Qualitative-quantitative analysis of multi-mycotoxin in milk using the high-performance liquid chromatography-tandem mass spectrometry coupled with the quick,easy, cheap,effective, rugged and safe method

High-performance liquid chromatography-tandem mass spectrometry coupled with the quick, easy, cheap, effective, rugged and safe method was established for the qualitative and quantitative detections of 20 mycotoxins in milk. The linear range of this method was 0.01–10 μg/L and the correlation coefficients were all greater than or equal to 0.9933. At three levels of addition, the spiked recoveries ranged from 80.00 to 112.50%, relative standard deviations were 2.67–14.97%, limits of quantitation were 0.02–4.00 μg/kg, and limits of detection were 0.007–1.300 μg/kg. This developed procedure for the identification and quantitation of mycotoxins provided prospective support for quality regulation.     

Analytical method for the accurate determination of tricothecenes in grains using LC-MS/MS: a comparison between MRM transition and MS3 quantitation

The current food crisis demands unambiguous determination of mycotoxin contamination in staple foods to achieve safer food for consumption. This paper describes the first accurate LC-MS/MS method developed to analyze tricothecenes in grains by applying multiple reaction monitoring (MRM) transition and MS(3) quantitation strategies in tandem. The tricothecenes are nivalenol, deoxynivalenol, deoxynivalenol-3-glucoside, fusarenon X, 3-acetyl-deoxynivalenol, 15-acetyldeoxynivalenol, diacetoxyscirpenol, and HT-2 and T-2 toxins. Acetic acid and ammonium acetate were used to convert the analytes into their respective acetate adducts and ammonium adducts under negative and positive MS polarity conditions, respectively. The mycotoxins were separated by reversed-phase LC in a 13.5-min run, ionized using electrospray ionization, and detected by tandem mass spectrometry. Analyte-specific mass-to-charge (m/z) ratios were used to perform quantitation under MRM transition and MS(3) (linear ion trap) modes. Three experiments were made for each quantitation mode and matrix in batches over 6 days for recovery studies. The matrix effect was investigated at concentration levels of 20, 40, 80, 120, 160, and 200 μg kg(-1) (n = 3) in 5 g corn flour and rice flour. Extraction with acetonitrile provided a good overall recovery range of 90-108% (n = 3) at three levels of spiking concentration of 40, 80, and 120 μg kg(-1). A quantitation limit of 2-6 μg kg(-1) was achieved by applying an MRM transition quantitation strategy. Under MS(3) mode, a quantitation limit of 4-10 μg kg(-1) was achieved. Relative standard deviations of 2-10% and 2-11% were reported for MRM transition and MS(3) quantitation, respectively. The successful utilization of MS(3) enabled accurate analyte fragmentation pattern matching and its quantitation, leading to the development of analytical methods in fields that demand both analyte specificity and fragmentation fingerprint-matching capabilities that are unavailable under MRM transition.     

Determination of alkylphenol and alkylphenolethoxylates in biota by liquid chromatography with detection by tandem mass spectrometry and fluorescence spectroscopy

A quantitative method for the simultaneous determination of octylphenol, nonylphenol and the corresponding ethoxylates (1 to 5) in biota is presented. Extraction methods were developed for egg and fish matrices based on accelerated solvent extraction followed by a solid-phase extraction cleanup, using octadecylsilica or aminopropyl cartridges. Identification and quantitation were accomplished by liquid chromatography-electrospray tandem mass spectrometry (LC-MS-MS) and compared to the traditional liquid chromatography with fluorescence spectroscopy detection. LC-MS-MS provides high sensitivity and specificity required for these complex matrices and an accurate quantitation with the use of 13C-labeled internal standards. Quantitation limits by LC-MS-MS ranged from 4 to 12 ng/g in eggs, and from 6 to 22 ng/g in fish samples. These methods were successfully applied to osprey eggs from the Chesapeake Bay and fish from the Great Lakes area. Total levels found in osprey egg samples were up to 18 ng/g wet mass and as high as 8.2 microg/g wet mass in the fish samples.     

Determination of tylosin in feeds by liquid chromatography with solid-phase extraction

A method was developed for the determination of tylosin in feeds. The method involves extraction of tylosin with methanol, concentration under a stream of nitrogen, and cleanup using Phenomenex C18 solid-phase extraction cartridge. Analyte separation and quantitation were achieved by gradient reversed-phase liquid chromatography and UV absorbance at 285 nm with a reference wavelength of 320 nm with column temperature of 45 degrees C. Average spike recoveries for samples prepared at 4 spiking levels (22.7, 181, 907, and 1000 g/ton) were 111.0, 94.9, 96.2, and 98.6%, respectively. The overall method precision at each of the 4 spiking levels was < or = 7.85% relative standard deviation. The limits of detection and quantitation (g/ton) were 2.16 and 7.20 g/ton, respectively.     

Determination of methylisothiazolinone and methylchloroisothiazolinone in cosmetic products by ultra high performance liquid chromatography with tandem mass spectrometry

Isothiazolinone biocides are broad‐spectrum preservatives that are widely used in cosmetics, household, and industrial products. An increase in the number of cases of allergic contact dermatitis to isothiazolinone preservatives, namely, methylisothiazolinone and methylchloroisothiazolinone, have been recently noticed. The Food and Drug Administration relies on analytical methods to quantify levels of use of cosmetic ingredients and support enforcement action against products that are not in compliance with the law. In this study, an efficient ultra high performance liquid chromatography with tandem mass spectrometry method was developed and validated for the determination of methylisothiazolinone and methylchloroisothiazolinone in selected cosmetic products. The lower limit of quantitation was determined to be 0.1 μg/g for both preservatives. A survey of 24 cosmetic products was conducted and found concentrations of methylisothiazolinone and methylchloroisothiazolinone ranging from not quantified, or below the lower limit of quantitation, to 89.64 μg/g and not quantified to 10.31 μg/g, respectively.     

Determination of low-level residual ethylene oxide by using solid-phase microextraction and gas chromatography

Current methods of analysis for ethylene oxide (EO) in medical devices include headspace and simulated-use extractions followed by gas chromatography with either a packed or a capillary column. The quantitation limits are about 0.5-1.0 microg/g for a packed column and about 0.1-0.2 microg/g for a capillary column. The current allowable levels of EO on medical devices sterilized with EO gas as outlined in International Organization for Standardization (ISO) 10993-7 may be significantly reduced from current levels by applying the ISO Draft International Standard 10993-17 method for establishing allowable limits. This may require EO test methods with detection and quantitation limits that are much lower than those of the currently available methods. This paper describes a new method that was developed for the determination of low-level EO by solid-phase microextraction using the direct-immersion method. Factors such as temperature and stirring were found to affect absorption efficiency and absorption time. A low extraction temperature (about 6 degrees C) was found to be more efficient than room-temperature extraction. Stirring was found to reduce absorption time by about 50%. Under these conditions, detection and quantitation limits of 0.002 and 0.009 microg/g, respectively, were obtained by using a capillary column. As a result, this method makes compliance with lower EO limits feasible.     

A generic method for the determination of acrylamide in thermally processed foods

A generic sample preparation method for the determination of acrylamide in foods was developed. The method entails extraction with methanol, purification with Carrez I and II solutions, evaporation and solvent change to water, and cleanup with Oasis HLB solid-phase extraction (SPE) cartridge. The final extract was analyzed by liquid chromatography-mass spectrometry (LC-MS) for quantitation. The chromatographic separation was performed on ODS-3 column using the isocratic mixture of 0.01 mM acetic acid in 0.2% aqueous solution of formic acid at a flow rate of 0.6 ml/min at 25 degrees C. The recoveries of acrylamide from potato chips, biscuits and coffee ranged between 92.8 and 101.5% with relative standard deviations of 4.1% or less. The limit of detection (LOD) and the limit of quantitation (LOQ) were 2 ng/g and 6 ng/g in the basis of signal to noise ratios of 3:1 and 9:1, respectively.     

Quantitation of camphechlor/toxaphene in cod-liver oil by integration of the HRGC/ECD-pattern

Summary Quantitation of camphechlor/toxaphene in biological matrices like cod-liver oil or fish is difficult because it is a very complex mixture of alicyclic polychlorinated compounds. Furthermore, many toxaphene components are biotransformed and photodegraded and the complex mass spectral fragmentation pattern of HRGC/MSD (electron impact (EI)) cannot be used for quantitation at the g/g-level or below. The use of several indicator-peaks after ECD-detection using the technical standard mixture for calibration does not characterize the entire pattern in a biological sample. Two averaging integration methods that are based on the entire HRGC/ECD-pattern of toxaphene compounds after separation from the PCB congeneres by adsorption chromatography on silicagel, allow a fast and accurate quantitation of the mixture in biological samples, e.g. cod-liver oil. Biological degradation does not disturb the determination because the whole pattern of the complex mixture is considered instead of only a few compounds of the parent mixture which could be degraded or not.     

Determination of plastic monomers in water by solid-phase microextraction coupled with liquid chromatography

A method is presented for the determination of 2 major plastic monomers, terephthalic acid and vinyl acetate, which are widely used to manufacture plastics that come in contact with foods. The analytes are extracted from aqueous solution by using solid-phase microextraction, followed by quantitation by liquid chromatography (LC) with UV detection. Multivariate optimization was applied and is described. The optimized method has linear ranges of 5-150 microg/g for terephthalic acid and 7.5-100 microg/g for vinyl acetate. Coefficients of variation at a spiking level of 20 microg/g were 13.6% for terephthalic acid and 3.1% for vinyl acetate; detection and quantitation limits were 0.59 and 1,99 microg/g, respectively, for terephthalic acid and 1.56 and 5.20 microg/g, respectively, for vinyl acetate. The characteristics of both the extraction technique and its coupling with LC are described and discussed.     

A Novel Method for the Quantitation of Warfarin and its Metabolites in Plasma

Abstract

A procedure for the rapid, quantitative recovery of warfarin and its metabolites (diastereoisomeric alcohol, 4′-, 6-, 7-, 8-benzylic-hydroxywarfarin and dehydrowarfarin) from plasma with Sep-Pak C₁₈ cartridges has been developed. A solution of warfarin and its metabolites in plasma was acidified with NH₄OAc buffer (pH 4.85), adsorbed on the Sep-Pak C₁₈ resin, washed free of polar constituents and eluted with methanol. Dilution of the eluate with buffer followed by gradient high performance liquid chromatography permitted accurate quantitation of the desired compounds when detected at 313 nm. The recovery of warfarin and each metabolite was greater than 95% over an investigated range of 0.5–10.0 μg/ml of plasma and the limit of quantitation by the assay was 0.1 μg/ml of plasma. For more rapid quantitation of warfarin, without simultaneous analysis of metabolites, the chromatographic parameters were modified so that elution of warfarin occurred within 13 minutes, and the sensitivity of the assay increased to 0.03 μg of warfarin/ml of plasma. The quantitative recovery of warfarin and its metabolites coupled with the chromatographic versatility of the method make it ideally suited for either detailed pharmacokinetic studies or routine plasma analysis of warfarin.     

Detection of multiple endocrine-disrupting chemicals in milk: Improved and safe high performance liquid chromatography tandem mass spectrometry method

Herein, an improved method for detecting the endocrine-disrupting chemicals in milk is presented, which is based on high performance liquid chromatography tandem mass spectrometry, coupled with a quick, effective, and safe method. The linearity of the proposed method was in the range of 0.05–100 μg/L, and all correlation coefficients were ≥0.9973. At three concentration levels, the spiked recoveries ranged from 77.7 to 107.5%, relative standard deviations ranged from 0.2 to 14.6%, limits of quantitation ranged from 0.1 to 40 μg/kg, limits of detection ranged from 0.03 to 13.3 μg/kg. The proposed method for the identification and quantitation of 26 endocrine disruptors present in milk is not only easy, fast, and cost-efficient but also provides a reference for the detection of various endocrine disruptors in milk and other dairy products.     

Determination of Thiamphenicol in Serum and Cerebrospinal Fluid with High-Pressure Liquid Chromatography

Abstract

A procedure for quantitation of thiamphenicol in serum and cerebrospinal fluid was developed using high-pressure liquid chromatography. The drug was extracted from biological samples with methanol and separated by reverse-phase high-pressure liquid chromatography. Detection and subsequent quantitation were performed at 254 nm by on-line ultraviolet spectrophotometry. After the intramuscular administration of a single dose of 1 g of thiamphenicol to a patient, a poor transmission of the drug across the hematoencephalic barrier was demonstrated by this assay.     

Determination of cyclamate in foods by ultraperformance liquid chromatography/tandem mass spectrometry

A highly sensitive and selective method that requires minimal sample preparation was developed for the confirmation and quantitation of cyclamate in a variety of foods by high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). Sample preparation consisted of homogenization followed by extraction and dilution of cyclamate with water. HPLC separation was achieved using a bridged ethyl hybrid C18 high-pressure column with a mobile phase consisting of 0.15% acetic acid and methanol. Under electrospray ionization negative conditions, quantitation was achieved by monitoring the fragment m/z = 79.7 while also collecting parent ion m/z = 177.9. Two food matrixes, diet soda and jelly, were subjected to a validation procedure in order to evaluate the applicability of the method. The cyclamate limit of detection for both matrixes was determined to be 0.050 microg/g with a limit of quantitation of 0.150 microg/g. The correlation coefficient of the calibration curves was >0.9998 from 0.0005 to 0.100 microg/mL. The method has been used for the determination of cyclamate in several foods and the results are presented.     

Quantitative analysis of the antifungal drug anidulafungin by LC-online SPE-MS/MS in human plasma

The objective of this study was to develop a fast and robust method for the quantitation of the antifungal drug anidulafungin in human plasma samples by generic two-dimensional liquid chromatography (online-SPE/reversed phase LC) coupled to a tandem-quadrupole mass spectrometer (LC-online SPE-MS/MS). Online SPE was performed using an Oasis HLB cartridge column and for reversed-phase chromatography a Nucleodur Gravity C(18) column was used. A 100 μL aliquot of human plasma was extracted with 200 μL of 80:20 MeOH-0.2 M ZnSO(4) (v/v) as precipitation reagent containing ascomycin as internal standard (IS). The supernatant was directly injected for analysis. The total run time was 4.5 min. Anidulafungin and ascomycin were detected in the positive ionization mode. The method performance data for anidulafungin, such as limit of detection (0.013 μg/mL), lower limit of quantitation (0.04 μg/mL), linearity (R(2) = 0.9999) and concentration range (0.04-10 μg/mL) were ascertained. Intra- and inter-day precisions were ≤6.6% and intra- and inter-day accuracies were 98.5-101.0 and 100.0-102.5%, respectively. The assay was successfully applied for quantitation of anidulafungin in patient plasma samples.     

Determination of tilmicosin residues in chicken, cattle, swine, and sheep tissues by liquid chromatography

A method was developed and validated for determination and quantitation of tilmicosin residues in swine, cattle, and sheep edible tissues, as well as chicken fat, skin, and muscle over a concentration range of 0.025 microg/g-20 microg/g. For chicken kidney and liver, the method was validated over a range of 0.060 microg/g-20 microg/g. The tissue sample was extracted with methanol and a C18 cartridge was used for solid-phase extraction cleanup. A reversed-phase gradient liquid chromatographic method with detection at 280 nm was used to separate the tilmicosin from matrix components in 30 min run time. The limit of quantitation (LOQ) of the method was 0.025 microg/g for all tested tissues except chicken kidney and liver, for which the LOQ was 0.06 microg/g. Average recoveries for tissue samples ranged from 73 to 98%. Relative standard deviation values ranged from 0.6 to 14.7%.     

Gas-liquid chromatographic determination of milk fat and cocoa butter equivalents in milk chocolate: interlaboratory study

A collaborative trial was conducted to validate an analytical approach comprising method procedures for determination of milk fat and the detection and quantification of cocoa butter equivalents (CBEs) in milk chocolate. The whole approach is based on (1) comprehensive databases covering the triacylglycerol composition of a wide range of authentic milk fat, cocoa butter, and CBE samples and 947 gravimetrically prepared mixtures thereof; (2) the availability of a certified cocoa butter reference material for calibration; (3) an evaluation algorithm, which allows reliable quantitation of the milk fat content in chocolate; (4) a subsequent correction to take account of the triacylglycerols derived from milk fat; (5) mathematical expressions to detect the presence of CBEs in milk chocolate; and (6) a multivariate statistical formula to quantitate the amount of CBEs in milk chocolate. Twelve laboratories participated in the validation study. CBE admixtures were detected down to a level of 0.5 g CBE/100 g milk chocolate, without false-positive or -negative results. The applied quantitation model performed well at the statutory limit of 5% CBE addition to milk chocolate, with a prediction error of 0.7%, and HorRat values ranging from 0.8 to 1.5. The relative standard deviation for reproducibility (RSDR) values for quantitation of CBEs in analyses of chocolate fat solutions ranged from 2.2 to 3.8% and for analyses of real chocolate samples, from 4.1 to 4.7%, demonstrating that the whole approach, based solely on chocolate fat blends, is applicable to real milk chocolate samples.     

Development and validation of an UPLC method for rapid determination of ibuprofen and diphenhydramine citrate in the presence of impurities in combined dosage form

A novel, stability-indicating gradient reverse-phase ultra-performance liquid chromatographic method was developed for the simultaneous determination of ibuprofen and diphenhydramine citrate in the presence of degradation products and process related impurities in combined dosage form. The method was developed using C18 column with mobile phase containing a gradient mixture of solvent A and B. The eluted compounds were monitored at 220 nm. Ibuprofen and diphenhydramine citrate were subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, and photolytic degradation. Major unknown impurity formed under oxidative degradation was identified using LC-MS-MS study. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantitation, accuracy, precision and robustness. The described method was linear over the range of 0.20-6.00 μg/mL (r>0.998) for Ibuprofen and 0.084-1.14 μg/mL for diphenhydramine citrate (r>0.998). The limit of detection results were ranged from 0.200-0.320 μg/mL for ibuprofen impurities and 0.084-0.099 μg/mL for diphenhydramine citrate impurities. The limit of quantitation results were ranged from 0.440 to 0.880 μg/mL for ibuprofen impurities and 0.258 to 0.372 μg/mL for diphenhydramine citrate impurities. The recovery of ibuprofen impurities were ranged from 98.1% to 100.5% and the recovery of diphenhydramine citrate impurities were ranged from 97.5% to 102.1%. This method is also suitable for the simultaneous assay determination of ibuprofen and diphenhydramine citrate in pharmaceutical dosage forms.     

气相色谱法测定烟草浸膏中的烟碱

为准确测定烟草浸膏中烟碱含量,以2-甲基喹啉为内标建立了测定烟草浸膏中烟碱的气相色谱-氢火焰离子化法(GC-FID),并测定了5个烟草浸膏样品.结果表明,方法的回收率为95.00%~98.58%,检出限为0.27 mg/g,定量限为0.89 mg/g.所测烟草浸膏中烟碱的质量分数在19.66~54.97 mg/g之间.方法简单、灵敏、准确,适用于烟草浸膏中烟碱的测定.     

A Validated GC-MS Assay for the Quantitation of Trichloroethylene (TCE) from Drinking Water

Trichloroethylene (TCE) is a common ground and surface water contaminant found in the United States. A validated GC-MS assay for the quantitation of TCE in drinking water is presented here. The limit of quantitation, 5 µg/L, is lower than current validated methods for the analysis of TCE from water. This assay requires a small sample volume, has simple sample preparation, fast run time, high recovery, and reproducible and accurate results.     

Simultaneous capillary GC of acids and sugars as their silyl(oxime) derivatives: Quantitation of chlorogenic acid,raffinose, and pectin substances

Our GC-MS method for the simultaneous quantitation of sugars and acids as their silyl(oxime) derivatives, from one solution by one injection, has been extended to the reproducible determination of high molecular weight compounds sensitive to decomposition yet requiring a high evaporation temperature (e.g. chlorogenic acid and rffinose) and for the quantitation of the decomposition products of pectin (i.e., for the determination of galacturonic acid at low ng levels in the presence of a 10–100 fold excess of glucose eluting just before the acid). The optimized GC procedure has been used for quantitation of the sugar and acid (including chlorogenic acid) composition of potato samples, and for the determination of the increasing amount of the decomposition products of pectin substances in apple pulp after different storage times.