Behaviour of several solid adsorbents for sampling tetraalkyllead compounds in air

The behaviour of various solid adsorbents for collecting tetraalkyllead compounds has been studied. A synthetic atmosphere containing a known concentration of tetraethyllead was produced and the tetraethyllead compound was trapped in a glass tube containing the solid adsorbent. The trapped compound was extracted with hexane in an ultrasonic bath, and the resulting solution was analysed by GC-MS. Porapak and Tenax, with retention efficiencies of 92 and 96%, respectively, were shown to be the more efficient at trapping this alkyllead compound than Chromosorb, active charcoal, Amberlites and polyurethane foam. The behaviour of both Porapak and Tenax for trapping other tetraalkyllead compounds in the presence of gasoline vapour was also studied.     

固体进样直接测定法测定铜精矿中汞

建立了固体进样直接测定法测定铜精矿中汞含量的方法。铜精矿样品在测汞仪的分解炉中经300℃干燥和750℃高温热分解后,汞被催化分解为汞原子,于850℃齐化成金汞齐。汞蒸气被氧气流带入单波长光学吸收池,在波长253.7 nm处测量汞的吸光度,采用标准曲线法计算汞量。方法的线性范围分别为0~1.00,0~100μg/mL,线性相关系数为0.9999,检出限分别为0.10,0.04 ng/g。5个汞含量不同的铜精矿样品测定结果的相对标准偏差为2.14%~4.35%(n=11),样品加标回收率为92.00%~104.02%。采用该方法分别对2个铜精矿样品和铜精矿国际标准物质进行测定,测定结果与标准分析方法测定值和标准物质标示值基本一致。该方法简便、快速、准确,可以作为标准方法推广使用。     

Determination of trace impurities in titanium dioxide by direct solid sampling electrothermal atomic absorption spectrometry

A true direct solid sampling electrothermal atomic absorption spectrometry method with Zeeman-effect background correction (Analytik Jena ZEEnit 60 AAS) was developed for the determination of As, Cd, Hg, Pb, Sb and Zn in powdered titanium dioxide of pharmaceutical, food and cosmetics grade. The interaction of the titanium matrix and graphite surface of the sample carrier boat in a transversely heated graphite tube atomizer was investigated. Conversion of titanium dioxide to interfering TiO₂–TiC-liquid phase, running out the sampling boat, was observed at temperatures above 2000 °C. The temperature program was optimized accordingly for these volatile analytes in atomization and cleaning steps in order to prevent this interference and to prolong significantly the analytical lifetime of the boat to more than one thousand runs. For all elements, calibration by aqueous standard addition method, by wet-chemically analyzed samples with different content of analytes and/or by dosing one sample in different amounts, were proved as adequate quantification procedures. Linear dynamic calibration working ranges can be considerably expanded up to two orders of magnitude within one measurement run by applying three-field dynamic mode of the Zeeman background correction system. The results obtained by true direct solid sampling technique are compared with those of other independent, mostly wet-chemical methods. Very low limits of detection (3σ criterion) of true solid sampling technique of 21, 0.27, 24, 3.9, 6.3 and 0.9 ng g^− 1 were achieved for As, Cd, Hg, Pb, Sb and Zn, respectively.     

Determination of olefinic aldehydes and other volatile carbonyls in air samples by DNPH-coated cartridges and HPLC

Summary The collection of low-boiling olefinic aldehydes on 2,4-dinitrophenylhydrazine (DNPH)-coated adsorbents (silica cartridges and glass denuders) is examined. Concurrent formation of two different hydrazones by both acrolein and crotonaldehyde is reported and discussed. Identification and quantitation of these compounds do not represent a problem in HPLC analysis, because of their separation from other C₃ and C₄ carbonyl derivatives present in airborne sample extracts.     

Development of diffusive solid phase microextraction method for sampling of epichlorohydrin in air

Epichlorohydrin is used frequently in many industrial processes. Exposure to this pollutant could induce harmful effects. The present work developed a novel solid phase microextraction (SPME) method for time weighted average determination of epichlorohydrin in the air by GC/MS. CAR/PDMS in 0.5?cm retracted mode was selected and the effect of environmental parameters on sampling properties of SPME was examined. Experimental sampling rate for epichlorohydrin (8.89?×?10^?3?cm³/min) was slightly less than theoretical value (9.059?×?10^?3?cm³/min). There was no significant difference among sampling rates at different temperature and velocities but relative humidity had a significant effect on the sampling rate. Limit of detection for SPME method was 0.8?ng per sample, which is good enough in comparison with the NIOSH 1010 method. Comparison of the results between the developed SPME and the NIOSH 1010 method on standard test atmosphere and field showed satisfactory agreement (y?=?1.162x?+?1.8 r ²?=?0.992 and y?=?1.009x+0.76 r ²?=?0.98 respectively).     

Determination of mercury in airborne particulate matter collected on glass fiber filters using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sampling

A study has been undertaken to assess the capability of high-resolution continuum source graphite furnace atomic absorption spectrometry for the determination of mercury in airborne particulate matter (APM) collected on glass fiber filters using direct solid sampling. The main Hg absorption line at 253.652 nm was used for all determinations. The certified reference material NIST SRM 1648 (Urban Particulate Matter) was used to check the accuracy of the method, and good agreement was obtained between published and determined values. The characteristic mass was 22 pg Hg. The limit of detection (3σ), based on ten atomizations of an unexposed filter, was 40 ng g^− 1, corresponding to 0.12 ng m^− 3 in the air for a typical air volume of 1440 m³ collected within 24 h. The limit of quantification was 150 ng g⁻¹, equivalent to 0.41 ng m⁻³ in the air. The repeatability of measurements was better than 17% RSD (n = 5). Mercury concentrations found in filter samples loaded with APM collected in Buenos Aires, Argentina, were between < 40 ng g⁻¹ and 381 ± 24 ng g⁻¹. These values correspond to a mercury concentration in the air between < 0.12 ng m⁻³ and 1.47 ± 0.09 ng m⁻³. The proposed procedure was found to be simple, fast and reliable, and suitable as a screening procedure for the determination of mercury in APM samples.     

Influence of the nature of the solid support and the dispersity of the active agent on the performance of chromatographic columns packed with surface-layer sorbents

Summary Retention ability of different types of solid supports with respect to active agents was studied using NaXtype zeolites as the example. The relative contribution of the zeolite (active agent) and the solid support to the overall adsorption of certain hydrocarbons was determined. The role of dispersity (particle size) and depth of penetration of the active agent in the pores of the solid support was investigated, using the uniformity criterion of Vigdergauz. The performance of chromatographic columns packed by surface-layer sorbents is compared with columns packed with the pure active agent.     

Correction of structured molecular background by means of high-resolution continuum source electrothermal atomic absorption spectrometry—Determination of antimony in sediment reference materials using direct solid sampling

A simple, fast and accurate procedure is proposed for the determination of antimony in certified sediment reference materials using direct solid sampling high-resolution continuum source electrothermal atomic absorption spectrometry and iridium as a permanent modifier. The less sensitive resonance line at 231.147 nm has been used in order to allow the introduction of larger sample mass. Six certified reference materials, one river, one estuarine and four marine sediments have been analyzed. The use of iridium as a permanent modifier caused an increase of 30% in sensitivity and stabilized antimony in the sediment to a pyrolysis temperature of 1100 °C. Significant background absorption with pronounced rotational fine structure was observed at the optimum atomization temperature of 2100 °C, which coincided with the analyte atomic absorption in time. This background was found to be due to the electron excitation spectra of mostly the SiO and in part the PO molecules, and could be eliminated by applying a least-squares background correction algorithm. A characteristic mass of 28 pg Sb was obtained, and the limit of detection (3σ, n = 10) was 0.02 μg g⁻¹, calculated for 0.2 mg of sample. The results obtained for six certified reference materials with concentrations between 0.40 and 11.6 ± 2.6 μg g⁻¹ Sb were in agreement with the certified values according to a Student's t-test for a 95% confidence level, using aqueous standards for calibration. The precision, expressed as relative standard deviation, ranged between 7% and 17% (n = 5).     

Determination of volatile organic compounds in contaminated air using semipermeable membrane devices

Semipermeable membrane devices (SPMDs) were evaluated as passive samplers for the determination of 26 volatile organic compounds (VOCs) in contaminated air of occupational environments. A direct methodology based on the use of head-space-gas chromatography-mass spectrometry (HS-GC-MS) was developed for VOCs determinations in SPMDs, without any sample pre-treatment and avoiding the use of solvents. A desorption temperature of 150 °C for 10 min was sufficient for a sensitive VOCs determination providing limits of detection in the range of 15 ng SPMD⁻¹ for 21 of 26 studied compounds. Linear and equilibrium uptake models were established for each VOC from compound isotherms. Highly volatile compounds were slightly absorbed and moderately volatile compounds were strongly absorbed by SPMDs. This study is the first precedent of the use of SPMDs for the simultaneous sampling of a wide number of VOCs. The use of SPMDs is a simple and low cost alternative to ordinary sampling devices such as Radiello^® diffusive samplers or badge-type solid-phase supports.     

Determination of cadmium in coal using solid sampling graphite furnace high-resolution continuum source atomic absorption spectrometry

This work describes the development of a method to determine cadmium in coal, in which iridium is used as a permanent chemical modifier and calibration is performed against aqueous standards by high-resolution continuum source atomic absorption spectrometry (HR-CS AAS). This new instrumental concept makes the whole spectral environment in the vicinity of the analytical line accessible, providing a lot more data than just the change in absorbance over time available from conventional instruments. The application of Ir (400 g) as a permanent chemical modifier, thermally deposited on the pyrolytic graphite platform surface, allowed pyrolysis temperatures of 700 °C to be used, which was sufficiently high to significantly reduce the continuous background that occurred before the analyte signal at pyrolysis temperatures <700 °C. Structured background absorption also occurred after the analyte signal when atomization temperatures of >1600 °C were used, which arose from the electron-excitation spectrum (with rotational fine structure) of a diatomic molecule. Under optimized conditions (pyrolysis at 700 °C and atomization at 1500 °C), interference-free determination of cadmium in seven certified coal reference materials and two real samples was achieved by direct solid sampling and calibrating against aqueous standards, resulting in good agreement with the certified values (where available) at the 95% confidence level. A characteristic mass of 0.4 pg and a detection limit of 2 ng g^–1, calculated for a sample mass of 1.0 mg coal, was obtained. A precision (expressed as the relative standard deviation, RSD) of <10% was typically obtained when coal samples in the mass range 0.6–1.2 mg were analyzed.Dedicated to the memory of Wilhelm Fresenius     

Determination of lead in hair and its segmental analysis by solid sampling electrothermal atomic absorption spectrometry

A rapid and practical solid sampling electrothermal atomic absorption spectrometric method was described for the determination of lead in scalp hair. Hair samples were washed once with acetone; thrice with distilled-deionized water and again once with acetone and dried at 75 °C. Typically 0.05 to 1.0 mg of dried samples were inserted on the platforms of solid sampling autosampler. The effects of pyrolysis temperature, atomization temperature, the amount of sample as well as addition of a modifier (Pd/Mg) and/or auxiliary digesting agents (hydrogen peroxide and nitric acid) and/or a surfactant (Triton X-100) on the recovery of lead were investigated. Hair samples were washed once with acetone; thrice with distilled-deionized water and again once with acetone and dried at 75 °C. Typically 0.05 to 1.0 mg of dried samples were inserted on the platforms of solid sampling autosampler. The limit of detection for lead (3σ, N = 10) was 0.3 ng/g The addition of modifier, acids, oxidant and surfactant hardly improved the results. Due to the risk of contamination and relatively high blank values, the lead in hair were determined directly without adding any reagent(s). Finally, the method was applied for the segmental determination of lead concentrations in hair of different persons which is important to know when and how much a person was exposed to the analyte. For this purpose, 0.5 cm of pieces were cut along the one or a few close strands and analyzed by solid sampling.     

固相萃取/气相色谱法测定禽蛋中19种农药残留

建立了QuEChERS及固相萃取净化技术结合气相色谱法测定禽蛋中19种农药(联苯菊酯、甲氰菊酯、氯菊酯、氯氰菊酯、氰戊菊酯、溴氰菊酯、敌敌畏、甲胺磷、乙酰甲胺磷、二嗪磷、乐果、甲基嘧啶磷、毒死蜱、杀螟硫磷、丙溴磷、氟虫腈、氟甲腈、氟虫腈硫醚及氟虫腈砜)残留的分析方法。蛋液样品经乙腈及QuEChERS提取盐包提取后,采用石墨化碳黑(GCB)吸附剂和十八烷基硅烷键合硅胶(C₁₈)SPE小柱净化,以Agilent DB-1701(30 m×0.32 mm,0.25μm)毛细管色谱柱分离,在气相色谱火焰光度检测器(Flame photometric detector,FPD)及电子捕获检测器(Electron capture detector,ECD)上检测,外标法定量。结果显示,19种农药在各自线性浓度范围内线性关系良好,相关系数(r²)均不小于0.999 3;在低、中、高3个加标水平下的回收率为78.6%～105%,相对标准偏差(n=6)为1.6%～9.3%,检出限(LOD,S/N=3)为0.138～8.33μg/kg,定量下限(LOQ,S/N=...     

Direct determination of iron in sand using solid sampling graphite furnace atomic absorption spectrometry

A fast and reliable method for the direct determination of iron in sand by solid sampling graphite furnace atomic absorption spectrometry was developed. A Zeeman-effect 3-field background corrector was used to decrease the sensitivity of spectrometer measurements. This strategy allowed working with up to 200 μg of samples, thus improving the representativity. Using samples with small particle sizes (1–50 μm) and adding 5 μg Pd as chemical modifier, it was possible to obtain suitable calibration curves with aqueous reference solutions. The pyrolysis and atomization temperatures for the optimized heating program were 1400 and 2500 °C, respectively. The characteristic mass, based on integrated absorbance, was 56 pg, and the detection limits, calculated considering the variability of 20 consecutive measurements of platform inserted without sample was 32 pg. The accuracy of the procedure was checked with the analysis of two reference materials (IPT 62 and 63). The determined concentrations were in agreement with the recommended values (95% confidence level). Five sand samples were analyzed, and a good agreement (95% confidence level) was observed using the proposed method and conventional flame atomic absorption spectrometry. The relative standard deviations were lower than 25% (n = 5). The tube and boat platform lifetimes were around 1000 and 250 heating cycles, respectively. Correspondence: Pedro V. Oliveira, Instituto de Química, Universidade de S?o Paulo, CP 26077, 05513-970 S?o Paulo, SP, Brazil     

Analysis of halogenated methoxybenzenes and hexachlorobenzene (HCB) in the picogram m−3 range in marine air

Summary Halogenated methoxybenzenes (halogenated anisoles) and hexachlorobenzene (HCB) have been analyzed in marine air samples from the lower troposphere of the East Atlantic Ocean, taken on the German, research vessel ‘Polarstern’ during two cruises in 1993 and 1994, and in air samples from the North Pacific Ocean (1995). The high-volume sampling method, sample preparation and analysis by HRGC-ECD and HRGC-MSD-SIM are described. The effectiveness of a new graphitized-carboncovered silica sorbent (ANGI-Sorb B) for the sampling of semi-volatiles is demonstrated. Eight congeners of the halogenated anisoles and HCB were detected in almost all marine air samples. The concentrations of the chloroanisoles, which show a distinct north-south interhemispherical gradient, were between 0.2 and 145 pg m⁻³; for the bromaanisoles concentrations were between 0.2 and 42 pg m⁻³. Only a weak inter-hemispheric gradient was observed for HCB at levels of 10–40 pg m⁻³. Levels of HCB were approximately 100 pg m⁻³ in continentally influenced air. Biogenic and indirect anthropogenic sources of the halogenated anisoles are discussed. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996     

环境水样中9种三唑类农药的固相萃取-气相色谱-质谱分析

应用C18柱萃取/富集,NH2柱净化,气相色谱-质谱联用技术检测,建立了环境水样中9种三唑类农药同时分析的方法。9种目标农药在0.025～0.500 mg/L质量浓度范围内线性关系良好,方法的检出限为0.002～0.009 μg/L。以实际水样为基底,加标质量浓度为0.025 μg/L和0.100 μg/L时,9种目标农药的基底加标回收率和相对标准偏差(n=3)分别为68.4%～113.9%,1.6%～6.9%(河水)和70.3%～115.2%,0.8%～8.2%(海水)。该方法操作简单、灵敏度高、选择性好,符合多种农药残留分析的要求,并成功地应用于福建九龙江河口区表层水样中三唑类农药的残留状况调查。     

Determination of trace impurities in aluminum nitride by direct solid sampling graphite furnace atomic absorption spectrometry

The trace impurities Cr, Cu, Fe, K, Mn, Sb and Zn were determined in powdered aluminum nitride by direct solid sampling graphite furnace atomic absorption spectrometry using a ZEEnit 60 atomic absorption spectrometer. This spectrometer features inverse Zeeman-effect background correction and a variable magnetic field enabling measurements in two sensitivity modes over a concentration range of three orders of magnitude. The measurement sensitivity can be adjusted to the analyte concentration in the sample. The use of chemical modifiers was not necessary. Calibration was carried out by means of calibration curves obtained with aqueous standard solutions. Accuracy was checked mainly by comparison of the results with those obtained by instrumental and radiochemical neutron activation analysis whereby, excluding the results for potassium, no significant differences were found by carrying out the t-test at the significance level 0.05. The limits of detection were between 0.05 ng g⁻¹ (Zn) and 80 ng g⁻¹ (Fe) and the relative standard deviations below 11 %. With the proposed method, up to ten measurement cycles can be carried out in one hour.     

大体积采样结合高分辨气相色谱-电子捕获负化学源-低分辨质谱法测定空气中的短链氯化石蜡

建立了大体积采样结合高分辨气相色谱-电子捕获负化学源-低分辨质谱(HRGC-ECNI-LRMS)测定空气中短链氯化石蜡(SCCPs)的定量分析方法。联合使用酸化硅胶复合层析柱和碱性氧化铝层析柱净化处理空气样品中的SCCPs,并对净化条件进行优化。使用该方法计算得到氯含量为58.1%~63.3%的SCCPs系列标准储备溶液的总响应因子与氯含量线性相关,相关系数(R²)大于0.99。该方法的仪器检出限(S/N≥3)为4.2 pg,定量限(S/N≥10)为12 pg。SCCPs的方法检出限(MDL)为0.34 ng/m³(n=7),实际样品加标回收率均达80%以上。该方法灵敏度高、选择性好,能满足空气样品中SCCPs的监测和分析需求。     

固相萃取–气相色谱–串联质谱法测定茶叶中9种农药残留量

建立固相萃取净化–气相色谱–串联质谱法同时测定茶叶中9种农药残留量的方法。茶叶样品用乙腈均质提取,提取液经固相萃取净化处理后,采用DB–5MS毛细管色谱柱分离,在多反应监测模式下测定,外标法定量。9种农药组分的质量浓度在0.01~0.50 mg/L范围内与其色谱峰面积呈良好线性,相关系数r~2大于0.998,方法测定下限(10 S/N)为0.002~0.01 mg/kg。以空白绿茶、红茶、普洱茶和乌龙茶为基体,在0.05,0.1,0.2 mg/kg 3个添加水平进行加标回收试验,加标回收率在73.6%~99.7%之间,相对标准偏差为4.2%~8.7%(n=6)。该法操作简便、快速,适用于茶叶中多种农药残留的测定。     

Determination of cadmium,copper and lead in alumina based catalysts by direct solid sampling graphite furnace atomic absorption spectrometry

Trace impurities of Cd, Cu and Pb were determined in alumina based catalysts using direct solid sampling graphite furnace atomic absorption spectrometry (DSS-GF AAS). The analyzed catalysts are widely used in petrochemical processes. The following analytical parameters were evaluated: pyrolysis and atomization temperatures, feasibility of calibration with aqueous solutions, the necessity for palladium as chemical modifier and the sample mass introduced into the atomizer. Test samples between 0.05 and 8.5 mg were used. Palladium was investigated as chemical modifier but no improvement in analytical performance was obtained and its use was considered unnecessary for all elements. The results obtained by DSS-GF AAS were compared with those of inductively coupled plasma optical emission spectrometry (ICP OES) and also with conventional solution analysis by GF AAS (Sol-GF AAS). Characteristic masses were 1.4, 9 and 20 pg, for Cd, Cu and Pb, respectively. Using DSS-GF AAS the relative standard deviation was always less than 10% and the results agreed with those obtained by Sol-GF AAS and ICP OES. Calibration using aqueous solutions showed good linearity within the working range (R² better than 0.99). Limits of detection (3σ, n = 10) for Cd, Cu and Pb using the proposed procedure were 0.2, 22, and 1.2 ng g^− 1, respectively.     

固相萃取-超高效液相色谱-串联质谱法测定人尿中苯氧乙酸除草剂和有机磷、拟除虫菊酯农药代谢物北大核心CSCD

基于96孔固相萃取-超高效液相色谱-串联质谱法,建立了人尿中2种苯氧乙酸除草剂、2种有机磷农药代谢物和4种拟除虫菊酯农药代谢物的测定方法。通过对液相色谱条件、质谱条件和样品前处理过程的系统优化,实现了在16 min内对8种目标分析物的分析测定。具体方法:1 mL尿液经β-葡萄糖醛酸酶酶解过夜,Oasis HLB 96孔固相萃取进行目标分析物的提取净化,甲醇洗脱;以0.1%(体积分数)乙酸乙腈和0.1%(体积分数)乙酸水作为流动相,Acquity BEH C_(18)作为分析柱进行色谱分离;负离子电喷雾(ESI-)多反应监测(MRM)模式下检测目标化合物,同位素内标法定量。2,4-二氯苯氧乙酸(2,4-D)、2,4,5-三氯苯氧乙酸(2,4,5-T)2种苯氧乙酸除草剂和3-苯氧基苯甲酸(3-PBA)、4-氟-3-苯氧基苯甲酸(4F-3PBA)、反式二氯乙烯基二甲基环丙烷羧酸(trans-DCCA)3种拟除虫菊酯农药代谢物在0.1~100μg/L内、对硝基苯酚(PNP)、3,5,6-三氯-2-吡啶酚(TCPY)2种有机磷农药代谢物、顺式二氯乙烯基二甲基环丙烷羧酸(cis-DCCA)1种拟除虫菊酯代谢物在0.2~100μg/L内线性关系良好,相关系数均大于0.9993;方法检出限为0.02~0.07μg/L,方法定量限为0.08~0.2μg/L;低、中、高3个水平下的加标回收率为91.1%~110.5%,日内精密度为2.9%~7.8%,日间精密度为6.2%~10%。应用该方法测定了214份尿液样本。结果显示除2,4,5-T外,其余7种目标分析物均有检出。TCPY、PNP、3-PBA、4F-3PBA、trans-DCCA、cis-DCCA、2,4-D的检出率为2.8%~99.1%。检出浓度(中位值)由高到低分别是2.0μg/L(TCPY)、1.8μg/L(PNP)、0.99μg/L(trans-DCCA)、0.81μg/L(3-PBA)、0.44μg/L(cis-DCCA)、0.35μg/L(2,4-D)和未检出(4F-3PBA)。该方法操作简便,定量准确,灵敏度高,每批次可完成96个样品测定,适用于人尿中多种农药及农药代谢物的批量分析测定。