Sample Sizes Small

Chromosome aberrations were detected in lymphocytes of individuals acutely intoxicated by methyl parathion by the inhalation route (Van Bao et al. 1974). Blood samples were taken 3-6 days after exposure and again at 30 and 380 days. A temporary but significant (p<0.05) increase was noted in the frequency of stable chromosomal aberrations in the exposed individuals. The study limitations include small sample size, absence of a control group, lack of quantification of exposure levels, and a possible concomitant exposure to other substances via the dermal route. 

By utilizing the HPLC method, it is possible to determine the level of each individual toxin in sample solutions. This provides a "toxin profile" that can be very useful in PSP toxin research studies. The ability to examine relative changes in toxin concentration and profile has greatly facilitated studies relating to toxin production by dinoflagellates, metabolism of toxins in shellfish, and movement of toxins up the food chain. Since the HPLC method is easily automated and requires only very small sample sizes (< 1 g tissue), it has clear advantages over other analytical procedures for the toxins in many research situations. Two examples of the utilization of HPLC for the study of the PSP toxins follow. 

HPLC has also been utilized in more complex food chain transfers. It has been known for some time that the toxins can be responsible for fish kills in the Bay of Fundy 18). The vectors for these fish kills are zooplankton that feed on toxic dinoflagellates. In two related studies (79 Sullivan, unpublished), HPLC was utilized to investigate the transport of toxins from dinoflagellates to zooplankton and then to fish. The HPLC method is ideally suited for this since only very small sample sizes (ca. 100,000 dinoflagellate cells) are required. 

Huan et al. [41] measured the behavior of a small fluidized bed consisting of 45-80 mustard seeds in a small-bore vertical magnet. The small sample size allowed short pulses, and spatial distribution of collision correlation times and granular temperature were measured directly and compared with the hydrodynamic theory of Garzo and Dufty [42], This paper [41] contains an excellent survey of previous experiments on fluidized beds. 

A randomized, double-blind, placebo-controlled trial evaluating the use of a monophasic OC containing 30 meg ethinyl estradiol and 3 mg drospirenone, a progesterone with anti-androgenic effects, showed improvement in the treatment arm compared with placebo.31 In particular, appetite, food cravings, and acne improved. However, active treatment was not associated with a statistically significant improvement in the overall outcome measure, the Calendar of Premenstrual Experiences (COPE) scale, perhaps because of the small sample size (n = 82). 

Cold splitless WCOT thick film Idem Reproducible and accurate sampling Controlled evaporation No discrimination on basis of b.p. Large volume injection Low detection limits Minimisation of solvent entering column Allows polar solvents Automation Small sample size introduction (<2 xL) Thermal degradation possible (long residence times of components in liner)... 

Small sample size (<100 mg for on-column) heterogeneity problems... 

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