X射线荧光光谱法测定农田底泥中8种元素

建立X射线荧光光谱法测定农田底泥样品中砷、铬、铜、锰、镍、铅、锌、铁8种元素含量的分析方法.以塑料环粉末压片法制样,选用50种土壤、水系沉积物标准物质拟合校准曲线,探讨各元素的测定条件.当待测样品与建立校准曲线的标准样品粒径均小于75μm时,能够有效减少矿物效应和粒度效应的影响,从而提高检测准确度;各元素在各自的含量范...     

近红外光谱法快速测定肼-70纯度

利用重量法精确配制不同肼质量分数的肼-70样品集,采用偏最小二乘法建立了肼质量分数的近红外光谱模型,以快速测定肼-70的纯度。样品恒温时间为5 min,光谱最佳预处理方式:均值中心化,一阶导数,21点平滑,模型最佳主因子数为4。近红外光谱法与碘酸钾直接滴定法测定结果相比相对偏差绝对值小于0.13%,经t检验,两种方法测定结果无显著性差异。近红外光谱法快速、准确,可用于肼-70产品的质量控制。     

微波消解 电感耦合等离子体质谱（ICP-MS）法测定土壤改良剂矸石骨料中植物所缺必需微量元素

本方法通过微波消解方式及HF:HClO3:HNO3混酸体系,建立电感耦合等离子体质谱法(ICP-MS)测定土壤改良剂矸石骨料中植物所缺必需微量元素(Cu 、Co、Zn、Mn)的方法。采用钪(⁴⁵Sc)为内标元素和统一高盐基体的外标标准曲线进行信号漂移的抑制以及基体干扰的消除,同时选择丰度大的⁶³Cu、⁵⁹Co、⁶⁴Zn和⁵⁵Mn同位素元素进行测试,通过测定国家标准物质和国标方法对比的方式验证方法的准确性。Cu、Co、Zn和Mn在0.1-100纳克/毫升范围内,校准曲线的线性相关系数均大于0.9999,分析方法检出限均小于0.292微克/克。将方法用于实际样品分析,相对标准偏差(n=11)不高于2.92%,加标回收率在96%~103.57%范围内。     

X射线荧光光谱法测定铁矿石中SiO2含量的校准曲线的评估

<正>SiO₂是铁矿石主要杂质成分之一,是评价铁矿石品质的重要指标,常采用X射线荧光光谱法^[1]测定其含量。测定前,需要先用具有一定浓度水平范围的标准样品系列建立校准曲线,校准曲线性能检验不仅是方法确认和验证的重要内容,还是测量溯源的有效途径,获得满意测量结果的基础。大多数日常检测中,仅用校准曲线的相关系数作为曲线质量的评判准则是不够的,这是因为相关系数只能说明数据点是否近似在一条直线上,而不能评估校准曲线的精密度和准确度。     

波长色散X射线荧光光谱法测定钴精矿中钴、铜和锰含量

采用高纯氧化物经四硼酸锂和偏硼酸锂熔融制备人工标准样品,以氧化镱为内标,制作校准曲线,建立了波长色散型X射线荧光光谱法测定钴精矿中钴、铜、锰元素的分析方法。重点研究了混合熔剂、试样稀释比、氧化剂和内标选择、方法检出限、方法准确度和精密度等,结果表明,各元素校准曲线线性范围宽,相关系数均大于0.999, 钴、铜、锰元素检出限分别达到0.002%、0.001%和0.001%,测试准确度和精密度可靠,方法满足行业检测需求。     

波长色散X射线荧光光谱法测定钴精矿中钴、铜和锰

采用高纯氧化物经四硼酸锂和偏硼酸锂熔融制备人工标准样品,以氧化镱为内标,制作校准曲线,建立了波长色散型X射线荧光光谱法测定钴精矿中钴、铜、锰元素的分析方法。重点研究了混合熔剂、试样稀释比、氧化剂和内标选择、方法检出限、方法准确度和精密度等,结果表明,各元素校准曲线线性范围宽,相关系数均大于0.999,钴、铜、锰元素检出限分别达到0.002%、0.001%和0.001%,方法的准确度和精密度可靠,满足行业检测需求。     

气相分子吸收光谱法测定水中硝酸盐氮

硝酸盐氮是水环境质量重点监测项目之一,建立节省人力、高效快捷、抗干扰能力强的测试水中硝酸盐氮的分析方法十分必要。本文从载气类型、载气流量、定量方式、加热温度、载流液配比等方面系统的优化气相分子吸收光谱法测定水中硝酸盐氮的仪器条件。在优化的仪器条件下,工作曲线相关系数为0.9995;检出限为0.006 mg/L,测定下限为0.024 mg/L;标准物质测定的相对误差范围在0.0%~0.6%,实际样品测定的相对标准偏差范围在0.5%~5.5%;实际样品加标回收率范围在89.0%~102%。方法的检出限、精密度和准确度良好,适用于水质硝酸盐氮的测定。     

氧弹分解-原子荧光法快速测定煤中汞

建立了氧弹分解-原子荧光法快速测定煤中Hg含量的方法。考察了吸收液种类、样品质量、吸收液体积、静置吸收时间对测定结果的影响,并对吸收反应机理进行了分析。结果表明,0.01 mol/L KMn O_4(3%H_2SO_4)溶液作为吸收剂时,对煤中Hg的吸收最好,回收率在96%~102%;随着样品质量的增加,回收率下降,0.2 g样品量最为适宜;5 m L吸收液、静置吸收10 min效果较好。校准曲线在0~2.0 ng/m L Hg范围线性良好,相关系数大于0.9995;方法检出限为7 ng/g。经t检验,氧弹分解-原子荧光法与直接测汞仪法无统计学意义上的差异,方法可用于煤中Hg含量的快速检测。     

X射线荧光光谱法同时测定矿石中铀和钍

建立了X射线荧光光谱法测定矿石样品中铀、钍含量的快速分析方法。采用高压粉末制样法,对不同含量的放射性样品的压片压力、粒径、含水率、用量等处理条件到进行单因素实验。在400 MPa压力下压制,克服了低压制样的弊端,制备的样片表面光滑、致密,大幅改善了制样重现性,有效地减少了部分基体效应,铀校准曲线的标准偏差从0.053%降到0.0071%,钍校准曲线的标准偏差从0.062%降到0.0057%。经国家一级标准物质验证,表明方法准确、可靠,能满足样品中铀、钍含量日常分析要求。     

液液萃取-程序升温大体积进样-气相色谱串联质谱法测定地表水中25种痕量有机氯农药

建立了液液萃取-程序升温大体积进样-气相色谱-串联质谱分析地表水中25种有机氯农药(OCPs)的方法。样品由正己烷溶液萃取氮吹仪浓缩后,经HP-5 ms色谱柱分离,在柱流速1.2 mL/min条件下电子轰击电离源多反应监测(MRM)模式进行检测,内标法定量。结果表明,取样量为250 mL时,25种OCPs方法检出限范围为0.32～1.34 ng/L,校准曲线的相关系数范围在0.9990～0.9999之间,各组份质量浓度在0～50.0μg/L线性范围内线性良好。低中高3组加标实际样品25种OCPs和2种替代物测定结果的相对标准偏差为3.5%～13%,加标回收率为74.0%～103%。方法能够满足地表水中有机氯的检测要求。     

Determination of hydrazine derivatives by flow-injection analysis with spectrophotometric detection

Flow-injection analysis for the determination of hydrazine derivatives based on their nucleophilic substitution reaction with 4-chloro-5,7-dinitrobenzofurazan in aqueous medium, and spectrophotometric detection has been described. The calibration graphs were linear in the range from 0.15 to 4.0 mug ml(-1) of hydrazine derivatives, with sampling rates of up to 28-32 samples h(-1). Interferences from amino compounds, benzoic acids, aliphatic amines and ammonia have been evaluated. The procedure has been applied to the determination of hydrazine derivatives in serum, urine, appressin drugs and artificial mixtures.     

A novel hydrazine electrochemical sensor based on the high specific surface area graphene

An ultrasensitive platform is presented for the determination of hydrazine by combining the high specific surface area and higher electrical conductivity of poly(sodium styrenesulfonate) (PSS) graphene nanocomposite film with amperometric detection. The PSS-graphene were synthesized by the Hummers method and used to modify a glassy carbon electrode. The material was characterized by scanning electron microscopy and is found to be suitable for sensing hydrazine. The overpotential of hydrazine on the modified electrode is 0.31 V which is lower than in many electrochemical sensors. The calibration curve for hydrazine is linear in the range from 3.0 to 300 µmol L^?1, and the detection limit is as low as 1 µmol L^?1. This is the first report in which such a high sensitivity and low limit of detection has been achieved. It is concluded that PSS graphene represents an efficient electron mediator for sensing hydrazine.     

Sensitive and Rapid Flow Injection Amperometric Hydrazine Sensor using an Electrodeposited Gold Nanoparticle Graphite Pencil Electrode

A gold (Au) nanoparticle-modified graphite pencil electrode was prepared by an electrodeposition procedure for the sensitive and rapid flow injection amperometric determination of hydrazine (N₂H₄). The electrodeposited Au nanoparticles on the pretreated graphite pencil electrode surface were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, and electrochemical impedance spectroscopy. Cyclic voltammograms showed that the Au nanoparticle-modified pretreated graphite pencil electrode exhibits excellent electrocatalytic activity toward oxidation of hydrazine because the highly irreversibly and broadly observed oxidation peak at +600?mV at the pretreated graphite pencil electrode shifted to ?167?mV at the Au nanoparticle pretreated graphite pencil electrode; in addition, a significant enhancement in the oxidation peak current was obtained. Thus, the flow-injection (FI) amperometric hydrazine sensor was constructed based on its electrocatalytic oxidation at the Au nanoparticle-modified pretreated graphite pencil electrode. The Au nanoparticle-modified pretreated graphite pencil electrode exhibits a linear calibration curve between the flow injection amperometric current and hydrazine concentration within the concentration range from 0.01 to 100?µM with a detection limit of 0.002?µM. The flow injection amperometric sensor has been successfully used for the determination of N₂H₄ in water samples with good accuracy and precision.     

Indirect simultaneous kinetic determination of semicarbazide and hydrazine in micellar media by H-point standard addition method

H-point standard addition method (HPSAM) is suggested as a simple and selective method for the determination of semicarbazide and hydrazine. The reduction of Cu²⁺ to Cu⁺ by semicarbazide and hydrazine in the presence of neocuproine (Nc) and the subsequent complex formation between Cu⁺ and Nc produced a sensitive spectrophotometric method for indirect determination of semicarbazide and hydrazine. The difference in the rate of reduction of Cu²⁺ with semicarbazide and hydrazine in cationic micellar media is the basis of this method. Semicarbazide can be determined in the range of 0.5-3.75 μg ml⁻¹ with satisfactory accuracy and precision in the presence of excess hydrazine. The proposed method was successfully applied to the simultaneous determination of semicarbazide (0.5-3.75 μg ml⁻¹) and hydrazine (0.5-5 μg ml⁻¹) and also to the selective determination of semicarbazide in the presence of hydrazine in several synthetic mixtures containing different concentration ratios of semicarbazide and hydrazine.     

离子色谱法检验液体炸药爆炸尘土中的肼离子

建立了离子色谱检测液体炸药爆炸尘土中肼离子的方法。用去离子水超声提取尘土样品中的肼离子,离心后取上清液并将其分别过OnGuardⅡ RP小柱和0.22 μm过滤膜,经IonPac CS-12A阴离子色谱柱(250 mm×4 mm)分离,采用5 mmol/L甲基磺酸等度淋洗,0.1 mol/L NaOH溶液柱后加碱,金电极安培检测器检测。结果表明,肼离子质量浓度在0.02~2.0 mg/L范围内的线性关系良好(相关系数r²=0.9997)。以信噪比(S/N)为3确定方法检出限为5.0 μg/L, S/N为10确定方法定量限为16.6 μg/L。方法回收率在95.4%~99.1%之间,相对标准偏差(RSD, n=5)在2.1%~3.3%之间。应用该方法检测液体炸药爆炸尘土中肼离子的含量为10.3 mg/kg。该方法操作简便,结果准确,适用于液体炸药爆炸尘土中肼离子的定量检测,满足刑事物证鉴定工作的需要。     

Determination of analytical limits in solid sampling ETAAS: a new approach towards the characterization of analytical quality in rapid methods

In the present study the lower analytical limits of solid sampling electrothermal atomization atomic absorption spectrometry (SS-ETAAS) were characterized by means of blank measurements and – for the first time – by means of the calibration curve method, where a calibration near the range of these limits (limit of decision, detection and quantification) was performed. The limit of decision as derived from blank measurements was calculated according to the 3σ-criterion to be 0.003 and 0.019 ng for Cd and Pb, respectively. For Pb and Cd a roughly threefold increase of these limits was observed when the calibration method according to DIN 32 645 was applied. When solid reference material was used, only a slight increase could be observed. The analytical limits were 2 to 20 times lower than reported for sample decomposition methods. The blank measurement and conventional calibration curve method, however, do not account for factors relating to solid sampling such as sample mass and matrix. Therefore, the calibration curve model was applied to data derived from comparisons between direct solid sampling ETAAS and a compound reference method (ETAAS following sample homogenization and digestion). The observed analytical limits were not found to be substantially increased if enough samples with low element contents were available for calibration. Coupling of the calibration curve model with the comparison of methods included real test samples and thus the relevant maximum sample mass and analyte content in the range of the lower analytical limits. As validation procedures frequently include comparisons of methods, the present approach might prove to be of some general interest for the characterization of analytical quality in rapid methods.     

Determination of analytical limits in solid sampling ETAAS: a new approach towards the characterization of analytical quality in rapid methods

In the present study the lower analytical limits of solid sampling electrothermal atomization atomic absorption spectrometry (SS-ETAAS) were characterized by means of blank measurements and--for the first time--by means of the calibration curve method, where a calibration near the range of these limits (limit of decision, detection and quantification) was performed. The limit of decision as derived from blank measurements was calculated according to the 3sigma-criterion to be 0.003 and 0.019 ng for Cd and Pb, respectively. For Pb and Cd a roughly three-fold increase of these limits was observed when the calibration method according to DIN 32 645 was applied. When solid reference material was used, only a slight increase could be observed. The analytical limits were 2 to 20 times lower than reported for sample decomposition methods. The blank measurement and conventional calibration curve method, however, do not account for factors relating to solid sampling such as sample mass and matrix. Therefore, the calibration curve model was applied to data derived from comparisons between direct solid sampling ETAAS and a compound reference method (ETAAS following sample homogenization and digestion). The observed analytical limits were not found to be substantially increased if enough samples with low element contents were available for calibration. Coupling of the calibration curve model with the comparison of methods included real test samples and thus the relevant maximum sample mass and analyte content in the range of the lower analytical limits. As validation procedures frequently include comparisons of methods, the present approach might prove to be of some general interest for the characterization of analytical quality in rapid methods.     

Flow injection determination of hydrazine with fluorimetric detection

A spectrophotometric flow injection system is described for the determination of hydrazine, involving oxidation of hydrazine by thallium(III) with concomitant formation of thallium(I). The optimum analytical conditions have been established. The linear range for hydrazine is 25-500 ng ml(-1) with a detection limit of 20 ng ml(-1). The sampling frequency is 40+/-5 samples h(-1). The relative standard deviation for 100, 250 and 500 ng ml(-1) is 3.5, 2.6 and 1.8%, respectively. The method has been applied to the determination of hydrazine in water.     

Determination of captopril in pharmaceutical preparation and biological fluids using two- and three-way chemometrics methods

Spectrophotometric method has been developed for the direct quantitative determination of captopril in pharmaceuticalpreparation and biological fluids(human plasma and urine)samples.The method was accomplished based on parallel factoranalysis(PARAFAC)and partial least squares(PLS).The study was carried out in the pH range from 2.0 to 12.8 and with aconcentration from 0.70 to 61.50 μg mL~(-1)of captopril.Multivariate calibration models such as PLS at various pH and PARAFACwere elaborated from ultraviolet spectra deconvolution and captopril determination.The best models for this system were obtainedwith PARAFAC and PLS at pH 2.0.The applications of the method for determination of real samples were evaluated by analysis ofcaptopril in pharmaceutical preparations and biological fluids with satisfactory results.The accuracy of the method,evaluatedthrough the RMSEP,was 0.5801 for captopril with best calibration curve by PARAFAC and 0.6168 for captopril with PLS at pH 2.0model.