Determination of phosphine by adsorption sampling with modified silica gel and colorimetry of phosphate

A method for determining phosphine was developed using adsorption sampling followed by colorimetric measurement. Two types of adsorbent used in this study were prepared from silica gel by impregnation with potassium permanganate (1% w/w) or (mercury(II) chloride and sodium chloride) (0.2 + 0.2% w/w). Each adsorbent (150 mg) packed in a glass tube had the capacity to adsorb 0.3 ppm of phosphine in 3 l of test gas passing through at a rate of 300 ml/min without breakthrough. The adsorbed phosphine was desorbed into solutions as phosphate and the recovered phosphate was determined by ICP-AES or by one of two kinds of colorimetric methods for phosphate based on the molybdenum blue method, i.e., the colorimetric method following JIS K 0102 and that following the NIOSH Manual of analytical method, No. S 332. When 0.01 ppm of phosphine in 3 l of test gas was adsorbed on the potassium permanganate adsorbent and determined by the JIS method, 93.8% of the phosphine was recovered as phosphate with a CV of 12.9% (n = 3). This method was applicable to field surveys of phosphine in workplaces. The other method with the mercury(II) chloride adsorbent followed by the NIOSH method resulted in lower recovery of phosphate in low phosphine concentration range. ICP-AES was less sensitive than the colorimetries. The effect of coexistent arsenite or silicate on the colorimetry of phosphate was assessed.     

A method for the determination of ethylenediamine in workroom air

An ethylenediamine-air mixture was generated in a dynamic gas mixing apparatus, and three different sampling techniques were tested. The analysis was performed using isotachophoresis. Sampling in an impinger flask containing hydrochloric acid (20 mmol/l) gave a quantitative recovery. Desorption losses were noticed when silica gel adsorption tubes were used. Cellulose filter support pads impregnated with oxalic acid were laborious to prepare, and the recovery was high only when freshly prepared filters were used. The use of impingers was found to be the most satisfactory method, and it was used for air monitoring in two factories handling ethylenediamine.     

工作场所空气中二硼烷的等离子体发射光谱测定

目的 建立工作场所空气中二硼烷的样品采集及测定方法.方法 工作场所空气中的二硼烷用氧化剂浸渍活性炭管采集.采用体积分数为3%的H2O2解吸,采用等离子体发射光谱(ICP-AES)方法对溶液中硼进行定量.结果 本方法采样效率为99.6%,二硼烷5.66μg和56.6μg加标水平的解吸效率分别为90.9%和99.5%,批内和批间精密度相对标准偏差均小于8.0%.标准曲线范围0.1～10.0 μg/ml(以硼含量计),该方法空气中的二硼烷的最低检出浓度为0.011 mg/m3(以采集15 L空气样品计),最低检出浓度为0.035 mg/m3(以采集15 L空气样品计).结论 该方法适用于工作场所空气中二硼烷的采集及浓度测定.

Abstract：

Objective A sampling method was established to collect diborane in the air of workplace and an ICP-AES method was developed to determine the Boron in desorbed solution.Method Diborane in the air of workplace was collected by solid sorbent tube filled with oxidant impregnated activated carbon.The adsorbed diborane was desorbed into 3% H2O2 aqueous,and then the desorbed Boron was determined by ICP-AES.Results The sampling efficiency of this method was 99.6% with the desorption efficiency of diborane with 5.660 μg and 56.6 μg spiked were 90.9% and 99.5%,respectively.Both the intra-and inter-precision RSD were less than 8%.The standard curve of this method ranged from 0.1 to 10.0 μg/ml (Boron),and the LOD and LOQ were 0.011 mg/m3 and 0.035 mg/m3 (15L samples) respectively.Conclusion The method established was suitable for diborane sampling and determination in the air of workplace     

A spectrophotometric method of determination of endosulfan (thiodan) in air

Airborne endosulfan is sampled in a train of a microfibre glass or cellulore membrane filter and silica gel, desorbed in methanol and saponified with potassium hydroxide to yield sulphur dioxide. The sulphur dioxide released is spectrophotometrically quantified as a red-purple pararosaniline methyl sulphonic acid produced with acid-bleached para-rosaniline and formaldehyde. The spectrophotometric procedure follows the Beer-Lambert law in the endosulfan concentration range of 2–140 μg and the coefficient of variation (CV) of this method is 6.0%. The sampling efficiency of silica gel for endosulfan vapour at a sampling rate of 1 l. min⁻¹ in the concentration range 0.5-3.0 mg m⁻³ is found to be 99.8% (CV = 4.9%). The desorption efficiency of methanol for endosulfan trapped in silica gel was measured and found to be 9% (CV = 2.0%). The method is free from interference by atmospheric sulphur dioxide.     

Adsorption and desorption of organic solvent vapours using silica gel (author's transl)

For a simple analysis of organic solvent vapours in working environmental air, we investigated the following method. First, join the adsorption tube (2 ml of 60--80 mesh silica gel packed in a 5 mm phi x 18 cm glass tube) to hand vacuum pump and suck 200 ml of the sample air. After adsorption, join this adsorption tube to the sampling bottle under reduced pressure. Second, open the cock of the sampling bottle and heat only the adsorption tube in an oven for 3 min. In the operation mentioned above, organic solvent vapours desorbed from the silica gel transfer smoothly into the sampling bottle. After desorption, take 1 ml of air from the sampling bottle and determine the sample quantities with the gas chromatograph. Sample solvents used were as follows: n-hexane, cyclohexane, benzene, toluene, m-xylene, styrene, 1.1.1-trichloroethane, dichloromethane, tetrachloroethylene, ethylacetate, acetone, methyl-ethylketone, methylisobutylketone, methanol, ethanol, n-propanol, and n-butanol. We obtained the following results. (1) 60--80 mesh silica gel is appropriate for this method. (2) Heating temperature to get 100% recovery varies with the type of organic solvent. m-Xylene and styrene require 250 degrees C, methylisobutylketone and n-butanol 200 degrees C, and the others 150 degrees C. (3) If the adsorption tube is preserved in a freezer at -20 degrees C, no decrease is observed for up to 7 days. At room temperatures, however, 1.1.1-trichloroethane, dichloromethane, tetrachloroethylene, n-hexane, and cyclohexane decreased by the amount 4-10% in the tube for each 24-hour period. These sample should be preserved at lower temperatures soon after absorbing on the silica gel. This method is simple and accurate, so valid for analysis of organic solvent vapours in the working environmental air.     

空气中贲亭酸甲酯测定方法的研究

[目的]建立空气中贲亭酸甲酯的监测分析方法。[方法]贲亭酸甲酯用硅胶吸附,丙酮解吸,GC-FID测定,以保留时间定性,外标法定量。[结果]以5L含90μg贲亭酸甲酯模拟气体作实验,吸附效率为82％。以18μg贲亭酸甲酯作实验,解吸效率为94％,采样体积为10L时,仪器最低检出限约为0．02mg／M^3。[结论]该方法定量准确,灵敏度高,操作简便,能满足空气中微量贲亭酸甲酯监测需要。     

Occupational exposure to airborne formaldehyde in hospital: setting an automatic sampling system,comparing different monitoring methods and applying them to assess exposure

Background:In recent years, under-vacuum sealing (UVS) and containers with formalin encapsulated in the lid have been proposed for the reduction of occupational exposure to airborne formaldehyde (FA) in healthcare environments.Objectives:We are presenting a study focused on the assessment of FA in hospitals: an automatic sampling system was set, different sampling devices were compared, and the concentration of FA was assessed, following its use in different scenarios.Methods:Three different devices for sampling/measuring FA were compared. They are based on: 1. silica gel cartridges impregnated with 2,4-dinitrophenylhydrazine (2,4-DNPH); 2. SPME® fiber using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine; 3. direct reading commercial instrumentation. Three typical scenarios using FA were investigated: operating theatres where small biopsies are soaked into closed-circuit system 4% FA containers, secretariat of pathology laboratories during the registration of biopsies and pathology laboratories during the filling procedure by UVS and the slicing of biopsies.Results:The automatic sampling system allowed short-, long-, and in continuous-sampling time to measure airborne FA. Different sampling devices provided comparable results when tested to assess FA concentration ranging from 0.020-0.320 ppm in a test chamber, although the devices based on 2,4-DNPH were the best in terms of sensitivity and accuracy. The results of 246 samples showed that the FA concentration was less than 0.04 ppm in 91% of the measurements.Conclusions:The automatic methods efficiently allow sampling and measurement of FA in hospital settings. When using safe practices, the concentration of FA is well below occupational limit values.Key words: Formaldehyde, environmental monitoring, under-vacuum sealing, occupational health     

Personal air sampling for vapors of aniline compounds.

A method has been developed for air sampling and laboratory analysis of vapors of seven aniline compounds: aniline, N,N-dimethylaniline, o-toluidine, 2,4-xylidine, panisidine, o-anisidine, and p-nitroaniline. Air is drawn by a personal sampling pump from a worker's breathing zone through a tube containing silica gel to collect any anilines present. In the laboratory each silica gel section is transferred to a glass-stoppered tube and desorbed with ethanol. An aliquot of this is analyzed by gas chromatography to determine the amount of each aniline compound present. The sampling tube can be used for short-term sampling at 1000 cm3/min or for sampling up to eight hours at 200 cm3/min. Maximum interference effects of water vapor have been considered. Results of retention, desorption, storage, accuracy, and precision studies are presented.     

Monitoring of formaldehyde in air

Any one of several monitoring methods, depending on requirement and circumstance, can be used to measure employee exposure to formaldehyde. Ordinarily, monitoring at DuPont is performed by sampling with impingers containing 1% aqueous sodium bisulfite or with silica gel tubes. The collected formaldehyde is measured spectrophotometrically after reaction with chromotropic acid. Results from studies on a selected number of formaldehyde monitoring methods reveal that reliable methods are available for area and personnel monitoring over both short term and long term. Accurate results are obtained from short-term monitoring (15 min at 1 L/min) with impingers of formaldehyde concentrations as low as 0.14 ppm. The current studies show that long-term monitoring (8 hr at 0.5 L/min) can be performed accurately at concentrations as low as 0.05 ppm. Accurate results also are obtained from short-term monitoring (15 min at 500 mL/min) with silica gel tubes of concentrations as low as 0.11 ppm formaldehyde; the lower limit established in the current studies for long-term monitoring (8 hr at 30 mL/min) is 0.15 ppm. Passive monitors provide the most convenient means of obtaining 8-hour time-weighted average (TWA) data. The Pro-Tek Formaldehyde Badge was demonstrated to reliably monitor formaldehyde concentrations varying from 0-0.5 ppm or 0-3 ppm. All of these methods satisfy the NIOSH criterion for acceptability that all results fall within +/- 25% of the true value at the 95% confidence level. Investigation of the Lion Formaldemeter disclosed that instantaneous and accurate (+/- 5%) measurement of formaldehyde in air can be made over a concentration range of 0.3-5 ppm in the absence of other substances that are oxidizable in its fuel cell detector.     

An evaluation of the effect of source and concentration on three methods for the measurement of formaldehyde in indoor air

Three methods for measuring formaldehyde (HCHO) in indoor air were evaluated under field and laboratory conditions using different sources and concentrations of formaldehyde in air. Two impinger methods (the chromotropic acid method and modified pararosaniline method) and the Draeger short-term detector tube method (with and without activation tubes) were compared when sampling for formaldehyde from a particle board box, formalin solution, and a conventional home. Concentrations of formaldehyde ranged from 0.05-0.5 ppm in air. All samples were collected independently using personal sampling pumps and a Draeger bellows pump. The results indicate that the Draeger tube method using an activation tube gives lower results than either of the impinger methods. Without using an activation tube (concentrations greater than 0.5 ppm), the Draeger tube method was comparable to the two impinger methods. In addition, there are indications that the chromotropic acid method gives different results than the modified pararosaniline method, depending on the source of formaldehyde. The modified pararosaniline method indicated higher results than the chromotropic acid method when sampling from a particle board++ box but not from a formalin source. Overall analytical precision for each method of analysis was good.     

Laboratory evaluation of stain-length passive dosimeters for monitoring of vinyl chloride and ethylene oxide

The effects of vapor concentration in the range of 1.2 to 5.1 ppm (vinyl chloride) and 8.3 to 29.1 ppm (ethylene oxide) on the response of new stain-length passive dosimeters were evaluated separately in a dynamic exposure chamber. The vinyl chloride dosimeter was prepared with a permanganate impregnated blend of Chromosorb W and silica gel, while a silica gel-coated plastic strip (TLC plate) impregnated with dichromate was used to detect ethylene oxide. The use of a TLC plate as the inert support allowed us to reduce the amount of reagent loaded per length of tube, thus significantly enhancing in the sensitivity of the unit, which was necessary for accurately detecting ethylene oxide at these low concentrations. At the vinyl chloride exposure of 8 ppm-hrs the length of stain was 0.76 cm and the 95% confidence interval about this point was +/- 1.4 ppm-hrs (18%). For the ethylene oxide dosimeter the length of stain at the exposure of 80 ppm-hrs was 0.90 cm and the 95% confidence interval about this point was +/- 16 ppm-hrs (20%). Although some shortening of the stain was noted at low relative humidity (26%) in the vinyl chloride device, no effect on the dosimeter response was observed over the range of relative humidity of 35 to 96%. The ethylene oxide dosimeter response was not affected by relative humidity in the range of 28 to 90%. The use of a TLC plate as the inert support of the colorimetric reagent has proven to be an excellent means of improving the sensitivity of these stain-length passive dosimeters.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sampling and analysis of some aromatic,aliphatic and chlorinated hydrocarbon vapours in air,a gas-liquid chromatographic and colorimetric method

Summary This paper describes the sampling of air and its analysis for mixtures of organic solvent vapours by personal and room air samplers. The application of a potassium carbonate to remove water vapour, and silica gel adsorption tube cooled by dry ice for collection of organic solvents were investigated. The development of a method for the extraction of organic solvents from silica gel by cumene, ethyl ether, pyridine and dimethyl sulfoxide and subsequent estimation of their amounts by gas chromatography or colorimetry is reported. This method was useful for the personal air sampler in the workshop using thinner. Ethyl cellosolve acetate, and N,N-dimethyl formamide being cooled by dry ice and mixture of dimethyl sulfoxide and N,N-dimethyl formamide being cooled by ice were useful as absorbing agents of organic solvents particularly in the room air sampler.Read before the 46th Annual Meeting of Japan Industrial Health Association, Osaka, April 8, 1973, and 47th Annual Meeting of Japan Industrial Health Association, Nagoya, March 29, 1974.     

Occupational dimethylformamide exposure

A diffusive sampling method with water as absorbent was examined in comparison with 3 conventional methods of diffusive sampling with carbon cloth as absorbent, pumping through National Institute of Occupational Safety and Health (NIOSH) charcoal tubes, and pumping through NIOSH silica gel tubes to measure time-weighted average concentration of dimethylformamide (DMF). DMF vapors of constant concentrations at 3-110 ppm were generated by bubbling air at constant velocities through liquid DMF followed by dilution with fresh air. Both types of diffusive samplers could either absorb or adsorb DMF in proportion to time (0.25-8 h) and concentration (3-58 ppm), except that the DMF adsorbed was below the measurable amount when carbon cloth samplers were exposed at 3 ppm for less than 1 h. When both diffusive samplers were loaded with DMF and kept in fresh air, the DMF in water samplers stayed unchanged for at least for 12 h. The DMF in carbon cloth samplers showed a decay with a half-time of 14.3 h. When the carbon cloth was taken out immediately after termination of DMF exposure, wrapped in aluminum foil, and kept refrigerated, however, there was no measurable decrease in DMF for at least 3 weeks. When the air was drawn at 0.2 l/min, a breakthrough of the silica gel tube took place at about 4,000 ppm.min (as the lower 95% confidence limit), whereas charcoal tubes could tolerate even heavier exposures, suggesting that both tubes are fit to measure the 8-h time-weighted average of DMF at 10 ppm.     

室内空气中甲醛的固相吸附气体采样管研制和性能评价

目的研制一种用于室内空气中甲醛采样测定的固相吸附气体采样管。方法固相吸附气体采样管由两端套有硅橡胶塞的玻璃管和管内带有甲醛吸收液的表面改性的合成纤维丝束组成。建立用该采样管对室内空气中甲醛采样和测定方法,并评价其性能。结果固相吸附气体采样管采样效率、洗脱效率分别为(98.73±0.86)%和(98.60±1.20)%;采样精密度RSD=4.02%(n=10)。该法与国标气泡吸收管法(GBT161291995)的测定结果经t检验,两种方法无显著性差异。结论研制的固相吸附气体采样管可用于室内空气中甲醛的采样测定。     

Chemical cartridge respirator performance: 1,3-butadiene

The chemical 1,3-Butadiene recently has been classified as a potential occupational carcinogen; subsequently, a reduction in the 8 hr TWA from 1000 ppm to 10 ppm has been proposed. Substantial quantities of 1,3-Butadiene are produced annually for use in the manufacture of a variety of rubber compounds, foams, resins and chemicals. Existing process environments may present a potential health hazard under the proposed standards, and the need for proper respiratory protection is evident. As a result, the performance of Scott organic vapor (642-OV), organic vapor/acid gas (642-OA) and acid gas (642-AG) twin cartridges has been determined for 1,3 butadiene. A cartridge test system was developed to generate challenge concentrations of 100 ppm and 1000 ppm; an infrared analyzer was used to measure breakthrough at 10 ppm. The residence time modeling concept developed previously was used to produce the performance characteristics for three types of activated carbon for residence times of 0.1 less than or equal to tau less than or equal to 1.0 sec. Kinetic adsorption capacities and adsorption rate constants were computed from this data, and cartridge performance also was predicted. The twin cartridges tested demonstrated reasonable adsorption capacity for 1,3 butadiene. Cartridge service life was found to be inversely proportional to airflow rate; it was reduced at elevated temperature and humidity conditions. Breakthrough times were approximately three times longer at 100 ppm than at 1000 ppm. When clean air was drawn through cartridges saturated with 1000 ppm 1,3 butadiene, desorption occurred readily. The rate of desorption and the peak concentration were found to be dependent upon the temperature, humidity and degree of saturation.     

工作场所空气中氨国家标准检验方法研究

目的 按照职业卫生标准制定指南建立合适的工作场所中氨的采样方法,并探讨采样和分析方法能很好对接的工作场所空气中氨的测定方法。方法 选用不同的采样介质,考察其采样效率,解吸效率、分析溶液对后续测定的影响;并考察建立的方法、技术指标与标准要求的符合性。结果 通过筛选发现,用酸性硅胶管、甲烷磺酸吸收液的短时间采样和长时间采样效率均大于95%,用甲烷磺酸解吸液解吸,平均解吸效率为91.1%;解吸液/吸收液采用分光光度法和离子色谱法分析的RSD均<4%。硅胶管采集的样品可以保存14天,采样后的吸收液可以保存7天。用2种方法对标样的测定结果都在给定的不确定度范围内,采用分光光度法和离子色谱测定,两种方法的测定结果经统计学检验,差异无统计学意义(P>0.05)。结论 采用装有5mL甲烷磺酸吸收液的大型多孔玻板吸收管和酸性硅胶管都可以采集工作场所空气中氨,纳氏试剂分光光度法和离子色谱法都可以用来对溶液中的氨进行定量。但考虑到对仪器的保护,采用离子色谱法检测时宜采用吸收液采样,而分光光度法检测时则两种采样方法均可使用。关键词 氨;工作场所;空气;离子色谱法;分光光度法     

工作场所空气中乙醛测定方法的规范化研究

目的建立一种实用的工作场所空气中乙醛的采样及测定方法。方法用浸渍2,4-二硝基苯肼（DNPH）的硅胶管采集空气样品,用乙腈在超声中洗脱,高效液相色谱分离,二极管阵列检测器检测。结果方法简便、准确、灵敏度高。标准曲线的相关系数为0．9995,加标回收率为97．16％～104．63％,相对标准偏差为0．08％～0．29％,平均采样效率为99．84％。结论本方法各项指标均达到《工作场所空气中毒物检测方法的研制规范》的要求,能准确地测定空气中乙醛含量。     

室内空气中氨的固相吸附气体采样管研制和性能评价

目的研制一种用于室内空气中氨采样测定的固相吸附气体采样管。方法固相吸附气体采样管是两端套有硅橡胶塞的玻璃管,管内填充带有氨吸收液的合成纤维丝束。建立用该管对室内空气中氨进行采样,采用靛酚蓝比色法测定,并评价其性能。结果固相吸附气体采样管的采样效率、洗脱效率分别为(97.96±0.49)%和(97.91±0.49)%,采样精密度RSD=3.72%(n=10),加标回收率为95.84%~103.28%。该方法与国标气泡吸收法的测定结果经t检验,两种方法差异无显著性。结论研制的固相吸附气体采样管可用于室内空气中氨的采样测定。     

Residential formaldehyde sampling--current and recommended practices

The usefulness of test results in assessing the health hazard potential of residential formaldehyde exposures depends in great measure on the accuracy and reliability of sampling/analysis methods employed, the protocol used in collecting samples, sampling objectives, and an understanding of residential formaldehyde dynamics and their relationship to environmental variables. Active sampling and analysis methods including detector tubes, the impinger/chromotropic acid method, the impinger/pararosaniline method, and the CEA continuous monitor are reviewed as to advantages and limitations for residential sampling. Passive dosimeter methods including the Dupont Pro-Tec Badge, 3M Monitor, Air Quality Research, Inc. Passive Formaldehyde Kit, and Envirotech, Inc. Dosimeter are also reviewed. Sampling considerations for one-time formaldehyde sampling using the impinger/chromotropic acid method are discussed in detail, including pre-sampling closure of residences, maintenance of a standard indoor temperature both before and during sampling, the undesirability of sampling during cold, dry winter weather, sample number, sampling location, height and duration, environmental measurements during sampling, source identification and sample storage. A model formaldehyde sampling protocol based on the impinger/chromotropic acid method is described.     

工作场所空气中二甲胺的溶剂解吸气相色谱测定法研究

[目的]建立工作场所空气中二甲胺的溶剂解吸气相色谱测定方法。[方法]采用硅胶管吸附空气中二甲胺,用酸性醇溶液解吸,再用碱性溶液中和后,进样气相色谱,使用高液担比的碱性色谱柱分离,FID检测器测定。[结果]该方法在测定范围79.7～478.2μg/mL时,线性方程为=1040.2x-25148（r=0.9999）。最低检出限为5μg/mL;最低检出浓度为1.3mg/m（3采样体积7.5L）;解吸效率86%～91%;穿透容量〉7.75mg（200mg硅胶）;样品于4℃冰箱内可保存7d。[结论]本研究建立的方法适合于工作场所空气中二甲胺浓度的监测。