190
4 The Measurement Process in Chemistry
Annex V
Determination of silica in rocks
Learning objective:
To exemplify a determination routinely performed by clinical control laboratories.
Reference:
W. R. Faulkner and S. Meites
Selected Methods for the Small Clinical Chemistry Laboratory
American Association for Clinical Chemistry, Washington, D.C., 1982, pp 353 - 355.
Triglycerides in Serum, Colorimetric Method
Introduction
Measurement of serum triglycerides is useful
for diagnosis of hyperlipidemia and hyperlipoproteinemia. The correct diagnosis and
treatment of hyperlipoproteinemia depends
on accurate and precise methods for triglyceride determination. Presented here is a
manual colorimetric method described by
Neri and Frings (I). This method is relatively
simple and requires only equipment that is
usually available even in small clinical
chemistry laboratories. It is ideally suited for
laboratories that do not have a large number
of requests for triglyceride assays and for
those wanting to make their own reagents.
Principle
Isopropanol extracts of serum are prepared
and then treated with alumina to remove glycerol, phospholipids and glucose. Triglycerides are then saponified to yield glycerol,
which is oxidized by sodium metaperiodate
to formaldehyde. Formaldehyde reacts with
acetylacetone to form a yellow dihydrolutine
derivative. The absorbance of this product at
405 nm is proportional to the serum concentration of triglycerides.
Materials and Methods
Reagents
1. Isopropanol. "Aldehyde-free:' analytical
grade reagent.
2. Alumina (AI20 3 ), washed. Wash alumina
(Woeim, neutral, activity grade 1 for chromatography; Waters Associates, Inc., Framingham, MA 01701) until fines are
removed. This usually requires eight to 10
washings, with approximately four bedvolumes of de-ionized water for each
wash. Dry the alumina in an oven for 15 to
18 h at 100-110°C. Do not keep the
alumina in the oven longer than 18 h. It
can be used satisfactorily for at least two
months when stored in a tightly stoppered
container at room temperature.
3. Saponification reagent. Dissolve 10.0 g of
KOH in 75 mL of water and 25 mL of isopropanol. This reagent is stable for at least
two months when stored at room temperature in a brown glass bottle.
4. Sodium metaperiodate reagent. Dissolve
77 g of anhydrous ammonium acetate in
700 mL of de-ionized water; add 50 mL of
glacial acetic acid and 650 mg of sodium
metaperiodate (NaI04 ). Dissolve the sodium metaperiodate in this solution and
dilute to 1 L with de-ionized water. Do not
change the order of addition of chemicals.
This reagent is stable for at least two
months when stored at room temperature
in a brown glass bottle.
5. Acetylacetone reagent. Add 0040 mL of
2,4-pentanedione to 100 mL of isopropanol. This reagent is stable for at least
two months when stored at room temperature in a brown glass bottle.
6. Standard. The stock standard contains
1.000 g of triolein (A grade; Calbiochem,
San Diego, CA 92112) per 100 mL of
isopropanol. Prepare a working standard
of 200 mgldL by diluting 2.0 mL of the
stock standard to volume with isopropanol in a 10-mL volumetric flask. The
4 The Measurement Process in Chemistry
Annex V
Determination of silica in rocks
Learning objective:
To exemplify a determination routinely performed by clinical control laboratories.
Reference:
W. R. Faulkner and S. Meites
Selected Methods for the Small Clinical Chemistry Laboratory
American Association for Clinical Chemistry, Washington, D.C., 1982, pp 353 - 355.
Triglycerides in Serum, Colorimetric Method
Introduction
Measurement of serum triglycerides is useful
for diagnosis of hyperlipidemia and hyperlipoproteinemia. The correct diagnosis and
treatment of hyperlipoproteinemia depends
on accurate and precise methods for triglyceride determination. Presented here is a
manual colorimetric method described by
Neri and Frings (I). This method is relatively
simple and requires only equipment that is
usually available even in small clinical
chemistry laboratories. It is ideally suited for
laboratories that do not have a large number
of requests for triglyceride assays and for
those wanting to make their own reagents.
Principle
Isopropanol extracts of serum are prepared
and then treated with alumina to remove glycerol, phospholipids and glucose. Triglycerides are then saponified to yield glycerol,
which is oxidized by sodium metaperiodate
to formaldehyde. Formaldehyde reacts with
acetylacetone to form a yellow dihydrolutine
derivative. The absorbance of this product at
405 nm is proportional to the serum concentration of triglycerides.
Materials and Methods
Reagents
1. Isopropanol. "Aldehyde-free:' analytical
grade reagent.
2. Alumina (AI20 3 ), washed. Wash alumina
(Woeim, neutral, activity grade 1 for chromatography; Waters Associates, Inc., Framingham, MA 01701) until fines are
removed. This usually requires eight to 10
washings, with approximately four bedvolumes of de-ionized water for each
wash. Dry the alumina in an oven for 15 to
18 h at 100-110°C. Do not keep the
alumina in the oven longer than 18 h. It
can be used satisfactorily for at least two
months when stored in a tightly stoppered
container at room temperature.
3. Saponification reagent. Dissolve 10.0 g of
KOH in 75 mL of water and 25 mL of isopropanol. This reagent is stable for at least
two months when stored at room temperature in a brown glass bottle.
4. Sodium metaperiodate reagent. Dissolve
77 g of anhydrous ammonium acetate in
700 mL of de-ionized water; add 50 mL of
glacial acetic acid and 650 mg of sodium
metaperiodate (NaI04 ). Dissolve the sodium metaperiodate in this solution and
dilute to 1 L with de-ionized water. Do not
change the order of addition of chemicals.
This reagent is stable for at least two
months when stored at room temperature
in a brown glass bottle.
5. Acetylacetone reagent. Add 0040 mL of
2,4-pentanedione to 100 mL of isopropanol. This reagent is stable for at least
two months when stored at room temperature in a brown glass bottle.
6. Standard. The stock standard contains
1.000 g of triolein (A grade; Calbiochem,
San Diego, CA 92112) per 100 mL of
isopropanol. Prepare a working standard
of 200 mgldL by diluting 2.0 mL of the
stock standard to volume with isopropanol in a 10-mL volumetric flask. The