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1.
A liquid chromatographic (LC) method was compared with the AOAC mouse bioassay method (18.086-18.092) for determination of paralytic shellfish toxins in shellfish tissues. Shellfish samples were collected from Massachusetts coastal waters as part of a state surveillance program, and extracts of shellfish meat were analyzed for toxins by using both analytical methods. Overall correlation of the LC and bioassay methods is good (r = 0.943), but for samples with toxicities less than 100 micrograms saxitoxin/100 g shellfish meat, the correlation is significantly less (r = 0.531). Limits of detection are 10 micrograms saxitoxin/100 g shellfish meat and 40 micrograms saxitoxin/100 g shellfish meat for the LC and bioassay methods, respectively. Analytical capacity of the LC method is limited to 12 samples/person-day compared with 30 samples/person-day for the bioassay. Sampling capacity of the LC method could be increased by using a fluorescence detector with a wider response range, which would eliminate the need for dilution of concentrated samples.  相似文献   

2.
A liquid chromatographic (LC) method for the determination of chloramphenicol (CAP) residues in meat at the 10 microgram/kg level was tested in an interlaboratory study. The method used, based on aqueous extraction and sample cleanup with a cartridge containing Extrelut, was published earlier. A prestudy to familiarize collaborators with the method was performed before the actual interlaboratory precision study. The meat samples used in the precision study were prepared by diluting dosed chicken and pig muscle tissues with blank tissues from other species. Fourteen laboratories received 20 meat samples; 13 laboratories actually participated in the study. Two blank samples and 2 positive samples each of pig, calf, chicken, lamb, and cow meat were tested. The chloramphenicol concentrations in the positive samples ranged from 6.5 to 21 micrograms/kg. The overall mean reproducibility coefficient of variation was 17.9% after the results per laboratory were corrected for the mean recovery obtained within each sample series. The overall mean recovery was 55.1% with a coefficient of variation of 18.0% at the 10 micrograms/kg level. The limit of detection, based on chromatograms of blank samples, was estimated to be 1.5 micrograms/kg of chloramphenicol. No false positives or false negatives were observed in the concentration range tested; only 2 false positive results above the detection limit (1.7 and 6 micrograms/kg) on a total number of 60 blank analyses (3.3%) were observed.  相似文献   

3.
The volatile compounds generated in meat from Iberian and lean pigs after four different treatments (raw, refrigerated, cooked, and refrigerated cooked meat) were analyzed. The different treatments showed different volatile profiles. Methyl alcohols and ketones (such as 2-ethyl-hexan-1-ol, 2-methyl-butan-1-ol, 3-methyl-butan-1-ol, and 3-hydroxy-butan-2-one) were the most representative in refrigerated meat because of the degradation of carbohydrates and proteins together with the Strecker degradation pathway. Lipid-derived volatiles were the most abundant in cooked meat and refrigerated cooked meat. Meat from different pig breeds presented different volatile profiles, probably due to different enzymatic and oxidative deterioration susceptibility. Otherwise, the fat content and its compositional characteristics also played an important role in the generation of volatiles. As compared to samples from lean pigs, muscles from Iberian pigs showed a higher content of heme iron that may have promoted the generation of higher content of total lipid-derived volatiles during the refrigeration of cooked meat. Despite that, the formation of volatiles with low thresholds and related to intense rancidity perception likely to be derived from polyunsaturated fatty acids was higher in lean pork than in meat from Iberian pigs. This might be expected to lead to a more intense development of a warmed over flavor during refrigeration of cooked samples from lean pigs.  相似文献   

4.
A liquid chromatographic (LC) method for the simultaneous determination of dextrose, sucrose, maltose, and lactose in sausage products has been developed. Dextrose, sucrose, maltose, and lactose are extracted from comminuted meat products with 52% ethanol. After filtration, the extracts are purified by passing them through a C18 Sep-Pak cartridge and 2 ion exchange resin Econo-columns in series. After concentration and filtration, extracts are analyzed by LC using a normal phase amino column and a differential refractometer detector. Homogeneously ground samples of cooked and fresh sausages are fortified with dextrose, sucrose, maltose, and lactose at 4 different concentrations. Average recovery for dextrose, sucrose, maltose, and lactose at all 4 levels of fortification was greater than 80% with a coefficient of variation less than 10%.  相似文献   

5.
A rapid, sensitive, liquid chromatographic (LC) method has been developed for determination of residuals of the processing aid, 4-hexylresorcinol, on shrimp meat. An aqueous homogenate of shrimp meat is extracted with ethyl acetate followed by precolumn preparation on a silica Sep-Pak cartridge. LC determination is preformed with a Nova-Pak C18 column, with UV detection at 214 nm. Sensitivity was 0.006 micrograms, and recovery from shrimp meat samples of known 4-hexylresorcinol addition was 94%. Shrimp treated with 4-hexylresorcinol under the recommended dip protocol had mean residuals of 1.18 ppm, with a standard deviation of 0.13 ppm.  相似文献   

6.
A liquid chromatographic (LC) method for the simultaneous determinations of benzoic acid, sorbic acid, and methyl, ethyl, propyl, and butyl parabens (methyl, ethyl, propyl, and butyl-p-hydroxybenzoates) in meat and nonmeat products was developed. Benzoic acid, sorbic acid, and parabens were extracted from meat and nonmeat products with 70% ethanol. After filtration, extracts were analyzed by reverse phase liquid chromatography. Homogeneously ground samples of fresh sausage and hamburger were fortified with benzoic acid, sorbic acid, and each paraben at 5 different concentrations. Average recovery (after discarding outliers) for each preservative at all 5 levels was greater than 95% with a coefficient of variation less than 5%.  相似文献   

7.
In this study, a liquid chromatography (LC)/turbo ion spray (TIS)-mass spectrometry (MS) method was developed to examine the chromatography or "fingerprint profile" of seven Cimicifuga herbs and six Cimicifuga racemosa (black cohosh) commercial products. Triterpene glycoside components were selected as chemical markers for analysis because they have appeared as a major compound group in Cimicifuga species. LC/MS chromatograms unveiled the patterns of C. racemosa, Cimicifuga dahurica, Cimicifuga foetida, Cimicifuga heracleifolia, Cimicifuga japonica, Cimicifuga acerina, and Cimicifuga simplex, which are very different from each other. 23-Epi-26-deoxyactein was found only in C. racemosa, C. dahurica, and C. foetida. A highly selective and sensitive LC/MS/MS method for quantitative analysis of 23-epi-26-deoxyactein with detection levels up to 2.5 ng in these samples was also developed and was applied to six commercial C. racemosa products. C. racemosa and its six commercial products contained about 6-15% of 23-epi-26-deoxyactein in total triterpene glycosides. On the other hand, the estimated amount of total triterpene glycosides in other commercial products was either greater or lesser than what the manufacturers claimed. The technique and LC/MS profiles generated in this study provide a reliable and reproducible method that can be readily utilized for botanical identification of Cimicifuga plants, for examination and validation of its commercial products, and for "chemical" quality control in the manufacture of black cohosh products.  相似文献   

8.
A liquid chromatographic (LC) method has been developed to determine narasin in feed premixes. Narasin is extracted from the premix with a methanol-water solvent, and the extracted solution is assayed by using LC. Recovery of narasin from a 12.5 g/lb premix is quantitative (100%), with a relative standard deviation of 1.44%. The results correlated well (coefficient 0.92) with a turbimetric bioassay method.  相似文献   

9.
The objective of this investigation was to provide a comprehensive analysis of the total lipid composition of present-day retail beef meat available at the consumer level and to evaluate the total lipid composition with special emphasis on the nutritional value. For this purpose, 40 beef cuts were obtained from four cattle farms based on either a natural grazing system (NGS) or an intensive production system (IPS). The total lipid composition was analyzed using complementary chemical and chromatographic procedures. The content of n-3 LC-PUFA, CLA, total trans-18:1, and branched-chain fatty acids was significantly higher in NGS beef than in IPS beef. The trans-18:1 and CLA profiles were affected by the different production systems, whereby they can be utilized empirically to differentiate between feeding regimen and production management. Fatty acid ratios that have health implications ( n-6/ n-3, LA/alphaLNA, and AA/EPA) were remarkably beneficial for NGS beef compared with IPS beef. In conclusion, from the human health perspective, beef raised on NGS is clearly superior with regard to a more favorable fatty acid profile in comparison to IPS beef.  相似文献   

10.
A liquid chromatographic method is described to determine simultaneously the following 11 synthetic antibacterial agents used in a fishery: nitrofuran derivatives furazolidone, nifurpirinol, difurazone, and furamizole; sulfa drugs sulfamerazine, sulfisozole, sulfamonomethoxine, and sulfadimethoxine; and, oxolinic, nalidixic, and piromidic acids. A Nucleosil C18 column was used with tetrahydrofuran-acetonitrile-phosphoric acid-water (29 + 1 + 0.06 + 69.94) as the mobile phase. Pretreatment of the fish meat sample with acetone extraction and alumina column cleanup gave good separation of the LC peaks without interference from any other components. Recovery of the antibacterial agents was ca 80%. The lower limit of detection of the drugs was 1-2 ng for 10 microL injection.  相似文献   

11.
Six laboratories collaboratively studied a liquid chromatographic (LC) method for the quantitative determination of primidone in tablets. Two lots each of commercially prepared 50 and 250 mg tablets and 2 authentic mixtures, at 50 and 250 mg levels, were sent to each collaborator. Samples were dissolved in the mobile phase, filtered, and injected into the chromatograph. Average recoveries for the 8 samples ranged from 97.5 to 101.2%, and coefficients of variation ranged from 0.53 to 3.01%. The LC method has been adopted interim official first action.  相似文献   

12.
Wang  J.  Jia  C. R.  Wong  C. K.  Wong  P. K. 《Water, air, and soil pollution》2000,120(3-4):381-396
Used lubricating oils are majorsources of polycyclic aromatic hydrocarbons (PAHs) inmarine environments. This study presents an improvedmethod for characterization PAHs in used lubricatingoils. Recoveries of sixteen certified PAHs spikedinto used lubricating oil indicated this method wasmore precise and efficient than those reportedpreviously. Aromatic and aliphatic compounds in usedlubricating oil were extracted by dimethylsulfoxide,then separated by a silica gel column using hexane anddichloromethane as solvents. Finally, gaschromatography-mass spectrometry was used inqualitative and quantitative analysis of various PAHsin oil samples. Sixteen certified PAHs andeighty-three other PAHs were identified and quantified usingPAH standards and previously reported retentionindices as references. The improved method was usedto determine PAH profiles in lubricating oil samplescollected from a gasoline-driven automobile aftervarious driving distances. One hundred and eightyaromatic compounds, including ninety-nine PAHs, wereidentified by the gas chromatographic method. Theseresults suggested that the new method was superior tomethods described in previous studies. Theconcentrations of PAHs, including the comparativelytoxic 5-ring PAHs, increased rapidly even after theautomobile had only been driven for a short distance. 2- and 3-ring PAHs, most of them are alkylated,dominated the PAH profiles of the collected oil samples.  相似文献   

13.
Tylosin, an antibiotic developed specifically for agricultural use, and erythromycin are the main macrolide antibiotics used in animal production. Two-dimensional thin layer chromatography has been used for detection of tylosin in poultry meat, eggs, and milk and for erythromycin in poultry meat. Detection limits reported are, for tylosin, 0.1 ppm in poultry meat, 0.05 ppm in egg, and 0.01 ppm in milk, and for erythromycin, 0.25 ppm in poultry meat. Liquid chromatography (LC) has also been used for determination of tylosin in milk, blood, and tissues of animals. Samples (milk, blood serum, or tissue homogenates in water or pH 2.2 buffer) were deproteinized with acetonitrile, tylosin was partitioned into methylene chloride, and the extracts were concentrated and dissolved in acetonitrile. Chromatography was done on a reverse phase end-capped C18 column using 0.002-0.005 M ammonium dihydrogen phosphate-acetonitrile-methanol (10 + 60 + 30-5 + 80 + 15). Solvent composition was varied with the type of sample analyzed. The method will detect 0.1 ppm tylosin in tissues and less in milk and blood serum. The LC method was more sensitive than microbiological assays for detection of tylosin in tissues of treated swine; recoveries of tylosin by the LC method were frequently several-fold higher.  相似文献   

14.
为了研究牦牛不同部位分割肉的品质特征,该研究测定了牦牛辣椒条、上脑、眼肉、外脊、里脊、小黄瓜条、大黄瓜条、米龙、霖肉9个部位分割肉的剪切力、蒸煮损失、失水率、L*、a*、b*、蛋白、脂肪、含水率9项品质特性,并通过方差分析法、标准化法、主成分法研究其品质特征。结果表明,除了脂肪和含水率外,其余7项品质特性均存在显著差异性（P＜0.05）。标准化分析结果表明小黄瓜条、大黄瓜条、米龙、霖肉4个后部肉具有相似特征,具有较好的嫩度、较高的蛋白含量、中等水平的持水能力。主成分分析共提取出3个主成分因子PC1（34.69%）、PC2（25.97%）、PC3（19.12%）,其中PC1可明显区分出中部肉与后部肉差异,根据因子载荷,牦牛肉化学组成（蛋白、脂肪、含水率）与这一差异密切相关。可以得出以下结论：不同部位牦牛肉品质存在差异,这一差异与其在牦牛胴体上的相对位置有关,而牦牛胴体的后部肉品质优于其他部位,因此可以作为开发高档产品的原料来源。  相似文献   

15.
A rapid liquid chromatographic (LC) method was developed for a sensitive determination of nitrite in cured meats, using ion-exclusion chromatographic separation and electrochemical detection (IEC-EC). The current AOAC colorimetric method requires 2 h shaking in a steam bath to eliminate interference from reducing compounds such as ascorbic acid. In the present method, nitrite was analyzed in the presence of ascorbic acid without interference, and the extraction time was reduced to 1 min. The extracted nitrite was determined by ion chromatography using anion-exclusion/HS column and amperometric detector equipped with platinum or glassy carbon electrode operating at +1.0 V vs Ag/AgCl reference electrode. The detection limit was 1 ppb as NO2-. The recoveries of 50 ppm nitrite added to frankfurter and meat stick were 103 and 99.6%, respectively, with relative standard deviations less than 4%. The high speed, sensitivity, and selectivity make the new method a useful alternative to the AOAC colorimetric method.  相似文献   

16.
A circular paper chromatographic method was developed for the separation of the amino acids in proteins into 7 subgroups. Butanol-acetic acid water (4+1+1) was used as the developing solvent. Eluted ninhydrin-stained aminograms gave rise to graphic profiles or numerical indexes based on absorbance percentages. The profiles can be used to compare protein-containing samples. Twenty different samples were studied through 190 comparisons of graphic profiles and coefficients of correlation, with only 4% misleading results. The method showed excellent reproducibility for the identification or differentiation of proteins and has the advantage of being performed with low-priced apparatus and reagents.  相似文献   

17.
Experiments were conducted to determine the volatile compounds in cooked chicken meat using a static headspace gas chromatographic (GC) technique. Preheating conditions for samples in vials were tested at 70, 80, and 90 degrees C for 20-120 min at each temperature. The majority of the peaks increased in size as the temperature and time increased. Optimum conditions were established as preheating at 80 degrees C for 30 min followed by analysis on a packed column of 8% Poly MPE on Tenax GC with the temperature programmed from 50 to 200 degrees C at 10 degrees/min. Coefficients of variation for major peaks ranged from 8.3 to 14.7%. These results were compared with those obtained with a capillary column analysis of samples preheated at the same conditions. Cooked and stored chicken patties, pretreated with different levels of sodium tripolyphosphate, were analyzed by the thiobarbituric acid (TBA) method and the headspace GC technique. Significant positive correlations were obtained between TBA numbers and the areas of 3 major peaks of the headspace profiles, indicating the applicability of the rapid headspace GC method for the determination of oxidative changes in chicken meat.  相似文献   

18.
质构仪穿透法测定肉制品嫩度的研究   总被引：12，自引：5，他引：12  
为了量化评定肉制品的食用物理特性——嫩度,试验以猪和牛不同部位的肌肉为材料,使用高精度TA-X12质构仪,模拟口腔咀嚼肌肉的穿透方法,测定了不同肌肉的穿透曲线。并比较分析了不同肌肉的穿透参数(包括3个极值点Y1,Y2,Y3,恒定值Y4和曲线所包围的面积Y5),与感官品评嫩度值之间的相关关系。结果表明：质构仪穿透法测得的第一个极值点(Y1)与猪和牛不同部位的肌肉的感官品评嫩度值相关系数分别为0.9784和0.9984,呈极显著的正相关关系(P<0.01),穿透法第一极值点(Y1)可作为猪肉、牛肉肉制品的嫩度测定量化参数。  相似文献   

19.
Twenty microsatellites (simple sequence repeats, SSR) were used to discriminate wild boar from domestic pig and to identify mixtures of the two. Reference groups of wild boar and pig samples were collected from the UK and Europe for genetic assignment tests. Bayesian Analysis of Populations software (BAPs) gave 100% correct assignment for blind wild boar and pig samples and correctly identified mixed samples. DNA was extracted from 12 commercial food samples (11 labeled as containing wild boar) including patés, salamis, and sausage, and good SSR profiles were obtained. Eleven samples were correctly assigned as pig, and two as mixed meats. One sample sold as wild boar meat was clearly assigned as pig. A further 10 blind samples of meat cuts were analyzed, eight wild boar and two pig, and all were correctly assigned.  相似文献   

20.
Sodium chlorate is being developed as a potential food-safety tool for use in the livestock industry because of its effectiveness in decreasing concentrations of certain Gram-negative pathogens in the gastrointestinal tracts of food animals. A number of studies with sodium chlorate in animals have demonstrated that concentrations of chlorate in meat, milk, wastes, and gastrointestinal contents range from parts per billion to parts per thousand, depending upon chlorate dose, matrix, and time lapse after dosing. Although a number of analytical methods exist for chlorate salts, very few were developed for use in animal-derived matrices, and none have anticipated the range of chlorate concentrations that have been observed in animal wastes and products. To meet the analytical needs of this development work, LC-MS, ion chromatographic, and colorimetric methods were developed to measure chlorate residues in a variety of matrices. The LC-MS method utilizes a Cl(18)O(3)(-) internal standard, is applicable to a variety of matrices, and provides quantitative assessment of samples from 0.050 to 2.5 ppm. Due to ion suppression, matrix-matched standard curves are appropriate when using LC-MS to measure chlorate in animal-derived matrices. A colorimetric assay based on the acid-catalyzed oxidation of o-tolidine proved valuable for measuring ≥20 ppm quantities of chlorate in blood serum and milk, but not urine, samples. Ion chromatography was useful for measuring chlorate residues in urine and in feces when chlorate concentrations exceeded 100 ppm, but no effort was made to maximize ion chromatographic sensitivity. Collectively, these methods offer the utility of measuring chlorate in a variety of animal-derived matrices over a wide range of chlorate concentrations.  相似文献   

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