Ralph O. Allen

Forensic determination of ricin and the alkaloid marker ricinine from castor bean extracts.

Liquid chromatography/mass spectrometry (LC/ MS) and matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS methods were developed for the presumptive identification of ricin toxin and the alkaloid marker ricinine from crude plant materials. Ricin is an extremely potent poison, which is of forensic interest due to its appearance in terrorism literature and its potential for use as a homicide agent. Difficulties arise in attempting to analyze ricin because it is a large heterogeneous protein with glycosylation. The general protein identification scheme developed uses LC/MS or MALDI-TOF for size classification followed by the use of the same instrumentation for the analysis of the tryptic digest. Fragments of the digest can be searched in an online database for tentative identification of the unknown protein and then followed by comparison to authentic reference materials. LC fractionation or molecular weight cutoff filtration was used for preparation of the intact toxin before analysis. Extracts from two types of castor beans were prepared using a terrorist handbook procedure and determined to contain 1% ricin. Additionally, a forensic sample suspected to contain ricin was analyzed using the presented identification scheme (data not shown). The identification of the alkaloid ricinine by GC/MS and LC/MS was shown to be a complementary technique for the determination of castor bean extracts.

Quantitation of polymerase chain reaction products by capillary electrophoresis using laser fluorescence.

In samples where the amount of DNA is limited, the polymerase chain reaction (PCR) can amplify specific regions of the DNA. A quantitative analysis of the PCR product would be desirable to ensure sufficient DNA is available for analysis. In this study, we examine the use of capillary electrophoresis (CE) with laser fluorescence detection for quantitation of PCR products. A coated open tubular capillary was used with a non-gel sieving buffer and a fluorescent intercalating dye to obtain results within 20 minutes. Using an internal standard, peak migration time was below 0.1% relative standard deviation (R.S.D.) with a peak area precision of 3% R.S.D. In comparison to quantitation by hybridization, (i.e., slot blot) and spectrophotometric analysis, capillary electrophoresis shows distinct advantages due to its ability to separate unincorporated primers and PCR byproducts from the targeted PCR product. The results demonstrate that CE can be used to monitor the quality and quantity of the PCR product.

Soapstone Artifacts: Tracing Prehistoric Trade Patterns in Virgimna

Rare earth element abundances in soapstone from quarries and artifacts in eastern Virginia were determined by instrumental neutron activation analysis. By comparing these abundances it was possible to trace artifactual material to the outcrops which served as the source of this material during the first millennium B.C. Certain known sociopolitical boundaries in prehistoric Virginia were inferred to be older than previously assumed.

Proton and deuteron radiolysis of argon matrix samples of O2 and Cl2. Infrared spectra of charged species

Argon matrix samples containing O2 and Cl2 have been bombarded with 2.0 keV protons and deuterons during condensation at 15°K. In the oxygen experiments, bands due to O3 and HO2 appeared. Of most interest is isolated O−3 at 804.3 cm−1. Deuteron radiolysis produced increased yields of the 644 cm−1 band which is confirmed as a DAr+n species. Proton and deuteron radiolysis of chlorine−containing samples produced HCl2x and DCl2x in high yields. Owing to the strong electron scavenging capability of chlorine, these species are probably anions.

The Dielectric Discharge as an Efficient Generator of Active Nitrogen for Chemiluminescence and Analysis

A predominantly blue “active nitrogen” afterglow was generated in pure flowing nitrogen or in air by using a dielectric discharge at pressures from 1 to 20 Torr. The afterglow contains triplet state molecules and vibrationally excited ground state molecules. These species are produced directly by electron impact without the formation and recombination of nitrogen atoms. The most intense emission is the N2 second positive band system. The N2 first positive and N2+ first negative systems are also observed. The spectral and electrical properties of this discharge are discussed in order to establish guidelines for the analytical use of the afterglow for chemiluminescence reactions. The metastatic nitrogen efficiently transfers its energy to atomic and molecular species which are introduced into the gas phase and these excited species emit characteristic radiation. The effects of electrothermal atomization of Zn and the introduction of gaseous species (e.g., NO) on the afterglow are described.

Changes in serum trace element levels following local irradiation of a solid tumor

The changes in concentrations of a number of trace elements have been determined by neutron activation analysis in tumor, liver, and blood serum of host animals, following local irradiation of a solid tumor (3924A Morris hepatoma). These trace element changes are compared to the changes observed in a parallel study of the effects of the chemotherapeutic agent 5-fluorouracil on the same tumor. Since the changes in some of the trace elements parallel the changes in pathological and biochemical factors resulting from the insult of radiation on the tumor, these trace elements may be valuable markers in the clinical evaluation of therapeutic response and as monitors of the long term effects of cancer therapy.

A study of trace and minor elements in the solid tumor model 3924A hepatoma before and after treatment with 5-fluorouracil☆

Abstract The changes in the concentrations of a number of trace elements have been determined by neutron activation analysis in a solid tumor model, blood and its host liver, following 5-fluorouracil administration. Studies have also been carried out for non-tumor bearing animals after 5-fluorouracil. The changes in some of the trace elements parallel destructive changes found in the tumor. Studies are in progress to determine if changes in the urinary concentrations of these trace elements parallel the time sequence of the destructive changes found in the tumor. The potential clinical usefulness of these trace elements are being evaluated along with other biological markers which may eventually be utilized to assess the therapeutic effectiveness of different treatment modalities as well as monitor the patient for possible reoccurrence of the cancer following treatment.

The determination of vanadium in geological materials by activation analysis with pre-irradiation separation

Abstract Vanadium is determined in silicate rocks by neutron activation after dissolution of the samples with HF/HNO 3 and separation by solvent extraction. The chemical yield of the pre-irradiation separation is determined by means of 48 V tracer. Results for 15 U.S. Geological Survey standard rocks are presented and discussed in relation to literature data. The method is especially useful at vanadium concentrations below 10 ppm, where purely instrumental neutron activation as well as other techniques commonly used for vanadium determinations in rocks, have inadequate sensitivity.

Matrix isolation technique for the study of some factors affecting the partitioning of trace elements

Abstract Some of the factors that affect the preferred positions of cations in ionic-solid solutions were investigated utilizing vibrational spectroscopy. Solid solutions of the sulfate and chromate ions codoped with La 3+ and Ca 2+ in a KBr host lattice were examined as a function of the polyvalent-cation concentration. The cation—anion pairing process was found to be random for Ca 2+ whereas the formation of La 3+ SO 4 2− ion-pairs with a C 2v bonding geometry is highly preferential to any type of La 3+ CrO 4 2− ion-pair formation. The relative populations of ion-pair site configurations are discussed in terms of an energy—entropy competition which can be applied to the partition of trace elements during magmatic processes.