Coupled Plasma Mass Spectrometric Detection Research Articles

Determination of cisplatin and some possible metabolites by ion-pairing chromatography with inductively coupled plasma mass spectrometric detection

A sensitive method is described for measuring cisplatin and some possible metabolites. The method combines reversed-phase ion-pairing liquid chromatography (LC) with inductively coupled plasma mass spectrometry (ICP-MS) for platinum-specific detection. Separation conditions for cisplatin hydrolysis products and the reaction products of cisplatin with methionine, cysteine, and glutathione have been investigated with sodium dodecylsulfate or heptanesulfonate as the ion-pairing agent. The detection limit for cisplatin was found to be 0.1 ng, corresponding to a concentration detection limit of 1 ng/ml when using an injection volume of 100 μl. This study has demonstrated the usefulness of LC—ICP-MS for cisplatin metabolism studies.

Speciation of iodo amino acids by high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection

High-performance liquid chromatography (HPLC) has been coupled with on-line inductively coupled plasma mass spectrometry (ICP/MS) for the speciation of iodide ion I - and five iodo amino acids (monoiodotyrosine, diiodotyrosine, 3,3',5- and 3,3',5'-triiodothyronine, and thyroxine) commonly found in thyroglobulin. The absolute detection limits were in a range from 35 to 130 pg as iodine: this is roughly 1 order of magnitude lower than those in conventional methods using stable isotope of iodine

Preliminary characterization of inductively coupled plasma mass spectrometry with flow injection into a gaseous (air) carrier

An assessment of some of the advantages and disadvantages of using air rather than water as a carrier in flow injection with inductively coupled plasma mass spectrometric detection was carried out for several analytes (AI, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb and Pb). Although the background increased in many instances, the enhancement in sensitivity was such that the corresponding detection limits were either similar or significantly improved (by a factor of 2–6), the greatest improvement being observed for elements with high ionization potentials. The only exception was nickel, for which a huge increase in background, presumably due to a stronger etching of the nickel sampler and skimmer by the no longer [water-cooled] plasma, led to a drastic degradation of the detection limit (by a factor of 30). For all elements, a significant memory effect was observed, which could only be eliminated by flushing with water between injections. A preliminary evaluation of flow injection into air bubbles was carried out, showing that an enhancement in sensitivity could also be observed, dependent on the size of the injection loop. With too large a loop (e.g., 0.5 ml instead of 0.1 ml), little change occurred.

Speciation of mercury by reversed-phase liquid chromatography with inductively coupled plasma mass spectrometric detection

An inductively coupled plasma mass spectrometer coupled with ultrasonic nebulization was used as a detector for the liquid chromatographic determination of mercury compounds. The detection limits were in the range 70–160 pg of Hg. The method was applied to the determination of methylmercury in a National Research Council of Canada Reference Material DORM-1 Dogfish Muscle, of thimerosal in contact lens solutions and of inorganic mercury in waste water reference solution. Good agreement was observed between the literature or expected values and the experimentally determined values. The precision was better than 8% for all determinations.

Speciation of eight arsenic compounds in human urine by high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection using antimonate for internal chromatographic standardization

Four anionic and four cationic arsenic compounds in urine were separated by anion- and cation-exchange high-performance liquid chromatography and detected by inductively coupled plasma mass spectrometry (ICP-MS) at m/z 75. The species were the anions arsenite, arsenate, monomethylarsonate and dimethylarsinate and the cations arsenobetaine, trimethylarsine oxide, arsenocholine and the tetramethylarsonium ion. Hexahydroxyantimonate(III) was co-chromatographed with the arsenic anions but detected at m/z 121 and used as an internal standard for their qualitative analysis. Arsenite was prone to oxidation to arsenate in urine but was stable after at least 4-fold dilution of the urine with water. Arsenite was unstable in both urine samples and standard mixtures when diluted with the basic (pH 10.3) mobile phase used for anion chromatography. This could not be prevented by adding ascorbic acid as antioxidant. The argon chloride interference at m/z 75 was eliminated by chromatographic separation of the chloride present in the sample from the arsenic analytes. The ClO+ ion detected at m/z 51 and 53 was used to monitor the retention time of chloride in the anion-exchange system. The chloride eluted about 100 s after the last analyte peak and the intensity of ArCl+ was negligible even after injection of a 1% NaCl solution (less than 200 ions s–1). The recovery of all arsenic species in urine was close to 100%. The chromatographic peaks were evaluated by their peak heights and calibration was carried out by the method of standard additions. The calibration graphs were linear for all species (r > 0.999). The limits of detection were 3–6 ng cm–3 for the cations and 7–10 ng cm–3 for the anions in urine.

Determination of rare earth elements by liquid chromatographic separation using inductively coupled plasma mass spectrometric detection

High-performance liquid chromatography (HPLC) is used to separate the rare earth elements (REEs) prior to detection by inductively coupled plasma mass spectrometry (ICP-MS). The use of HPLC–ICP-MS in series combines the separation power and speed of HPLC with the sensitivity, isotopic selectivity and speed of ICP-MS. The detection limits for the REEs are in the sub-ng ml–1 range and the response is linear over four orders of magnitude. A preliminary comparison of isotope dilution and external standard results for the determination of REEs in National Institute of Standards and Technology (NIST) Standard Reference Material (SRM 1633a) Fly Ash is presented.

Lead speciation by gradient high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection

Speciation of inorganic lead (PbII), triethyllead chloride (TEL), triphenyllead chloride (TPhL) and tetraethyllead (TTEL) was investigated using gradient high-performance liquid chromatography (HPLC) with detection by inductively coupled plasma mass spectrometry (ICP-MS). Ion-pair reversed-phase chromatography was used. The detection limits were 0.37, 0.14, 0.17 and 3.9 ng of Pb for PbII, TEL, TPhL and TTEL, respectively. The reproducibility of peak height measurements ranged from 3.1 to 4.2%(relative standard deviation). The method was evaluated by analysing National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 2715 Lead in Reference Fuel for tetraethyllead and a water Quality Control Sample from the Environmental Protection Agency for inorganic lead. Both the direct solution nebulization and HPLC–ICP-MS results compare favourably with reference values. The applicability of the method to other alkyllead compounds is discussed.

Determination of tri- and tetra-organotin compounds by supercritical fluid chromatography with inductively coupled plasma mass spectrometric detection

Supercritical fluid chromatography (SFC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) is used for the separation and detection of tetra- and tri-organotin compound mixtures. The carbon dioxide effluent from the SFC system, using a capillary column (SB-biphenyl-30), does not require a modification in the standard ICP-MS operating conditions. Several parameters such as interface temperature, oven temperature, carbon dioxide pressure programme, mobile phase composition and column length are evaluated in order to optimize the separation conditions of several organotins. Detection limits of 0.26, 0.80, 0.57 and 0.20 pg are found for tetrabutyl tin, tributyltin chloride, triphenyltin chloride and tetraphenyltin, respectively. The relative standard deviation for five 0.05 mm3 injections containing 0.5 ng of Sn ranged from 1.3 to 3.4%.

Arsenic speciation by ion chromatography with inductively coupled plasma mass spectrometric detection.

Four As compounds were successfully separated and detected by single-column ion chromatography with inductively coupled plasma (ICP) mass spectrometric detection. The mass spectral interferent ArCl+ was reduced by chromatographically resolving chloride from the negatively charged arsenic species. Determination of four As species was investigated in urine, club soda and wine. Detection limits of 0.16 ng of As(III), 0.26 ng of As(v), 0.073 ng of dimethylarsinic acid (DMA) and 0.18 ng of methylarsonic acid (MMA) in wine were obtained. Sensitivity was further improved by using an He-Ar mixed gas ICP as the ionization source. However, the intensity of the ArCl+ interference was also increased using this plasma. Detection limits of 0.063 ng of As(III), 0.037 ng of As(v), 0.032 ng of DMA and 0.080 ng of MMA in club soda were achieved using the He-Ar plasma source. Similar limits of detection were found in urine and wine.

High-Performance Liquid Chromatographic Determination of Iron-Containing Proteins with On-Line Inductively Coupled Plasma Mass Spectrometric Detection

An inductively coupled plasma mass spectrometer was employed as an iron detector in gel permeation liquid chromatography to separate ferritin, hemoglobin, myoglobin, and cytochrome-c, by use of potassium hexacyanoferrate(III) as the iron standard. The absolute detection limits for the four proteins were 0.01, 1, 0.7, and 0.4μg, respectively, at 10μl injections. These values were an order-of-magnitude lower than those obtained by using an inductively coupled plasma atomic emission spectrometer as detector. From the peak area in the Fe chromatograms, the number of Fe atoms per molecule was evaluated for myoglobin and cytochrome-c to be 0.97 and 1.0, respectively.

Speciation of arsenic in urine using high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection

High-performance liquid chromatography (HPLC) has been coupled with inductively coupled plasma mass spectrometry (ICP-MS) for the speciation of four arsenic compounds commonly found in urine. Arsenite (As3+), arsenate (As5+), dimethylarsinate (DMA) and monomethylarsonate (MMA) were separated via anion-exchange HPLC and detected on-line using ICP-MS. The absolute detection limits ranged from 20 to 91 pg of arsenic in aqueous media and 36–96 pg in urine. The four species were determined in two freeze-dried urine standards using the method of standard additions. The total of the four species was found to be within 13% of the average reported total arsenic concentration for both freeze-dried urine standards containing elevated levels of As5+. The relative standard deviation of peak-height measurements was less than 10% for each of the four species in urine. The determination of As3+ is complicated by the presence of an interfering peak, which is believed to arise from the co-elution of chlorine-containing species and subsequent formation of 40Ar35CI+ ions (m/z= 75).

Determination of thimerosal in biological products by liquid chromatography with inductively coupled plasma mass spectrometric detection

A liquid chromatography system has been interfaced to an inductively coupled plasma mass spectrometer in order to analyse injectable biological products for thimerosal. Thimerosal is a mercury containing antimicrobial agent used as a preservative in these materials. Sample types analysed ranged from vaccines and toxoids (influenza virus vaccine and tetanus toxoid) to diluents, containing only the preservative in a saline solution. Samples were analysed quantitatively for thimerosal content and qualitatively for the presence of decomposition products detectable by this method, such as methylmercury chloride, dimethylmercury and mercury(II) chloride. Flow injection was used to confirm that all mercury species in the samples were determined by liquid chromatography.

Inductively coupled plasma mass spectrometric detection for phosphorus and sulfur compounds separated by liquid chromatography

Anionic compounds containing phosphorus or sulfur are separated by reversed phase liquid chromatography (LC) with tetraalkylammonium salts as ion pairing reagents. Phosphorus and sulfur in the separated compounds are detected on-line as 31P + or 34S + by inductively coupled plasma-mass spectrometry (ICP-MS). Inorganic phosphates and nucleotides are separated with detection limits of 0.4–4 ng P. These detection limits are superior by several orders of magnitude to those reported for phosphorus detection by atomic emission spectrometry (AES). Sulfur compounds studied include inorganic sulfates and amino acids; detection limits are ~7 ng S and are comparable or superior to previous results for AES detection. In general, the analyte sensitivity decreases as the concentration of organic modifier (methanol or acetonitrile) in the mobile phase increases. Therefore, the Chromatographic conditions are designed to minimize the concentration of organic modifier necessary.

Inductively coupled plasma mass spectrometric detection for multielement flow injection analysis and elemental speciation by reversed-phase liquid chromatography

L'echantillon est introduit par nebulisation ultrasonique. Les limites de detection absolues pour l'analyse d'injection en ecoulement varient de 0,01 a 0,1 ng pour la plupart des elements si l'on utilise des injections de 10 μL