Determination of aflatoxins B1, B2, G1 and G2 by high-performance liquid chromatography with electrochemical detection

A new approach to the determination of afiatoxins B₁, B₂, G₁ and G₂ is given; the method involves high-performance liquid chromatography with amperometric detection in the differential-pulse mode at the dropping mercury electrode with 1-s drop time. These aflatoxins can be determined simultaneously with good resolution but with some compromise in sensitivity. The detection limit of underivatized aflatoxin standards is around 5 ng. Average recoveries of aflatoxins from peanut butter by the Beebe method were G₂ 81%, G₁ 87%, B₂ 77% and B₁ 76%.     

超高效液相色谱法快速测定发酵茶叶中的黄曲霉毒素

建立了用超高效液相色谱/紫外检测器测定发酵茶叶中黄曲霉毒素B1、B2、G1和G2的方法.用CH2Q2提取黄曲霉毒素,提取液经浓缩后,用LC-CN固相萃取小柱净化,超高效液相色谱测定.在浓度范围20～200μg/L(B1、G1),15～120μg/L(B2、G2)内具有良好的线性相关关系.黄曲霉毒素的回收率为81.4%～92.3%,相对标准偏差RSD 1.6%～4.2%.检出限为0.32μg/kg(B1、G1),0.18μg/kg(B2、G2)(S/N=3).     

Determination of aflatoxins B1, G1, B2 and G2 in medicinal herbs by liquid chromatography-tandem mass spectrometry

An easy method for the determination of aflatoxins B1, G1, B2 and G2 in Rhammus purshiana by LC coupled to mass spectrometry has been developed. Aflatoxins were extracted with a mixture of methanol and water and then it was purified by solid-phase clean-up using a polymeric sorbent, not described previously, for the determination of these toxins. The eluted extract was injected into the chromatographic system using a reversed-phase C18 short column with an isocratic mobile phase composed of methanol-water (30:70). A single-quadruple mass spectrometry using an electrospray ionization source operating in the positive ion mode was used to detect aflatoxins due to derivatization presenting several disadvantages. Recoveries of the full analytical procedure were 110% for aflatoxin B1, 89% for aflatoxin B2, 81% for aflatoxin G1 and 77% for aflatoxin G2. Detection limit (S/N = 3) was 10 ng and quantification limit (S/N = 10) was 25 ng, calculated as amount in medicinal herb.     

固相萃取-高效液相色谱/串联质谱检测谷物中黄曲霉毒素B1、B2、G1、G2和M1

建立了高效液相色谱/串联质谱(LC-MS/MS)同时检测谷物中的黄曲霉毒素B1、B2、G1、G2和M1的方法.并优化了液相色谱条件和质谱的相关参数.谷物样品经研磨成粉末后,直接经甲醇-水( V∶V=10∶90)提取,Oasis HLB固相萃取净化,乙腈-水(0.2％甲酸)梯度洗脱,选择电喷雾离子源(ESI),正离子扫描...     

Simultaneous determination of aflatoxins B1, B2, G1, G2, M1 and M2 in peanuts and their derivative products by ultra-high-performance liquid chromatography-tandem mass spectrometry

A reliable ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous determination of aflatoxins B1, B2, G1, G2, M1 and M2 in peanuts and their derivative products was developed. The sample was extracted by 84% of acetonitrile aqueous solution and the extract was purified by a reliable solid phase extraction-based clean-up method. Then, the analytes were separated on Acquity UPLC HSS T3 column (100 mm × 2.1 mm, 1.8 μm particle size), and eluted with a mobile phase consisting of (A) water containing 0.1% formic acid and (B) acetonitrile/methanol (50/50, v/v). The separated compounds were detected with a Waters Micromass Quattro Ultima Pt tandem quadrupole mass spectrometer operating in positive electro-spray ionization using multiple reaction monitoring mode. The established method was extensively validated by determining the linearity (R² ≥ 0.9990), average recovery (74.7-86.8%) and precision (relative standard deviation ≤ 10.9%). It was shown to be a suitable method for simultaneous determination of the six aflatoxins in peanuts and their derivative products. Finally, a total of 73 samples randomly collected from different areas in Zhejiang province were screened for aflatoxins with the proposed method. The results showed that 31 samples of peanut butter, 14 samples of fresh peanut and 5 samples of musty peanut were contaminated with aflatoxins. Meanwhile, this was the first report on aflatoxins M1 and M2, which were found in unprocessed peanuts and their derivative products.     

An ultra-high-performance liquid chromatography-tandem mass spectrometry method for simultaneous determination of aflatoxins B1, B2, G1, G2, M1 and M2 in traditional Chinese medicines

An ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous determination of aflatoxins B1, B2, G1, G2, M1 and M2 in traditional Chinese medicines (TCMs) was developed. The approach was characterized in details and a special focus was placed on the recovery rates of isolation procedure in different TCM matrices, i.e. rhizomes and roots, seeds, flowers, grasses and leaves. For this purpose, [¹³C₁₇]-aflatoxinB1 was employed as the internal standard and a reliable solid phase extraction-based clean-up method was developed. The observed recovery rates of the six aflatoxins ranged from 85.6% to 117.6% in different matrices. Then, the established method was successfully applied to the determination of the six aflatoxins in various TCMs. For 30 commercial samples analyzed, 16 were contaminated with aflatoxins. The mean levels (incidence) of aflatoxins B1, B2, G1 and G2 in positive samples were 1.40 (68.8%), 1.27 (50.0%), 0.50 (43.8%) and 0.94 (43.8%) μg kg⁻¹, respectively. Interestingly, aflatoxin M1 was detected in two samples with the maximal content of 0.70 μg kg⁻¹. No sample was contaminated with aflatoxin M2. Meanwhile, a possible association between the contamination levels and the selected herbs was clarified in the present study.     

Simultaneous determination of aflatoxins B1, B2, G1, G2 in Fructus Bruceae by high‐performance liquid chromatography with online postcolumn photochemical derivatization

A simple, reliable, and highly sensitive method for the simultaneous determination of aflatoxin B₁, B₂, G₁, G₂ in Fructus Bruceae was developed using high‐performance liquid chromatography coupled to online postcolumn photochemical derivatization and fluorescence detection. Aflatoxins were first extracted by a methanol/water mixture and then cleaned up with an AflaTest? immunoaffinity column. Different clean‐up and derivatization methods were compared and optimized. The established method was extensively validated to show satisfactory performance of linearity (R² ≥ 0.9997), recovery (74.3–100.8%), and precision (RSDs ≤ 2.8%) for the investigated aflatoxins. This proposed method was also applied to 11 F. Bruceae samples and the results showed that 10 out of 11 were contaminated with aflatoxins ranging from 0.26 to 27.52 μg/kg and the occurrence of aflatoxin B₁, the most toxic one, was as high as 91% in all the samples, highlighting the severe contamination and the necessity to set legal limits for aflatoxins in F. Bruceae.     

Determination of lawsone in henna powders by high performance thin layer chromatography

The lawsone content has been evaluated quantitatively in eight commercial henna powders and two collected henna leaves. The phenolic, chloroform-soluble fraction of the majority of the examined samples showed the presence of lawsone and two other pigments. Here we aimed to optimize high performance thin layer chromatography for the determination of lawsone. Upon using the optimized method the examined samples showed considerable variation in lawsone concentration ranging from 0.004 up to 0.608 wt%, indicating that some samples were almost devoid of lawsone. Some of these products were subjected to preliminary in vivo toxicity studies.     

Ultra-performance liquid chromatography/tandem mass spectrometry for the simultaneous analysis of aflatoxins B1, G1, B2, G2 and ochratoxin A in beer

The simultaneous analysis of aflatoxins B1, G1, B2, G2 and ochratoxin A in beer was carried out by ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS). Mycotoxins were extracted, purified and concentrated from the beer sample in one step using a solid-phase extraction (SPE) cartridge that contained a polymeric sorbent. Optimization of different parameters, such as type of SPE sorbent, type and amount of wash solvent and pH of the sample, was carried out. The mobile phase consisted of a gradient of methanol + water (0.1% HCOOH) and a reversed-phase C18 column was used for the separation. The mass spectrometer used an electrospray ionization source operated in the positive mode to detect aflatoxins and in the negative mode to detect ochratoxin. UPLC/MS/MS is a rapid and sensitive technique that allows the separation of the five toxins in only 3.2 min. The limit of detection is 1 pg.     

Surveillance and control of aflatoxins B1, B2, G1, G2, and M1 in foodstuffs in the Republic of Cyprus: 1992-1996.

Aflatoxins (AFs) B1, B2, G1, and G2 in locally produced and imported foodstuffs (nuts, cereals, oily seeds, pulses, etc.) were monitored and controlled systematically and effectively from 1992-1996. Samples (peanuts, pistachios, etc.) with total AFs above the Cyprus maximum level (ML) of 10 micrograms/kg fluctuated between 0.7 and 6.9%. The results indicate the effectiveness of monitoring, as well as the need for constant surveillance and control, especially at critical control points (sites of import, primary storage, etc.), to prevent unfit products from entering the Cyprus market. The control included sampling, retainment, analysis, and destruction of foodstuff lots with AF levels above MLs. The highest incidence of aflatoxin contamination was observed in peanut butter (56.7%) and the highest level of AF B1 was found in peanuts (700 micrograms/kg). Levels of AF M1 in raw and pasteurized milk analyzed in 1993, 1995, and 1996 were within both the Cyprus ML (0.5 microgram/L) and the lower ML (0.05 microgram/L) of some European countries. Only 12% of samples had detectable levels of AF M1. Analyses were performed by immunochemical methods. When recoveries were lower than 80%, the AF levels were corrected for recovery.     

High-performance liquid chromatography tandem mass spectrometry for simultaneous detection of aflatoxins B1, B2, G1 and G2 in Indian medicinal herbs using QuEChERS-based extraction procedure

Since the discovery of aflatoxins (AFs) in the 1960s, much research has focused on detecting the toxins in contaminated food and feedstuffs. But the quality determination in medicinal plant matrices with respect to AFs is scare. Hence, a simple, accurate and sensitive high-performance liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) method was developed for simultaneous determination of AFs AFB₁, AFB₂, AFG₁ and AFG₂ in two Indian popular medicinal herbs i.e. senna (Cassia angustifolia) and kalmegh (Andrographis paniculata). AFs have been extracted from herb matrix using a QuEChERS (quick, easy, cheap, effective, rugged and safe)-based extraction procedure followed by applying primary secondary amine and C18 for further clean-up step and then were quantified under the multiple reaction monitoring together with positive ionisation modes. Matrix-matched calibration was used for quantification in order to reduce the matrix effect. Validation of the method was carried out in herbs by recovery experiments. Recoveries of the spiked samples were in the range of 61.9–111.5% with an inter-day and intraday relative standard deviation lower than 20.0%. Limits of detection and quantification ranged from 0.41 to 0.95 ng mL^?1 and 1.2 to 3.8 μg kg^?1, respectively. The expanded uncertainty of the method was <21% for all the toxins in both the herbs. Finally, the proposed method was successfully applied to determine AF residues in real field samples of senna and kalmegh obtained from different locations in India.     

Determination of aflatoxins B1, B2, G1, and G2 and ochratoxin A in ginseng and ginger by multitoxin immunoaffinity column cleanup and liquid chromatographic quantitation: collaborative study

The accuracy, repeatability, and reproducibility characteristics of a method using multitoxin immunoaffinity column cleanup with liquid chromatography (LC) for determination of aflatoxins (AF; sum of aflatoxins B1, B2, G1, and G2) and ochratoxin A (OTA) in powdered ginseng and ginger have been established in a collaborative study involving 13 laboratories from 7 countries. Blind duplicate samples of blank, spiked (AF and OTA added) at levels ranging from 0.25 to 16.0 microg/kg for AF and 0.25 to 8.0 microg/kg for OTA were analyzed. A naturally contaminated powdered ginger sample was also included. Test samples were extracted with methanol and 0.5% aqueous sodium hydrogen carbonate solution (700 + 300, v/v). The extract was centrifuged, diluted with phosphate buffer (PB), filtered, and applied to an immunoaffinity column containing antibodies specific for AF and OTA. After washing the column with water, the toxins were eluted from the column with methanol, and quantified by high-performance LC with fluorescence detection. Average recoveries of AF from ginseng and ginger ranged from 70 to 87% (at spiking levels ranging from 2 to 16 microg/kg), and of OTA, from 86 to 113% (at spiking levels ranging from 1 to 8 microg/kg). Relative standard deviations for within-laboratory repeatability (RSDr) ranged from 2.6 to 8.3% for AF, and from 2.5 to 10.7% for OTA. Relative standard deviations for between-laboratory reproducibility (RSDR) ranged from 5.7 to 28.6% for AF, and from 5.5 to 10.7% for OTA. HorRat values were < or = 2 for the multi-analytes in the 2 matrixes.     

Determination of platinum, palladium and rhodium in Pt-catalysts by high performance thin layer chromatography using densitometry

The determination of palladium and platinum in alumina-supported bimetallic Pt-Re, Pd and Pt catalysts at the 0.03 and 0.3% (m/m) levels, respectively, and of rhodium and platinum in platinum sieve catalysts at the 0.04% (m/m) level and in the 4.75–19.75% (m/m) range, respectively, is described. The platinum group metals in fresh or spent catalysts are determined chromatographically using densitometry by forming theirN,N-diethyl-N-benzoylthiourea complexes. The precision of the method, %RSD, is 0.4–3.5, 2.2–6.7, and 4.2–6.0 for Pt, Pd and Rh, respectively. The accuracy was tested using alumina-based and active carbon platinum and palladium standards. The results were also compared with those obtained by FAAS. There was at most 8% difference between the results obtained with these methods, except for one active carbon based Pd standard.     

Application of dispersive liquid-liquid microextraction for the determination of aflatoxins B1, B2, G1 and G2 in cereal products

The application of dispersive liquid-liquid microextraction (DLLME) technique for the rapid analysis of aflatoxins B(1), B(2), G(1) and G(2) in maize, rice and wheat products has been evaluated. After extraction of aflatoxins from cereal matrices with a mixture of methanol/water 8:2 (v/v), the analytes were rapidly transferred from the extract to another small volume of organic solvent, chloroform, by DLLME. Aflatoxins were determined using high performance liquid chromatography with florescence detection and photochemical post-column derivatization. Parameters affecting both extraction and DLLME procedures, such as extraction solvent, type and volume of DLLME extractant, volume of water and salt effect, were systematically investigated and optimized to achieve the best extraction efficiency. Under the optimal experimental conditions, the whole analytical method provides enrichment factors around 2.5 times and detection limits (0.01-0.17 μg kg(-1)) below the maximum levels imposed by current regulation for aflatoxins in cereals and cereal products intended for direct human consumption. Recoveries (67-92%) and repeatability (RSD<10, n=3), tested in three different cereal matrices, meet the performance criteria required by EC Regulation No. 401/2006 for the determination of the levels of mycotoxins in foodstuffs. The proposed method was successfully applied to the analysis of retail cereal products with quantitative results comparable to the immunoaffinity chromatography (IAC). The main advantages of developed method are the simplicity of operation, the rapidity to achieve a very high sample throughput and low cost.     

Determination of aflatoxins B1 and B2 using ion mobility spectrometry

This paper describes total determination of aflatoxins B1 and B2 in pistachio samples using corona discharge ion mobility spectrometry (IMS). A new injection port was designed to introduce liquid samples into the IMS. Using this port, the liquid solvent (methanol) containing standard aflatoxins or an extracted sample was directly introduced into the injection port. Calibration curves resulting from experimental analyses were linear within two orders of magnitude and relative standard deviations (R.S.D.) were less than 10%. The limit of detection (LOD) was found to be 0.25 ng for both aflatoxins. Addition of ammonia as the dopant to the carrier gas improved the LOD by a factor of 2.5. Pistachio samples were analyzed to demonstrate the capability of the proposed method in detecting aflatoxins in real samples.     

Overpressured layer chromatographic determination of aflatoxin B1, B2, G1 and G2 in red paprika

Determination of aflatoxin B1 and total aflatoxin (B1 + B2 + G1 + G2) in red paprika powder is described using column chromatographic sample clean-up, overpressured layer chromatography (OPLC) separation and fluorescence densitometric evaluation. Two OPLC methods were developed for separation of the four aflatoxins. The detection limit and quantification limit of aflatoxins in red paprika were 0.5 and 1 μg/kg in both methods, respectively. Recovery experiment was carried out with sample containing 1.74 μg/kg aflatoxin B1 and 3.56 μg/kg total aflatoxins measured by European standard HPLC method. Mean recovery amounted to 78.5% (SD 16.1%, n = 5) for aflatoxin B1 and 81.8% (SD 17.1%, n = 5) for total aflatoxins in the case of method 1. It was 105.3% (SD 10.7%, n = 5) for aflatoxin B1 and 97.4% (SD 18.6%, n = 5) for total aflatoxins using the method 2. Despite of that the Hungarian climate is not proper for the toxin production of moulds high aflatoxin B1 contaminated red paprika purchased from the market was found, which may originate from mixing of imported paprika containing very high level toxin with Hungarian one.     

Development of a microwave-assisted-extraction-based method for the determination of aflatoxins B1, G1, B2, and G2 in grains and grain products

This article describes the use of microwave-assisted extraction (MAE) as a pretreatment technique for the determination of aflatoxins B₁, G₁, B₂, and G₂ in grains and grain products. The optimal operation parameters, including extraction solvent, temperature, and time, were identified to be acetonitrile as the extraction solvent at 80 °C with 15 min of MAE. The extracts were cleaned up using solid-phase extraction followed by derivatization with trifluoroacetic acid and were determined by liquid chromatography–fluorescence detection. A Sep-Pak cartridge was chosen over Oasis HLB and Bond Elut cartridges. By the use of aflatoxin M₁ as an internal standard, relative recoveries of the aflatoxins ranged from 90.7 to 105.7 % for corn and from 88.1 to 103.4 % for wheat, with relative standard deviations between 2.5 and 8.7 %. A total of 36 samples from local markets were analyzed, and aflatoxin B₁ was found to be the predominant toxin, with concentrations ranging from 0.42 to 3.41 μg/kg.