas chromatography-mass spectrometry and analysis of emission characteristics
CAI Meizhen
2022, 40 (12):  1111-1118.  DOI: 10.3724/SP.J.1123.2022.01022
Abstract ( 17 )   HTML ( 3 )   PDF (1513KB) ( 6 )  

Polycyclic aromatic hydrocarbons (PAHs) have attracted global attention because they are carcinogens and mutagenic to humans. To date, more than 200 PAHs have been found. The United States Environmental Protection Agency (USEPA) has designated 16 PAH species as priority control pollutants due to their highly toxic substances. Herbal incense is frequently used in daily life. As a result, it is critical to investigate its impact on human health and environmental safety. However, research on particle-phase PAHs is very limited and inapplicable. The current research focuses mainly on bamboo incense, which has a simpler formula than herbal incense.
In this study, the emission factor and emission characteristics of particle-phase PAHs from herbal incense were described. A method combining ultrasonic and gas chromatography-mass spectrometry (GC-MS) was developed for the simultaneous determination of 16 particle-phase PAHs of herbal incense. The settings for extraction solvent, ultrasonic time, and instrument analysis conditions were optimized. In the test chamber, samples were collected by burning 0.8 g of herbal incense. After combustion, PAHs adsorbing on the particles of herbal incense were collected on a quartz filter. The whole filter sample was sliced and extracted with n-hexane-dichloromethane (1∶1, v/v). A rotary evaporator was used to concentrate the extract. GC-MS was used to analyze the prepared sample. The internal standard method was used to perform quantitative analysis on the target compounds. The linearities of the 16 target PAHs were good between mass concentrations of 0.1-5.0 μg/mL, with correlation coefficients greater than 0.998. The method detection limits (MDLs) of the 16 PAHs ranged from 0.4 to 3.8 ng/g. The 0.625 μg/g and 1.25 μg/g spiked recoveries ranged from 77.4% to 99.5% and 82.0% to 101.3%, respectively. The relative standard deviations (RSDs) of the 16 PAHs were ranged from 0.7% to 7.2% (n=6). The emission factors of particle-phase PAHs from five different kinds of herbal incense ranged from 4.60 to 11.89 μg/g. The highest concentration of phenanthrene (Phe) was found in 16 particle-phase individual PAHs of herbal incense. Fluoranthene (Flu), pyrene (Pyr), chrysene (Chr) and anthracene (Ant) concentration were ranked after Phe. The sum of these five proportions was 73.00%-89.97%. The proportion of Phe in herbal incense particle-phase PAHs was significantly higher than that of other indoor combustion sources. As a result, Phe could be used to identify individual PAHs in the particle-phase of herbal incense. The particle-phase PAHs were mainly distributed on the 3-ring and 4-ring, with a sum of 83.84% to 96.31% on the 3-ring and 4-ring. The proportion of high-molecular weight PAHs in the samples ranged from 44.25% to 63.31%. The proportion of low-molecular weight PAHs in the samples ranged from 36.69% to 55.75%. The incense source could be distinguished from other indoor combustion sources by its distinctive Phe/Flu ratio. The established method has high sensitivity, simple operation, and requires fewer samples. This method is suitable for rapidly detecting PAHs in burning incense. At the same time, it provides scientific data for further studies on the distribution and health effects of particle-phase PAHs of herbal incense.

Rapid screening of 14 antibacterial drugs in anti-acne cosmetics using ion mobility spectrometry coupled with solid-phase extraction
XUE Gaoxu, WANG Qinyi, CAO Ling, SUN Jing, YANG Gongjun, FENG Youlong, FANG Fang
2022, 40 (12):  1119-1127.  DOI: 10.3724/SP.J.1123.2022.05025
Abstract ( 10 )   HTML ( 3 )   PDF (878KB) ( 2 )  

The main methods currently used to detect illegally added chemicals in cosmetics include thin-layer chromatography, high performance liquid chromatography (HPLC), gas chromatography (GC), and liquid chromatography-mass spectrometry (LC-MS). Compared with other analytical techniques, these methods have the advantages of high sensitivity, specificity, and accuracy, all of which are required in practical detection work. However, they also present a number of limitations, such as long analysis times and requirements for skilled operators and strictly controlled laboratory environments. Supervision, a growing trend in market surveillance, requires rapid and effective methods to screen illegally added chemicals. The suspected samples are sealed for some time and then sent to the laboratory for further testing. Ion mobility spectrometry (IMS) is a new type of trace gas separation technology that was developed in recent years. The principle behind IMS is the separation and characterization of chemical species based on differences in the migration speed of their gas-phase ions under an electric field. As this technology has the advantages of miniaturization, easy operation, and quick responses, it is widely used in food and drug quality testing, as well as other related fields. However, it is rarely used in cosmetic detection, likely because the cosmetics matrix is highly complex, which can interfere with ion determination. Thus, optimizing the pretreatment process of cosmetics for IMS is important. In this work, solid-phase extraction (SPE) is combined with IMS to establish a method for the rapid screening of 14 antibacterial drugs in anti-acne cosmetics. The IMS detection parameters, sample extraction conditions, and SPE clean-up conditions (SPE column, type of leachate, type and volume of eluent) were studied and optimized in detail. The sample was extracted with 80%(v/v) acetonitrile aqueous solution (containing 0.2% (mass fraction) trichloroacetic acid), loaded onto an activated Oasis® MCX SPE column, leached with 3.0 mL of methanol, and eluted with 1.0 mL of 2% ammonia methanol solution. The eluate was then directly injected into the IMS instrument. The IMS parameters were as follows: positive ion source voltage=2200 V, transfer tube voltage=8000 V, inlet temperature=180 ℃, transfer tube temperature=180 ℃, ion gate voltage=50 V, gate voltage pulse width=85 μs, and migration gas flow rate=1.2 L/min. The migration times for the 14 antibacterial drugs ranged from 11 to 17 ms, and the detection limits for the target compounds ranged from 0.2 to 1.2 μg/g. Owing to the narrow linear range of IMS, a quantitative method employing HPLC was also established to optimize the SPE pretreatment step and verify the positive samples. Chromatographic separation was conducted on a Phenomenex Luna C18 column (250 mm×4.6 mm, 5 μm), with a column flow rate of 1.0 mL/min and gradient elution with mobile phases A (0.01 mol/L potassium dihydrogen phosphate adjusted to pH 4.0 with phosphoric acid) and B (acetonitrile). The column temperature was set to 35 ℃, and the injection volume was fixed at 5 μL. A total of 25 cosmetics samples were screened, and one positive sample was found to be consistent with the results of HPLC. The proposed method is fast, simple, and efficient, and it can be used for the rapid screening of the 14 antibacterial drugs in anti-acne cosmetics. Pretreatment can significantly reduce the influence of the cosmetic matrices on the determination results, improve instrument sensitivity, and effectively decrease the occurrence rate of false positives and negatives. The technique developed in this work can improve the efficiency of screening for illegally added chemicals and expand the applications of IMS for detecting various chemicals in complex matrices, such as cosmetics.

Technical Notes
Determination of 10 organic acids in alcoholic products by ion chromatography-tandem mass spectrometry
MU Yingqi, WU Yixuan, WANG Xiao, HU Liming, KE Runhui
2022, 40 (12):  1128-1135.  DOI: 10.3724/SP.J.1123.2022.01020
Abstract ( 35 )   HTML ( 3 )   PDF (1214KB) ( 18 )  

A method was developed for the determination of 10 organic acids in liquor, yellow rice wine, and dry red wine by ion chromatography-triple quadrupole mass spectrometry (IC-MS/MS). First, the liquor samples were diluted with deionized water, degassed with nitrogen, and analyzed by IC-MS/MS. Then, the yellow rice wine and dry red wine samples were purified with different solid-phase extraction cartridges. Finally, the GCB solid-phase extraction cartridge was selected for purification, diluted with deionized water, and analyzed by IC-MS/MS. The samples were separated using a Dionex IonPac AS11-HC anion analysis column with high capacity and strong hydrophilicity, with an KOH aqueous solution as the eluent, which was produced by an automatic generator for gradient elution. After being suppressed using a suppressor, the eluent was injected directly into the electrospray ionization tandem mass spectrometry (ESI-MS/MS), ionized in negative ion mode, detected in multiple reaction monitoring (MRM) mode, and quantified using an external standard method. Oxalic acid, fumaric acid, maleic acid, malic acid, tartaric acid, citric acid, quinic acid, and aconitic acid showed good linear relationships in the range of 0.05-2 mg/L. Succinic acid and lactic acid showed good linearities in the range of 0.05-5 mg/L and 0.05-10 mg/L, respectively. The correlation coefficients (r2) were >0.99. The limits of detection (LODs) and limits of quantification (LOQs) were 1.0-8.0 μg/L and 3.5-26.5 μg/L, respectively. The average recoveries ranged from 83.0% to 112.1%, and the relative standard deviations (RSDs) were <9.1% in spiked samples at three levels. The proposed method allowed easy pretreatment without using organic solvents or derivatization processing. Overall, the proposed method is accurate, rapid, sensitive, and it is suitable for the qualitative and quantitative analyses of the 10 organic acids in three wine samples. Moreover, it can be used for the determination of flavor and quality of alcoholic products.

Rapid determination of 10 fat-soluble vitamins in health foods by ultra performance convergence chromatography
LI Jiachen, CAO Ling, FANG Fang, SHI Haiwei, HUANG Qing, TAN Li, DUAN Qiaolian, FENG Youlong
2022, 40 (12):  1136-1142.  DOI: 10.3724/SP.J.1123.2022.02010
Abstract ( 32 )   HTML ( 5 )   PDF (1425KB) ( 9 )  

Fat-soluble vitamins are important efficacy indicators in health foods because they are essential for human physiological functions. The existing method for the simultaneous determination of fat-soluble vitamins has various problems, such as limited determination components, complex sample, pretreatment process, and high requirements for personnel operating ability. Therefore, establishing a fast, simple, and accurate method that can detect various common fat-soluble vitamins at the same time is necessary. In this study, a method for the simultaneous determination of 10 commonly used fat-soluble vitamins such as vitamin A acetate (VA acetate), vitamin A palmitate (VA palmitate), vitamin E acetate (VE acetate), vitamin K1 (VK1), α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol, vitamin D2(VD2) and vitamin D3 (VD3) in health foods was established by ultra performance convergence chromatography (UPC2). First, the contents of about 1.0 g of capsule samples were accurately weighed. A grinder was used to grind tablet samples into powder. The powder mixture was then precisely weighed at 2.0 g. Both substances were placed in 50 mL brown stopper tubes. The test tube was then filled with 20 mL 75% dimethylsulfoxide (DMSO) aqueous solution for demulsification. The tubes were then sonicated before being extracted with n-hexane. The centrifuged supernatant was added to vials for detection. Viridis HSS C18 SB column (100 mm×3.0 mm, 1.8 μm) was applied and CO2 was used as the mobile phase A. After comparing the influence of acetonitrile, methanol, and their mixture on chromatographic peak separation, acetonitrile-methanol (85∶15, v/v) was used as the mobile phase B. The injection volume was 1 μL. Using simulator software, the optimal chromatographic conditions were obtained after a set of three-factor orthogonal experiments of flow rate, gradient slope, and column temperature. The flow rate and column temperature were both set at 1.9 mL/min and 30 ℃. Furthermore, the maximum absorption wavelength of these 10 fat-soluble vitamins was selected for detection. Ten vitamins were baseline separated after 7 min of gradient elution. The limits of detection (LODs) and quantification (LOQs) of capsule samples were 0.4-60 μg/g and 2-150 μg/g, respectively, whereas the results for tablet samples were 0.2-30 μg/g and 0.8-75 μg/g. The linear ranges of the 10 fat-soluble vitamins were 0.1-100 μg/mL. The recoveries of spiked samples ranged from 96.5% to 113.9%, with RSD values less than 4%. Precision, stability, and repeatability RSD values were all less than 2%. By comparison, the determination results of this method were basically consistent with the existing national food safety standards. This method is simple, rapid, sensitive, and accurate, and it can meet the detection requirements of the 10 fat-soluble vitamins in health foods. Simultaneously, this method lays the foundation for the rapid and simultaneous detection of fat-soluble vitamins in existing health foods.