Comparison of Two Analytical Methods for the Analysis of Methylmercury in Fish

In this study, we compared a high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS) method and an isotope dilution gas chromatography mass spectrometry (ID-GC-MS) method for the analysis of methylmercury (MeHg) in fish samples. Using HPLC-ICP-MS, the limit of detection (LOD) was 2.0 ngHg?·?g^?1 for inorganic Hg and was 5.0 ngHg?·?g^?1 for MeHg. In comparison, the LOD for MeHg was 3.4 ngHg?·?g^?1 for using ID-GC-MS. Certified reference material (CRM) results agreed well with certified values for both methods. The mean recovery for analysis of CRM BCR 463 by HPLC-ICP-MS was 99?±?2.1 % for MeHg and was 103?±?2.1 % for total Hg. Two CRMs, BCR 463 and CRM DORM2, were analyzed by ID-GC-MS, the mean recovery of MeHg was 87?±?1.9 % for BCR 463, and the mean recovery of MeHg was 102?±?2.9 % for CRM DORM2. Matrix samples spiked with Hg or MeHg at various concentrations were analyzed by two methods. For HPLC-ICP-MS method, the mean recovery for MeHg spiked samples was 93?±?4.2 %. For ID-GC-MS method, the mean recovery for MeHg spiked samples was 91?±?5.2 %. A total of 19 predatory fish and 54 tuna fish samples were analyzed using both methods. No significant difference was observed between the MeHg data generated from both methods. The average relative standard deviation (RSD) between the two datasets for 19 predatory fish samples was 8.8 %. The average RSD between two datasets for 54 tuna fish samples was 4.4 %.The HPLC-ICP-MS method offers substantial advantages over the method of ID-GC-MS because the former method can determine the total mercury (Hg) and MeHg in a single chromatographic run and the analysis time is much shorter. The latter method is time consuming due to overnight digestion and having to conduct presample analysis for signal-matched isotope dilution spiking and requires more expensive isotope labeled reagents.     

Determination of Nitrite and Nitrate in Brazilian Meats Using High Shear Homogenization

Nitrate and nitrite are usually added to processed meat products to protect against the growth of microorganisms. Two sample preparation methodologies using either manual grinding (with a mortar and pestle) or mechanical high shear homogenization were investigated and compared. The results showed that high shear homogenization was the most suitable for the extraction of nitrite and nitrate from ham, salami, and bacon samples, achieving high extraction recoveries (>98%) together with low relative standard deviations (RSDs) for the samples analyzed. Analyses were performed using capillary electrophoresis. A running buffer consisting of 60 mmol L⁻¹ tetraborate and 0.2 mmol L⁻¹ cetyltrimethylammonium bromide enabled separation of the analytes in <5 min. In validation experiments, good repeatability was obtained for both migration times (<0.8% RSD) and peak areas (<1.1% RSD). Analytical curves for nitrite and nitrate were linear (r > 0.998) in the 0.2- to 2.5-mg L⁻¹ and 0.5- to 5-mg L⁻¹ concentration ranges, respectively. The limits of detection were 0.15 mg L⁻¹ for nitrite and 0.17 mg L⁻¹ for nitrate. The method developed was applied to the analysis of different kinds of meats (sausage, ham, salami, bacon, and others) produced in Brazil. The ranges of concentration found were 17.3–46.4 mg kg⁻¹ (nitrite) and 69.9–198.1 mg kg⁻¹ (nitrate). The contents of nitrate and nitrite in the samples were below the Brazilian legislation limit values (150 and 300 mg kg⁻¹ for nitrite and nitrate, respectively).     

Two Methods for Determining Extract Release Volume (ERV) of Fresh and Spoiled Beef and Poultry Meats

When the ERV of ground and diced beef that underwent microbial spoilage at 5°C was determined in the conventional way by use of Waring Blendor and by use of Stomacher 400 (Tekmar Co., Cincinnati, OH), comparable values were obtained. However, for ground or diced chicken meat, Stomacher values were consistently higher than those when using the Blendor. The basis for differences between the two methods for chicken meat is unclear.     

食品微生物检验中两种均质方法的比较

目的比较食品微生物检验中两种均质方法对检验结果的影响。方法采用旋刀式均质方法和拍击式均质方法均质,测定细菌、霉菌回收率,并对经两种均质方法检验的食品微生物项目结果进行分析。结果细菌回收率旋刀式均质方法略高于拍击式均质方法,霉菌回收率拍击式均质方法略高于旋刀式均质方法。结论食品微生物检验过程要根据样品的不同形态特点和检验项目选择合适的均质方法。     

蛋白质组分分析方法比较研究

采用蛋白质连续累进提取法与组分快速提取法测定了21个小麦面粉样品的蛋白质组分，以比较两种蛋白质组分分析方法的特点。连续累进提取法将小麦蛋白质分离成清蛋白、球蛋白、醇溶蛋白和谷蛋白；快速提取法将小麦蛋白质分离成单体蛋白、可溶性谷蛋白和不溶性谷蛋白。结果表明：单体蛋白与清蛋白、球蛋白、醇溶蛋白含量及清蛋白、球蛋白、谷蛋白之和均无关系；可溶性谷蛋白含量与清蛋白、弱化度呈负相关，与醇溶蛋白、谷蛋白、沉淀值呈极显著或显著正相关；不溶性谷蛋白与醇溶蛋白、谷蛋白、沉淀值、稳定时间、评价值、弱化度呈极显著或显著相关。连续累进提取法适合于小麦品质常规检测，快速提取法适用于小麦早代材料品质检测。两种方法对于预测小麦的加工品质有着相同的重要作用，应根据样品量及检测精度进行选择。     

白酒中氨基甲酸乙酯检测方法比较

建立并使用了高效液相色谱法(HPLC)与气相色谱-质谱联用法(GC-MS)两种白酒样品中EC的检测方法,两种方法定量分析的线性关系良好,相关系数在0.997以上。其中HPLC法检出限为4.0μg/L,回收率在84.9%~105.1%之间,RSD<6.84%;GC-MS法检出限为1.3μg/L,GC-MS检测回收率在95.3%~104.7%之间,RSD<4.26%。结果显示,两种方法的准确性和重复性均符合实验要求。其中HPLC法具有前处理操作方便,且试剂毒性相对较低的优点,但GC-MS方法的精确性和稳定性则比HPLC法更高,且检出限更低、总体处理及进样时间更短,单位时间内能更快、更精确地对酒样中氨基甲酸乙酯进行检测。结合产业实际发展情况,白酒的氨基甲酸乙酯检测量日益增多,检测限要求更低,故使用GC-MS法检测白酒中的氨基甲酸乙酯更能满足今后的检测工作需求。     

Comparison of Sample Storage Methods for Vitamin B6, Assay in Broiler Meats

Five methods were compared for storage stability of vitamin B₆ in broiler meat samples. Maximum retention of vitamin B₆ was observed in the N₂-packed freeze-dried samples at -34°C (101–103% up to 20 mo). Good retentions occurred in the intact tissues of half birds at -34°C (90% in 16 mo) and in ground meat samples (200g portions) at -34°C (91% up to 12 mo). Significantly lower retentions were found in freeze-dried samples stored at room temperature (85–77% in 1–5 mo, respectively) and for ground meat small portion samples (5g) at -34°C (84–72% in 3–5 mo, respectively).     

啤酒中戊聚糖检测方法的比较

为了能够准确测定麦芽、麦汁和啤酒中的戊聚糖,通过比较地衣酚-盐酸法和间苯三酚法在测定不同样品时的精密度和回收率得出:间苯三酚测定麦芽中戊聚糖较为准确,通过测定几种麦芽,发现不同品种的麦芽之间戊聚糖存在较大的差异;麦汁不能直接采用两种方法测定,经过酵母发酵处理之后的麦汁采用地衣酚-盐酸法测定时结果较为准确;地衣酚-盐酸法测定啤酒的戊聚糖较为准确,通过测定几种啤酒,发现不同啤酒中戊聚糖存在明显差异。     

牛奶中抗生素残留量两种检测方法的比较

采用国标TTC方法、SNAP快速检测法对100份生奶的抗生素残留量进行检测.结果显示:SNAP方法与国标TTC方法测定的结果没有显著性差异,提示上述SNAP快速法、可应用于牛奶中抗生素残留的检测,可以考虑作为国标方法的补充.     

蜂蜜中微量铁的两种测定方法及比较

探讨了蜂蜜中微量铁2种测定方法。在最佳条件下采用邻二氮菲分光法测定蜂蜜试样;为保证检测结果质量,采用火焰原子吸收法对其结果进行重复检测。结果表明:采用邻二氮菲分光法和火焰原子吸收法测出某市售蜂蜜试样中铁含量分别为2.49、2.52μg/g,两者校准曲线相关性均较好,检出限分别为0.006 mg/L和0.01 mg/L,精密度RSD为0.79%和1.80%,加标回收率均在96.8%~102.7%,2种方法的测定结果无显著性差异(t=0.617,P0.05)。     

两种硫酸根含量测定方法的比较

为了更快更准确地测定出卤水中硫酸根离子的含量,参照国家标准方法,我们对两种硫酸根含量的测定方法——分光光度法和容量滴定法进行了比较。     

油脂密度检测方法的探讨

油脂密度是油脂大宗贸易中需检测的一个重要指标,本实验对国标GB/T 5526-85<植物油脂检验比重测定法>和现代仪器自动密度仪法测定油脂密度进行了比较并讨论了计算净含量时的空气质量问题,结果表明采用自动密度仪法测得的油脂密度和国标法相吻合,并且自动密度仪法更简便快捷、结果重现性好,精确度高;计算净含量时由密度仪测得的...     

不同国家标准中羽毛微生物检验方法对比与分析

羽绒产品的质量好坏与消费者切身利益相关,其中微生物项目的合格与否将对消费者健康与人身安全产生重要影响,本文就GB/T 10288—2003《羽绒羽毛检验方法》与GB/T 14272—2011《羽绒服装》标准中涉及羽绒产品的微生物检验方法进行了对比分析,以期为其检测提供有益的借鉴。     

云南松松塔多糖含量测定两种方法的比较

通过对云南松松塔中多糖的含量的测定,比较硫酸-蒽酮和硫酸-苯酚两种常用多糖测量方法。通过精密度试验、稳定性试验、回收率试验等方面,对硫酸-蒽酮和硫酸-苯酚两种常用多糖测量方法进行比对。结果表明:硫酸-苯酚法在云南松松塔多糖含量测定中较硫酸-蒽酮法优越,硫酸-苯酚法测定云南松松塔多糖含量时,操作简便,精密度、稳定性高,为云南松松塔等植物的多糖含量测定提供了参考。     

两种测定方法检测白兰地酯类的结果比较

GB／T11856--2008中白兰地酯类测定采用指示剂法对去除酒样中的不挥发物之后的蒸馏液进行测量,本实验对用电位滴定法对酒样直接测定进行条件摸索研究,并比较两种测定方法的结果。结果表明,两者效果有着显著差别,可能是白兰地中合有不挥发的酯类物质而导致。     

两种化学调质方法在造纸污泥脱水的效果比较

本文以某典型生产包装用纸与新闻纸纸厂生产中产生的污泥为原料,通过用无机高分子聚合氯化铝(PAC)与有机高分阴离子聚丙烯酰胺(APAM)联用与阳离子聚丙烯酰胺应用比较,使用正交实验设计方法进行探讨,以比阻值作为评价脱水性能的指标,研究表明PAC与APAM联用方法的脱水比阻较小,同时成本较低,具有技术可行性与较高的经济效益。     

纬编针织物缝纫破损两种测试方法比较

采用破洞法和缝纫应力法对纬编针织物缝纫破损进行了测试与分析,结果表明,两种测试方法在缝纫破损试验中实验结论具有一致性,建议生产中两种方法结合使用。     

Browning Potential of Liquid Smoke Solutions: Comparison of Two Methods

The color-forming potential of carbonyl compounds from liquid smoke solutions with selected amino acids was determined with a colori-metric procedure used in industry and compared with a color analysis on filter oaoer discs. The two methods provided different evaluations of formed colors. Of the carbonyls tested, glycolaldehyde, methyl-glyoxal and glyoxal showed significant browning potential, while formaldehyde and hydroxyacetone showed very little color formation. Measurement of browning potential of amino acids varied between the procedures. The disc assay procedure enabled better characterization of smoke colors produced.     

猪用生长激素(PST)脂质体包封率测定方法的比较

试验对测定包封率的两种方法即凝胶柱分离法和鱼精蛋白凝聚法进行了比较，测得PST脂质体的包封率分别为75．26％、84．58％，PST回收率分别为90．4％和98．22％。因此确定了鱼精蛋白法为试验产品包封率的测定方法。