The mechanism of volatile hydride generation (HG) and the formation of analyte atoms in the quartz cell atomizer used in the determination of hydride-forming elements (As, Bi, Ge, Pb, Sb, Sn, Te etc.) by atomic absorption spectrometry (AAS), have been critically reviewed. The nascent hydrogen mechanism failed to explain hydride generation under different experimental conditions when tetrahydrob...

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to determine the effect of ambient probe incidence angle on the amount and direction of analyte molecules transported from the sample surface for desorption electrospray ionization (DESI). Incidence angle was critical to both the lateral dispersion and vertical take-off angles of analyte molecules desorbed from the surface; as t...

In environmental epidemiology, measurements of exposure biomarkers often fall below the assay's limit of detection. Existing methods for handling this problem, including deletion, substitution, parametric regression, and multiple imputation, can perform poorly if the proportion of "nondetects" is high or parametric models are mis-specified. We propose an approach that treats the measured analyt...

Using an image-based method for label-free detection of biochemical binding density distribution on the surface of a photonic crystal biosensor mbedded within standard format multiwell microplates, a new method for automatic referencing of assay errors due to variability in the bulk efractive index of the analyte test sample is demonstrated. The new method involves application of the immobilize...

The dependence of analyte sensitivity and vaporization efficiency on the operating parameters of an inductively coupled plasma mass spectrometer (ICPMS) was investigated for a wide range of elements in aerosols, produced by laser ablation of silicate glass. The ion signals were recorded for different carrier gas flow rates at different plasma power for two different laser ablation systems and c...

We report a facile method to design NIR ratiometric fluorescent probes in terms of analyte-induced carbamate cleavage. Two examples, CyNB and CyNN3, exhibit a significant analyte-triggered response with ratiometric fluorescence change in the NIR range and dual-emission ratiometry in living cells.

A stable isotopically labeled (SIL) analogue is believed to be the most appropriate internal standard in a quantitative bioanalytical liquid chromatography/tandem mass spectrometry (LC/MS/MS) assay. It is assumed that a SIL internal standard always compensates for variability in chemical derivatization, sample extraction and LC/MS/MS analysis due to its nearly identical chemical and physical pr...

This research work regards the design and realization of an absorption spectrophotometer based on a LED light source in place of the usually employed Xenon lamp. The advantage of the use of LED technology resides in several factors such as the reducing of the analyte temperature variations and thus noise generation, which occur if a Xenon light source is used, beside of the high luminous effici...

This paper presents a discriminating approach to detecting the existence of underlying determinism in speech phonemes using the surrogate data method. The discrimination is made using a statistical measurement of neighboring trajectory directions. This approach is experimentally verified with both deterministic and stochastic time series and then applied to speech phonemes from the TIMIT databa...

Ethnographic studies in West Africa show that the practice of sending children away to be raised by relatives and nonrelatives is widespread among many ethnic groups. This paper is an attempt to explore the demographic relevance of the practice. The fostering information is obtained from two sources: the responses given by women to the question on children away from home, and by linking all chi...