Microchimica Acta

Non-metallic inclusions in steel are formed due to interactions between liquid steel and its environment in the melting shop (refractories and slags). Particles not trapped in the slag remain in the cast steel, impairing steel properties in service. Inclusion composition varies and certified standards covering the whole compositional range are unavailable. The present study describes the preparation of a set of homogeneous, glassy and crystalline standards with a wide compositional range for use in analysing non-metallic steel inclusions. For this, materials were designed based on knowledge of the compositional range of interest in the Al2O3–SiO2–CaO–MgO–CaF2 system, which is the matrix of the most frequent steel inclusions. The composition and microstructural homogeneity of the reference materials was verified.

A method for the microdetermination of fluorine in organic compounds containing phosphorus is described. After combustion in a Vycor flask, the species containing phosphorus are oxidized to orthophosphate with alkaline hypobromite. Phosphate is adsorbed on zinc oxide which need not be removed prior to titration of the fluoride. Fluoride is titrated potentiometrically with 0.02M lanthanum(III) in 50% ethanol solution at pH 5–7. A fluoride ion-specific indicator electrode and a calomel reference electrode are used in conjunction with an expanded-scale pH meter to monitor the emf. This method can also be used for the determination of total fluorine in inorganic hexafluorophosphates. For the more stable compounds such as potassium hexafluorophosphate, a combustion aid (paraffin) must be added to promote combustion.

Das Nachweisvermögen des Heißextraktionsverfahrens wird durch adsorbierte und chemisorbierte Gase an der Probenoberfläche prinzipiell begrenzt. Um ihren Beitrag am ermittelten Gesamtgas auf ein Minimum zu senken, muß die Entfernung der Oberflächengase innerhalb der Analysenapparatur und unmittelbar vor der Analyse erfolgen. Zu diesem Zweck wurde eine im Hochvakuum arbeitende Ionenätzvorrichtung entwickelt und mit der in Teil I der Arbeit beschriebenen Vakuumheißextraktionsanlage gekoppelt. Das so erreichte Nachweisvermögen für Volumensauerstoff liegt bei 0,1 ppm.

Dimenhydrinate exhibits a single adsorptive stripping peak at a hanging mercury drop electrode after accumulation at 0.0V vs Ag/AgCl electrode at pH 3.8 (acetate buffer). The addition of trace amounts of copper ions enhanced the dimenhydrinate peak and its height depends on the concentration of each dimenhydrinate and Cu2+. The adsorptive stripping response was evaluated with respect to accumulation time and potential, concentration dependence, electrolyte, the presence of other purines, surfactants and other metal ions, and some variables. The calibration graph for dimenhydrinate determination is linear over the range 2.0×10−8−2.0×10−7 M (pre-concentration for 60s). The correlation factor is found to be 0.985 and RSD is 3.2% at 1.0×10−7 M. Detection limit is 1.0×10−8 M after 5 min accumulation. The determination of dimenhydrinate in pharmaceutical formulations by the proposed method is also reported.

The authors report that a glassy carbon electrode modified with the [Ni(phen)2]2+ complex and single-walled carbon nanotubes represents a useful sensor for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The material was characterized by scanning electron microscopy, and the electrode by cyclic voltammetry and electrochemical impedance spectroscopy. The experiments showed that this electrode responds to AA, DA and UA, best at working potentials of 0.130 V, 0.334 V, 0.486 V (vs. SCE), over the wide linear ranges from 30 to 1546 μM (for AA), 1 to 780 μM (for DA), and 1 to 1407 μM (for UA). The respective detection limits are 12 μM, 1 μM and 0.76 μM at an S/N ratio of 3. The modified electrode was successfully applied to the determination of AA, DA and UA in real samples.

Fe3O4@nitrogen-doped carbon core-double shell nanotubes (Fe3O4@N-C C-DSNTs) were successfully synthesized and applied as a novel nanosorbent in ultrasonic assisted dispersive magnetic solid phase extraction (UA-DMSPE) of tribenuron-methyl, fenpyroximate, and iprodione. Subsequently, corona discharge ion mobility spectrometry (CD-IMS) was employed for the detection of the extracted analytes. Effective parameters on the extraction recovery percentage (ER%) were systematically investigated and optimized. Under optimal conditions, UA-DMSPE-CD-IMS demonstrated remarkable linearity in different ranges within 1.0 – 700 ng mL−1 with correlation coefficients exceeding 0.993, repeatability values below 6.9%, limits of detection ranging from 0.30 to 0.90 ng mL−1, high preconcentration factors (418 - 435), and ER% values (83 – 87%). The potential of the proposed method was further demonstrated by effectively determining the targeted pesticides in various environmental soil and water samples, exhibiting relative recoveries in the range 92.1 – 102%.