Analysis of dithiocarbamate fungicides. Second-derivative UV-spectroscopic determination of CS2, COS,and thiram (TMTD)

The application of second-derivative UV-spectroscopy offers a highly sensitive and selective method for the determination of CS₂ and COS, as acid hydrolysis products of dithiocarbamate und thiuram disulphide fungicides, using a methanolic amine absorption reagent (ethylenediamine, piperidine). With standard concentrations of 0.08–1.1 μg CS₂/ml and 0.3 to 2.0 μg COS/ml, respectively, calibration curves with good correlation coefficients (r>0.999) were obtained. In comparison to the official method of the Deutsche Forschungsgemeinschaft (DFG method S15) the proposed alternative is at least 100 times more sensitive to CS₂. Using the second derivative method it is possible not only to clearly differentiate between CS₂ and COS but also to quantify both gases without resorting to tedious background corrections as compared to the direct photometric methods. Additionally, second derivative spectroscopy allows the direct determination of thiram in the concentration range 1–10 μg/ml after its extraction with chloroform. For example, thiram in water (10 μg/l) and in thiram/talc standards (10 mg/g) were determined with good precision (±2.0%).     

Analysis of dithiocarbamate fungicides. Reaction products of the thiuram disulphide fungicide thiram (TMTD) during acid hydrolysis

The acid hydrolysis products (CS₂, COS, and H₂S) of thiram (tetramethylthiram disulphide, TMTD) absorbed in a methanolic amine reagent (ethylenediamine, piperidine) were investigated by second derivative UV spectroscopy. When the hydrolysis temperatures are below the boiling point the formation of the side products COS and H₂S at the expense of CS₂ is unavoidable. Failure to carefully scrub the liberated gases with a lead acetate solution leads to the absorption of H₂S also in the amine reagent and, like COS, causes an absorption at 230 nm that is erroneously attributed to COS. With the second-derivative technique it has been undoubtedly proved that, under the conditions of the Deutsche Forschungsgemeinschaft method S 15, thiram liberates CS₂ and COS in a molar ratio of 1.92 to 0.06 (average of eight determinations) but not in a molar ratio of 1.5 to 0.5, as previously reported by some workers. Under these conditions it is impossible, contrary to earlier claims, to differentiate thiram from other dithiocarbamates based on the ratio of the hydrolysis products in residue analysis.

---

Analytik der Dithiocarbamat-Fungicide. Reaktionsprodukte des Thiuramdisulfid-Fungicids Thiram (TMTD) während der Säurehydrolyse

Zusammenfassung Mittels Derivativ-UV-Spektroskopie wurden die Produkte der Säurehydrolyse (CS₂, COS und H₂S) des Fungicids Thiram (TMTD) nach Absorption in einem methanolischen Aminreagens (Ethylendiamin, Piperidin) ermittelt. Bei Hydrolysetemperaturen unter dem Siedepunkt ist die Bildung der Nebenprodukte COS und H₂S auf Kosten von CS₂ unvermeidlich. Erfolgt kein sorgfältiges Waschen der hydrolytisch freigesetzten Gase mit einer Bleiacetatlösung, so wird auch H₂S im Aminreagens absorbiert, das wie COS eine UV-Absorption bei 230 nm verursacht und die COS-Bestimmung verfälscht. Mit der Derivativspektroskopie konnte eindeutig gezeigt werden, daß Thiram unter den Bedingungen der DFG-Methode S 15 zu CS₂ and COS im molaren Verhältnis von 1,92 zu 0,06 (8 Messungen) hydrolysiert wird und nicht, wie von anderen Autoren angenommen, im molaren Verhältnis von 1,5 zu 0,5. Daher ist es, den gehegten Hoffnungen entgegen, nicht möglich, auf der Basis der Verteilung der Hydrolyseprodukte Thiram von anderen Dithiocarbamaten rückstandsanalytisch zu unterscheiden.

     

固体酸SiO_2-Ti(SO_4)_2-Zr(SO_4)_2催化麻疯树籽油醇解反应的研究

通过溶胶-凝胶法制备了Si O2载体,所得载体再通过浸渍法制备得到负载Ti(SO4)2和Zr(SO4)2的复合型固体酸催化剂Si O2-Ti(SO4)2-Zr(SO4)2,利用热重分析(TG-DTG)和傅里叶红外光谱(FTIR)对催化剂的特性进行初步表征。此外,以转化率为指标,研究了复合型固体酸催化剂在麻疯树籽油醇解反应中的催化活性,并考察催化剂用量、醇油摩尔比、反应温度和反应时间对醇解反应的影响。TG-DTG分析结果表明,催化剂的焙烧温度应选择300℃,此条件下可以制备催化活性较好的催化剂;FTIR表征结果表明,浸渍Ti(SO4)2和Zr(SO4)2后,该活性物质成功负载到Si O2载体表面。单因素实验结果表明最佳反应条件为:反应温度120℃,催化剂用量5%,醇油摩尔比15∶1,反应时间5 h;在此条件下,麻疯树籽油的转化率最高可达92.53%。     

柱前衍生-超高效液相色谱荧光法同时测定啤酒中黄曲霉毒素B1、B2、G1、G2

目的建立柱前衍生-UPLC-FLD法测定啤酒中黄曲霉毒素B1、B2、G1、G2的方法。方法样品直接经过乙腈稀释提取,提取液经过离心后,取上清液用多功能柱净化,净化液经氮气吹干、用三氟乙酸衍生后,经定容、微孔滤膜过滤、进液相色谱分析,以ACQUITY UPLC HSS T3柱(2.1 mm×100 mm,1.8μm)分离,荧光检测器检测,外标法定量。结果 4种黄曲霉毒素线性范围较宽,相关系数r在0.999 2~0.999 6之间,黄曲霉毒素B1、B2、G1、G2检出限分别为0.05、0.02、0.08、0.02μg/kg。加标回收率90.47%~108.17%之间,回收率的RSD在0.97%~8.13%之间。结论本法操作简便、准确度好、精密度高,干扰性小,能满足啤酒中黄曲霉毒素B1、B2、G1、G2的同时测定。     

免疫亲和层析净化-高效液相色谱法同时测定牛奶和奶粉中黄曲霉毒素B1、B2、G1、G2、M1、M2

建立牛奶和奶粉中黄曲霉毒素B1、B2、G1、G2、M1、M2的免疫亲和层析净化和柱后衍生高效液相色谱测定方法。样品经溶解、离心、过滤后,通过免疫亲和柱,黄曲霉毒素特异性抗体选择性地与存在的黄曲霉毒素抗原键合,形成抗体-抗原复合体。甲醇-乙腈混合溶液(4:5,v:v)洗脱,带荧光检测器的高效液相色谱仪经柱后衍生测定,外标法定量。标准曲线线性良好,添加回收率在57.0%～88.7%,相对标准偏差在3.37%～16.9%,牛奶中各黄曲霉毒素检出限:B1为2ng/kg,B2为1ng/kg,G1、G2为3ng/kg,M1、M2为5ng/kg;奶粉中B1为20ng/kg,B2为10ng/kg,G1、G2为30ng/kg,M1、M2为50ng/kg,检测低限能够满足各国对牛奶和奶粉中黄曲霉毒素的限量要求。该方法准确、快速、灵敏度高,适用于牛奶和奶粉中黄曲霉毒素的测定。     

纳米Ag@TiO2、Fe@TiO2和Zn@TiO2的抑菌活性比较研究

探索常见金属离子掺杂对抑菌片的抑菌性能的影响,为新型纳米TiO₂抑菌片的制备与改善提供技术基础。选择固定质量分数的Ag⁺、Zn²⁺和Fe³⁺掺杂TiO₂,通过抑菌圈、MIC与MBC方法综合评价其抑菌性能,对微观结构进行表征分析,探讨抑菌性能差异的原因。结果表明:抑菌性能大小顺序为Ag@TiO₂> Zn@TiO₂> Fe@TiO₂,Zn@TiO2 的抑菌活性较好但抑菌稳定性差Ag@TiO2对大肠杆菌和金黄色葡萄球菌的MIC、MBC均是10、20 mg/L,Zn@TiO₂对大肠杆菌和金黄色葡萄球菌的MIC、MBC均是30、50 mg/L。表征发现抑菌活性强弱主要归因于纳米TiO₂表面与金属离子共同产生的活性位点数量及稳定性,与孔结构或表面宫能团的关联不大。     

Evaluation and Improvement of Extraction Methods for the Analysis of Aflatoxins B1, B2, G1 and G2 from Naturally Contaminated Maize

The extraction procedure for aflatoxin determination in maize is based on a methanol–water (8 + 2 v/v) or an acetone–water (85 + 15 v/v) mixture. Initially, the extraction efficiency of two solvents was evaluated for each aflatoxin. Different results were obtained for highly contaminated maize: significantly higher levels of aflatoxin B₁ were obtained by acetone–water, on the contrary higher levels of aflatoxin G₂ were achieved by methanol–water. Then, acetone–water mixtures in different proportions (7 + 3, 6 + 4 and 5 + 5 v/v) were tested to improve the extraction of aflatoxin G₂. Applying these extraction mixtures, the values both of aflatoxin B₁ and of other aflatoxins were generally higher compared to those obtained by acetone–water 85 + 15; moreover, acetone–water (6 + 4) and (7 + 3) showed the best extraction efficiency for all aflatoxins.     

Aeromonas spp. simultaneously harbouring blaCTX-M-15, blaSHV-12, blaPER-1 and blaFOX-2, in wild-growing Mediterranean mussel (Mytilus galloprovincialis) from Adriatic Sea,Croatia

Aeromonas species are becoming renowned as emerging pathogens by increasingly giving rise to a wide spectrum of food and waterborne infections in humans. Another worrisome feature of aeromonads is the growing frequency of antibiotic resistance as a consequence of their prominent diversity in terms of resistance determinants. This study aimed at determining the antimicrobial resistance pattern, prevalence and characterization of acquired β-lactamases, including extended-spectrum-β-lactamases (ESBLs) and AmpC cephalosporinases, as well as the presence of class 1 and 2 integrons, in Aeromonas isolates from wild-growing Mediterranean mussel (Mytilus galloprovincialis) of the eastern coast of Adriatic Sea, Croatia. Isolates were tested for susceptibility to 16 antibiotics and β-lactam/β-lactamase inhibitor combinations. Cephalosporin-resistant isolates were further screened by PCR for genes encoding AmpC (bla_FOX, bla_CMY, bla_MOX, bla_LAT, bla_BIL, bla_DHA, bla_ACC, bla_MIR, bla_ACT), ESBLs (bla_TEM, bla_SHV, bla_CTX-M, bla_PER, bla_VEB, bla_GES/IBC, bla_OXA) and integrases (intI1, intI2, intI3). Location of bla genes was characterized by plasmid DNA fingerprinting and Southern blot hybridization. Plasmids carrying ESBL genes were investigated for transferability by conjugation and PCR-based replicon typed. Out of 147 Aeromonas isolates recovered, 30 (20%) demonstrated multiple resistance profile, with co-resistance most frequently detected against penicillins, piperacillin/sulbactam and tetracycline. ESBL-encoding genes were detected in 21 (13 Aeromonas caviae and 8 Aeromonas hydrophila) isolates, with bla_CTX-M-15 gene identified in 19 and bla_SHV-12 in 12 isolates. Among them, 10 isolates simultaneously harboured bla_CTX-M-15 and bla_SHV-12, while 3 isolates additionally carried an AmpC β-lactamase bla_FOX-2 gene. bla_PER-1 gene was identified in a single isolate also harbouring the bla_CTX-M-15 gene. While bla_SHV-12 was chromosomally encoded, bla_CTX-M-15 was located on conjugative IncFIB-type plasmids of ~ 40 kb in A. caviae isolates. IntI1 and intI2 genes were detected in 57.1% and 33.3% of ESBL-producing isolates.     

滇橄榄叶羟基酪醇对CS2致小鼠睾丸组织损伤的保护作用

目的:研究从滇橄榄叶中提取的羟基酪醇（hydroxytyrosol from Phyllanthus emblica Linn leaves,PHT）对二硫化碳（carbon disulfide,CS₂）致小鼠睾丸组织损伤的保护作用。方法:实验小鼠随机分为对照组（蒸馏水）、CS₂染毒组（50 mg/m3）和3个PHT干预组（450、150、50 mg/kg）,4周后计算睾丸脏器系数、检测精子质量、测定睾丸组织匀浆中的超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）活性及丙二醛（MDA）含量并观察睾丸组织病理切片,采用Western blot实验检测睾丸组织中凋亡相关因子蛋白的表达情况。结果:经过干预后,PHT高、中剂量组睾丸脏器系数均高于CS₂染毒组（P<0.01）,且PHT高剂量组与对照组间无统计学差异（P>0.05）;各PHT剂量组精子计数和精子活动率均高于CS₂染毒组（P<0.01）,但低于对照组（P<0.01）;各PHT剂量组精子畸形率低于CS₂染毒组（P<0.01）,且PHT高剂量组与对照组的精子畸形率无统计学差异（P>0.05）;观察睾丸组织病理切片发现,与CS₂染毒组相比,各PHT剂量组的睾丸组织形态均得到了改善,其中PHT高剂量组与对照组的病理切片在镜下未观察到明显差别;氧化应激指标与凋亡相关因子蛋白的表达情况表明,各PHT剂量组睾丸组织中MDA含量均低于CS₂染毒组（P<0.01）,PHT高剂量组与对照组间MDA含量无显著差异（P>0.05）;各PHT剂量组睾丸组织中SOD和GSH-Px活性高于CS₂染毒组（P<0.05）,但低于对照组（P<0.01）;与CS₂染毒组相比,PHT高、中剂量组睾丸组织中Bax和Caspase-3表达降低,Bcl-2表达升高（P<0.01）,且各剂量组与对照组间也存在差异（P<0.05）。结论:CS₂可以引起小鼠睾丸氧化损伤,且PHT可以针对CS₂所致的睾丸组织损伤发挥拮抗作用,其机制可能与PHT的强抗氧化性维持了部分抗氧化酶的活性,缓解了氧化损伤,从而减少了细胞凋亡因子的形成有关。     

Shelf-stability enhancement of precooked red claw crayfish (Cherax quadricarinatus) tails by modified CO2/O2/N2 gas packaging

Three types of packaging systems were compared for their influence on the storage stability (2 °C) of precooked and peeled red claw crayfish tails. Modified atmosphere packaging (MAP; with 80%CO₂/10%O₂/10%N₂) almost totally inhibited the growth of aerobic bacteria and coliforms when compared with aerobic polyvinylchloride packaging (PVCP) and vacuum packaging (VP). MAP also prevented a pH rise, purge loss, and texture toughening or softening of stored red claw when compared with PVCP or VP (P<0.05). Lipid oxidation was minimal in all three packaging systems. Thus, MAP offers an attractive means to preserve the shelf life of precooked red claw stored under refrigerated retail display conditions.     

Tungsten permanent chemical modifier with co-injection of Pd(NO3)2 + Mg(NO3)2 for direct determination of Pb in vinegar by graphite furnace atomic absorption spectrometry

A tungsten carbide coating on the integrated platform of a transversely heated graphite atomizer (THGA^®) used together with Pd(NO₃)₂ + Mg(NO₃)₂ as modifier is proposed for the direct determination of lead in vinegar by graphite furnace atomic absorption spectrometry. The optimized heating program (temperature, ramp time, hold time) of atomizer involved drying stage (110 °C, 5 s, 30 s; 130 °C, 5 s, 30 s), pyrolysis stage (1000 °C, 15 s, 30 s), atomization stage (1800 °C, 0 s, 5 s) and clean-out stage (2450 °C, 1 s, 3 s). For 10 μL of vinegar delivered into the atomizer and calibration using working standard solutions (2.5–20.0 μg L⁻¹ Pb) in 0.2% (v/v) HNO₃, analytical curve with good linear correlation (r = 0.9992) was established. The characteristic mass was 40 pg Pb and the lifetime of the tube was around 730 firings. The limit of detection (LOD) was 0.4 μg L⁻¹ and the relative standard deviations (n = 12) were typically <8% for a sample containing 25 μg L⁻¹ Pb. Accuracy of the proposed method was checked after direct analysis of 23 vinegar samples. A paired t-test showed that results were in agreement at 95% confidence level with those obtained for acid-digested vinegar samples. The Pb levels varied from 2.8 to 32.4 μg L⁻¹. Accuracy was also checked by means of addition/recovery tests and recovered values varied from 90% to 110%. Additionally, two certified reference materials were analyzed and results were in agreement with certified values at a 95% confidence level.     

K8[Cd(H2O)CuW11O39]/PANI/ZnS三元复合材料的合成、表征及光催化性能

采用静电自组装法将杂多酸K₈[Cd(H₂O)CuW₁₁O₃₉]和中间体PANI/ZnS成功复合成三元复合催化剂K₈[Cd(H₂O)CuW₁₁O₃₉]/PANI/ZnS,并利用IR、UV、XRD、N₂吸附-脱附、SEM、XPS等手段进行表征,研究该催化剂光催化降解龙胆紫染料的能力。确定反应的优化条件为:龙胆紫溶液初始p H 2,初始质量浓度5 mg/L,催化剂用量10 mg,此时龙胆紫溶液脱色率可达92.15%。重复降解实验证明,K₈[Cd(H₂O)CuW₁₁O₃₉]/PANI/ZnS经过3次降解后仍具有良好的催化活性,龙胆紫溶液脱色率达到70.14%。     

Static, Controlled (CO2) Atmosphere Packaging of Retail Ready Pork

Wrapped boneless pork loin roasts and slices were stored at 4°in bulk under constant CO₂ concentrations of 50% and 100% for 1 and 2 wks. Samples stored under 50% CO₂ for 2 wks could subsequently be displayed (aerobic) for 3 days without becoming unacceptable or for 6 days if previously held under 100% CO₂ for 14 days. Aerobic shelf-life at 4°of the latter samples equalled that of fresh pork chops under simulated retail display. Physicochemical characteristics during storage did not limit acceptability. Reusable master packs have application for distribution of retail ready cuts under controlled atmosphere packaging.     

呋喃氟尿嘧啶衍生物M1、M2的合成

目的探索高效低毒的抗肿瘤药物。方法替加氟(FT-207)为先导化合物,经取代反应、水解反应制得N1-(四氢-2-呋喃基)-N3-乙酸基-5-Fu,在N,N,-二环己基碳酰亚胺(DCC)作用下分别与2-氨基-1,3,4-噻二唑及2-氨基-5-甲基-1,3,4-噻二唑反应,生成目标化合物M1及M2。结果 M1及M2结构经红外光谱、质谱、元素分析和核磁共振氢谱确证。结论合成路线合理,操作简便,值得进一步研究。     

CaO-CeO2 @LiFe5 O8磁性固体碱催化剂的表征及性能评价

首先采用溶胶凝胶法制备了LiFe_5O_8磁核,并用共沉淀法制备了CaO-CeO_2@LiFe_5O_8磁性固体碱催化剂。通过XRD、SEM、TEM和CO_2-TPD对催化剂进行表征,并对其性能进行评价。结果表明:成功地制备了CaO-CeO_2@LiFe_5O_8磁性固体碱催化剂,并且CaO-CeO_2也成功地被吸附在LiFe_5O_8磁核表面,催化剂具备十分优良的铁磁性; CO_2-TPD表征结果说明,制备的催化剂具备较强的碱性,用于棕榈油酯交换反应体系中,生物柴油收率可达到95. 37%;制备的催化剂具有很好的耐酸、耐水性,重复使用5次后仍然保持较好的催化活性,且在外加磁场中易分离。     

红提葡萄低O2和高CO2处理效果研究

以红提葡萄为试验材料,研究(0±0.2)℃,2.5%O2+5%CO2、2.5%O2+10%CO2、2.5%O2+15%CO2和8%、10%、12%O2条件下气体处理效果。结果表明:CO2对红提葡萄有明显的抑菌作用,(0±0.2)℃处理50d,2.5%O2协同5%、10%、15%CO2处理比单纯低8%、10%、12%O2处理效果好,腐烂率低,硬度变化小;2.5%O2,5%～10%CO2可以取得较好的保鲜效果;2.5%O2+15%CO2处理50d未见高CO2伤害症状,表明新疆产红提葡萄耐高CO2能力强;单纯低O2贮藏时,O2含量在±2%范围变化时就会对果肉硬度、果胶酶活力、PPO活力及SSC产生显著性影响(P<0.05)。     

免疫初乳中IgG1和IgG2的分离纯化

采用硫酸胺盐析,DE－52离子交换色谱,SephacryIS-100凝胶过滤色谱从免疫初乳分离纯化出了IgG1和IgG2,经SDS－PAGE电泳及免疫电泳证实为纯品,并对IgG1和IgG2的抗体凝集价进行了测定。     

Comprehensive Evaluation and Prediction of the Effectiveness of H2O2-assisted Na2CO3 Pretreatment of Corn Stover Using Multivariate Analysis

In this study, multivariate analysis methods, including a principal component analysis (PCA) and partial least square (PLS) analysis, were applied to reveal the inner relationship of the key variables in the process of H₂O₂-assisted Na₂CO₃ (HSC) pretreatment of corn stover. A total of 120 pretreatment experiments were implemented at the lab scale under different conditions by varying the particle size of the corn stover and process variables. The results showed that the Na₂CO₃ dosage and pretreatment temperature had a strong influence on lignin removal, whereas pulp refining instrument (PFI) refining and Na₂CO₃ dosage played positive roles in the final total sugar yield. Furthermore, it was found that pretreatment conditions had a more significant impact on the amelioration of pretreatment effectiveness compared with the properties of raw corn stover. In addition, a prediction of the effectiveness of the corn stover HSC pretreatment based on a PLS analysis was conducted for the first time, and the test results of the predictability based on additional pretreatment experiments proved that the developed PLS model achieved a good predictive performance (particularly for the final total sugar yield), indicating that the developed PLS model can be used to predict the effectiveness of HSC pretreatment. Therefore, multivariate analysis can be potentially used to monitor and control the pretreatment process in future large-scale biorefinery applications.