Concentrations in water column

Marine clams and worms tended to underrepresent chlordane concentrations in the ambient sediments. Concentration factors were less than 0.2 for clams and 0.6 for worms (Ray et al. 1983). Similarly, chlordane concentrations in clams from the Shatt al-Arab River in Iraq closely reflected chlordane concentrations in water particulates when compared to levels in water columns or in sediments (DouAbul et al. 1988). 

Step 2 Sample injection from autosampler into trap column 1 for 3 to 5 min using 100% pump 1. Sample is focused, filtered, and concentrated in trap column 1. Condition pumps 3 and 4 to 95% water in composition. Switching valve A = on switching valve B = on. 

Heptachlor and heptachlor epoxide were detected in water column samples at different depths in Lake Pontchartrain in New Orleans, Louisiana. Heptachlor was detected in the 1.5-meter ebb- and flood- tide samples and in the 10-meter flood-tide samples at concentrations of 0.6, 9.1, and 9.3 ppt, respectively. Heptachlor epoxide was detected in the 1.5-meter ebb- and flood-tide samples and in the 10-meter flood-tide sample at concentrations of 2, 3.9, or 2.5 ppt, respectively (McFall et al. 1985). 

Figure 8. Analysis of perchlorate ion at 100, 10 and 1 ppb concentrations in water using 18-crown-6 in an aqueous mobile phase and a polystyrene reversed phase column (from ref. 75)...

This equation requires the plot of Vp versus x. If the original concentration in the column is [c ] and, after a time of settling t, the remaining concentration measured at the sampling port is [c], the fraction of particles remaining in the water column adjacent to the port is... 

Table 4-13 contains the static yield stresses of the xanthan dispersions in water (Column A), of the three starches in water (Column B) and their sum (Column C), and those of the mixed starch-xanthan dispersions (Column D). One can say that there is synergism between xanthan and starch if values in Column D are higher than those in Column C if they are lower, there is antagonism. From the table, it seems that WXM (except with 1% xanthan concentration) and CWS starches exhibited synergistic... 

The water-insoluble portion was then washed with 10 mL of MeOH to separate MeOH-soluble and MeOH-insoluble portions. The obtained water-soluble and MeOH-soluble portions, the sum of which nearly corresponds to the supercritical water-soluble portion, were then analyzed by the high perfonnance liquid chromatograph (HPLC) (Shimadzu LC-lOA) which consists of a high pressure pump (Shimadzu Co., Model LC-IOAT). HPLC analysis conditions were as follows [Column SHI ODS-11, Column temperature 40 6. Carrier solvent CHjOH/HjO = 20/80 (O- -IO min), 20/80 - 100/0 (10 20 min), 100/0 (20- 30 mm), Flow rate 0.7 ml/min. Detector a spectrophotometric detector (SPD) (A =254 nm) or a refractive index detector (RID)], or [Column ULTRONPS-80P, Column temperature SOTl. Carrier solvent H2O, Flow rate 1,0 ml/min, Detector SPD (A =254 nm) or RID], To obtain the yields of monosaccharides and their decomposed products, their standard samples (Nacalai tesque, extra pure reagent) with known concentrations in water were analyzed by HPLC as a standard in a similar manner. 

Figure 15.7 Comparison between experimental and calculated band profiles of 2-phenylethanol in gradient elution. Experimental conditions mobile phase flow rate 1 mL/min. initial mobile phase composition 10% ACN in water column temperature 40°C column dead volume Vq = 2.71 mL. Concentration of the sample solution Cq = 132.5 mmol/L. Gradient, 2% ACN/min. Experimental band profiles (square symbols) and profiles calculated using a composite isotherm (linear plus Langmuir terms), taking into account (solid line) or not (dotted line) the adsorption of ACN on the stationary phase, (a) Injection volume, Vj = 4 mL sample size, 0.53 mmol, loading ratio, 29 molecule per 100 bonded groups, (b) Injection volume, Vj = 6 mL sample size, 0.80 mmol, loading ratio, 43 molecule per 100 bonded groups. Reproduced with permission from M.Z. El Fallah and G. Guiochon, Anal. Chem., 63 (1991) 2244 (Fig. 8). ( 1991, American Chemical Society.

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