LAB 7 - Sodium Flashcards
prior to flame photometry and ion-selective electrodes, the most popular method of determining sodium in body fluids involved its ___
precipitation as the triple salt, sodium uranyl zin acetate
the precipitation as the triple salt, sodium uranyl zin acetate for sodium determination is introduced by ___ with subsequent utilization of the precipitate in several ways
kolthoff in 1927
one approach for sodium determination is the colorimetric measurement of the solubilized residue itself, either directly, as reported by ___
albanese and lein
one approach for sodium determination is by monitoring the color fade of the yellow supernate after precipitation, as described by
bradbury
the method presented is essentially adaptation of bradbury’s scheme, wherein __
sodium is precipitated from a protein-free supernate as the triple salt
relationship of the absorbance to the sodium concentration
decrease in absorbance (high transmittance) of the supernate-color reagent mixture is proportional to the sodium content of the specimen
sodium color reagent
solution of uranyl acetate 5.3 g/dl
zinc acetate 15.4 g/dl
both in aqueous acetic acid-ethanol mixture
precipitating reagent for sodium determination
aqueous solution of trichloroacetic acid 10 g/dl
sodium standard (140 mmol/L)
sodium chloride 4.091 g/L in aqueous trichloroacetic acid
equivalent to sodium value of 140 mmol/L when used as directed
stability of all reagents for sodium determination
15-25*C until expiration labels
anticoagulant we can use for sodium determination
lithium heparinate
ammonium heparinate
lithium oxalate
urine specimen for sodium determination
24 hr urine specimen
ratio of 24 hr urine to distilled water
1:10 (1+9)
depending on sodium content, a dilution of 1:5 or 1:2 may be required
sample stability of sodium
sodium levels remain stable for at least 14 days at 15-25*C
interfering substances of sodium determination
contaminated glassware - greatest error
all glassware must be washed with ____ rinsed thoroughly with distilled water, dried, and stored in dust free area
nitric acid
in preparation of protein free supernate
In a properly labelled tubes, we are adding ____ ml of serum, plasma, or diluted urine to each
0.5 ml
in preparation of protein free supernate
after adding 0.5 ml of plasma, urine, and serum in each tube, what’s the next step
add 0.5 ml of precipitating reagent dropwise to each tube with vigorous mixing
in preparation of protein free supernate
how many mns we need to stand the solution before we centrifuge it
5 mns
in preparation of protein free supernate
speed and how many minutes we need to centri the tubes after standing it for 5 mns
5-10 mns high speed
in sodium determination, what is the component of a reagent blank
distilled water 0.5 ml
color reagent 2.5 ml
in sodium determination, what is the component of a standard cuvette
standard 0.5 ml
color reagent 2.5 ml
in sodium determination, what is the component of a sample cuvette
supernate 0.5 ml
color reagent 2.5 ml
sodium determination
after remixing contents of all tubes, we need to incubate it for how many minutes at what temperature
10 mns at room temperature 15-30*C
next step in sodium determination after mixing and incubating it at room temp is what
centrifuging it at high speed for 5 mns
we read the sodium at what nm
420 nm, zero the spectro with water.
in sodium determination, we must read the blank, standard, unknown within how many minutes
30 mns
formula for sodium determination
mmol/L =
abs (rb) - abs (U)
/ abs (rb) - abs (S)
X 140
equivalent sodium standard value is
140 mmol/L
another formula intended for urine sodium
urine sodium (mmol/L) X 24h volume
divided by
1000
urine sodium (mmol/L) came from the general formula
normal range for serum/plasma sodium
135-155 mmol/L
normal range for urine sodium
75-200 mmol/24h
