CuCO 3 .Cu(OH) 2. It is bright green and
crystallizes in the monoclinic system
but usually occurs as aggregates of
Übres or in massive form. It is gener-
ally found with *azurite in associa-
tion with the more important copper
ores and is itself mined as an ore of
copper (e.g. in Zaïre). It is also used as
an ornamental stone and as a gem-
stone.
MALDIMatrix absorption laser des-
orption ionization. A technique for
producing ions for mass spec-
troscopy, used especially for large
biological species. The sample is ab-
sorbed on an inert matrix from
which ions are desorbed by a laser.
maleic acidSee butenedioic acid.maleic anhydrideA colourless
solid, C 4 H 2 O 3 , m.p. 53°C, the anhy-
dride of cis-butenedioic acid (maleic
acid). It is a cyclic compound with a
ring containing four carbon atoms
and one oxygen atom, made by the
catalytic oxidation of benzene or its
derivatives at high temperatures. It is
used mainly in the manufacture of
alkyd and polyester resins and
copolymers.MALDI 340m
OHOHOOOOOMaleic anhydridemalic acid (2-hydroxybutanedioic
acid)A crystalline solid,
HOOCCH(OH)CH 2 COOH. l-malic acid
occurs in living organisms as an in-
termediate metabolite in the *Krebs
cycle and also (in certain plants) in
photosynthesis. It is found especially
in the juice of unripe fruits, e.g.
green apples.malonic acidSee propanedioic
acid.maltThe product of the hydrolysis
of starch by β-amylase that occurs
during the germination of barley in
brewing. See also maltose.maltose(malt sugar)A sugar con-
sisting of two linked glucose mol-
ecules that results from the action of
the enzyme amylase on starch. Mal-
tose occurs in barley seeds following
germination and drying, which is the
basis of the malting process used in
the manufacture of beer and malt
whisky.
malt sugar See maltose.mancudeDescribing an organic
compound that contains the maxi-
mum possible number of noncumu-
lative double bonds, as in the
*annulenes. It is an acronym. maxi-
mum non-cumulative double.
Mandelin testA *presumptive
test for amphetamines and alkaloids.
The Mandelin reagent is a 1% solu-
tion of ammonium vanadate
(NH 4 VO 3 ) in concentrated sulphuric
acid. Different substances give differ-
ent colours. Mescaline, for example,
produces an orange colour, heroin a
brown colour, and amphetamine a
blue-green colour.
manganate(VI)A salt containing
the ion MnO 4 2–. Manganate(VI) ions
are dark green; they are produced by
manganate(VII) ions in basic solution.manganate(VII)(permanganate)A
salt containing the ion MnO 4 –. Man-
ganate(VII) ions are dark purple and
strong oxidizing agents.manganeseSymbol Mn. A grey
brittle metallic *transition element,
a.n. 25; r.a.m. 54.94; r.d. 7.2; m.p.
1244 °C; b.p. 1962°C. The main
sources are pyrolusite (MnO 2 ) and
rhodochrosite (MnCO 3 ). The metal