Cuvettes mixing contents

Remove the cuvette and add to it 0.2 ml of serum. Mix the contents of the cuvette and replace it quickly in position. Carefully record the absorbance exactly at intervals of 30 seconds for 2 to 3 minutes. In case, the absorbance happens to rise very rapidly, repeat step 3 by diluting 0.1 ml of the serum to 0.2 ml with DW,... 

Figure 6.5 Transparent analytical test pack (100 mm X 80 mm) for Du Pont aca analyser containing all the reagents for the assay of glucose. A wide range of test packs is available for use in the automated discrete analyser. Once the pack is loaded into the instrument, sample and diluents are automatically injected. The sealed reagent compartments are then broken open at various stages in the assay and the contents of the pouch are mixed and incubated. The transparent pouch then serves as a cuvette for absorbance measurements.

Measure the absorbance of all solutions at 520 nm, using water as the reference. Mix the contents of each tube before transferring them to the cuvette. 

Figure 8-1. Experimental arrangement for measuring leaf transpiration and photosynthesis. The water vapor and the COz contents of the gas entering a transparent chamber enclosing a leaf are compared with those leaving. A fan mixes the air in the leaf cuvette. If because of transpiration (Jwv) the water vapor concentration increases from 0.6 mol m-3 for the air entering to 1.0 mol m-3 for that leaving for a gas flow rate of 1.0 x 10 5m3 s 1 (10 cm3 s ), then Jwv for a leaf of area 1.0 x 10-3 m2 (10 cm2) would be (1.0 mol m-3 - 0.6 mol m-3) (1.0 x 10-5 m3 s 1)/(1.0 x 10-3 in2), or 0.004 mol m"2 s l.

Add 1.5 mL of biuret reagent to each tube and mix well by inverting several times while holding a piece of hydrocarbon foil over the opening. Incubate the tubes for 15 minutes at 37°C. Transfer the contents to cuvettes. 

In the modified colour reaction for small amounts of vitamin D (e. g., extracts with about 400 lU per 2.5 ml), the solutions for a single determination are pipetted into test tubes as described above but are treated with only 2.0 ml reagent. After briefly mixing, the contents are introduced into 1 cm cuvettes and after precisely 20 sec the extinction measured with a spectrophotometer at 500 nm against the blank solution. 

Immediately after preparation of the dilutions, 4 mL of the mixed reagent are added with a piston pipette. The contents of the bottles are mixed well. The standards are diluted 1 25 with distilled water no sooner than 1 h after reagent addition. They are then measured against distilled water at 670 nm in a 5 mm cuvette (see Section 5.3.1.9). Note that the zero standard must also be diluted. From the results, a standard curve is prepared which should pass through the origin if the zero fraction of the absorbance is subtracted see Fig. 5-3. 

The mitochondria were suspended in 0.25 M sucrose to give approximately 25-30 mg protein per milliliter of mitochondrial suspension. Protein was determined according to Lowryi. The mitochondrial suspension was stored at -20 C and thawed only immediately prior to use. Difference spectra were recorded according to the following standard procedure to both the reference (R) and sample (S) cuvettes were added 0.5 ml of mitochondrial suspension, 0.2 ml 0.1 M sodium phosphate buffer (pH 7.4) and 0.2 ml 10% sodium deoxycholate. After thorough mixing of the contents,... 

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