国产离子色谱仪直接进样测定饮用水中溴酸盐

建立了一种无需样品前处理、直接进样、电导检测饮用水中痕量溴酸盐的离子色谱分析方法.采用配有抑制型电导检测器的国产离子色谱仪,以Shodex SI-52 4E阴离子色谱柱为分析柱,3.6mmol/L的Na2CO3溶液为淋洗液,流速为0.7ml/min,进样体积为500μl.该方法在5～100μg/L范围内具有良好的线性(r=0.99997),相对标准偏差(RSD)小于5.0%,实际样品的加标回收率在95.8%～105.8%之间,方法检出限为2μg/L,能满足相关标准的要求.设备购置费用低,方法操作简便,精密度高,重现性好,运行成本低,结果令人满意,具有很好的实用价值.     

Detection of herbicides in drinking water by surface-enhanced Raman spectroscopy coupled with gold nanostructures

This study aimed to use surface-enhanced Raman spectroscopy (SERS) to detect herbicide residues (atrazine and arsenic trioxide) in drinking water. Gold-coated nanosubstrates were used in the SERS measurements to acquire enhanced Raman signals of herbicides in drinking water. Compared with the control, characteristic patterns of SERS spectra were distinguishable for atrazine at 3 ppb and arsenic trioxide at 1 ppb. Partial least squares analysis was used to develop quantitative models for detection of two herbicides in drinking water and calibration curves were plotted with R² of 0.988 and 0.991 for atrazine and arsenic trioxide, respectively. The study of limit of detection (LOD) demonstrates that at 99.86 % confidence interval, SERS can detect both herbicides at 0.1 ppm in drinking water. Satisfactory recoveries were obtained for samples with concentration at and higher than the LOD (92.3–119.3 % for atrazine and 88.2–102.1 % for arsenic trioxide). These results demonstrate that SERS coupled with gold nanostructures holds great potential for rapid detection of herbicide residues and other chemical contaminants in drinking water.     

涡旋辅助分散液液微萃取分光光度法测定饮用水中的亚硝酸根

目的建立涡旋辅助分散液液微萃取分光光度法检测饮用水中亚硝酸根的含量。方法在酸性条件下,亚硝酸根与对硝基苯胺和二苯胺反应生成红色偶氮化合物,通过测定红色偶氮化合物间接测定亚硝酸根的含量,以分光光度法检测,外标法定量。确定萃取剂种类,利用正交试验对萃取剂的用量、酸浓度和涡旋时间进行优化。结果在浓度10～200μg/L范围内线性关系良好(r2=0.9912),检出限为2.0μg/L,富集倍数为14。加标回收率为87.3%～106.3%,相对标准偏差0.8%～4.4%。结论该方法具有简单、快速、灵敏度高、准确性好,适用于饮用水中亚硝酸根的日常监测。     

毛细管区带电泳-间接紫外检测法测定饮用水中5种阴离子

目的建立毛细管区带电泳-间接紫外检测法测定饮用水中5种阴离子的新方法。方法样品无需滤膜过滤可直接进样。用未涂覆熔融石英毛细管(75μm×80 cm,有效长度为70 cm)作为分离柱。以20 mmol/L邻苯二甲酸、100 mmol/L二乙醇胺和0.5 mmol/L十六烷基三甲基溴化铵为分离缓冲体系。结果 Cl~-、NO_3~-、SO_4~(2-)、F~-和H_2PO_4~-这5种阴离子的校正峰面积与质量浓度分别在0.5～100.0、0.2～20.0、0.5～100.0、0.2～4.0和0.2～5.0 mg/L范围内呈线性相关,相关系数分别为0.998 8、0.999 9、0.999 7、0.999 7、0.999 8。检出限均为0.05 mg/L,定量限均为0.15 mg/L,方法精密度均小于5%(n=6)。低、中和高质量浓度加标回收率在81.6%～108.6%之间,相对标准偏差在0.6%～3.7%之间(n=6)。用本法分析了7份饮用水样品,并与离子色谱法的结果相比较,除矿泉水中Cl~-结果偏低外,其余基本吻合。结论本方法简单,所用试剂环保,为饮用水中5种阴离子的常规检测提供了一种新方法,但不适合测定水样中低浓度的Cl~-。     

碳纳米管富集-火焰原子吸收法测定饮用水中的微量镉

采用硝酸活化后的碳纳米管吸附柱来富集饮用水中的镉,用火焰原子吸收光谱法测定洗脱液中的镉。对碳纳米管吸附与洗脱镉的有关实验条件进行了详细的研究与优化,确定了碳纳米管富集饮用水中镉的最佳条件。实验结果表明,用0.50mol/LHNO3活化的碳纳米管吸附柱能定量吸附饮用水中的镉,并用0.50mol/LHNO3能完全洗脱碳纳米管所吸附的镉。本法的加标回收率为102.1%～106.4%,结果准确可靠,可应用于实际水样中微量镉的测定。     

固相微萃取结合气相色谱-质谱检测饮用水中 5种异味化合物

目的建立固相微萃取(SPME)结合气相色谱-质谱法检测饮用水中5种挥发性痕量异味化合物的分析方法。方法采用CAR/DVB/PDMS纤维涂层萃取头插入装有5种标准化合物的40 m L顶空瓶中,加入6 g Na Cl,80℃下平衡20 min,吸附40 min,经过气相色谱-质谱检测,对饮用水中常见的5种致异味化合物(2-甲基异莰醇(MIB)、2,4,6-三氯茴香醚(2,4,6-TCA),土臭素(GSM),2-甲氧基-3-异丙基吡嗪(IPMP),2-甲氧基-3-异丁基吡嗪(IBMP))进行检测。分别优化固相微萃取的萃取头、加盐量、萃取温度以及萃取时间等因素。结果最优提取条件:65μm PDMS/CAR/DVB纤维头,30%(m/v)加盐量,萃取温度60℃,萃取时间40 min。5种异味化合物在1~100 ng/L范围内线性关系良好,R20.971,检出限分别为1.0、1.0、0.8、1.0、1.0 ng/L,精密度小于10%。结论本方法检测限低,灵敏度高,是检测饮用水样异味的良好方法。     

新型固相萃取-高效液相色谱检测饮用水中的 邻苯二甲酸脂类物质

目的建立基于新型高效的样品前处理技术即固相萃取-高效液相色谱联用技术同时检测饮用水中七种邻苯二甲酸酯类物质的方法。方法以3-氨基丙基三乙氧基硅烷作为功能单体,四乙氧基硅烷作为交联体,并加入醋酸,合成新型的高选择性材料,并用作为固相萃取材料,吸附七种邻苯二甲酸脂类物质。结果高效液相色谱等度分析方法的最佳检测条件为:流动相为乙腈和水(96:4,V:V);运行时间20 min;检测波长为230 nm;流速1.0 m L/min;柱温30℃;进样量20μL。目标化合物线性范围较宽,其中DMP、DBP、DIDP为0.5~100 mg/L,DCHP、BBP、DEHP为0.5~25 mg/L,DEP为0.5~10 mg/L;该方法对7种目标化合物的检测限在0.18μg/L~1.86μg/L范围内,6次重复实验精密度在1.18%~5.20%之间,标准添加回收率在63.5%~108.4%之间。结论该方法可以用于饮用水中苯二甲酸脂类物质的定量检测。     

大体积进样气相色谱串联质谱法测定饮用水中29种半挥发性有机物

建立了饮用水中29种半挥发性有机物的三重四级杆气质联用仪大体积进样检测方法。水样样品经甲基叔丁基醚液液萃取,采用溶剂放空模式程序升温大体积进样,MRM多反应离子监测,内标法定量。结果表明:在0.2~10.0μg/L质量浓度范围内,各化合物的响应值与浓度呈良好的线性关系(r>0.994),方法检出限为0.003~0.110μg/L,加标回收率在61.7%~108.6%,相对标准偏差(n=6)为1.5%~8.7%。该方法样品前处理简单,灵敏度高,适用于饮用水中29种半挥发性有机物的同时测定。     

Inactivation of escherichia coli O157:H7 in cattle drinking water by sodium caprylate

Escherichia coli O157:H7 is an important foodborne pathogen. Cattle serve as one of the major reservoirs of E. coli O157:H7, excreting the pathogen in feces. Environmental persistence of E. coli O157:H7 is critical in its epidemiology on farms, and the pathogen has been isolated from cattle water troughs. Thus, there is a need for an effective method for killing E. coli O157:H7 in cattle drinking water. In this study, the efficacy of sodium caprylate for killing E. coli O157:H7 in cattle drinking water was investigated. A four-strain mixture of E. coli O157:H7 was inoculated (6.0 log CFU/ml) into 100-ml samples of well water containing 0, 75, 100, or 120 mM sodium caprylate. Water samples containing 1% (wt/vol) bovine feces or feed also were included. The samples were incubated at 21 or 8 degrees C for 21 days. Water samples were analyzed for viable E. coli O157:H7 on days 0, 1, 3, 5, and 7 and weekly thereafter. Triplicate samples of each treatment and control were included, and the study was repeated twice. The magnitude of E. coli O157:H7 inactivation in water significantly increased (P < 0.01) with increases in caprylate concentration and storage temperature. At 120 mM, sodium caprylate completely inactivated E. coli O157:H7 in all the samples after 1 to 20 days, depending on the treatments. The presence of feces or feed also had a significant effect (P < 0.01) on the antibacterial property of caprylate; the presence of feces decreased the antibacterial effect, whereas addition of feed enhanced the effect. These results indicate that sodium caprylate is effective in killing E. coli O157:H7 in cattle drinking water, but detailed cattle palatability studies of water containing caprylate are necessary.     

宰前短期饮水中添加VC对育肥猪肉品质的影响

试验考察宰前48 h饮水中添加VC对育肥猪血液指标、肉品质的影响.结果表明:宰前饮水短期添加VC对育肥猪胴体品质无影响;与对照组相比,添加VC 500和1 000 mg/L组血浆VC含量提高(P＜0.05),肉的亮度L*24h降低(P＜0.05);添加500 mg/L组肉的红度(α*24h)增加(P＜0.05).添加V...     

Heterotrophic plate count monitoring of treated drinking water in the UK: a useful operational tool

The count of general or heterotrophic bacterial populations in treated drinking water in the UK has been undertaken since the 1880s. Counts of heterotrophic bacteria at 22 and 37 degrees C are used widely as part of an overall assessment of treated drinking water quality. There were no legislated standards for water quality in the UK until adoption of the first EU Directive in 1989. The UK has, however, never stipulated numerical standards or guidelines for heterotrophic bacteria, although their enumeration has long been part of the assessment of 'wholesome' water, on which advice regarding microbiological quality was given in a series of documents known as 'Report 71'. The current regulations stipulate only that there should be 'no abnormal change' in numbers normally associated with a given supply. This paper reviews the historical context regarding the enumeration, and interpretation of results, of heterotrophic bacteria from treated drinking water, and information regarding current practices by UK water suppliers. The appropriateness of using heterotrophic bacteria counts as an operational tool or as a health parameter is briefly discussed in the light of the UK experience.     

Development of a sensitive detection method for stressed E. coli O157:H7 in source and finished drinking water by culture-qPCR

A sensitive and specific method that also demonstrates viability is of interest for detection of E. coli O157:H7 in drinking water. A combination of culture and qPCR was investigated. Two triplex qPCRs, one from a commercial source and another designed for this study were optimized from 5 different assays to be run on a single qPCR plate. The qPCR assays were specific for 33 E. coli O157:H7 strains tested and detected 500 cells spiked in a background of 10(8) nontarget bacterial cells. The qPCR detection was combined with an enrichment process using Presence Absence (P/A) broth to detect chlorine and starvation stressed cells. qPCR analysis performed post-enrichment allowed the detection of 3-4 cells/L as indicated by a sharp increase in fluorescence (lowering of Ct values) from pre-enrichment levels, demonstrating a 5-6 log increase in the number of cells. When six vulnerable untreated surface water samples were examined, only one was positive for viable E. coli O157:H7 cells. These results suggest that the culture-PCR procedure can be used for rapid detection of E. coli O157:H7 in drinking water.     

Arsenic and manganese contamination of drinking water resources in Cambodia: coincidence of risk areas with low relief topography

Arsenic contamination of groundwater has been identified in Cambodia, where some 100,000 family-based wells are used for drinking water needs. We conducted a comprehensive groundwater survey in the Mekong River floodplain, comprising an area of 3700 km(2) (131 samples, 30 parameters). Seasonal fluctuations were also studied. Arsenic ranged from 1 to 1340 microg L(-1) (average 163 microg L(-1)), with 48% exceeding 10 microg L(-1). Elevated manganese levels (57% >0.4 mg L(-1)) are posing an additional health threat to the 1.2 million people living in this area. With 350 people km(-2) potentially exposed to chronic arsenic poisoning, the magnitude is similar to that of Bangladesh (200 km(-2)). Elevated arsenic levels are sharply restricted to the Bassac and Mekong River banks and the alluvium braided by these rivers (Kandal Province). Arsenic in this province averaged 233 microg L(-1) (median 100 microg L(-1)), while concentrations to the west and east of the rivers were <10 microg L(-1). Arsenic release from Holocene sediments between the rivers is most likely caused by reductive dissolution of metal oxides. Regions exhibiting low and elevated arsenic levels are co-incident with the present low relief topography featuring gently increasing elevation to the west and east of a shallow valley-understood as a relict of pre-Holocene topography. The full georeferenced database of groundwater analysis is provided as Supporting Information.     

In situ hybridization of microcolonies using catalyzed reporter deposition with tetramethylbenzidine: a method for detecting low numbers of bacterial cells in drinking water

In this study, catalyzed reporter deposition in situ hybridization (CARD—ISH) with tetramethylbenzidine (TMB) was used for rapid detection of the food pathogens Salmonella typhimurium and Escherichia coli. The bacteria in a sample were concentrated by membrane filtration. The filter membranes with the cells thus removed were incubated on nutrient agar for 4–5 h to allow the formation of microcolonies. Instead of fluorescent tyramide, 3,3′,5,5′-tetramethylbenzidine (TMB), which yields a blue precipitate, was used for signal amplification after in situ hybridization. Microcolonies amplified with TMB produced blue signals, which were sufficiently intense to allow visual evaluation either using a stereomicroscope, or even with the naked eye. Therefore even low cell numbers of hygienically critical bacteria can be detected on the filter membrane without a protracted examination. This enables the detection of low cell numbers (<10 cfu) in a sample of 100 ml tap water within 9–10 h.     

大体积全自动固相萃取-气相色谱-质谱法同时测定饮用水中43种半挥发性有机物

目的 建立大体积全自动固相萃取-气相色谱-质谱(SPE-GC-MS)法同时测定饮用水中43种半挥发性有机物(SVOCs)。方法 1.0 L饮用水样品经HLB固相萃取柱富集、净化后,分别以2 ml乙酸乙酯、4 ml二氯甲烷洗脱,洗脱液氮吹浓缩至0.5 ml,用乙酸乙酯定容至1.0 ml,经HP-5 ms UI超高惰性毛细管柱(30 m×250 μm, 0.25 μm)分离,采用GC-MS的选择离子扫描模式(SIM)分析,以保留时间和特征离子定性,内标法定量。结果43种SVOCs均得到有效分离,方法的线性关系良好,相关系数r²≥0.995,方法检出限为0.000 13～0.008 2 μg/L,定量限为0.000 42～0.027 μg/L,平均回收率为70.0%～138%,精密度为0.3%～12.1%。应用该方法测定16份不同水质样品,结果共检出六氯苯、五氯硝基苯和萘等10种SVOCs。结论 本方法灵敏、高效,适用于饮用水中多种SVOCs的同时检测,可为突发公共卫生事件提供依据。     

Dynamics of the functional gene copy number and overall bacterial community during microcystin-LR degradation by a biological treatment facility in a drinking water treatment plant

Information is limited on the potential for microcystins (MCs) degradation by carrier-attached biofilms obtained in winter that were not exposed to detectable levels of MCs in the preceding months. Under controlled laboratory conditions, we confirmed that microcystin-LR (MCLR) was effectively biodegraded within 5.5 days in cultures of the biofilm sampled in winter. Quantitative polymerase chain reaction (qPCR) assays revealed that seasonal variations in the MCLR-degradation potential of the biofilm were closely related to the initial MCLR-degrader population in the biofilm. Indigenous MCLR-degraders in the biofilm could accumulate by exposure to natural MCLR in the water column, accelerating MCLR-degradation. The qPCR assay suggested that MCLR may be a primary substrate for the degraders in the presence of another labile organic carbon associated with the biofilm under the present study conditions. qPCR and PCR-denaturing gradient gel electrophoresis (DGGE) for 16S rDNA demonstrated that the overall bacterial population from the winter biofilm rapidly increased with the MCLR-degrader population and remained stable after day 3.5, while the overall bacterial community structure shifted throughout the entire biodegradation period. This study is important to the in-depth understanding of microbial degradation of MCs and could facilitate the bioremediation of MCs in polluted habitats.     

固相萃取-超高效液相色谱-串联质谱法测定瓶装饮用水中双酚A、双酚S

目的建立固相萃取(solid phase extraction,SPE)结合超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)测定瓶装饮用水中双酚A(bisphenol A,BPA)、双酚S(bisphenol S,BPS)的方法。方法利用BPA-D_4和BPS-~(13)C_(12)混合同位素内标,经Waters Oasis系列的HLB固相萃取柱富集样品,以甲醇-水为流动相,经Waters BEH C_(18)色谱柱分离,采用UPLC-MS/MS在负离子电离(electron spray ionization,ESI-)模式和多反应监控(multiple reaction monitoring,MRM)模式下检测。结果用该方法测定时,BPA在1~50μg/L范围内线性良好,BPS在0.2~10μg/L范围内线性良好,相关系数r均为0.9999,BPA的平均回收率为99.5%~100.7%,相对标准偏差为0.8%~4.6%;BPS的平均回收率为95.9%~102.1%,相对标准偏差为1.3%~2.5%,BPA的最低检出浓度为20 ng/L,BPS的最低检出浓度为5 ng/L。结论此方法操作简单、灵敏度高、重现性好,适用于瓶装饮用水中双酚A、双酚S的检测。     

Influence of soaking on the nutritional quality of common beans (Phaseolus vulgaris L.) cooked with or without the soaking water: a review

Bean soaking seems to be unanimously recommended by scientists; however, there is no consensus regarding the need to discard the soaking water before cooking. Thus, the present study proposes to review the influence of maceration on the nutritional quality of common beans (Phaseolus vulgaris L.) cooked with or without the soaking water, in an attempt to achieve agreement among scientists. The article search was done in a systematic way and eleven studies were found. Of these, three compared the use or not of the soaking water for cooking, seven of them discarded the soaking water and one used the soaking water. This review discusses each nutrient and antinutrient regarding the effects of soaking and compares them with other studies done with legumes. The results were not unanimous but there was a greater advantage to discarding the soaking water before cooking.     

Judging a product by its cover: Packaging sustainability and perceptions of quality in food products

In this paper, we test the influence of packaging sustainability on consumers’ perceived quality of food products using two experiments featuring raisins, chocolate bars and coffee. First, the results show that the perceived quality of a food product is more positive when it is packed in a sustainable packaging than when it is packed in a conventional packaging. Next, we demonstrate that product sustainability moderates the influence of packaging sustainability. Finally, we show that the perceived naturalness of the product induced by package and product sustainability explains the perception of product quality.