Biomedical subjects

M Ravreby

Publications and source records attributed to M Ravreby.

3 recordsLinked to original sources

PubMed1992

A statistical approach to drug sampling: a case study.

In many countries it is left to the discretion of the court to accept or reject conclusions based on sampling procedures as applied to the total drug exhibit. As an alternative to this subjective approach, a statistical basis is presented using binomial and hypergeometric distributions to determine a lower limit for the proportion of units in a population which contains a drug, at a given confidence level. A method for calculating the total weight of a drug present in a population within a given confidence interval is also presented. In the event of no failures (all units sampled contain a drug), a sample size of six or seven units is generally sufficient to state that a proportion of at least 0.70 of the population contains a drug at a confidence level of at least 90%. When failures do occur in the sample, point estimation is used as the basis for selecting the appropriate sample size.

Forensic Medicine↗

PubMed1987

Quantitative determination of cocaine and heroin by Fourier transform infrared spectrophotometry.

Cocaine hydrochloride salt (HCl) and heroin HCl were determined quantitatively by choosing a carbonyl absorption peak as the analytical peak and measuring absorbance versus concentration in standard KBr pellets. The effect of various additives and diluents such as starch, sugars, mannitol, caffeine, and procaine was also studied. Methods were devised to correct for interference contributions based on spectral subtraction of the interfering component or subtraction of the interfering spectral contribution based on absorbance ratios with a noninterfering spectral peak. In mixtures containing both the free base and the hydrochloride salt, the most satisfactory method for determining the concentration was by area integration of the two carbonyl peaks.

Cocaine↗

PubMed1982

Analysis of long-range bullet entrance holes by atomic absorption spectrophotometry and scanning electron microscopy.

Bullet residue and primer particles were analyzed by scanning electron microscopy with energy dispersive analysis (SEM-EDA) and by flame and flameless atomic absorption spectrophotometry (AAS). The residue and particles were on cloth targets around entrance holes produced by bullets fired at distances of 10 to 200 m. Primer particles and their chemical constituents were almost always detected by SEM-EDA around the holes produced by rifles and pistols fired at long ranges, and in many cases the barium and antimony associated with primer particles were detected by flameless AAS. Particles were also detected by SEM-EDA on the rear of bullets fired into and recovered from wooden blocks. Usually a hole caused by a bullet jacketed with gilding metal could be distinguished from one caused by a bullet jacketed with yellow brass alloy. Paint from bullet tips of military tracers was also detected. Analysis of the various residues around entrance holes provides a means for identifying the type of ammunition used.

Barium↗