LAB 8 - CALCIUM

Question 1

a sophisticated and costly way of measuring free calcium is through

Answer 1

ion-selective electrode

Question 2

a sophisticated and costly way of measuring total calcium is through

Answer 2

atomic absorption spectrophotometry

Question 3

the most simple and inexpensive method for total calcium assay is based on its direct combination with some reactant, such as _____ to form a STABLE color reaction

Answer 3

ortho-cresolphthalein complexone (OCPC)

Question 4

the procedure of direct combination with some reactant for calcium determination to form a stable color reaction will eliminates the _____

Answer 4

precipitation of either calcium or protein

Question 5

the elimination of precipitation of either calcium or protein is required in the early reports of __ and ____ and of ____ and _____

Answer 5

stern and lewis, and of connerty and briggs

Question 6

the procedure presented in the stan bio is essentially based on the ____ of ____

Answer 6

micromethod of sarker y chauhan

Question 7

micromethod of sarker y chauhan

where calcium is
___

Answer 7

dissociated from proteins in an acid solution, followed by its direct reaction with OCPC

Question 8

in a subsequent alkaline medium, the Ca-OCPC complex forms what color complex

Answer 8

purple color complex

Question 9

the Ca-OCPC complex, purple color, is measured at what nm

Answer 9

550 nm

Question 10

RS of the color and the amount of calcium in the sample

Answer 10

the amount of calcium in the sample is proportional to the color development in the reaction

Question 11

the magnesium interference in calcium determination is blocked by

Answer 11

8-hydroxyquinoline and that of heavy metals controlled by potassium cyanide

Question 12

total calcium color reagent

Answer 12

solution of o-cresolphthalein complexone 0.10 mmol/L
8-hydroxyquinoline 17.2 mmol/L

in dilute hydrocloric acid

Question 13

total calcium base reagent

Answer 13

solution of 2 amino 2 methyl 1 propanol 970 mmol/L in aqueous potassium cyanide solution

Question 14

total calcium standard value

Answer 14

10 mg/dl

Question 15

steps in reagent preparation

Answer 15

equal volume of color and base reagents may be mixed to make a working reagent

allow the working reagent to stand at room temperature for at least 15 mns before use

Question 16

how many mns we need to stand the working reagent before use

Answer 16

15 mns at room temperature

Question 17

the working reagent is stable up to

Answer 17

7 days when stored at room temperature 15-30C or
14 days when refrigerated 2-8C

Question 18

reagent storage and stability for color and base reagents

Answer 18

2-8*C until expiration date

Question 19

reagent storage and stability for calcium standards

Answer 19

15-25*C until expiration date

Question 20

spectrophotometer absorbance reading for calcium

Answer 20

550 nm

Question 21

specimen of choice for calcium determination

Answer 21

serum

Question 22

anticoagulant for plasma

Answer 22

heparin

Question 23

in calcium determination, after blood collection, we must separate the serum from clot or the plasma from cells within ___

Answer 23

2 hrs

Question 24

urine (24 hr collection) should be maintained at what ph to prevent precipitation

Answer 24

acid pH

Question 25

in urine collection, we must use ___ in collection vessel

Answer 25

10 ml of 6M HCL

Question 26

Precipitated calcium salts in alkaline urine may be redissolved by acidification of a well-mixed aliquot to pH 1 with concentrated ____.

Answer 26

HCl

Question 27

what to do to specimens showing a precipitate

Answer 27

discard, as calcium may have combined with fatty acids or proteins

Question 28

contaminated glassware must be washed with ____

Answer 28

20% nitric acid rinsed well with distilled or deionized water, dried, and stored in a dust free area

Question 29

anticoagulants to be avoided

Answer 29

oxalates, edta, etc

Question 30

Abnormally high bilirubin or hemoglobin levels can yield falsely _____ calcium values

Answer 30

low

Question 31

component of the reagent blank tube for calcium det

Answer 31

color reagent 0.5 ml base reagent 0.5 ml

Question 32

component of the standard tube for calcium det

Answer 32

standard 0.01 ml color reagent 0.5 ml base reagent 0.5 ml

Question 33

component of the unknown tube for calcium det

Answer 33

specimen 0.01 ml color reagent 0.5 ml base reagent 0.5 ml

Question 34

we must read the sample in 550 nm for how many mns

Answer 34

within 60 mns

Question 35

urine samples giving absorbance values which exceed the linearity(15 mg/dl ) should be diluted for what ratio

Answer 35

3 fold 1:3 1 parts urine 2 parts distilled water

Question 36

serum or urine calcium formula

Answer 36

au/as X 10

Question 37

urine calcium another formula

Answer 37

urine calcium (mg/dl) X F X volume for 24 hr divide them all by 100

Question 38

ref range for serum calcium

Answer 38

9.2 - 11 mg/dl

Question 39

ref range for urine calcium

Answer 39

100-240 mg/24hrs