DETERMINATION OF AFLATOXIN CONTAMINATION IN OLIVES BY IMMUNOAFFINITY COLUMN USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

Eighty‐two whole black olive samples gathered from six different olive oil processing facilities were surveyed to determine levels of aflatoxins using immunoaffinity column extraction and reversed‐phase high‐performance liquid chromatography. Two different analytical procedures adopted for the analysis of aflatoxins were investigated for their suitability by spiking the blank olive samples with five different known levels of aflatoxins to determine which one had higher recovery rates. Although some of the olive samples had been exposed to adverse conditions, such as rain and high temperatures, none were found to contain aflatoxins at the determined detection limit. Although the samples were kept in high relative humidity (75%) and high temperature (30C) for 3 months and were tested at 1‐month intervals, no aflatoxins were detected. In addition, the olives were inoculated on a potato dextrose agar medium and incubated for 7 days at 25C to characterize the microflora. Because there is no evidence of aflatoxins in fresh whole olives, the next step of processing the contaminated olives into olive oils and testing them for the aflatoxins was not pursued.     

PURIFICATION OF BARLET MALT α-AMYLASE BY IMMUNOAFFINITY CHROMATOGRAPHY

Immunoaffinity chromatography was used to purify the high pl α-amylase (α-amylase II) in a one step procedure after fractionation of the whole barley malt extract on Sephadex G25. The immunoglobulin G (IgG) fraction of an immune serum specific for the malt α-amylase II was immobilized on Ultrogel. A mild desorption procedure was used, combining distilled water elution with an interrupted elution. The purification was achieved within half a day including kernel extraction. The quality of the purification was assayed by SDS polyacrylamide gel electrophoresis, crossed immunoelectrophoresis and isoelectric focusing. For the second technique, an immune serum was used which was polyspecific for malt proteins including the high pl α-amylase (α-amylase II). The effect of this procedure on the specific activity of the enzyme and on its antigenicity was evaluated. The results underline the efficiency of the purification procedure and indicate that α-amylase II accounts for a few percent of the total soluble protein in malts. However, the α-amylase II fraction was not completely free from α-amylase I. The procedure resulted in a partial loss of the enzymatic activity but not of the antigenicity.     

ASSESSMENT OF BEER FOAM STABILITY BY HIGH PERFORMANCE LIQUID IMMUNOAFFINITY CHROMATOGRAPHY (HPLIAC)

An assay based on high performance liquid immunoaffinity chromatography (HPLIAC) was developed for measuring foam stability using an antiserum raised against foam produced from a commercially available lager (lager C). Foam stability of ten commercial beers (4 bitters, 4 lagers including lager C and 2 stouts) tested by HPLIAC showed a correlation of 0.733 with head retention value (HRV). This correlation increased to 0.998 when the data obtained for the lagers were considered on their own. Fast protein liquid chromatography (FPLC) of three fractions (fractions 1–3), depicting foam drainage over 30 min, identified differences between the lagers and the rest of the beers tested in fraction 3. Two peaks (I & II) which adsorbed on Superose 12 were present in similar concentrations in all the beers tested but a third peak (III), which eluted in the void volume, was present in low concentrations in the lagers as compared to the rest. It is suggested that components of I and II are essential for foaming but that HRV depends upon the concentration of III. Hence an antiserum raised against a beer of high HRV might provide a generic immunoaffinity adsorbent for assessing foam stability.     

SCALE UP ISOLATION OF IMMUNOGLOBULINS FROM PIG SERUM BY IMMOBILIZED METAL AFFINITY CHROMATOGRAPHY

The immunoglobulins (Ig's) are proteins with a well-known structure and function. In immunocompetent animals (individuals), these proteins counteract the pathogenic microorganisms. However, under pathological conditions or in a precocious weaning, exogenous immunoglobulins, among other treatments, are being used to avoid and cure some diseases. There is much interest in developing alternative methods for the isolation of functional immunoglobulins from sources different than maternal colostrum and milk. Pig serum contains a high concentration of Ig's and it has the advantage of containing not only IgG but also IgA and IgM in a greater proportion than found in any other species. Pig serum is a major contaminant generated by meat producers that could be used as a biotechnological alternative for blood or milk whey. Immunoglobulins G, A and M were isolated from porcine serum using Nickel-Iminodiacetate-Sepharose 6B in a single step at an analytical level. The procedure was easily scaled up to a 30 ml bed column. Serum immunoglobins (176 ml; 8.7 g) were adsorbed to the gel in buffer, pH 6.0, containing 1.0 M NaCl, and the purified immunoglobulins (735 mg) were eluted using the same buffer, but at pH 5.0. This separation was repeated 27 times without loss of gel capacity. The source of immunoglobulins, the longevity of the adsorbent, the gel capacity (29 mg/ml bed volume) and the mild conditions allowed rapid isolation of high concentrations of immunoglobulins. This method can serve as an alternative to those currently available for obtaining the three major immunoglobulins for inclusion in animal feeding.     

A SIMPLE METHOD FOR THE ISOLATION OF PURINE NUCLEOSIDES FROM WORT AND BEER USING COLUMN CHROMATOGRAPHY

Column chromatography using a variety of dextran based gel matrices was used to fractionate nucleosides in wort and beer. The gel matrices Sephadex G10 and Sephasorb HP Ultrafine were found to elute guanosine, deoxyguanosine, adenosine and deoxyadenosine in a single fraction whereas Sephadex LH20 and Sephadex G25 both yielded two fractions containing nucleosides. The first nucleoside containing fraction from Sephadex LH20 contained guanosine and the second fraction contained deoxyguanosine, adenosine and deoxyadenosine. In contract the first nucleoside containing fraction from Sephadex G25 contained both adenosine and deoxyadenosine and the second fraction contained guanosine and deoxyguanosine. Fractionation of low molecular weight components from wort and beer by column chromatography provides a simple technique for the isolation of purine nucleosides. This may be used to monitor directly the presence of purine nucleosides throughout the brewing process and to obtain quantitative estimates of the content of purine nucleosides in beer.     

利用毛细管电泳法测定乳品中乳铁蛋白含量

将样品经样品缓冲液处理,毛细管柱选择为直径50 μm,有效长度400 mm的涂层中性毛细管柱;柱温为40℃;缓冲溶液为柠檬酸缓冲液(pH为3.0±0.2);工作电压为21 kV;检测波长为214nm;进样时间为5s,进行检测.结果乳铁蛋白平均回收率为75%～91%;相对标准偏差(RSD)为1.1%～2.8%;最低检出限位0.003mg/mL.该方法简便,准确,灵敏度高,能快速检测乳品中乳铁蛋白含量.     

QUANTITATIVE DETERMINATION OF N-NITROSODIMETHYLAMINE IN MALT AND BEER BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY USING FLUORESCENCE DETECTION

A method has been developed for the analysis of NDMA in malt and beer. It is based on denitrosation of NDMA by HBr and derivatisation with NBD-CI followed by HPLC with fluorescence detection. The method is compared with results obtained with the Thermal Energy Analyzer.     

AN IMPROVED METHOD OF CHOLESTEROL DETERMINATION IN EGG YOLK BY HPLC

An improved method for cholesterol determination in egg yolk is reported in this paper. Egg yolk was first diluted. Cholesterol was then extracted with ether and petroleum ether, and quantified by reverse phase chromatography on a Zorbax ODS column (0.46 × 15cm, 5–6 μm) using a mobile phase of acetonitrile and 2-propanol (4:1) with a flow rate of 0.6 mL/min. A linear correlation was observed between cholesterol concentration at 0.05–0.40 mg/mL and its peak heights with a correlation coefficient of 0.9993 (n = 5). The average recovery was 98.9%, and detection limit was 0.02 mg/mL. No differences in cholesterol concentration were observed between egg yolk samples with and without saponification. Rapid and reproducible quantification of cholesterol in egg yolk can be completed with this simplified method.     

阳离子交换树脂分离纤维低聚糖的研究

首次采用工业用001×7阳离子交换树脂对纤维低聚糖的分离进行了研究，探讨了进样浓度、树脂柱长度和洗脱荆对分离效果的影响。研究结果表明，低的进样浓度不能提高分离效果；短的树脂柱只能把葡萄糖从混合纤维低聚糖中分离出来，而长的树脂柱能分离出葡萄糖和纤维二糖；20％乙醇作洗脱剂时。纤维三糖也能被分离出来；纤维四糖、纤维五糖和纤维六糖总是同时被洗脱出来。为进一步工业化分离纯化纤维低聚糖奠定了理论基础。     

THE DETERMINATION OF BEER COMPONENTS BY GAS-LIQUID CHROMATOGRAPHY

A procedure is presented for the routine analysis of organic beer components. Beer is extracted with carbon disulphide to yield a concentrate which is submitted to a single quantitative dual-column gas chromatographic analysis. A satisfactory overall order of reproducibility, sensitivity and speed is achieved under the conditions described. At least 15 clearly-resolved peaks are obtained representing alcohols, esters and acids. The method is illustrated by the determination of capric acid, caprylic acid and β-phenylethanol in eight commercial bottled lagers.     

DETERMINATION OF NITRATE IN BEER BY ION CHROMATOGRAPHY

¹A method, relying on ion chromatography, for the determination of nitrate in beer, has been collaboratively tested by members of the European Brewery Convention (EBC) and the Brewery Convention of Japan (BCOJ). Precision values were judged to be acceptable. Repeatability (r₉₅) and reproducibility (R₉₅) values were 1.5, 0.96, 5.1, and 9.3, 10.4, 13.5 respectively for corresponding mean levels of 6.5, 26.2 and 52.8 mg/litre. However, r₉₅ and R₉₅ values of 1.5 and 2.3 respectively were obtained for an aqueous solution of nitrate ions at a mean level of 20.7 mg/litre. The determination of nitrate is recommended for use and inclusion in Analytica-EBC, as an additional analyte in the International Method which relies on ion chromatography for estimating chloride, sulphate and phosphate.     

烃类脉冲裂解产物的气相色谱分析

本文根据并联脉冲微型反应装置的特点,设计了一种带有预切反吹装置的气相色谱体系.用此体系能除去烃类脉冲裂解产物中C_5以上的重质组份,一次性分析氢和C_1—C_4烷烯烃,并能较准确地测量焦碳沉积量.分析迅速,装置简便     

高速逆流色谱法纯化制备辛弗林

建立了离子交换柱色谱-高速逆流色谱法纯化制备辛弗林的方法.高速逆流色谱溶剂系统为乙酸乙酯-正丁醇-水-三氟乙酸(1:2:3:0.003,体积比),下相为固定相,上相为流动相,从含辛弗林10%的枳实粗提物中纯化制备出辛弗林产品,经高效液相色谱分析纯度为95.2%.