Arsenic speciation by ion-exchange chromatography with on- line determination by hydride generation: electronic modification of the D.C. plasma by photon counting

A method using L-cysteine for the determination of arsenous acid (As(III)), arsenic acid (As(V)), monomethylarsonic acid (MMAA), and dimethylarsinic acid (DMAA) by hydride generation was demonstrated. The instrument used was a d.c. plasma atomic emission spectrometer (OCP-AES). Complete recovery was reported for As(III), As(V), and DMAA while 86% recovery was reported for MMAA. Detection limits were determined, as arsenic for the species listed previously, to be 1.2, 0.8, 1.1, and 1.0 ngemL-l, respectively. Precision values, at 50 ngemL-1 arsenic concentration, were f.80/0, 2.50/0, 2.6% and 2.6% relative standard deviation, respectively. The L-cysteine reagent was compared directly with the conventional hydride generation technique which uses a potassium iodide-hydrochloric acid medium. Recoveries using L-cysteine when compared with the conventional method provided the following results: similar recoveries were obtained for As(III), slightly better recoveries were obtained for As(V) and MMAA, and significantly better recoveries for DMAA. In addition, tall and sharp peak shapes were observed for all four species when using L-cysteine. The arsenic speciation method involved separation by ion exchange .. high perfonnance liquid chromatography (HPLC) with on-line hydride generation using the L.. cysteine reagent and measurement byOCP-AES. Total analysis time per sample was 12 min while the time between the start of subsequent runs was approximately 20 min. A binary . gradient elution program, which incorporated the following two eluents: 0.01 and 0.5 mM tri.. sodium citrate both containing 5% methanol (v/v) and both at a pH of approximately 9, was used during the separation by HPLC. Recoveries of the four species which were measured as peak area, and were normalized against As(III), were 880/0, 290/0, and 40% for DMAA, MMAA and As(V), respectively. Resolution factors between adjacent analyte peaks of As(III) and DMAA was 1.1; DMAA and MMAA was 1.3; and MMAA and As(V) was 8.6. During the arsenic speciation study, signals from the d.c. plasma optical system were measured using a new photon-signal integrating device. The_new photon integrator developed and built in this laboratory was based on a previously published design which was further modified to reflect current available hardware. This photon integrator was interfaced to a personal computer through an AID convertor. The .photon integrator has adjustable threshold settings and an adjustable post-gain device.

A List of Officers of the reduced Independent Companies who are to receive half pay from the days hereafter mentioned, to the 24th of December 1791, both days inclusive, or to the days of their death or Provision respectively.

Sir George Yonge (1732-1812) was a baronet, politician and colonial governor. He was a Member of Parliament for Honiton from 1754-1761 and 1763-1796, British Secretary at War from 1782-1783 and 1783-1794, and Governor of the Cape colony from 1799-1801.

Scottish Rite (Masonic Order) French Language Collection, 1787-1825, 1907, n.d.

The origins of the Scottish Rite of Freemasonry can be traced to France around 1754, when a Chapter of Claremont was founded in Paris. Initially this chapter had seven degrees, but by 1758 there were twenty-five degrees, known as the Rite of Perfection. In 1761, Stephen Morin was appointed to introduce the Rite into the New World. He began with Kingston, Jamaica and San Domingo. Further establishments were made in New Orleans, LA(1763); Albany, NY (1767); Philadelphia, PA (1782); and Charleston, SC (1783). In order to improve the disorganized state of the degrees in Europe, “Grand Constitutions” were enacted in 1786. These Constitutions formally brought into existence the “Ancient and Accepted Scottish Rite”. None of the degrees of the Scottish Rite would seem to have origins in Scotland. “Scottish” is translated from the French word “Ecossais”, which is found in some of the French titles of some of the degrees of the Rite of Perfection. It is possible that the Scottish connection is a result of the involvement of a Scotsman, Andrew Michael Ramsey, who may have devised some of the degrees.