Atomic number 30,

Atomic symbol Zn,

Atomic weight 65.38,

Electron configuration— 8-18-2.

ZINC (COLORIMETRIC METHOD)

(Courtesy: Tulip Group of Companies)

For the determination of zinc in serum and urine

(laboratory reagent for professional use only).

Summary

Zinc is important in man for growth and sexual

development. It is present in various organs and is a

component of many enzymes. Zinc found in serum is

totally bound to protein with over 60% being bound to

albumin. Increased levels are found in patients associated

with gastrointestinal disorders accompanied with nausea,

vomiting, high fever and a metallic taste. Decreased levels

are found in cirrhosis, lung carcinomas, sickle cell anemia,

acute myocardial infarction, renal failure, corticosteroid

and oral contraceptive therapy.

Principle

Zinc in an alkaline medium reacts with nitro-PAPS to form

a purple colored complex. Intensity of the complex formed

is directly proportional to the amount of zinc present in

the sample.

 Alkaline

Zinc + Nitro-PAPS Purple colored Medium complex

Normal Reference Values

Serum : 60–120 µg/dL

Urine : 100–1000 µg/24 h

It is recommended that each laboratory establish its

own normal range representing its patient population.

Contents 25 mL 75 mL

L1: Buffer reagent 20 mL 60 mL

L2: Color reagent 5 mL 15

S: Zinc standard (200 µg/dL) 2 mL 2 mL

Storage/Stability

Contents are stable at 2–8°C till the expiry mentioned on

the labels.

Reagent Preparation

Reagents are ready to use.

Working reagent: Pour the contents of 1 bottle of L2

(Enzyme reagent 2) into 1 bottle of L1 (Enzyme reagent 1).

This working reagent is stable for at least 2 weeks when

stored at 2–8°C.

Alternatively for flexibility as much of working reagent

may be made as and when desired by mixing together

4 parts of L1 (Enzyme reagent 1) and 1 part of L2 (Enzyme

reagent 2). Alternatively 0.8 mL of L1 and 0.2 mL of L2

may also be used instead of 1 mL of the working reagent

directly during the assay.

Sample Material

Serum (Free from hemolysis) or urine.

Zinc is reported to be stable in serum for 7 days at 2–8°C.

Procedure

Wavelength/filter : 570 nm (Hg 578 nm)/yellow

Temperature : RT

Light path : 1 cm

504 Concise Book of Medical Laboratory Technology: Methods and Interpretations Pipette into clean dry test tubes labeled as blank (B),

standard (S), and test (T):

Addition

Sequence

B

(mL)

S

(mL)

T

(mL)

Working reagent 1.0 1.0 1.0

Distilled water 0.05

Zinc standard (S) - 0.05

Sample - - 0.05

Mix well and incubate at RT (25°C) for 5 minutes.

Measure the absorbance of the standard (Abs S), and Test

sample (Abs T) against the blank, within 20 minutes.

Calculations

 Abs T

Zinc in µg/dL = _________ × 200 Abs S

Linearity

This procedure is linear upto 700 µg/dL. If values exceed

this limit, dilute the sample with distilled water and repeat

the assay. Calculate the value using the proper dilution

factor.

Notes

Chelating agents such as EDTA, oxalate and citrate, present

even in traces, prevent the formation of the color complex,

hence necessary care should be taken during the assay.

Highly lipemic samples could interfere and should be

cleared by centrifugation of filtration before use.

For a seminal fluid assay, centrifuge the sample for

10 min at 3000 RPM. Dilute the supernatant 1 + 99 with

normal saline before use.

System Parameters

Reaction : End point Interval :

Wavelength : 578 nm Sample

volume

: 0.05 mL

Zero setting :  Reagent

blank

Reagent

volume

: 1.00 mL

Incubation

temperature

: RT Standard :  200 µg/dL

Incubated time : 5 min Factor :

Delay time : — React slope : Increasing

Read time : — Linearity : 700 µg/dL

No. of read : — Units : µg/dL

Normal Values

Serum : 60–120 µg/dL or 9.18–18.4 µmol/L

Urine : 100–1000 µg/24 h

Less than 60 µg/dL is considered as deficiency state.

Clinical Relevance

Toxic Level Symptoms

Cough, chest discomfort, tachycardia, hypertension,

gastrointestinal discomfort, nausea, vomiting, diarrhea,

metallic taste in the mouth. Treatment includes removal

of intake and peritoneal dialysis.

Deficiency Symptoms

May progress from decreased weight, low sperm count,

and impaired wound healing to alopecia, hypogonadism,

ataxia, tremors, and impaired resistance to infection.

Treatment includes dietary replenishment, medication or

hyperalimentation.

Values are Increased in

Anemia, arteriosclerosis, coronary heart disease, dietary

intake of acidic food or beverages from galvanized

containers, industrial exposure to zinc (welding), and

primary osteosarcoma of bone. Drugs include cisplatin,

corticosteroids, estrogens, interferon, oral contraceptives

(containing estrogen), phenytoin, and thiazides.

Values are Decreased in

Acrodermatitis enteropathica, alopecia, alcoholism,

anemia (hemolytic), celiac sprue, cirrhosis, diarrhea,

gallbladder disease, hepatic metastases, hypoalbuminemia,

hypogonadal dwarfism, acute infections, leukemias,

lymphomas, malabsorption, myocardial infarction,

dietary deficiency, pregnancy (especially third trimester),

receiving parenteral nutrition, chronic renal failure, acute

stress, thalassemia major, enteric fever, and pulmonary

tuberculosis. Drugs include antimetabolites, chlorthalidone,

cisplatin, diuretics, estrogens, histidine, and penicillamine.

COPPER

Oxidation state + 1 + 2,

Atomic number 29,

Atomic symbol Cu,

Atomic weight 63.546,

Electron configuration—8-18-1.

Colorimetric Method

(Courtesy: Tulip Group of Companies)

For the determination of copper in serum. (Laboratory

reagent for professional use only).

Summary

Copper is widely distributed in the various organs of

the body. The highest concentration is found in the liver

Clinical Chemistry 505

followed by the brain and kidneys. It plays an important

part in the iron metabolism by converting the ferrous ions

to a ferric state. Over 90% of the copper in plasma is bound

to the protein ceruloplasmin. Increased levels are found

in chronic/malignant diseases, e.g. leukemia, cirrhosis,

various infections and in patients on oral contraceptives

and estrogens. Decreased levels are found in Wilson’s

disease, decreased synthesis of ceruloplasmin, malabsorption, malnutrition, and nephrotic syndrome.

Principle

Copper, released from ceruloplasmin, in an acidic medium,

reacts with Di-Br-PAESA to form a colored complex.

Intensity of the complex formed is directly proportional to

the amount of copper present in the sample.

 Acidic

Copper + Di-Br-PAESA Colored complex

 Medium

Normal Reference Values

Serum (males) : 80–140 µg/dL

(females) : 80–155 µg/dL

(newborns) : 12–67 µg/dL

(children upto 10 years) : 30–150 µg/dL

It is recommended that each laboratory establish its

own normal range representing.

Contents 25 mL 75 mL

L1: Buffer reagent 12.5 mL 37.5 mL

L2: Color reagent 12.5 mL 37.5 mL

S: Copper standard (200 µg/dL) 2 mL 2 mL

Storage/Stability

Contents are stable at 2–8°C till the expiry mentioned on

the labels.

Reagent Preparation

Reagents are ready to use. Protect from bright light.

The cold Buffer (L1) when retrieved from 2–8°C may

have a particulate suspension. The suspension clears up

once the Buffer attains a temperature over 25°C.

Working Reagent

For larger assay series a working reagent may be prepared

by mixing equal volumes of L1 (Buffer reagent) and L2

(Color reagent). The Working reagent is stable at 2–8°C for

at least 3 weeks. Keep tightly closed.

Sample Material

Serum, free from hemolysis.