Residue depletion of ractopamine and its metabolites in swine tissues, urine, and serum

Ractopamine hydrochloride is a beta-adrenergic leanness-enhancing agent approved for use in swine in the United States. Depletion of ractopamine and its metabolites from animal tissues, urine, and serum is of interest for the detection of illegal use. The objectives of this study were to measure the residues of ractopamine in swine incurred samples after treatment with dietary ractopamine for 28 consecutive days. An efficient and sensitive analytical method was developed for the detection of parent ractopamine and its metabolites in swine tissues, urine, and serum by HPLC-FLD. After extraction, enzymatic digestion, and solid-phase cleanup of the samples, ractopamine residues were determined by liquid chromatography (LC) with fluorescence detector. The limits of detection (LOD) for tissues, urine, and serum were 1 ng g(-1), 0.5 ng mL(-1), and 0.5 ng mL(-1), respectively. Recoveries ranged from 70.5 to 94.5% for samples fortified at 1-50 ng g(-1) or ng mL(-1). Sixty pigs were fed twice daily for 28 consecutive days with feeds containing 18 mg kg(-1) ractopamine HCl. The residue concentrations in urine, liver, and kidney were 650.06 ng mL(-1), 46.09 ng g(-1), and 169.27 ng g(-1), respectively, compared with those in muscle, fat, and serum (4.94 ng g(-1), 3.28 ng g(-1), and 7.48 ng mL(-1), respectively) at the feeding period of 7 days. The residue concentrations at withdrawal period of 0 days in all edible tissues were lower than tolerance values established by the FDA and MRL values listed by the JECFA. These data support the withdrawal time of 0 days established by the FDA for ractopamine used as feed additive in swine.     

Rapid determination of lignin content of straw using fourier transform mid-infrared spectroscopy

To determine lignin content in triticale and wheat straws, calibration models were built using Fourier transform mid-infrared spectroscopy combined with partial least-squares regression. The best model for triticale and wheat straws was built using averaged spectra with raw spectrum in spectrum format and constant in path length as spectral pretreatments. The values of r(2), root-mean-square error of prediction (RMSEP), and residual predictive deviation (RPD) for the triticale straw model were 0.935, 0.305, and 3.89, respectively. The r(2), RMSEP, and RPD values for the wheat straw model were 0.985, 0.163, and 8.50, respectively. Both models showed good predictive ability. A model built using both triticale and wheat straws indicated that the values of r(2), RMSEP, and RPD were 0.952, 0.27, and 4.63, respectively. This model also showed good predictive ability and could predict lignin contents in triticale and wheat straws with the same high accuracy.     

Rapid liquid chromatographic determination of dimetridazole and ipronidazole in swine feed

A simple and rapid method is described for the determination of dimetridazole (DMZ) and ipronidazole (IPR) in swine feeds at various levels (0.11-110 ppm). The drugs are released from feed by prewetting with a buffer, followed by extraction with either methanol or methylene chloride, depending on the drug level; if necessary, an acid-base cleanup is used before the liquid chromatographic analysis. The analytes are separated on a C18 column and monitored at 320 nm for detection and quantitation. Recoveries of DMZ from several feed formulations averaged 108% at the 92.8 ppm level with a standard deviation (SD) of 4.00% and a coefficient of variation (CV) of 3.70%, 101% at the 11.2 ppm level with an SD of 11.9% and a CV of 11.8%, and 100% at the 0.112 ppm level with an SD of 9.27% and a CV of 9.25%. Recoveries of IPR averaged 77.1% at the 12.9 ppm level with an SD of 1.75% and a CV of 2.27%; IPR recoveries averaged 35.2% at the 0.129 ppm level with an SD of 3.39% and a CV of 9.63%.     

大白菜中马拉硫磷农药的表面增强拉曼光谱快速检测

为了检测大白菜中马拉硫磷农药残留,该文采用表面增强拉曼光谱技术结合化学计量学方法建立马拉硫磷残留的快速检测模型。采用硫酸镁、N-丙基乙二胺、石墨化炭黑和C18去除大白菜中蛋白质、脂肪、碳水化合物等物质的影响。利用不同预处理方法对原始光谱信号进行预处理,建立大白菜中马拉硫磷残留的偏最小二乘模型。研究发现,大白菜中马拉硫磷的检测浓度达到1.082 mg/L以下;归一化预处理后建立的模型预测性能最好。配制5个未知浓度样本验证模型的准确度,预测值与真实值相对误差的绝对值为0.70%~9.84%,预测回收率为99.30%~109.84%;配对t检验的结果表明样本的预测值与真实值之间无明显差异,说明模型是准确可靠的。结果表明,SERS(surface-enhanced Raman spectroscopy)方法可以实现大白菜中马拉硫磷残留的快速检测。     

Rapid quantitative assessment of the adulteration of virgin olive oils with hazelnut oils using Raman spectroscopy and chemometrics

The authentication of extra virgin olive oil and its adulteration with lower-priced oils are serious problems in the olive oil industry. In addition to the obvious effect on producer profits, adulteration can also cause severe health and safety problems. A number of techniques, including chromatographic and spectroscopic methods, have recently been employed to assess the purity of olive oils. In this study Raman spectroscopy together with multivariate and evolutionary computational-based methods have been employed to assess the ability of Raman spectroscopy to discriminate between chemically very closely related oils. Additionally, the levels of hazelnut oils used to adulterate extra virgin olive oil were successfully quantified using partial least squares and genetic programming.     

表面增强拉曼光谱快速检测生鲜肉中的瘦肉精

为了快速检测生鲜肉中的瘦肉精,该研究利用表面增强拉曼光谱技术,以沙丁胺醇为检测目标物,建立了一种快速检测肌肉组织和肝脏中瘦肉精含量的方法。在碱性环境下利用乙酸乙酯对样品中沙丁胺醇进行提取,采用Savitzky-Golay 5点平滑法和自适应迭代重加权惩罚最小二乘法消除光谱噪声以及荧光背景对分析建模的影响。为检测方法的重复性,对50个相同沙丁胺醇质量分数(1 mg/kg)的肌肉组织样品进行信号采集,对沙丁胺醇特征峰强度进行分析,621、814、1 253、1 489、1 609 cm~(-1) 5个特征峰强度的相对标准偏差(RSD)为6.54%、6.07%、8.65%、7.44%、6.81%,说明该方法具有较好的重复性。建立沙丁胺醇标准溶液的预测模型,沙丁胺醇浓度与其特征峰强度相关性较好,决定系数R~2为0.968。对肌肉组织和肝脏中沙丁胺醇含量进行检测,检测范围分别为0.01~5和0.02~5 mg/kg,检出限分别为0.01和0.02 mg/kg,其含量与预测实测值决定系数为0.912和0.921。研究表明,该方法可以实现肌肉组织和肝脏中沙丁胺醇含量的定量预测。     

Rapid prediction of soil mineralogy using imaging spectroscopy

Hyperspectral images provide rich spectral and spatially continuous information that can be used for soil mineralogy discrimination. This paper proposes a method to evaluate the feasibility of Hyperion image in the rapid prediction of soil mineralogy. Four areas in Egypt were chosen for the current study. Preprocessing of the Hyperion data was done before applying the atmospheric correction. The minimum noise fraction transformation was used to segregate noise in the data. Various techniques were applied to the studied areas in which mixture tune matched filtering gave good results in a prediction of the end-members. Then, it employed to predict soil minerals in each cell using a spectral unmixing method. Illite, chlorite, calcite, dolomite, kaolinite, smectite, quartz, hematite, goethite, vermiculite, palygorskite and some feldspar were identified. In addition, sand and limestone, calcite and dolomite, and sand surface from similarly bright clouds can be distinguished easily based on the proposed method. The soil minerals obtained from X-ray diffraction analysis of the soil samples are in conformity with spectrally dominant mineralogy from Hyperion data. Different minerals can be identified using this method without any knowledge of field spectra or any a priori field data, thus configuring a “true” remote sensing method.     

Rapid determination of the main organic acid composition of raw Japanese apricot fruit juices using near-infrared spectroscopy

The potential of near-infrared (NIR) spectroscopy to rapidly determine citric and malic acid contents of raw Japanese apricot (Japanese "ume", also known as the Japanese plum) fruit juice was investigated. In total, 314 raw juice samples with different organic acid compositions were collected over a long growth period, and spectra (1100-1850 nm) of these samples were acquired using an NIR spectrophotometer with a 1-mm path length. Calibrations were performed using a partial least-squares regression method based on a calibration sample set (211 samples), while validations were performed based on a validation sample set (103 samples). The results revealed good agreement between NIR spectroscopy and capillary electrophoresis, including the correlation coefficient (r2), standard error of prediction (SEP), and bias; no statistically (p = 0.05) significant differences were found for these parameters. Moreover, standard deviation ratios of reference data in the validation sample set to the SEP were higher than 3, indicating that NIR spectroscopy may represent an acceptable method for quantitative evaluation of citric and malic acids in raw Japanese apricot fruit juice.     

Rapid determination of the attenuation limit of beer using middle-infrared (MIR) spectroscopy and a multivariate model

A new approach for the determination of the attenuation limit of beer samples using the specific fingerprint region of middle-infrared (MIR) spectroscopy in combination with multiple regression by partial least-squares (PLS) was developed using an attenuated total reflectance (ATR) module. A specific spectral region between 1200 and 800 cm(-1) was identified as highly informative for the quantification of the limit of attenuation. The absorptions in this region are induced by vibrational bands of ethanol (1080, 1040, and 880 cm(-1)) and dissolved extract, in majority maltotriose (1160-1140 and 1040-980 cm(-1)). The multivariate calibration results in a root mean squared error of calibration (RMSEC) of 0.40% and a validation procedure with independent samples results in a root mean squared error of validation (RMSEV) of 0.50%. A repeatability test, concerning the precision of the developed MIR method as well as the reference method, was analyzed using Student's t test. The test has shown no significant difference between the two random samples.     

Determination of ractopamine in cattle and sheep urine samples using an optical biosensor analysis: comparative study with HPLC and ELISA

A biosensor method, using the surface plasmon resonance (SPR) principle, was developed for the determination of ractopamine in cattle and sheep urine. A monoclonal antibody was used to compete with ractopamine in the sample and ractopamine immobilized on the sensor chip. Addition of bovine serum albumin (BSA, 1 mg/mL) as an antibody stabilizer to the incubation buffer was required to achieve a stable biosensor response throughout each sample set. The calibration curve gave a mean IC(50) of 4.7 +/- 0.21 ng/mL (n = 7). Over sample concentrations from 2.5 to 10 ng/mL recoveries were typically approximately 100-110%, whereas inter- and intra-assay reproducibilities (% CV) were usually less than 10 and 6%, respectively. Comparison of biosensor results with results obtained from high-performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assays (ELISA) using enzyme-hydrolyzed urine (to convert ractopamine conjugates to free ractopamine) gave correlation coefficients of 0.94 for sheep and 0.86 for cattle. Slopes of the lines, with zero intercepts, equaled 0.80 for sheep and 0.74 for cattle. For untreated (nonhydrolyzed) urine samples, the correlations between biosensor and HPLC results were 0.95 for sheep and 0.72 for cattle with slopes of 1.18 (sheep) and 1.69 (cattle). The slopes greater than unity indicate that the biosensor responded to ractopamine metabolites in addition to free ractopamine. The biosensor assay is an excellent analytical tool to screen ractopamine residues in sheep or cattle urine, and the results should be extendible to other species with suitable validation.     

Rapid determination of domoic acid in serum and urine by liquid chromatography-electrospray tandem mass spectrometry

A rapid, selective, and sensitive LC-MS/MS method was developed for the quantitative determination of domoic acid in serum and urine samples. Samples were prepared for analysis using an Oasis HLB SPE column. Determination was by a reversed phase HPLC using a mixture of methanol, acetonitrile, and water containing 1% acetic acid and an electrospray ionization (ESI) ion-trap mass spectrometer (Finnigan LCQ). The method was validated by analyzing five replicates each of negative control bovine serum or urine fortified with domoic acid at the 0.005 microg/g method detection limit (MDL) and at the 0.05 microg/g level. Recoveries ranged from 90 to 95% for fortifications at the MDL and from 92 to 98% for fortifications 10 times higher than the MDL. The diagnostic utility of the method was tested by analyzing samples from live animals showing clinical signs suggestive of domoic acid poisoning submitted to the veterinary toxicology laboratory.     

基于近红外光谱的沼液挥发性脂肪酸含量快速检测

挥发性脂肪酸(Volatile Fatty Acids,VFA)作为厌氧发酵过程的重要中间产物,其在厌氧反应器中的累积能够反映出产甲烷菌的不活跃状态或厌氧发酵条件的恶化。为了实现对农牧废弃物厌氧发酵进行过程分析和状态监控,将近红外光谱(Near Infrared Spectroscopy,NIRS)与偏最小二乘(Partial Least Squares,PLS)相结合构建玉米秸秆和畜禽粪便厌氧发酵液乙酸、丙酸和总酸含量快速检测模型。将竞争自适应重加权采样法(Competitive Adaptive Reweighted Sampling,CARS)与遗传模拟退火(Genetic Simulated Annealing,GSA)算法相结合构建CARS-GSA算法对沼液中的乙酸、丙酸和总酸进行特征波长优选,原始光谱数据1 557个波长点经预处理和波长优选后,得到乙酸、丙酸和总酸特征波长变量分别为135、101和245个,建立的回归模型验证决定系数分别为0.988、0.923和0.886,预测均方根误差(Root Mean Squared Error of Prediction,RMSEP...     

近红外光谱快速检测食用油必需脂肪酸

为了建立食用油必需脂肪酸快速检测的方法,该研究提出了基于近红外光谱技术检测食用油中α-亚麻酸和亚油酸含量的快速测定方法。对光谱信息分别采用偏最小二乘回归方法(PLS)和最小二乘支持向量机(LS-SVM)建立模型。比较了多种光谱预处理方法对模型预测能力的影响。结果表明对于亚油酸含量的预测,采用Savitzky-Golay平滑法结合多元散射校正(MSC)的光谱预处理所建立的LS-SVM模型最优。预测集的决定系数(R2)、预测均方根误差(RMSEP)和剩余预测偏差(RPD)分别达到了0.989,0.0161和9.4783。对于α-亚麻酸含量的预测,采用Savitzky-Golay平滑法结合标准正态变换(SNV)的光谱预处理所建立的LS-SVM模型最优。α-亚麻酸含量预测结果的R2、RMSEP和RPD为0.972,0.0036和6.0561,据此表明,应用近红外光谱技术能够检测食用油中α-亚麻酸和亚油酸的含量,为快速检测食用油的必需脂肪酸提供了参考。     

Rapid analysis of methanol in grape-derived distillation products using near-infrared transmission spectroscopy

Samples of distillates derived from the production of wine-fortifying spirit were analyzed for methanol by gas chromatography (GC) and near-infrared spectroscopy (NIRS). NIRS calibration models were developed which could accurately predict methanol concentrations in samples of fortifying spirit that had been produced over a period of three years from four different commercial distillation facilities. The best accuracy of the predictive models, as measured by the standard error of prediction value, was 0.06 g/L methanol. Other distillation fractions, produced during preparation of commercial fortifying spirit, were also examined. The most useful NIRS calibration models used partial least squares regression on continuous spectra from a scanning instrument, but it was demonstrated that calibrations could also be developed with a smaller number of fixed wavelengths, using multiple linear regression models. NIRS offers the advantages of rapid analysis, with simple routine operation, and may offer the potential for in-line process control in the operation of a commercial distillation facility.     

Rapid determination of carbohydrates, ash, and extractives contents of straw using attenuated total reflectance fourier transform mid-infrared spectroscopy

Analysis of the chemical components of lignocellulosic biomass is essential to understanding its potential for utilization. Mid-infrared spectroscopy and partial least-squares regression were used for rapid measurement of the carbohydrate (total glycans; glucan; xylan; galactan; arabinan; mannan), ash, and extractives content of triticale and wheat straws. Calibration models for total glycans, glucan, and extractives showed good and excellent predictive performance on the basis of slope, r2, RPD, and R/SEP criteria. The xylan model showed good and acceptable predictive performance. However, the ash model was evaluated as providing only approximate quantification and screening. The models for galactan, arabinan, and mannan indicated poor and insufficient prediction for application. Most models could predict both triticale and wheat straw samples with the same degree of accuracy. Mid-infrared spectroscopic techniques coupled with partial least-squares regression can be used for rapid prediction of total glycans, glucan, xylan, and extractives in triticale and wheat straw samples.     

Rapid determination of free fatty acids in poultry feed lipid extracts by SB-ATR FTIR spectroscopy

A simple, rapid, and reproducible method has been developed for the quantitative determination of free fatty acid (FFA) content in lipids extracted from poultry feeds by Fourier transform infrared (FTIR) spectroscopy with the use of a single-bounce attenuated total reflectance (SB-ATR) accessory. An FTIR calibration curve was prepared by gravimetrically adding oleic acid (15-37%) to pure refined, bleached, and deodorized (RBD) canola oil and measuring the area of the COOH absorption band at 1710 cm-1. The oil from each of 12 poultry feed formulations was extracted using conventional Soxhlet extraction, and after evaporation of the solvent, the FFA content was determined by the conventional AOCS titrimetric procedure and by the SB-ATR/FTIR method. The SB-ATR/FTIR FFA predictions were related to those determined by the AOCS titrimetric method by linear regression, producing an R value of 0.999 and a SD of +/-0.28% FFA. Time-course spectra collected as lipids extracted into hexane indicated that a 15 min extraction was adequate to obtain a representative sample for FFA determination, with further extraction resulting in little, if any, change in the proportion of FFA in the lipid extract. Only a small volume of the hexane extract ( approximately 20 mL) yielded sufficient material for the SB-ATR/FTIR analysis. Thus, by shortening the extraction time and taking a small sample so as to reduce solvent removal time, the SB-ATR/FTIR procedure provides a very simple and rapid means of determining the FFA content of poultry feed lipids.     

Rapid prediction of solid wood lignin content using transmittance near-infrared spectroscopy

A rapid transmittance near-infrared (NIR) spectroscopic method has been developed to characterize the lignin content of solid wood. Using simple, multiple regression, and partial least-squares statistical analysis the lignin contents of wood wafers, taken from increment cores, and synthetic wood, prepared by blending milled wood lignin and holocellulose, were compared and quantified. Strong correlations were obtained between the predicted NIR results and those obtained from traditional chemical methods. In addition to the experimental protocol and method development, NIR results from wood samples with different particle sizes and various lignin contents are discussed.     

Rapid screening of wood chemical component variations using transmittance near-infrared spectroscopy

A rapid transmittance near-infrared (NIR) spectroscopy method was developed to predict the variation in chemical composition of solid wood. The effect of sample preparation, sample quantity (single versus stacked multiple wood wafers), and NIR acquisition time on the quantification of alpha-cellulose and lignin content was investigated. Strong correlations were obtained between laboratory wet chemistry values and the NIR-predicted values. In addition to the experimental protocol and method development, improvements in calibration error associated with utilizing stacked multiple wood wafers as opposed to single wood wafers are also discussed.