以环境友好型絮凝剂代替碱性铅粉进行糖料甘蔗试验分析,为减少糖料甘蔗品质分析中碱性铅粉的使用提供参考.结果表明,13种絮凝剂中,以乙酸锌和氢氧化钙的过滤效果相对较好;复合型絮凝剂(乙酸锌+氢氧化钙)中乙酸锌和氢氧化钙加入量与蔗汁比例分别为0.5%和0.4%时,可代替碱性铅粉满足糖料甘蔗试验要求,加入混合絮凝剂后有利于沉降速度的提高,减少蔗汁在沉降池中的停留时间,甘蔗品质参数蔗汁糖度、蔗糖分检测结果与碱性铅粉处理结果误差为:蔗汁糖度0.001～0.008(允许误差0.01),蔗汁蔗糖分0.001～0.006(允许误差0.02),满足国家标准GB/T 10499-2014《糖料甘蔗试验》要求.

3-硝基丙酸是由节菱孢霉菌等真菌产生的一种有毒代谢产物,常见于霉变甘蔗及其制品中,摄入会损害人的中枢神经系统,严重的可致人死亡.因此,建立准确、高效的3-硝基丙酸检测方法对大众身体健康的防护和推进甘蔗产业的健康有序发展具有重要意义.本文综述了国内外最新的甘蔗及其制品中3-硝基丙酸含量的检测方法,分析了各种方法的优缺点,并对其未来的发展方向进行展望,为构筑更为精准、灵敏、高效的3-硝基丙酸的检测方法提供参考.

合成了一种有机-无机介孔二氧化硅杂化材料(SBA-15-Tpy),通过透射电镜显微镜、X射线衍射、热重分析和N2吸附-解吸曲线对其进行表征,并基于该材料建立了在水中对Cu2+和Co2+的选择性识别.研究表明,SBA-15-Tpy与Cu2+和Co2+结合后会分别在800 nm和510 nm处产生新的吸收峰,加入其它金属离子后不发生明显的吸收峰值变化.在最优条件下,检测Cu2+和Co2+的线性范围分别为2.0～200.0 μmol/L 和10.0～200.0 μmol/L,检出限分别为0.48 μmol/L 和4.28 μmol/L.将上述方法用于江水中Cu2+和Co2+的测定,回收率在96.0％～108.5％之间.

[Objective] To provide scientific data basis for processing and consumption of maize in Guangxi,the content of selenium (Se) of maize from Guangxi was determined and its effects on the health of adults and Lactating women were assessed.[Method] 196 samples were collected from the main maize producing areas of Guangxi,and their Se contents were determined.The health risk of Se intake daily from maize to the average adults and lactating women in Guangxi was evaluated using upper tolerable limit (UTL),upper intake limit (UIL),and adequate intake (AI) as reference.[Result] The average amount of Se in 196 samples was 27.1 μg · kg-1,the maximum amount was 175 μg · kg-1;The Se-rich maize (whose Se content was more than 40 lμg · kg-1) accounted for 29.6 ％.The risk index of Se in maize to Guangxi residents was 0.005 ％-66.74 ％ for average adults,and 0.005 ％-25.73 ％ for lactating women.[Conclusion] The maize produced in Guangxi was of high Se content,while the health risk of Se in maize to the average adults and lactating women in Guangxi was relative low,therefore,the intake of Se via the consumption of maize was relatively safe.

The conditions for determination of trace Se by atomic fluorescence spectrometry after hydrochloric acid extraction was op-timized using single factor and response surface methodology,and the content of inorganic Se in selenium-enriched cassava was de-termined. The results showed that,the optimal conditions for inorganic Se extraction were:an extraction agent of 30%HCl,100℃ of water bath temperature,30 min of water bath time,and 30 min of ultrasonic time. The optimal instrument parameters for Se determi-nation were:a carrier liquid of 6. 0%HCl,a KBH4of 2. 0%,and a medium solution with 12. 5%HCl. The recovery rate of the meth-od was 93. 0% ～107%,and the detection limit was 0. 465 μg·L-1. The method could be used for the determination of inorganic and organic Se in cassava samples. The experimental results also showed that Se in selenium-enriched cassava mainly existed as or-ganic Se species,and the organic Se in most cassava samples were accounted for more than 70%of total Se,meet the"Requirements of selenium content in organic selenium-rich foods"(DBS42/002-2014).

A determination method for abamectin residues in cabbage and orange was established in this study by using ultra high performance liquid chromatography-ultraviolet (UPLC-UV). Samples were extracted with acetonitrile, and mixed with ethylenediamine-N-propylsilane (PSA) and C18 matrix dispersion scavenger for purification by using a ACQUITY UPLC BEH C18 column (2. 1×100 mm, 1. 7 μm). The column temperature was set as 35 ℃, the mobile phase was composed of acetonitrile-water (70:30, V/V) with a flow rate of 0. 25 m L/min, and the ultraviolet detection wavelength was set as 245 nm. Abamectin had different matrix effects on cabbage and orange samples and therefore, external standard of the blank matrix-matched calibration curves was used for quantification. The results showed that abamectin had good linear relationship in the range of 0. 2510 mg/L, and the correlation coefficients were all more than 0. 9999. In the range of 0. 050. 5 mg/kg, the average addition recovery was 83. 0％100. 2％, and the relative standard deviation (RSD) was 1. 17％1. 30％. The limits of detection (LOD) of abamectin in cabbage and orange (S/N=3) were 0. 0109 mg/kg and 0. 0160 mg/kg, respectively. The proposed method was simple, accurate and sensitive, which could be used for the analysis of abamectin in cabbage and orange.

[目的]探索土壤环境中不同污染浓度的重金属镉(Cd)、汞(Hg)、铜(Cu)和铅(Pb)对荸荠生长的影响及空间分布规律,为荸荠的安全种植及合理布局提供理论支持.[方法]以广西主要荸荠品种桂蹄2号为研究对象,分别进行不同污染浓度的镉、汞、铜和铅的盆栽试验,设0、0.25、1、1.75、2.5 T(T为每个重金属土壤环境限量值)5个添加量浓度,土壤中重金属浓度为添加量浓度+试验土壤本底浓度.在荸荠成熟后,分析荸荠果肉、皮和茎叶中各元素分布及富集积累规律.[结果]荸荠在不同浓度的各重金属处理下均能正常生长,吸收重金属元素特征分别为:铜、铅和镉在不同部位含量分布为:茎叶＞皮＞果肉;汞分布为:皮＞果＞茎叶.荸荠中不同部位重金属的含量随着土壤中重金属含量的增加而增加.在0.25 T汞处理下和2.5T铅处理下,荸荠果肉中汞和铅的含量分别超过《食品安全国家标准食品中污染物限量》(GB2762-2017)中新鲜蔬菜水果的限量值.[结论]低浓度重金属的处理会促进荸荠产量的提高,荸荠各部位对重金属吸收累积具有显著的分布规律:镉、铅和铜元素地上茎叶植株吸收多,块茎吸收少,汞则相反;荸荠对铅和镉耐受性强,在土壤达到环境限量值时,荸荠果肉中铅和镉含量符合标准要求;汞容易被荸荠吸收,在有汞污染风险的区域建议不要种植.

Nitrogen-doped graphene oxide (NGO) was synthesized by a one-step hydrothermal method and characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM).A NGO modified carbon paste electrode (NGO/CPE) was prepared,and the electrochemical behaviors of capsaicin at NGO/CPE were studied.Experimental results showed that the voltammetric response of capsaicin at NGO/CPE was greatly improved when compared with bare carbon paste electrode (CPE).Some parameters such as NGO concentration,accumulation time and pH were optimized.Capsaicin was determined by using differential pulse voltammetry.Under optimal conditions,the peak current was linearly proportional to capsaicin concentration in the range of 5.0 to 1 200 μg/L,with a limit of detection (LOD) of 2.0 μg/L (RsN =3).The proposed method was applied for the determination of capsaicin in hot pepper samples,and the results well agreed with those obtained by colorimetry.