The application of butanol as dilution agent for the inductively coupled plasma-atomic emission spectrometric determination of boron and phosphorus in lubricating oils

An evaluation of butanol-1 as dilution solvent for the determination of boron (B) and phosphorus (P) in lubricating oils by inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been performed. Standard solutions of boric acid and tri-n-butyl phosphate (TBP) in butanol were employed as calibrants for B and P, respectively. Solutions of phosphoric acid and tris(2-ethylhexyl)phosphate (TEHP) in butanol were also tested as possible P standards. Increased concentrations of oil in the sample in the range of 0 to 20% showed no significant effects on B and P emission intensities indicating that matrix matching is not required for lubricating oils of about 2–15 cPoise. Detection limits in absence of spectral interferences were 0.06 μg B/g oil and 2 μg P/g oil. Overall estimated precision was 2.5% for B concentrations above 4 μg/g oil, and 6.5% for P concentrations above 20 μg/g oil. We evaluated the performance of a high resolution scanning spectrometer for mitigating the effects of overlapping spectral interferences from iron (Fe) and copper (Cu) on B and P emission lines. An interference from Fe 249.782 nm on the primary B line at 249.773 nm is observed for Fe concentrations higher than 100 μg/g oil, but a secondary B line at 249.678 nm is completely resolved from Fe 249.653 nm. In the case of P 213.618 nm, a contribution of the right wing of a Cu line at 213.598 nm generates a signal equivalent to P 18 μg/g oil for Cu 1000 μg/g oil. Received: 25 June 1997 / Revised: 16 September 1997 / Accepted: 7 October 1997     

Multielement analysis of gypsiferous soils using a sequential inductively coupled plasma-atomic emission spectrometric method

The amount of major, minor, and trace elements (Ca, Mg, Fe, Na, Sr, Mn, Cu, Cr, V, Mo, B, Ni, Li, and Ba) in gypsiferous soils formed by evaporitic processes was determined. A sequential analysis method by atomic emission spectroscopy with an inductively coupled plasma was used, working with partial matrix matching between the reference standards and the real samples. Furthermore, a simplified method, based on two calibration graphs (Fe and Li), was developed for calibrating the analysis procedure.     

Erbium determination in preforms of optical fibres by inductively coupled plasma-atomic emission spectrometry

Erbium which is used in the composition of heavy metal fluoride optical fibres was determined in preforms of these materials by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The new analytical procedure developed comprises: solid sample dissolution, via an alkaline fusion with sodium carbonate, and acid leaching with dilute hydrochloric acid, and measurements of emission intensities of 337.276 nm. This method has a detection limit of 31 ng/ml and a reproducibility of 0.90% r.s.d.     

Evaluation of vapor generation for the determination of nickel by inductively coupled plasma-atomic emission spectrometry

Volatile species of Ni were generated by merging acidified aqueous samples and sodium tetrahydroborate(III) in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the inlet tube of the plasma torch. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for detection. The operating conditions (chemical and physical parameters) and the concentrations of different acids were evaluated for the efficient generation of Ni vapor. The detection limit (3 sigma(blank)) was 1.8 ng mL(-1). The precision (RSD) of the determination was 4.2% at a level of 500 ng mL(-1) and 7.3% for 20 ng mL(-1) (n=10). The efficiency of the generation process was estimated to be 51%. The possible interfering effect of transition metals (Cd, Co, Cu, Cr, Fe, Mn, Zn), hydride forming elements (As, Ge, Pb, Sb, Se, Sn, Te), and Hg on Ni signal was examined. This study has demonstrated that Ni vapor generation is markedly free of interferences.     

Inductively coupled plasma-atomic emission spectrometric determination of rare earth elements in geological materials

Inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been applied to the determination of the rare earth elements (REE) lanthanum to lutetium (except terbium) in a range of geological materials. Group separation of the REE is carried out by sintering the sample with sodium peroxide to remove the bulk of the matrix, followed by fluoride precipitation with an yttrium carrier. This minimizes spectral interferences and provides sensitivities that are adequate for concentration levels around crustal abundances. The precision (2σ) is 3–5% for most of the elements and about 10% for some of the less abundant elements with concentrations that approach the limit of determination. Comparison of results obtained on a range of reference samples with literature values demonstrates the suitability of the procedures to provide rare earth abundance data for geochemical investigations.     

Observations on the determination of oxygen in silver halides using inductively coupled plasma-atomic emission spectrometry

This paper reports on a novel method for the determination of oxygen in silver halides using inductively coupled plasma-atomic emission spectrometry (ICP-AES). A heating system was designed and set up to heat the sample and to release oxygen which was then sent into the plasma by the argon carrier gas. A demountable extended ICP torch was assembled to prevent air from entering the analytical region of the ICP. The nonresonance near infrared atomic oxygen line, O(I) 777.19 nm, was used for the determination of oxygen. The detection limit of the method was 1.6 μg of oxygen. Pure oxygen was used for calibration. The method had a precision of 4.74% RSD for about 15 μg of oxygen in samples.     

Development and characterization of bottom-viewed inductively coupled plasma-atomic emission spectrometry

In bottom-viewed inductively coupled plasma-atomic emission spectrometry (BV-ICP-AES), emission from the central channel of the plasma is measured axially from the bottom of the plasma. A straight quartz tube was used as a hollow light pipe (HLP) to collect plasma emission in this study. The HLP also serves as an injector for aerosols transport and injection into the ICP. The optical characteristics of HLPs with the original reflective surface and roughened outer surface are reported. The roughened HLP is effective in rejecting light beams that are not in line with the HLP. The transmission efficiency of the HLP, however, is high (> 70%) for light beams from a source that has the same dimension as the entrance of the HLP and is flush with the HLP. The HLP is effective in rejecting background emission from the core of the plasma that encircles the plasma central channel and yet efficient in light collection from the central channel of the plasma.     

Evaluation of spray chambers for use in inductively coupled plasma-atomic emission spectrometry

A laboratory-built spray chamber featuring aerosol collection at the centre of the chamber by means of a funnel is described and compared with a commercially available, dual tube chamber. The influence of some chamber design parameters on the emission signal intensity and stability, the nebulizer efficiency and chamber clean-out time is studied.     

On-line preconcentration and simultaneous determination of heavy metal ions by inductively coupled plasma-atomic emission spectrometry

A flow injection analysis system for on-line preconcentration and simultaneous determination of Bi³⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe³⁺, Ni²⁺, Pb²⁺ and Zn²⁺ in aqueous samples by inductively coupled plasma (ICP)-atomic emission spectrometry with a charge coupled detector is described. The preconcentration of analytes is accomplished by retention of their chelates with sodium diethyldithiocarbamate in aqueous solution on a solid phase containing octadecyl silica in a minicolumn. Methanol, as eluent, is introduced into the conventional nebulizer of the ICP instrument. The effects of different parameters, including preconcentration flow rate (equal to sample flow rate (SR)), eluent flow rate (ER), weight of solid phase (W) and eluent loop volume (EV), were optimized by the super-modified simplex method. The optimum conditions were evaluated to be SR 7.2 ml min⁻¹, ER 3.5 ml min⁻¹, W of 100 mg and EV of 0.8 ml. An enrichment factor of 312.5 for each analyte was obtained. The detection limits of the proposed method for Bi³⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe³⁺, Ni²⁺, Pb²⁺ and Zn²⁺ were evaluated as 1.3, 1.0, 0.8, 0.3, 14.7, 0.5, 5.5 and 0.1 ng l⁻¹, respectively. The effect of several metal ions on percent recovery was also studied. The method was applied to the recovery of these heavy metals from real matrices and to the simultaneous determination of these cations in different water samples.     

Use of enzymatic hydrolysis for the multi-element determination in mussel soft tissue by inductively coupled plasma-atomic emission spectrometry

A systematic evaluation of different variables affecting the enzymatic hydrolysis of mussel soft tissue by five enzymes, three proteases (pepsin, pancreatin and trypsin), lipase and amylase, has been carried out for the determination of trace elements (As, Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Enzymatic hydrolysis methods offers advantages such as a less species alteration, safer laboratory conditions and a less contaminant wastes. The enzymatic hydrolysis was performed in an incubation camera Boxcult with orbital and horizontal shaker. Variables affecting the enzymatic hydrolysis process were simultaneously studied by applying a Plackett-Burman design (PBD). For a confidence interval of 95%, the significant factors for all enzymes and for most of the elements were the pH, the incubation temperature and the ionic strength. These significant factors were optimized later by using a central composite design (CCD), which gave optimum conditions at pH of 1, incubation temperature of 37 °C and ionic strength fixed by sodium chloride at 0.2 M when using pepsin. For pancreatin, trypsin, lipase and amylase there were found two different optimum condition sets. The first one involves the use of a 0.5 M phosphate buffer (ionic strength), at a pH of 6 and at an incubation temperature of 37 °C, which allows the quantitative extraction of Al, Cr, Mn, Pb and Zn. The second conditions set employees a 0.1 M phosphate buffer (ionic strength), a pH of 9 and an incubation temperature at 37 °C, and it results adequate to extract As, Cd, Cu, Fe and Ni. Analytical performances, repeatability of the over-all procedure and accuracy, by analyzing DORM-1, DORM-2 and TORT-1 certified reference materials, were finally assessed for each enzyme. Good agreement with certified values has been assessed for most of the elements (As, Cd, Cr, Cu, Mn, Ni, Pb and Zn) when using trypsin, pepsin and/or pancreatin, except for Cd and Pb in DORM-1 and DORM-2 because of the certified contents in such certified reference materials are lower than the limit of detection (0.10 and 0.16 μg g⁻¹ for Cd and Pb, respectively, for the use of trypsin).     

An indirect method for the determination of chromium species in water samples by sequential inductively coupled plasma-atomic emission spectrometry

Determination of Cr(VI) and Cr(III) in water samples by inductively coupled argon plasma-atomic emission spectrometry (ICP-AES) was performed indirectly employing an on-line system. For this purpose a column with copper shavings was used to reduce Cr(VI) to Cr(III) in acidic media, generating Cu(II) ions in the flow path. This process permitted the evaluation of concentrations in the range of 1–50 mg/l. The protocol allowed a throughput of 100 samples per hour with 10% precision in the concentration     

In-situ determination of cross-over point for overcoming plasma-related matrix effects in inductively coupled plasma-atomic emission spectrometry

A novel method is described for overcoming plasma-related matrix effects in inductively coupled plasma-atomic emission spectrometry (ICP-AES). The method is based on measurement of the vertically resolved atomic emission of analyte within the plasma and therefore requires the addition of no reagents to the sample solution or to the plasma. Plasma-related matrix effects enhance analyte emission intensity low in the plasma but depress the same emission signal at higher positions. Such bipolar behavior is true for all emission lines and matrices that induce plasma-related interferences. The transition where the enhancement is balanced by the depression (the so-called cross-over point) results in a spatial region with no apparent matrix effects. Although it would be desirable always to perform determinations at this cross-over point, its location varies between analytes and from matrix to matrix, so it would have to be found separately for every analyte and for every sample. Here, a novel approach is developed for the in-situ determination of the location of this cross-over point. It was found that the location of the cross-over point is practically invariant for a particular analyte emission line when the concentration of the matrix was varied. As a result, it is possible to determine in-situ the location of the cross-over point for all analyte emission lines in a sample by means of a simple one-step sample dilution. When the original sample is diluted by a factor of 2 and the diluted sample is analyzed again, the extent of the matrix effect is identical (zero) between the original sample and the diluted sample at one and only one location — the cross-over point. This novel method was verified with several single-element matrices (0.05 M Na, Ca, Ba and La) and some mixed-element matrices (mixtures of Na–Ca, Ca–Ba, and a plant-sample digest). The inaccuracy in emission intensity due to the matrix effect could be as large as − 30% for conventional measurements in the normal analytical zone, but is reduced to within 5% with this new method. The major currently known limitation is that the accuracy of the method is highly sensitive to fluctuations and noise in the vertical emission-intensity profile, so the stability of the ICP system must be controlled to preferably within 1%.     

Determination of phosphorus in lubricating oils by cool-flame emission spectroscopy

The phosphorus content of lubricating oils is determined by measurement of the emission from the HPO molecular species at 528 nm in a cool hydrogen-nitrogen diffusion flame. The oil is ashed in the presence of potassium hydroxide and an aqueous extract of the melt is treated with ion-exchange resin to remove interferents, before aspiration into the flame. Analytical results are presented on samples containing phosphorus in the range 0.009-0.2%. The precision of the method is +/- 5% at the 0.04% phosphorus level.     

Simultaneous determination of metallic elements in precipitates and inclusions extracted from steel by inductively coupled plasma-atomic emission spectrometry

A study was made about the possibility of extracting complex precipitates, containing carbides, nitrides, intermetallic compounds, from low-alloy steels, high-alloy steels and heat-resistant super alloys by single electrolysis operation, followed by the simultaneous determination of all metallic elements in the precipitates by inductively coupled plasma-atomic emission spectrometry (ICP-AES). As a result, it was found that 4–5 metallic elements, such as Nb, Mo and Cr, whose determination had been considered difficult even by wet chemical analysis, can be simultaneously determined in the dissolved state in which Na₂S₂O₇ and tartaric acid (20%) added for the treatment of precipitates are concomitants.ICP-AES simplifies the analytical operation considerably and shortens the analytical time from about 18 h by conventional methods to about 1 h.     

Simultaneous determination of major, minor and trace elements in airborne particulates by inductively coupled plasma-atomic emission spectroscopy

Summary A method for the simultaneous multi-element determination of major, minor and trace elements in airborne particulates by ICP-AES was proposed based on multi-acid digestion. The methods for sample decomposition under high and ambient pressure were compared using a mixture of nitric, perchloric and hydrofluoric acids. The ambient pressure technique was finally adopted. Spectral interferences were taken into account and corrected. A recovery study was conducted for most of the elements, and a good agreement was obtained with the certified values of NBS SRM 1648 urban particulate materials using the recommended method.

---

Simultanbestimmung von Haupt-, Neben- und Spurenbestandteilen in atmosphärischen Teilchen durch ICP-AES

Zusammenfassung Das Verfahren beruht auf dem Aufschluß mit einem Säuregemisch (Salpeter-, Perchlor-, Flußsäure) bei normalem Druck. Ein Druckaufschluß wurde ebenfalls geprüft, war jedoch weniger geeignet. Störungen wurden durch Korrekturen berücksichtigt. Im Vergleich mit einem Standard-Referenzmaterial wurde befriedigende Übereinstimmung erzielt.

     

Effect of HF addition on the microwave-assisted acid-digestion for the determination of metals in coal by inductively coupled plasma-atomic emission spectrometry

The microwave-assisted acid-digestion for the determination of metals in coal by ICP-AES was investigated, especially focusing on the necessity of adding HF. By testing five certified reference materials, BCR-180, BCR-040, NIST-1632b, NIST-1632c, and SARM-20, it was found that the two-stage digestion without HF (HNO₃ + H₂O₂ was used) was very effective for the pretreatment of ICP-AES measurement. Both major metals (Al, Ca, Fe, and Mg) and minor or trace metals (Co, Cr, Cu, Mn, Ni, Pb, and Zn) in coal gave good recoveries for their certified or reference values. The possibility of ‘HF-memory effect’ was cancelled by the use of a set of vessels which had been never contacted with HF. Twenty-four Japanese standard coals (SS coals) were analyzed by the present method, and the concentrations of major metals measured by the present method provided very high accordance with those from the authentic JIS (Japanese Industrial Standard) method.     

Determination of impurities in highly pure platinum by inductively coupled plasma-atomic emission spectrometry

In this work, a cyclone spray chamber system is used in conjunction with an inductively coupled plasma-atomic emission spectrometer instead of the conventional Scott-type chamber system to reduce the lower limit of detection achieved by the instrument, and an internal standard element (Y) is introduced to eliminate the effects caused by the drift in the plasma background level. An ICP-AES method for the determination of 13 impurity elements in a highly pure platinum sample has been developed. In this method, it is not necessary either to add a platinum matrix to the calibration standard or to separate and concentrate the elements to be determined in the samples. The effect of the platinum matrix on the elements to be analyzed is corrected for by a background equivalent concentration subtraction method. The determination ranges of the method are as follows: 0.00010-0.0050% for Mg, Mn, Cu, Ag, Fe and Zn; 0.00030-0.015% for Au, Ir, Ni and Pb; 0.00050-0.025% for Rh and Al; and 0.00080-0.040% for Pd. The method is simple, rapid and accurate, and can be applied to the analysis of 99.9–99.995% pure platinum.     

电感耦合等离子体原子发射光谱法测定自来水中的8种元素

采用电感耦合等离子体原子发射光谱法(ICP-AES)测定了化学实验室自来水中铝、钾、锶、钡、锰、钴、钼、硒8种元素的含量;对仪器的工作条件进行了优化,确定了各元素的分析波长和检出限.结果表明,所述方法可以方便地用于测定化学实验室自来水样品中的8种元素,相对标准偏差为0.08%～6.90%.     

On-line complexation/preconcentration system for the determination of lead in wine by inductively coupled plasma-atomic emission spectrometry with ultrasonic nebulization

An on-line lead preconcentration and determination system implemented with inductively coupled plasma-atomic emission spectrometry (ICP-AES) with ultrasonic nebulization (USN) in association with flow injection was studied. For the preconcentration of lead, a Pb-quinolin-8-ol complex was formed on-line at pH 6.8 and retained on Amberlite XAD-16 resin. The lead was removed from the microcolumn by countercurrent elution with nitric acid. A total enhancement factor of 225 was obtained with respect to ICP-AES with pneumatic nebulization (15.0 for USN and 15.0 for the column). The detection limit for Pb for the preconcentration of a 10 mL wine sample was 0.15 microg/L. The precision for 10 replicate determinations at a Pb level of 25 microg/L was a relative standard deviation of 2.5%, calculated from the peak heights obtained. The calibration graph obtained by using the preconcentration system for lead was linear with a correlation coefficient of 0.9995 for levels near the detection limit up to > or = 1000 microg/L. The method was successfully applied to the determination of lead in wine samples.     

Neptunium estimation in the spent fuel dissolver solution by inductively coupled plasma-atomic emission spectroscopy

This paper deals with the optimization of experimental conditions for the estimation of Np in spent fuel dissolver solution using 2-thenoyltrifluoroacetone (HTTA) as extractant. The quantitative extraction of Np from the dissolver solution employing 0.5 M HTTA/xylene was followed by its estimation by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) after stripping it from the organic phase with 8 M HNO₃. The reliability of the method was checked by standard addition technique. The method is precise and accurate yielding Np analytical recovery of 99 ± 1%.