Anal. Chem. 1980, 52, 581-583
58 1
Stationary Cold-Vapor Atomic Absorption Spectrometric Attachment for Determination of Total Mercury in Undigested Fish Samples Soo-Loong Tong" and Wooi-Kwee Leow Department of Chemistry, University of Malaya, Kuala Lumpur, Malaysia
Trace mercury in the environment and biological materials has been of great interest for the past two decades because of its toxicological effect. Extensive research on mercury analysis has been carried out and among the few techniques available, the cold-vapor atomic absorption spectrometric method based on the principle first proposed by Poluektov e t al. ( I ) and Hatch and Ott ( 2 ) has received the greatest attention and is most widely used currently. Many modifications t o the cold-vapor atomic absorption technique (3, 4 ) have been reported but basically all involve measurements of the transient atomic absorption signal of the elemental mercury vapor. T h e precision and sensitivity of these methods are affected by the relative dead volumes of the liquid and vapor phases, the flow rate of the carrier gas, the dimensions of the absorption cell, and the reduction conditions. Recently, a very simple stationary cold-vapor method (5) has been proposed whereby a stoppered 4-cm UV-cell is used for the reduction, the partition of the reduced mercury between the liquid and gas phases, and the subsequent atomic absorption measurement. This method has a minimum number of analytical variables and higher sensitivity is achieved by minimizing the dilution of the elemental mercury in the vapor phase. However, in common with other cold-vapor techniques, this method is not ideal for mercury determinations in biological samples because of difficulties with sample digestion, which is tedious and time-consuming. Extreme care must be taken to avoid losses and contamination. Also, in cases where very low absolute detection limit is required, such as in blood analysis, a digestion procedure which leads t o multiple dilution of the sample is to be avoided. Few reports have appeared in the literature on the direct determination of mercury without actually destroying the organic materials. Magos (6, 7)determined total and inorganic mercury in biological samples by the use of stannous chloride-cadmium chloride under violent conditions. Matsunaga e t al. (8) reported a simple procedure for the extraction of mercury from fish. Both of these groups have employed the conventional cold-vapor atomic absorption technique. In the present study, a new stationary cold-vapor atomic absorption attachment has been developed, and its application to the direct determination of total mercury in undigested biological samples was investigated. T h e construction, ODeration, and performance of the attachment are described. The recovery, accuracy, and precision in applying the proposed method for the determination of total mercury in a series of fish samples, the comparison of results with those obtained following sample destruction, and the analysis of NBS Orchard Leaves S R M 1571 and Bovine Liver SRM 1577, are also reported.
EXPERIMENTAL Apparatus. All atomic absorption measurements were made on an Instrumentation Laboratory IL-251 double-beam spect ruphotometer equipped with an automati (1 bw kground corrector arid a chart recorder The nebulizer-burner of the instrument w a s repldced by the neu stationary cold-vapor attachment shown 1 1 1 Figure 1. The absorption cell -7th quartz window was properly aligned witti the atoniic light beam arid then tightlb held in I wtion The reaction \esse15 with short neck (-2 cm) bere made 1 mL \taidird flasks and attached to the ahwrption cell (2~18% kt;* ('lo/ 1'4 I [ , i r i t 4 Varidn Iiwrcun t,
