Source apportionment and predictable driving factors contribute to antibiotics profiles in Changshou Lake of the Three Gorges Reservoir area, China.

Lakes, crucial antibiotic reservoirs, lack thorough exploration of quantitative relationships between antibiotics and influencing factors. Here, we conducted a comprehensive year-long investigation in Changshou Lake within the Three Gorges Reservoir area, China. The concentrations of 21 antibiotics spanned 35.6-200 ng/L, 50.3-348 ng/L and 0.57-57.9 ng/g in surface water, overlying water and sediment, respectively. Compared with abundant water period, surface water and overlying water displayed significantly high antibiotic concentrations in flat and low water periods, while sediment remained unchanged. Moreover, tetracyclines, fluoroquinolones and erythromycin posed notable risks to algae. Six primary sources were identified using positive matrix factorization model, with aquaculture contributing 21.2%, 22.7% and 25.4% in surface water, overlying water and sediment, respectively. The crucial predictors were screened through machine learning, redundancy analysis and Mantel test. Our findings emphasized the pivotal roles of water quality parameters, including water temperature (WT), pH, dissolved oxygen, electrical conductivity, inorganic anions (NO3⁻, Cl⁻ and F⁻) and metal cations (Ca, Mg, Fe, K and Cr), with WT influencing greatest. Total nitrogen (TN), cation exchange capacity, K, Al and Cd significantly impacted sediment antibiotics, with TN having the most pronounced effect. This study can promise valuable insights for environmental planning and policies addressing antibiotic pollution.

Efficient degradation of 2,4-dichlorophenol in water by sequential electrocatalytic reduction and oxidation with a Pd-MWCNTs/Ni-foam electrode.

Our previous study indicated excellent dechlorination efficiency and phenol conversion rate in the electrocatalytic reduction of 2,4-dichlorophenol (2,4-DCP) with a Pd-MWCNTs/Ni-foam electrode; it is deserved to investigate whether this electrode can efficiently degrade phenol in electro-Fenton oxidation (EFO) process and realize the effective mineralization of 2,4-DCP in aqueous solution. In this work, the sequential electrocatalytic reduction and oxidation of 2,4-DCP were studied after examining phenol degradation in the EFO process. The results showed that the removal efficiency of 0.31 mM phenol could reach 96.76% after 90-min degradation with the rate constant of 0.0367 min-1, and hydroxy radicals (·OH) were the main active species in the EFO process. In the sequential electrocatalytic reduction and oxidation processes, the removal efficiencies of 2,4-DCP, phenol, and total organic carbon (TOC) reached 99.72%, 97.07%, and 61.45%, respectively. The possible degradation mechanism of 2,4-DCP was proposed through monitoring the reaction products, and the stability and reusability of the electrode were also examined. This study suggested that 2,4-DCP in wastewater can be effectively mineralized to realize its efficient degradation through the sequential electrocatalytic reduction and oxidation.

A comparative study of tea polyphenols and its palmitic acid-modified derivatives: their effects on the microbial ecosystem and biogenic amines in Chinese sausage.

Control of biogenic amines (BAs) is important to guarantee the safety of sausage-like fermented meat products. This study investigated the influences of tea polyphenols (TP) and its lipophilic palmitic acid-modified derivatives, palmitoyl-TP (pTP) and palmitoyl-epigallocatechin gallate (pEGCG), on BAs and microbial ecosystem in Chinese sausages. TP, epigallocatechin gallate (EGCG), pTP, and pEGCG all reduced the formation of BAs and N-nitrosodimethylamine at 0.05% (g/g); yet, compared with TP and EGCG, the modified derivatives exhibited stronger action on BAs decreasing (P < 0.05), and pEGCG showed the highest effect (a reduction of total BAs from 376.22 to 168.98 mg/kg compared to control). The improved inhibitory effect of pTP and pEGCG should be attributed to their stronger dual-directional regulation of the bacterial and fungal communities during the natural fermentation of sausage. The modified pTP and pEGCG highly suppressed the growth of Staphylococcus, Candida, and Kurtzmaniella, all of which were positively correlated with BAs formation (all P < 0.05). However, pTP and pEGCG worked more effectively than the unmodified ones to promote Lactobacillus, Lactococcus, and Debaryomyces (all P < 0.05). The results above are significant for the application of palmitoyl-TP and similar TP derivatives in meat products in consideration of food safety. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05717-z.

Changes in N-nitrosamines, Residual Nitrites, Lipid Oxidation, Biogenic Amines, and Microbiota in Chinese Sausages Following Treatment with Tea Polyphenols and Their Palmitic Acid-modified Derivatives.

This study aimed to investigate the effects of tea polyphenol (TP), epigallocatechin gallate (EGCG), and their palmitic acid-modified derivatives palmitoyl-TP (pTP) and palmitoyl-EGCG (pEGCG) on the accumulation of N-nitrosamine and biogenic amines (BAs), residual nitrites, and lipid oxidation in Chinese sausages. The microorganisms, color, and texture properties of sausages were evaluated. TP, EGCG, pTP, or pEGCG significantly inhibited the accumulation of N-nitrosodimethylamine (NDMA) and BAs, residual nitrites, and lipid oxidation, but enhanced the redness, hardness, and chewiness of sausages. The concentration of NDMA in sausages was reduced by 58.11%, 63.51%, 36.49%, and 44.59%, respectively, after treatment with TP, EGCG, pTP, and pEGCG. Both EGCG and pEGCG exhibited excellent inhibitory effects on the predominant BAs, including putrescine, tyramine, cadaverine, histamine, and 2-phenylethylamine. Palmitoyl-EGCG was found to be the strongest inhibitor of lipid oxidation. Besides, the four antioxidants weakly affected the population of total aerobic bacteria and lactic acid bacteria but totally suppressed the growth of undesirable Enterobacteriaceae. The principal component and correlation analyses proved that BAs, nitrites, lipid oxidation, and microbiota were responsible for the formation of NDMA. The results indicated that palmitic acid-modified TPs and similar derivatives might serve as potential preservatives to improve the safety and quality of fermented meat products.

Electrochemical oxidation of carbamazepine in water using enhanced blue TiO2 nanotube arrays anode on porous titanium substrate.

In this study, a blue TiO2 nanotube arrays anode on porous titanium substrate (Ti-porous/blue TiO2 NTA) was successfully fabricated by facile anodization and in situ reduction, and was used to investigate the electrochemical oxidation of carbamazepine (CBZ) in aqueous solution. The surface morphology and crystalline phase of the fabricated anode were characterized by SEM, XRD, Raman spectroscopy and XPS, and the electrochemical analysis confirmed that blue TiO2 NTA on Ti-porous substrate had larger electroactive surface area, better electrochemical performance and higher ⋅OH generation ability than that on Ti-plate substrate. The removal efficiency of 20 mg L-1 CBZ in 0.05 M Na2SO4 solution reached 99.75% at 8 mA cm-2 after 60 min electrochemical oxidation, and the rate constant was 0.101 min-1 with low energy consumption. EPR analysis and free radical sacrificing experiments showed that ⋅OH played a key role in the electrochemical oxidation. The possible oxidation pathways of CBZ were proposed through the identification of degradation products, and the main reactions may involve deamidization, oxidization, hydroxylation and ring-opening. Compared with Ti-plate/blue TiO2 NTA anode, Ti-porous/blue TiO2 NTA anode displayed excellent stability and reusability, and is promising to be used in the electrochemical oxidation of CBZ in wastewater.

Electrochemical degradation of three phthalate esters in synthetic wastewater by using a Ce-doped Ti/PbO2 electrode.

A Ce-doped Ti/PbO2 electrode was prepared in a deposition solution containing Ce3+ and Pb2+ ions by electrodeposition, and the surface morphology, crystal structure and elemental states were characterized by SEM, XRD and XPS. The electrode was used to investigate the simultaneous degradation of three phthalate esters (PAEs), i.e., dimethyl phthalate (DMP), diethyl phthalate (DEP) and dibutyl phthalate (DBP) in synthetic wastewaters. The results showed that the electrode exhibited excellent electrocatalytic activity and good reusability and stability, and the removal efficiencies of 5 mg L-1 DBP, DMP and DEP in 0.05 M Na2SO4 (pH 7) reached 98.2%, 95.8% and 81.1% at current density of 25 mA cm-2 after 10 h degradation, respectively. The degradation processes followed pseudo first-order kinetic model very well, and the observed rate constants of DBP, DEP and DMP were 0.42, 0.40 and 0.29 h-1, respectively. The energy consumption in three PAEs degradation was also assessed. The main degradation products of the three PAEs were identified by using liquid chromatography-tandem mass spectrometry, and the possible degradation pathways mainly included dealkylation, hydroxyl addition, decarboxylation and benzene ring cleavage. This work is a promising candidate for efficient treatment of multiple PAEs in wastewater and protection of the aquatic ecological environment.

[Electrocatalytic Oxidation of Sulfadiazine with Ni-Doped Sb-SnO2 Ceramic Ring Particle Electrode].

The excessive use and abuse of antibiotics has brought about serious threats to water environmental safety and human health. It is necessary to develop efficient, cheap, and environmentally friendly treatment technologies for antibiotics. In this work, a Ni-doped Sb-SnO2 microporous ceramic ring particle electrode was prepared by the dipping method and characterized by scanning electron microscopy, energy dispersion spectroscopy, and X-ray diffraction. The electrocatalytic oxidation ability and kinetic characteristics of sulfadiazine (SDZ) were studied using the prepared electrode, and the degradation pathways of SDZ were analyzed preliminarily. The results showed that Ni and Sb-SnO2 crystals were loaded on the particle electrode surface, which is beneficial for electron transfer and SDZ adsorption and improvement of electrocatalytic oxidation efficiency. Under the conditions of 0.02 mol·L-1 NaCl solution (pH 8), 15 mA·cm-2 of current density, and 15 g particle electrode, 50 mg·L-1 SDZ could be completely removed on the three-dimensional electrode within 15 min. The removal efficiency of TOC in the reaction solution reached 80.8% for 3 h degradation and was 17.6% higher than that with two-dimensional electrode. The kinetic process of the electrocatalytic oxidation could be well described by the first-order reaction kinetic model, and the rate constant was 0.329 min-1. The degradation products of SDZ were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the possible pathways of electrocatalytic degradation mainly include the fractures of S-N bond on sulfamido and C-N bond on pyrimidine ring, desulfonation, deamination, and·OH oxidation.

Discrimination of the species and authenticity of Rhizoma Coptidis based on stable isotope and multielement fingerprinting and multivariate statistical analysis.

It is essential to be able to identify the source species and to determine the authenticity of traditional Chinese medicines (TCM) in order to prevent the use of false or inferior medicines. In this work, a stable and reliable method of discriminating among the three source species of Rhizoma Coptidis and checking the authenticity of Rhizoma Coptidis samples was established. The technique involved evaluating stable isotope ratios and the contents of multiple elements in samples along with the use of multivariate statistical techniques. The stable isotope ratios δ13C, δ15N, δ2H, and δ18O and the concentrations of various inorganic elements (Li, B, Na, Mg, Al, P, Si, K, Ca, Ti, Mn, Fe, Cu, Zn, Sr, and Ba) in authentic Rhizoma Coptidis samples from three source species (n = 56) and in counterfeit Rhizoma Coptidis samples (n = 39) were determined. The results showed that there were significant differences between the samples from different source species according to multivariate statistical analysis. The three species were clearly distinguished using hierarchical cluster analysis (HCA). Employing stepwise linear discriminant analysis (SLDA), a classification model for differentiating the three species was developed, and this model achieved 100% classification accuracy when applied to samples. In addition, authentic samples and counterfeit samples were successfully discriminated using stable isotope and multielement fingerprint analysis and orthogonal projections to latent structures discriminant analysis (OPLS-DA), and OPLS-DA models for checking the authenticity of Rhizoma Coptidis were established and verified. Therefore, stable isotope and multielement analysis combined with multivariate statistical analysis was shown to be a promising method of discriminating among the three source species of Rhizoma Coptidis and of establishing the authenticity of Rhizoma Coptidis samples. Graphical abstract.

[Rapid determination of spirotetramat and its metabolite residues in milk by ultra performance liquid chromatography-tandem mass spectrometry].

A method for the rapid and simultaneous determination of spirotetramat (BYI08330) and its four metabolites in milk was developed with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted with acetonitrile for precipitating proteins, degreased with hexane, and analyzed by UPLC-MS/MS in positive electrospray ionization and multiple reaction monitoring (MRM) mode. Good linear relationships between peak areas and mass concentrations of the analytes were obtained in the range of 0.5-50 µ g/L with correlation coefficients greater than 0.998 (n=6). The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) were 0.05-0.30 µ g/L and 0.17-1.00 µ g/L, respectively. The recoveries at the spiked levels of 1.0, 2.0 and 10 µ g/L were in the range of 80.0%-108.8% with relative standard deviations (RSDs) of 4.8%-15.2% (n=6). The method is fast, sensitive and accurate, and can be used to simultaneously determine BYI08330 and its four metabolites in milk.

Simultaneous detection of 15 antibiotic growth promoters in bovine muscle, blood and urine by UPLC-MS/MS.

An analytical method was established for the rapid detection of antibiotic growth promoters (AGPs) in bovine muscle, and bovine blood and bovine urine, using ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). After the addition of an aqueous solution of EDTA-Na2, the pH of bovine urine samples was directly adjusted to 5.2 by acetic acid-ammonium acetate and purified by HLB solid-phase extraction cartridge; bovine muscle and bovine blood samples processing were extracted with acetonitrile (ACN) and ACNwater (90:10; v/v) without any purification step. The samples were then centrifuged, concentrated and analysed by UPLC-MS/MS on an ACQUITY UPLC® BEH C18 column using gradient elution. The developed method was validated and mean recovery percentages at three spiked levels were 74-119%, 76-115% and 76-119%, respectively, in bovine muscle, bovine blood, and bovine urine. The relative standard deviation (RSD) ranged from 1.0% to 14.7% in spiked bovine muscle, bovine blood and bovine urine. The limits of detection (LOD) of all analytes were in the ranges 0.11-3.82 µg kg-1, 0.10-2.49 µg kg-1 and 0.06-4.53 µg kg-1 in bovine muscle, bovine blood, and bovine urine, respectively. The method was sensitive, accurate and was applied to monitor real samples. To the best of our knowledge, this is first method available for simultaneous determination of several classes of APGs in bovine muscle, and bovine blood and bovine urine.

Electrocatalytic reduction of low-concentration thiamphenicol and florfenicol in wastewater with multi-walled carbon nanotubes modified electrode.

The electrocatalytic reduction of thiamphenicol (TAP) and florfenicol (FF) was investigated with multi-walled carbon nanotubes (MWCNTs) modified electrode. MWCNTs was dispersed in pure water with the assistance of dihexadecyl phosphate (DHP), and then modified on glassy carbon electrode (GCE). The electrocatalytic reduction conditions, such as bias voltage, supporting electrolyte and its initial pH, and the initial concentrations of TAP and FF, were also optimized. The experimental results indicated that the removal efficiencies of 2mgL-1 TAP and FF in 0.1M NH3·H2O-NH4Cl solution (pH 7.0) reached 87% and 89% at a bias voltage of -1.2V after 24h electrocatalytic reduction, respectively. The removal process could be described by pseudo first-order kinetic model, and the removal rate constants of TAP and FF were obtained as 0.0837 and 0.0915h-1, respectively. The electrocatalytic reduction products of TAP and FF were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the possible reduction mechanisms were preliminarily analyzed. Electrocatalytic reduction is promising to remove low-concentration TAP and FF in wastewater with the MWCNTs modified electrode, and may cut down their toxicity through dehalogenation and carbonyl reduction.

[Determination of 21 illegally added chemical drugs in health foods using ultra performance liquid chromatography-tandem mass spectrometry coupled with QuEChERS].

A method for the simultaneous determination of 21 illegally added chemical drugs in improving sleep and immunity health foods using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. Oral liquid and health wine samples were shaken with acetonitrile and acetonitrile-water-formic acid (60:39:1, v/v/v), respectively, then purified by QuEChERS method. The extracts were separated on an Acquity UPLCTM BEH C18 column (50 mm×2.1 mm, 1.7 µm) with gradient elution of acetonitrile and 2 mmol/L ammonium acetate solution containing 0.1% (v/v) formic acid as mobile phases. The electrospray ionization in positive ion mode was used for analysis in multiple reaction monitoring (MRM) mode. The results showed that the target drugs had a good linear relationship in the range of 1-100 µg/L with the correlation coefficients (R2) ≥ 0.992. The limits of detection (LODs) and limits of quantification (LOQs) were 0.07-3.41 µg/kg and 0.22-11.36 µg/kg, respectively. The average recoveries of the 21 chemical drugs in oral liquid and health wine were in the range of 61.4%-116.5% and 67.4%-98.4% with the relative standard deviations (RSDs) of 0.2%-13.4% and 0.2%-11.8%, respectively. The developed method is sensitive and reliable. It has been successfully used for the detection of illegally added chemical drugs in real samples.

[Removal of Chloramphenicol in Wastewater by Electrocatalytic Reduction with Carbon Nanotubes-Modified Electrode].

In order to develop treatment technique for antibiotics and protect water environmental quality, the carbon nanotubes (CNTs) modified electrode was prepared with surfactant-assisted dispersion, the electrocatalytic reduction ability and kinetic characteristics of chloramphenicol were studied using the modified electrode, and the reduction mechanism was investigated preliminarily. The results showed that CNTs could be effectively dispersed by dihexadecyl phosphate (DHP), and the removal rate of 2 mg·L-1 chloramphenicol reached 97.21% after 24 h reduction using the modified electrode under the optimal ratio of CNTs to DHP and the modified amount of CNTs dispersion. The kinetic process of the electrocatalytic reduction could be well described by the first-order reaction kinetic model, and the removal rate constant and half-time were 0.1574 h-1 and 4.40 h, respectively. The reduction products were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) to reveal the possible reduction pathway, which indicated that the electrocatalysis could not only reduce nitro-group in chloramphenicol, but also further reduce carboxyl group and dechlorination, and thus significantly decrease its toxicity.

Determination of the potential illegal addition of ß-blockers to function foods by QuEChERS sample preparation and UPLC-MS/MS analysis.

A novel method was established for the determination of 11 ß-blockers in sedative functional foods using QuEchERS sample preparation coupled with UPLC-MS/MS. The analytes were extracted twice with acetic acid-acetonitrile-methanol (0.1:3:7, v/v/v), and the extracts were purified with mixed QuEchERS adsorbents. Separation was performed on a C18 column, and detection using electrospray ionisation in positive-ion mode. The linear range for the 11 analytes was from 1 to 500 µg l(-1), and the correlation coefficients were above 0.9990. The limits of detection and quantification were 0.02-0.16 and 0.07-0.54 µg kg(-1), respectively. The average recovery for 11 analytes at the three spiking levels varied from 71.8% to 121.9%, and the relative standard deviation was 2.4-12.6%. The method was applied to the analysis of ß-blockers in 22 real samples, but none of the analytes was detected. The proposed method is sensitive, efficient, reliable and applicable to real samples.

Simultaneous determination of 18 preservative residues in vegetables by ultra high performance liquid chromatography coupled with triple quadrupole/linear ion trap mass spectrometry using a dispersive-SPE procedure.

A new method combining dispersive-solid phase purification procedure with ultra high performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometry was developed for simultaneous determination of 18 preservative residues in vegetables. The new method not only had the advantages of dispersive-solid phase purification procedure such as high recoveries, easy operation, rapid analysis, little solvent usage and wide analysis range of preservatives, but also had the advantages of ultra high performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometry to be operated in positive mode and negative mode simultaneously. The method was validated for the following representative matrices: radish (tuber), tomato (eggplant fruit), cabbage (leafy), cowpea (bean), cucumber (melon) and so on. Samples were extracted with hexane-ethyl acetate (1:2, v/v), and then detected by ultra high performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometry after being cleaned up with dispersive-solid phase purification procedure. Significant matrix effects were compensated by using the matrix-matched calibration curves. 18 preservatives showed good linearity over the range of 5.0-100.0 µg/L with correlation coefficients of 0.9904-1.000. The limits of detections were in the range of 0.04-4.16 µg/kg and the limits of quantity were in the range of 0.13-13.85 µg/kg. The recoveries of 18 preservatives ranged from 76.0% to 120.0% with the spiked levels of 2, 4 and 10 µg/kg into homogenized vegetables, and the relative standard deviations (RSDs) ranged from 0.3% to 14.8%. Compared with the reported literatures, the method is more rapid, simple, highly sensitive, reliable and can meet testing requirements of 18 preservative residues in vegetables.

[Simultaneous determination of zeranols and chloramphenicol in foodstuffs of animal origin by combination immunoaffinity column clean-up and liquid chromatography-tandem mass spectrometry].

A combination immunoaffinity column (IAC-CZ) clean-up and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical method was successfully developed for zearalenol, beta-zearalenol and zearalenone) and chloramphenicol (CAP) in foodstuffs of animal origin. The samples (fish, liver, milk and honey) were enzymatically digested by beta-glucuronidase/sulfatase for about 16 h and then extracted with ether. The extracts were evaporated to dryness and then the residues were dissolved by 1.0 mL of 50% acetonitrile solution. After filtered and diluted with PBS buffer, the reconstituted solution were cleaned-up with a IAC-CZ and then analyzed by LC-MS/MS in multiple reaction monitoring (MRM) mode. The chromatographic separation was performed on a Shimadzu Shim-pack VP-ODS column with gradient elution by acetonitrile and 2 mmol/L ammonium acetate solution. The detection was carried out by electrospray negative ionization mass spectrometry in MRM mode. The proposed method was validated by the limit of detection (0.04-0.10 microg/kg), linearity (R2 > or = 0.999 0), average recoveries (70.9%-95.6%) and precisions (2.0% - 11.8%). The developed method is reliable, sensitive and has good applicability. The combination immunoaffinity column was proved to be an effective pretreatment technique to decrease the matrix effect, and it met the requirements of residue analysis of co-occurring zeranols and chloramphenicol.

Simultaneous determination of 30 hormones illegally added to anti-ageing functional foods using UPLC-MS/MS coupled with SPE clean-up.

A novel analytical method employing solid-phase extraction (SPE) coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the simultaneous determination of 30 hormones in anti-ageing functional foods (capsules, powders and tablets). The analytes were extracted with acetic acid-acetonitrile (1-99 v/v), methanol and acetone, respectively. The extract was purified using a combined column, followed by analyte detection with electrospray ionisation in positive- or negative-ion modes. The results indicated that the 30 compounds had good linear correlations in the range of 1-1000 µg kg⁻¹, and the correlation coefficients were above 0.99. The limits of detection (LOD) and limits of quantification (LOQ) were 0.03-2 and 0.1-5 µg kg⁻¹, respectively. The average recovery of 30 compounds at the three spiked levels varied from 74.7% to 124.1%, and the relative standard deviation (RSD) was 2.4-15.0%. This method was applied to the analysis of hormones in 14 real samples of which seven hormones (such as estrone, dienestrol) were detected in four samples, but the remainder of the hormones were not detected. The developed method is sensitive, efficient, reliable and applicable to real samples.

Simultaneous determination of 16 synthetic colorants in hotpot condiment by high performance liquid chromatography.

A simultaneous determination method for 16 synthetic colorants in hotpot condiment was developed by high performance liquid chromatography. The samples were successively extracted with 2 mol/L carbamide solution containing 5% ammonia (dissolved in methanol) and methanol-acetone solution, and then the target analytes could be divided into two groups named as lipid-soluble and water-soluble colorants by ethyl acetate-cyclohexane with liquid-liquid extraction. The lipid-soluble and water-soluble colorants were purified by gel permeation chromatography and solid phase extraction column packed with polyamide resin, respectively. The obtained two eluates were combined, concentrated, and separated by C18 column and determined by diode array detector. Good linear relationships between peak areas and the concentrations of the synthetic colorants were obtained in the range of 0.01-50.0mg/L with correlation coefficients above 0.999 (n=10). The limits of detection and quantitation were 1-3 and 10 µg/kg for 16 synthetic colorants, respectively. The average recoveries at the spiked levels of 5, 10, 20 and 50 µg/kg were in the range of 63.2-97.1% with relative standard deviations (n=6) around 1.5-10.6%. This method is sensitive and reliable, and can be used to simultaneously determine 8 lipid-soluble and 8 water-soluble colorants in hotpot condiment.

[Simultaneous determination of residues of six zeranols in eggs by high performance liquid chromatography with immunoaffinity cleanup column].

An immunoaffinity cleanup-high performance liquid chromatography (IAC-HPLC) method was established for the simultaneous determination of residues of six zeranols (alphazeranol, beta-zeranol, alpha-zearalenol, beta-zearalenol, zearalanone and zearalenone) in eggs. The enzymolyzed samples were extracted with methyl tert-butyl ether, and subsequently reextracted with a sodium hydroxide solution. After the pH value was adjusted to 7, the extract was cleaned up on an immunoaffinity column. The chromatographic separation was performed on an Agilent Eclipse XDB-C18 column (150 mm x 4.6 mm, 3.5 microm) using methanol-acetonitrile-water (50:15:35, v/v/v) as the mobile phase at a flow rate of 1.0 mL/min and ultraviolet (UV) detection at 270 nm. The six zeranols had good linear relationships in the range of 0.01-0.2 mg/L with the correlation coefficients not less than 0.999 8; the recoveries of six target compounds at different spiked levels ranged from 73.2% to 95.7% and the relative standard deviations were less than 8%. The limit of detection (S/N > or = 3) was 1.0 microg/kg for each zeranol. The method is stable, reliable and accurate, and can be used for the determination of trace residues of the six zeranols in eggs.