Sequential determination and chemical speciation analysis of inorganic As and Sb in airborne particulate matter collected in outdoor and indoor environments using slurry sampling and detection by HG AAS.

In this work, fast sequential determination and chemical speciation analysis of inorganic arsenic and antimony in airborne particulate matter collected in outdoor and indoor environments using slurry sampling and detection by hydride generation atomic absorption spectrometry (HG-AAS) is proposed. A Doehlert design was applied to optimise the hydride generation conditions of As and Sb for fast sequential determination in the same aliquot of particulate matter samples after preparation of the slurry. The limits of quantification (LoQ) obtained for As and Sb were 0.3 and 0.9 ng m-3, respectively. The accuracy of the analytical method was confirmed by analysis of the certified reference material of urban particulate matter (SRM NIST 1648a), presenting concordance with certified values of 92.7±7.7% for As and 91.2±9.5% for Sb. Precision was expressed as relative standard deviation (% RSD, n=3), with our results presenting values better than 3.4% and 4.2% for total inorganic As and Sb, respectively. For all analysed samples, total As concentrations and its inorganic species were below the LoQ of the analytical method (<0.3 ng m-3). However, the averages of total inorganic Sb concentrations in airborne particulate matter, collected as total suspended outdoor particles (TSPoutdoor), inhalable particulate matter (PM10), and total suspended indoor particles (TSPindoor), were 3.1±0.5, 2.4±0.6, and 2.6±0.4 ng m-3, respectively. Trivalent Sb (Sb3+) was the predominant inorganic species in all samples investigated, with mean percentages of 76%, 72%, and 73% in TSPoutdoor, PM10, and TSPindoor, respectively. The presence of Sb and its predominant inorganic form (Sb3+) can be attributed to vehicular traffic close to the sampled urban areas. Therefore, fast sequential determination of As and Sb and their inorganic species in particulate matter samples prepared as slurry by FS-HG-AAS is an efficient, accurate, and precise method and can be successfully applied to routine analysis.

Dual-opposite end multiple injection method applied to sequential determination of Na+, K+, Ca+2, Mg+2 ions and free and total glycerol in biodiesel by capillary zone electrophoresis.

A novel method for the sequential determination of sodium, potassium, calcium, and magnesium and free and total glycerol in biodiesel by capillary zone electrophoresis is proposed herein. The inorganic cations were separated along an effective length of 43.5 cm. The samples to quantify the free and total glycerol were injected into the opposite capillary end, close to the detection window, with an effective length of 8.5 cm. It was possible to achieve the separation of six analytes within 3 min. The quantification limits for the cations and glycerol ranged from 0.071 to 0.5 mg kg-1 to and 0.0017% to 0.017% w/w, respectively. Despite the complexity of the injection steps, the values for the instrumental, intraday and interday precision were better than 2.13, 4.49 and 5.68% (RSD), respectively, for the cations and the free and total glycerol. The method has good accuracy and specificity, which was statistically confirmed through an interlaboratory assay, where the method was compared with official methods.

A sequential determination of 90Sr and 210Po in food samples.

The latest EU Council Regulation 2016/52/Euratom updates the emergency limits on radionuclides in foods including 210Po and 90Sr, two of the most important radionuclides for radiological dose from the ingestion pathway. A novel and straightforward method has been developed for sequential determination of 90Sr and 210Po in food samples using ultra low-level liquid scintillation counting and alpha-particle spectrometry. For 90Sr analysis, the method makes use of stable strontium as yield tracer, and 210Po is determined through self-deposition using 209Po as a yield tracer. The quantification limit for this method is 25.0 and 2.0Bqkg-1 for 90Sr and 210Po, respectively. The proposed radiochemical separation can be completed within 2days for a batch of 12 samples. The radiochemical procedure was validated by its application for the measurement of IAEA certified reference materials, and through participation in a national intercomparison exercise. Results are also presented in seafood from the Mediterranean coast.

Sequential determination of multi-nutrient elements in natural water samples with a reverse flow injection system.

An integrated system was developed for automatic and sequential determination of NO2-, NO3-, PO43-, Fe2+, Fe3+ and Mn2+ in natural waters based on reverse flow injection analysis combined with spectrophotometric detection. The system operation was controlled by a single chip microcomputer and laboratory-programmed software written in LabVIEW. The experimental parameters for each nutrient element analysis were optimized based on a univariate experimental design, and interferences from common ions were evaluated. The upper limits of the linear range (along with detection limit, µmolL-1) of the proposed method was 20 (0.03), 200 (0.7), 12 (0.3), 5 (0.03), 5 (0.03), 9 (0.2) µmolL-1, for NO2-, NO3-, PO43-, Fe2+, Fe3+ and Mn2+, respectively. The relative standard deviations were below 5% (n=9-13) and the recoveries varied from 88.0±1.0% to 104.5±1.0% for spiked water samples. The sample throughput was about 20h-1. This system has been successfully applied for the determination of multi-nutrient elements in different kinds of water samples and showed good agreement with reference methods (slope 1.0260±0.0043, R2=0.9991, n=50).

Sequential determination of trace 4-aminoazobenzene in multiple textiles based on nanoarrayed functionalized polystyrene substrate by surface enhanced Raman spectroscopy.

Achieving reproducible signals is a key point to improve the analytical precision and accuracy of surface enhanced Raman scattering (SERS) technique and further expand the application scope of SERS for on-site and rapid analysis of real sample with complex matrice. In this work, a novel Au@hydroxyl-functionalized polystyrene (Au@PS-OH) substrate was prepared by atom transfer radical polymerization and chemical assembly method, which possessed promised potential for the rapid and sequential analysis of multisamples coupling with SERS technique. Au@PS-OH substrate with regular nanoarrayed morphology possessed excellent anti-agglomeration capability even for testing solutions with strong basicity or acidity, mechanic and chemical stability due to the large amount of Au nanoparticles homogeneously and stably fixed on substrate surface. Moreover, excellent hydrophobicity of Au@PS-OH substrate could keep testing droplets of multiple samples stable and uniform spherical shape with similar contact angles to substrate, which guaranteed the reproducible SERS light paths and SERS signals during real sequential analysis. Then, an Au@PS-OH based SERS analytical method was developed and practically applied for the sequential determination of trace 4-aminoazobenzene in various textiles. It was satisfactory that the contents of trace 4-aminoazobenzene in black woolen, green woolen and yellow fiber cloth could be actually found and calculated to be 106.4, 120.9 and 140.8mg/kg with good recoveries of 76.0-118.9% and relative standard deviations of 1.6-5.1%. It is expected that this SERS method is suitable for on-site and rapid analysis of multiple samples in a short period.

Sequential determination of Cd and Cr in biomass samples and their ashes using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis.

High-resolution continuum source graphite furnace atomic absorption spectrometry, because of the use of only one radiation source for all elements, offers the possibility of sequential determination of two or more elements from the same sample aliquot if their volatilities are significantly different. Cd and Cr were determined sequentially in samples of biomass and biomass ashes employing direct solid sample analysis. The use of a chemical modifier was found to be not necessary, and calibration could be carried out using aqueous standard solutions. A pyrolysis temperature of 400°C and an atomization temperature of 1500°C were used for the determination of Cd; no losses of Cr were observed at this temperature. After the atomization of Cd the wavelength was changed and Cr atomized at 2600°C. The limits of detection (LOD) and quantification (LOQ) were 1.1 µg kg(-1) and 3.7 µg kg(-1), respectively, for Cd and 21 µg kg(-1) and 70 µg kg(-1), respectively, for Cr using the most sensitive line at 357.869 nm, or 90 µg kg(-1) and 300 µg kg(-1), respectively, using the less sensitive line at 428.972 nm. The precision, expressed as relative standard deviation was around 10%, which is typical for direct solid sample analysis. The values found for Cd in biomass samples were between <1.1 µg kg(-1) and 789 µg kg(-1), whereas those for Cr were between 7.9 mg kg(-1) and 89 mg kg(-1); the values found in the ashes were significantly lower for Cd, between <1.1 µg kg(-1) and 6.3 µg kg(-1), whereas the trend was not so clear for Cr, where the values were between 3.4 mg kg(-1) and 28 mg kg(-1).

Sequential determination of new peptaibols asperelines G-Z12 produced by marine-derived fungus Trichoderma asperellum using ultrahigh pressure liquid chromatography combined with electrospray-ionization tandem mass spectrometry.

Thirty-eight short peptaibols in a microheterogeneous mixture derived from the fermentation broth of a marine-derived fungus Trichoderma asperellum were determined using ultrahigh pressure liquid chromatography in combination with electrospray-ionization tandem mass spectrometry (UHPLC-ESIMS/MS) techniques, including thirty-two new peptaibols namely asperelines G-Z13. The C-terminus bonded to proline (aspereline Z9) or hydroxyprolinol (aspereline Z12) is rarely found in nature. So far, it is the largest number of peptaibols to be detected at once on the basis of the selected ion monitoring (SIM) mode coupled to precursor scan techniques.

Sequential determination of fat- and water-soluble vitamins in Rhodiola imbricata root from trans-Himalaya with rapid resolution liquid chromatography/tandem mass spectrometry.

A rapid method was developed to determine both types of vitamins in Rhodiola imbricata root for the accurate quantification of free vitamin forms. Rapid resolution liquid chromatography/tandem mass spectrometry (RRLC-MS/MS) with electrospray ionization (ESI) source operating in multiple reactions monitoring (MRM) mode was optimized for the sequential analysis of nine water-soluble vitamins (B1, B2, two B3 vitamins, B5, B6, B7, B9, and B12) and six fat-soluble vitamins (A, E, D2, D3, K1, and K2). Both types of vitamins were separated by ion-suppression reversed-phase liquid chromatography with gradient elution within 30 min and detected in positive ion mode. Deviations in the intra- and inter-day precision were always below 0.6% and 0.3% for recoveries and retention time. Intra- and inter-day relative standard deviation (RSD) values of retention time for water- and fat-soluble vitamin were ranged between 0.02-0.20% and 0.01-0.15%, respectively. The mean recoveries were ranged between 88.95 and 107.07%. Sensitivity and specificity of this method allowed the limits of detection (LOD) and limits of quantitation (LOQ) of the analytes at ppb levels. The linear range was achieved for fat- and water-soluble vitamins at 100-1000 ppb and 10-100 ppb. Vitamin B-complex and vitamin E were detected as the principle vitamins in the root of this adaptogen which would be of great interest to develop novel foods from the Indian trans-Himalaya.