蜂蜜中喹诺酮类、四环素类、氯霉素类抗生素的液相色谱-串联质谱测定法

建立同时测定蜂蜜中喹诺酮类、四环素类、氯霉素的液相色谱-串联质谱法。样品以乙腈-水(0.2%甲酸)(体积比80∶20)溶液超声提取,离心,取上清液过Oasis PRIME HLB固相萃取柱,流出液2 mL氮吹近干,用1 mL 0.1%甲酸水∶乙腈(95∶5)定容至1 mL,过PTFE滤膜,LC-MS/MS正负离子同时扫描测定喹诺酮类、四环素类、氯霉素类抗生素的含量。该方法的线性范围0.5～50 ng/mL,相关系数0.995,加标0.5～20.0μg/kg,回收率为71.5%～104.5%,RSD为1.9%～9.6%,喹诺酮类检出限为1.0μg/kg,四环素类检出限为2.0μg/kg,氯霉素类检出限为0.5μg/kg。结论:该方法灵敏、快速、准确,适用于蜂蜜的喹诺酮、四环素、氯霉素检测。     

流动注射-化学发光法测定氯霉素

基于碱性介质中,氯霉素对H2O2-鲁米诺化学发光体系有增敏作用,结合流动注射分析,建立了一种流动注射-化学发光法灵敏检测氯霉素的方法。结果表明,最佳实验条件为:流路选择氯霉素和KMnO4先混合,再注入鲁米诺(NaOH)溶液中;氧化剂选择H2O2,其浓度为6.0×10-4mol/L;鲁米诺中NaOH的浓度为8.0×10-5mol/L;鲁米诺浓度为1.0×10-4mol/L;选择混合管长度为5 cm。在最佳条件下,该方法检测氯霉素的线性范围为8.0×10-8~1.0×10-5g/mL,检出限(3σ)为5×10-8g/mL,对5×10-7g/mL氯霉素进行11次平行测定,相对标准偏差(RSD)为1.3%。用该法对氯霉素胶囊中氯霉素的含量进行了测定。     

高效液相色谱串联质谱测定鸡、猪肉中万古霉素

建立了鸡肉和猪肉样品中万古霉素的高效液相色谱串联质谱检测方法。鸡肉和猪肉样品经5%三氯乙酸:乙腈(4:1)提取,阳离子交换固相萃取柱净化后,以0.1%甲酸5 mmol乙酸铵溶液和乙腈作为流动相,经C_(18)色谱柱分离后,采用多反映离子监测模式进行测定,外标法定量。结果表明,万古霉素在1.0～20.0 ng/mL范围内呈现良好的线性关系,相关系数(r~2)大于0.99,在5,25,50μg/kg加标水平下,万古霉素平均回收率60%～120%,方法检出限(LOD)为2.0μg/kg,方法定量限(LOQ)为5.0μg/kg。     

气相色谱-质谱法测定牙膏中的二甘醇

利用毛细管柱气相色谱-质谱(GC-MS)测定牙膏中二甘醇的量,检出限为5 mg/kg,二甘醇的线性范围为5μg/mL~500μg/mL,回收率为95.2%~102.2%,相对标准偏差(RSD)为1.19%~1.54%。     

超高效液相色谱质谱/质谱法的测定广东地区市售8类动物源食品中氯霉素残留的调查分析

随机抽取了市售的牛肉、虾肉、蜂蜜、贝类、鸡肉、猪肉、牛奶及鱼肉食品等8类动物源食品样品1709份,采用超高效液相-质谱法对食品中氯霉素的含量进行了检测调查分析。方法在0.5~50μg/L范围内呈良好的线性关系,相关系数R为0.997,检出限为0.1μg/kg,回收率在75%~120%之间。样品中除鸡肉、猪肉、牛肉、虾肉未检出外,其它种类的样品中均有检出。蜂蜜、贝类、牛奶及鱼肉样品中氯霉素的检出率分别为0.86%、1.41%、0.62%和0.39%;其含量范围分别为0.0~1.8μg/kg、0.0~4.5μg/kg、0.0~0.5μg/kg和0.0~2.6μg/kg。调查结果表明,市场上食品中氯霉素存在一定程度的污染,相关部门应该引起重视,并加强食品中违禁药物的监测工作。     

3-甲基-4-硝基-5-氯吡唑的HPLC测定法

目的:采用高效液相色谱法测定3-甲基-4-硝基-5-氯吡唑含量.方法:用Waters symmetryC8(3.9mm×150mm,5μm)色谱柱,流动相为乙腈-0.1%磷酸溶液(50:50),流速1mL/min,柱温:25℃,检测波长274nm.结果:在160.48μg/mL～401.20μg/mL范围成线性(r=0.9998,n=5),平均回收率为98.93%,RSD=1.91%.     

UPLC-MS/MS测定野拔子蜂蜜中氯霉素残留

采用同位素内标-液质联用法测定野拔子蜂蜜中氯霉素残留量。样品经乙酸乙酯提取,MCS复合型固相萃取柱净化,采用ZORBAX SB-C_(18)色谱柱分离,以0.05%的氨水溶液-乙腈为流动相进行梯度洗脱,采用电喷雾-正离子多反应监测模式检测,同位素内标法定量。该法氯霉素的浓度为0.1～5.0 ng/mL时,线性关系良好(r0.999),回收率为93.7%～99.3%,定量限为0.15μg/kg,检出限为0.05μg/kg。说明该方法灵敏度及准确度良好,能满足野拔子蜂蜜中氯霉素残留分析的要求。     

化妆品中6-甲基香豆素的高效液相色谱-紫外检测器法测定

建立了高效液相色谱-紫外检测器法测定化妆品中6-甲基香豆素含量的方法。样品通过甲醇超声提取20 min,离心、过滤,Agilent ZORBAX300SB-C18(4.6×250 mm,5μm)分析柱分离分析,紫外检测器检测,外标法定量。方法在0.101 9～10.19μg/mL范围内线性关系良好,相关系数(r)=0.999 99,回收率在94.67%～103.15%之间,相对标准偏差(RSD)小于3%,检出限(S/N=3)为0.05 mg/kg,定量限(S/N=10)为0.10 mg/kg。采用该方法测定了15种化妆品中6-甲基香豆素的含量,结果满意,可以满足实验室日常检测工作的需要。     

HPLC法测定消毒洗手液中邻苯基苯酚钠的含量

建立了一种高效液相色谱法(HPLC)测定消毒洗手液中邻苯基苯酚钠含量的检测方法。方法以体积比70:30的甲醇-磷酸溶液(0.25 mL磷酸加入到1 000 mL水中)为流动相,流速1.0 mL/min,检测波长245 nm,进样体积10μL。结果显示邻苯基苯酚钠的保留时间为7 min左右,线性范围5～100μg/mL,方法的最低检出质量比为2.5 mg/kg,最低定量质量比为8.5 mg/kg,平均回收率为96.07%～107.06%,精密度(RSD)为0.24%～0.75%。该方法样品处理快速简便,分析方法准确可靠,适用于消毒洗手液中的邻苯基苯酚钠含量的测定。     

柑橘中除草醚残留量的气相色谱-质谱法测定

建立了柑橘中除草醚除草剂农药残留量气相色谱质谱检测方法。用乙腈提取试样中残留的药物,经中性氧化铝固相萃取小柱净化,采用气相色谱分离,质量选择检测器检测,外标法定量。除草醚农药在0.01μg/mL～5.0μg/mL浓度范围具有良好线性关系,线性相关系数在0.9989～0.9996,空白样品中添加0.01 mg/kg、0.05 mg/kg、0.1 mg/kg三个浓度,回收率在80.1%～104.3%之间,相对标准偏差在3.2%～14.3%之间。以信噪比为10计的方法检测限(LOD)为0.01 mg/kg,方法快速、简单,完全能够满足农药残留检测要求。     

Optimization of primary freeze drying conditions for powdered chicken meat hydrolysate from mechanically deboned chicken residues

Abstract

In this study, mechanically deboned chicken meat residues were hydrolyzed by protease enzyme and chicken meat hydrolyzate was freeze-dried in order to produce high-quality meat powder. Due to its high cost, energy and time consumption, freeze-drying conditions needed to be optimized. Response surface methodology was used for optimization with the independent variables shelf temperature, lyophilization temperature and freezing rate. The responses were sublimation time, solubility and in vitro protein digestibility. The optimum conditions were shelf temperature, 15?°C; lyophilization temperature, –10?°C; and freezing rate, 2.0?°C/min. Sublimation time, solubility and in vitro protein digestibility for this optimum conditions were found to be 590.344?min, 25.626% and 23.808%, respectively.     

Mechanical properties of chicken feather fibers

Chicken feather fibers (CFFs) are attractive for composite applications. In this study, mechanical properties of the feather barbs were investigated statistically. The strain at break of CFFs had a Gaussian distribution with a mean value of 6.93%. The tensile modulus of CFFs was 3.59 ± 1.09 GPa and average tensile strength was 203 ± 74 MPa, respectively. Both tensile modulus and tensile strength among different feathers were significantly different. The failure of the CFFs followed a Weibull distribution with a scale parameter value of 178.7 MPa and a shape parameter value of 2.32. Overall, the well‐investigated mechanical properties of the CFFs are beneficial for the further study of its applications in composite materials. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Suitable cooling program for chicken fat dry fractionation

The impacts of the cooling program on crystal morphology, crystal suspension filtration properties and the characteristics of fractions resulting from chicken fat dry fractionation were assessed. The quality of the fractions was found to depend on the nature of the crystallized material and was also closely related to the filtration properties of the crystal suspension, which in turn were controlled by the cooling conditions. A slow cooling rate during the nucleation step was necessary to enhance process selectivity, and this rate could be accelerated once the first crystals had formed. These findings enhanced our understanding of the mechanisms involved during dry fractionation and highlighted the efficacy of a three‐phase cooling program, including (1) cooling from 70 to 26 °C, (2) slowdown in the cooling rate, and (3) a second rapid cooling down to the final temperature at which the fat is held for a specified time.     

Functional properties of collagenous material from chicken feet

Collagenous material was obtained from chicken feet skins and tendons, defatted with ethylic ether and treated with 0.05 M and 0.6 M NaCl solutions. Part of the material was dried at 35 degrees C in a forced air convection oven and another was freeze-dried. The air dried material had 77.2 g/100 g of collagen and the freeze-dried material 76.7 g/100 g. Both dehydrated materials showed the same behaviour for gel formation and cold water holding capacity. The material air dried had higher emulsifying capacity than the freeze-dried one. The collagen of freeze-dried material had higher solubility in 0.5 M acetic acid and water at 70 degrees C than air dried material. Gel strength, emulsion stability and water holding capacity at 60 degrees C were higher for freeze-dried material. The results indicate the potential use of these materials as functional ingredients in meat products.     

Extraction of phospholipids from structured dry chicken egg

Chicken egg contains a high level of phospholipids (PL) in the yolk. Recovering yolk total lipids and extracting egg PL with efficiency are important to the availability and utilization of these health‐promoting lipid products. In this study, we prepared two structured dry egg yolk materials and used two common solvents to extract and concentrate the PL. We found that drum‐dried flake‐like yolk is an ideal starting material for lipid extraction. Anhydrous ethanol can extract almost all the neutral lipids and PL. PL with purity over 90% can be prepared by cold acetone precipitation from the total lipids.     

气相色谱法测定鸡肉中二硝甲酚的残留量

本文研究了鸡肉中二硝甲酚残留量的气相色谱测定方法。样品中二硝甲酚用丙酮提取，经重氮甲烷甲基化和氟罗里硅土柱净化一，采用BP21石英毛细管柱于气相色谱仪进行测定。本实验采用添加法测定回收率，添加水平为0.02-0.2mg/kg时，其平均回收率为84.6%-89.5%。本方法的最低检出限为测定0.02mg/kg。     

Catalysis of linoleate oxidation by soluble chicken muscle proteins

A soluble fraction of a chickenMusculus gastrocnemius muscle was used to characterize the catalyst of linoleate oxidation. Separation of the chicken muscle extract into low (free metal) and high (protein) molecular weight fractions revealed that the molecular weight of the major catalyst of linoleate oxidation in chicken muscle extract was greater than 700 daltons. Catalysis of linoleate oxidation by the protein fraction exhibited a pH optimum of 5.9. Subjecting the protein fraction to heat treatments at increasing temperatures (30–90 C) decreased the catalysis of linoleate oxidation. Addition of two mM EDTA had no effect on the catalysis of linoleate oxidation. Cyanide (2 mM), glutathione (1 mM) and cysteine (1 mM) decreased the oxidation of linoleate by the protein fraction 21.0%, 22.9% and 29.0% respectively. Characterization of the oxidative catalyst in chicken muscle extract indicated that free metals and hemoproteins contribute to overall catalysis of linoleate oxidation but are not the sole catalysts. Heat inactivation of the oxidative catalyst and the observed pH optimum suggests that the unidentified catalyst is proteinacious and may be an enzyme.     

Composition and structure of phospholipids in chicken muscle tissues

Lipids extracted from breast muscle and thigh muscle of one-year old chickens on a standard MSU-Z-4 diet have been fractionated by silicic acid column chromatography into nonphospholipids, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl choline (lecithin), and sphingomyelins. Phospholipid fractions were identified by thin-layer chromatography and the quantity of each determined by gravimetric analysis, analysis of the phosphorus content, and infrared spectra. The phospholipid content of thigh muscle (dark meat) lipids was higher than that in the breast muscle (white meat). Phosphatidyl choline and phosphatidyl ethanolamine were found in relatively greater amts than phosphatidyl serine and sphingomyelins. Enzymatic hydrolysis followed by gas-liquid chromatographic analysis of the fatty acids liberated and those in the lysocompounds was used to establish the positional specificity of the fatty acids in the phosphoglycerides. The polyunsaturated fatty acids are located primarily at the β-position and the saturated fatty acids at the α′-position. The qualitative and quantiative determination of the plasmalogens was also accomplished. Michigan Agriculture Experiment Station Journal Article No. 3527. Presented at the AOCS Meeting in Chicago, October, 1964.     

Identification of some previously unknown aldehydes in cooked chicken

Aldehydes present in a flavor concentrate, obtained from cooked chicken were separated and isolated by means of gas liquid chromatography. Subsequently, they were converted into their 2,4-dinitrophenylhydrazones and identified by thin layer chromatography on Kieselguhr G-Carbowax 750 and Silica Gel G-AgNO₃ and by analysis after partial hydrogenation. Finally, they were compared with model substances. Besides the aldehydes which had been found earlier in cooked chicken the following new aldehydes were identified: 3-c-nonenal; 4-c-decenal; 2-t,4-c,7-c-decatrienal; 2-t,5-c-undecadienal; 2-t-dodecenal; 2-t,4-c-dodecadienal; 2-t,6-c- and 2-t,6-t-dodecadienal; 2-t-tridecenal; 2-t,4-c-tridecadienal; 2-t,4-c,7-c-tridecatrienal; and 2-t,4-c-tetradecadienal. Three of them, 4-c-decenal; 2-t,6-c-dodecadienal; and 2-t,4-c,7-c-tridecatrienal are typical breakdown products of arachidonic acid, and to a major extent also 2-t,5-c-undecadienal.     

鸡粪烘干尾气的处理研究

采用化学吸收法（酸、减吸收）与喷淋、水洗相结合,对鲜鸡粪烘干所产生的恶臭气体富集,通过降臭工序达到环境保护检测部门认可,除臭工序是先气体除尘,通过喷淋塔,再经过化学吸收（酸、减吸收）水洗相结合,解决了环境污染问题。