Application of HPLC for the Determination of PSP Toxins in Shellfish

A high performance liquid chromatographic (HPLC) procedure for determination of the toxins associated with paralytic shellfish poisoning (PSP) is compared to the standard AOAC mouse bioassay method on 100 shellfish samples representing a variety of species. For those samples with toxin content below the detection limit of the bioassay (35 μg saxitoxin (STX)/100g) HPLC analysis indicated a similar low level with a range of <10 to 56 μg STX/100g (n = 60). A correlation coefficient of 0.92 was determined for the 40 samples exhibiting toxicity in the bioassay (i.e., >35 μg STX/100g). Among the advantages of the HPLC method over the bioassay are significantly better sensitivity, greater sample through-put, and ability to determine the levels of each individual PSP toxin.     

Semiautomated Method for the Analysis of PSP Toxins in Shellfish

The method uses an autoanalyzer continuous flow reaction system to oxidize toxin in standard acid extracts of shellfish, prepared for mouse bioassay, to derivatives which are detected by fluorescence. Oxidation is by periodic acid under alkaline (NH₄OH) conditions and is followed by acidification by acetic acid. Concentrations of 10 μg/100g toxin and above can be measured with good reproducibility and accuracy: coefficient of variation was 9.5% for samples with 60 μg/100g or greater. Correlation with the mouse bioassay was 0.82 for 204 samples (toxin from 0–2000 μg/100g). The method is proposed to screen shellfish samples for PSP toxins with only samples falling into the range 60–250 μg/100g being subject to the more tedious and expensive mouse bioassay.     

Comparison of Four Methods for Determining Protease Activity in Milk

Four methods (absorbance at 280 nm; the Lowry method; the fluor-escamine method, and the trinitrobenzenesulfonic acid method) for determining hydrolysis of milk proteins were compared. Each method was applied to the trichloracetic acid soluble fraction of milk protein, which had been digested with trypsin for various periods of time. Detectability was measured as the ratio between standard error of estimate and slope calculated from the linear regression analysis of Deming for cases when both variables were subject to error. Although it was nondimensional, the detectability thus calculated was simple and reliable for comparing assay methods which were based on different analytical principles. Detectability as well as the detection limit measured according to Schwerdtfeger showed that, of the methods compared, the fluorescamine method was most reliable and sensitive.     

Determination of Paralytic Shellfish Poisoning (PSP) toxins in dietary supplements by application of a new HPLC/FD method

Over the past years the importance of food additives and the development of so-called novel food increased permanently. Especially, the application of dietary supplements was on the rise. Then, more and more new products based on plants hitherto not used for human consumption were launched. Algae products containing valuable amounts of essential nutrients such as amino acids and trace elements play a decisive role. On the other hand, some algae including the blue-green algae (cyanobacteria) are capable of synthesizing harmful substances depending on species and provenience. Therefore, methods must be available to evaluate possible risks caused by toxins in algae-based dietary supplements. There are different groups of toxins related to marine algae and cyanobacteria. However, both marine algae and cyanobacteria are able to produce Paralytic Shellfish Poisoning (PSP) toxins which are potential neurotoxins. Hence, analytical methods for PSP determination have to be developed. The method for PSP toxin determination described below is based on ion-pair chromatography of the underivatized PSP toxins followed by post-column oxidation and fluorescence detection (FD). The determination of very low amounts of PSP toxins in different matrices of novel food is possible. In addition, the method allows to compare PSP profiles of various algae-based dietary supplements.     

A Comparison of Available Methods for Determining Salt Levels in Cheese

Comparative salt analyses were run on seven different types of cheese using each of four methods: Mohr, Volhard, ion selective electrode, and chloride analyzer. The results of Volhard, Mohr, and chloride analyzer methods were similar for unaged cheese varieties, i.e., Mozzarella, Cheddar, Ricotta, Romano, and Provolone, but concentrations detected with the ion selective electrode were lower than the other three methods. Results were similar with aged Cheddar and process cheeses except the Mohr procedure proved unreliable. A constant correction factor could be used to make the ion selective electrode results similar to that obtained with the Volhard procedure.     

Comparison of HPLC and GC Methods for Measuring Lactic Acid in Ground Beef

A rapid method for measurement of lactic acid in refrigerated ground beef was developed using high performance liquid chromatography (HPLC) with an Aminex HPX-87H ion exclusion column. The method was compared with an existing gas chromatography procedure. Nine samples of ground beef, consisting of three grades based on fat content, were tested over six days of aerobic and two weeks of anaerobic storage. No significant difference was found in reproducibility between the two methods as measured by their variance. There also was no significant difference between the variances for grade of beef or for duration of aerobic or anaerobic storage. The following equation was developed to relate the two methods: GC =−138.43 + 1.1254 (HPLC).     

海地瓜多糖中蛋白含量测定方法比较

比较4种常用的蛋白定量方法来测定海参多糖中蛋白含量,建立海参多糖中蛋白含量的测定方法。氨基酸组成折算出海地瓜多糖中蛋白含量为(5.06±0.31)%,将此结果作为其他测定方法比较的标准。采用4种常用的蛋白定量方法:Folin-酚法、BCA法、考马斯亮蓝法、荧光光度法进行测定,对测定结果进行比较分析。Folin-酚法、BCA法、荧光光度法测定多糖中蛋白含量分别为(4.92±0.20)%、(6.29±0.51)%、(3.88±0.25)%。考马斯亮蓝在反应中不显色,此法检测不出多糖中蛋白。经比较分析,Folin-酚法精确度高,重现性好,测定时间短,操作简便,对仪器要求低,可以准确简便地测定海地瓜多糖中蛋白含量。     

Comparison of Spectrophotometric and HPLC Methods to Quantify Betacyanins

Quantitative data for betacyanins determined by a spectrophotometric method and a high performance liquid chromatography (HPLC) method were compared. Pigment solutions at pH 4.0, 5.0 and 6.0 were heat treated under a nitrogen atmosphere and analyzed for pigment losses at appropriate intervals. Fresh, blanched and canned beets were measured for pigment content by the two methods. Quantitative determinations of pigment in all purified or undegraded samples compared well when analyzed by either method. Discrepancies between results of the two procedures occurred and increased up to 15% with extended heat treatment of the pigment. The differences were: attributed to formation of degradation products or interfering substances. Of the two, the HPLC method is preferred when interfering substances are present.     

小麦粉中过氧化苯甲酰的色谱测定法的比较与改进

本文通过采用高效液相色谱法与气相色谱法分别测定小麦粉中的过氧化苯甲酰,并对检测结果进行比较,发现两种检测方法的结果均令人满意,且两法的检测结果不存在显著性差异。但相对而言,气相色谱法操作较繁琐,耗时较长,适合于少量样品的检测,而高效液相色谱法操作较简便、快捷,更适合于大批量样品的检测。     

生物素测定方法的分析

生物素是一种B族维生素。近几年,生物素受到了广泛的关注,与此同时,生物素测定方法的研究也取得了迅速的发展。文中介绍了近年来生物素测定常用的几种方法,包括微生物法、高压液相色谱法、生物传感器法、毛细管电泳法、荧光法、ELISA法、微分脉冲伏安法,并简单介绍了生物素分析的研究现状与进展。     

HPLC法测定大蒜中蒜氨酸和大蒜素的含量

建立了大蒜中大蒜素和蒜氨酸含量测定的HPLC法。结果表明:蒜氨酸的测定条件为,YMC-PackODS-A C18(25 cm×4.6 mm)色谱柱,流动相为20%甲醇,流速0.7 mL/min,检测波长214 nm;大蒜素的测定条件为,YMC-Pack ODS-A C18(25 cm×4.6 mm)色谱柱,流动相为85%甲醇,流速0.8 mL/min,检测波长214 nm;蒜氨酸和大蒜素的平均回收率分别为,89.9%±1.6%和87.2%±1.3%,精密度(RSD)分别为1.02%和1.46%;大蒜中蒜氨酸和大蒜素的含量分别为,1.67%和0.93%。     

溶菌酶的生物测定方法研究

论述了以溶壁微球菌 (Micrococcuslysodeikticus)为试验菌检测溶菌酶活性的 2种生物测定方法 ,即传统的细胞悬浮液比浊法和纸片琼脂平板扩散法。实验结果表明 ,2种方法检测数据的t检验在α =0 0 5显著性水平上无显著性差异 ,但同一样品用琼脂平板扩散法重复测定数据的标准方差均小于比浊法 ,平均变异率分别为 3 4%和 5 6% ,说明琼脂平板扩散法测定数据的离散程度小 ,重现性好 ,准确度高。而且 ,平板法操作简单 ,1次可检测样品数量大 ,是现行比浊法检测溶菌酶活性的 1种有价值的替代方法     

硫代葡萄糖甙测定方法的新进展

对近来新开发的硫代葡萄糖甙分析方法进行了介绍，包括膜在测定硫式方面的应用、对硫甙酶解产物的测定、酶联免疫吸附测定硫甙、使用硫甙的碱降解产物测定硫甙、色质联用分离鉴定硫甙、高子对液相色谱和亲水作用液相色谱的应用等，并对各种测定方法进行了比较与总结。     

Three Methods for Determining Nonheme Iron in Turkey Meat

The ferrozine, the Schricker and modified Schricker methods were used to measure the non-heme iron in raw and cooked turkey meat. The ferrozine method gave the lowest non-heme iron values, while results from the Schricker and modified Schricker were not different (p<0.05). When hemoglobin (Hb) was added to breast meat, how-ever, differences (p<0.05) between the Schricker and modified Schricker, and Schricker and ferrozine methods were observed in cooked meat with NaCl. Cooking and addition of NaCl caused increase in measured nonheme iron content and had a synergistic effect on the release of nonheme iron in meat.     

制革常用蛋白酶活力测定方法及结果的比较

介绍了制革蛋白酶活力常用的测定方法LVU法、福林法和胰酶转化倍数法的测定原理和方法。对21种制革中常用的胰蛋白酶、高浓度的细菌蛋白酶和制革工业用酶制剂，分别用三种方法进行了活力检测，结果表明，在相同的反应pH和温度下(LVU标准条件pH 8．2，37℃)，福林法和LVU法两种测定方法的结果基本一致。活力1：24倍国产胰酶的LVU法活力为2．4万左右。以此为基础，在确定酶制剂用量时，对于用不同活力测定方法表征的酶制剂可更方便地换算。     

阴离子表面活性剂测定的方法研究

阴离子表面活性剂在日常生活和工业生产中广泛应用,大量的阴离子表面活性剂进入水体中可引起水质的恶化,已成为水质监测的一项必测指标.国内外近年来阴离子表面活性剂的测定方法很多,有分光光度法、荧光光度法、色谱法共振光散射法、离子选择性电极分析法和流动注射分析法等,测定阴离子表面活性剂方法向着更快、更准、更易操作的方向发展.     

当归油中藁本内酯含量测定的两种方法及比较

建立了当归油中藁本内酯含量的两种测定方法：气相色谱内标法（邻苯二甲酸二乙酯）和紫外分光光度比色测定法.紫外分光光度法测定样品藁本内酯含量值一般大于气相色谱法测定值,平均误差为5.268%.气相色谱内标法是一种较准确科学的方法,而紫外分光光度法是一种简单快捷又经济的方法,可供实验过程中跟踪藁本内酯含量变化.     

几种油料粗脂肪测定方法的对照

半油料粗脂肪测定的三种方法－－同时测定脂肪和水分的索氏抽提法，索氏抽提浸泡法，阿贝折射仪法与国标法进行了对照实验。结果表明，对于几种常见油料样品，三种方法测定的相对偏差平均值均小于0．002％。     

Comparison of Microbiological and Radiometric Assays for Determining Total Folacin in Spinach

Several commercially available forms of spinach were analyzed for total folacin content by the microbiological assay using Lactobacillus casei and a radiometric assay. Types of products included frozen uncooked, fresh raw, microwave and conventionally cooked fresh and creamed strained spinach. Folacin content ranged from 0.62 mcg/g for strained spinach to 2.50 mcg/g for uncooked frozen spinach, when assayed microbiologically. With the radiometric assay, folacin values were significantly higher (P<0.05) than with the L. casei assay. The microbiological assay appears more suitable for determination of total folates in complex food matrices than the radioassay.     

小麦陈化度鉴别方法初探

本课题采用四氮唑盐染色法、愈创木酚反应法、发芽率(势)法、红外光谱分析法以及《粮油储存品质判定规则》有关项目等，对6个年份小麦样品的陈化度进行了测定和对照分析。结果表明：四氮唑盐染色法具有显色明显、操作简单、快速、无需昂贵仪器、能定量表述小麦陈化度等优点，可应用于小麦购、销、储存中陈化度的鉴别。