Phosphorus

provides a much faster response, and allows to map
the pressure over the entire surface. This technique is
currently being applied to the challenging problem of
insect ﬂight.

Room-Temperature Phosphorescence
in Microcrystalline/Colloidal Media

A microcrystalline or a colloidal-like suspension
generated by syringe injection of a dilute organic so-
lution of a PAH into pure water fulﬁls all the criteria
for colloidal dispersion, except that the particles are
larger. In this crystalline state, molecular diffusion
is negligible and intermolecular photophysical events
depend upon the crystal-formation step. A major
spectral feature observed for many colloidal PAHs is
intense RTP. This phenomenon is quite similar to
SS-RTP. Generally, all colloidal RTP spectra exhibit
large blue shifts compared to cryogenic temperature
conditions, while the spectral resolution is much bet-
ter than in MS-RTP spectra and only slightly worse
than in low-temperature phosphorescence. It should
be noted that colloidal RTP is completely insensitive
to oxygen quenching. These features are observed in
RTP spectra of ﬂuorene, naphthalene, dibenzofuran,
biphenyl, and others PAHs. However, the analytical
potential of this technique is rather limited.

See

also:

Bioluminescence.

Chemiluminescence:

Overview. Flow Injection Analysis: Principles; Instru-
mentation. Fluorescence: Overview; Instrumentation.
Liquid Chromatography: Overview; Principles. Lumi-
nescence: Overview; Solid Phase. Phosphorescence:
Principles and Instrumentation. Polycyclic Aromatic
Hydrocarbons: Environmental Applications.

Further Reading

Bruzzone L, Badı´a R, and Dı´az-Garcı´a ME (2000) Room-

temperature phosphorescent complexes with macromo-
lecular assemblies and their (bio)chemical applications.
Critical Reviews in Analytical Chemistry 30(2–3):
163–178.

Cline Love LJ, Skrilec M, and Habarta JG (1980)

Analysis

micelle

stabilized

room

temperature

phosphorescence in solution. Analytical Chemistry 52:
754–759.

Dı´az-Garcı´a ME and Sanz-Medel A (1986) Facile chemical

deoxygenation of micellar solutions for room tempera-
ture

phosphorescence.

Analytical

Chemistry

58:

1436–1440.

Donkerbroek JJ, Veltkamp AC, Gooijer C, Velthorst NH,

and Frei RW (1983) Quenched room temperature
phosphorescence detection for ﬂow injection analysis
and liquid chromatography. Analytical Chemistry 55:
1886–1893.

Hurtubise RJ (1990) Phosphorimetry: Theory, Instrumen-

tation and Applications. New York: Wiley-VCH.

Kuijt J, Ariese F, Brinkman UATh, and Gooijer C (2003)

Room temperature phosphorescence in the liquid state as
a tool in analytical chemistry. Analytica Chimica Acta
488: 135–171.

Li L-D, Chen X-K, Mou L, Long W-Q, and Tong A-J

(2000) Non-protected ﬂuid room temperature phospho-
rescence properties of a-naphthyloxyacetic acid and
b

-naphtyloxyacetic acid. Analytica Chimica Acta 424:

177–183.

Oglesby DM, Puram CK, and Upchurch BT (1995) Opti-

mization of measurements with pressure sensitive paints.
NASA Technological Memorandum 4695 (available
electronically at http://techreports.larc.nasa.gov/ltrs/ltrs.
html).

Vo-Dinh T (1984) Room Temperature Phosphorimetry for

Chemical Analysis. New York: Wiley.

PHOSPHORUS

I D McKelvie and A Lyddy-Meaney

, Monash Univer-

sity, Churchill, VIC, Australia

Introduction

Phosphorus in the hydrosphere may originate from
natural diffuse sources such as the weathering of
phosphate minerals, the decay of algae, plants, run-
off from grazing and agricultural land, or it may be
derived from anthropogenic point sources such as
sewage and industrial efﬂuent discharges. Phosphorus

plays a critical role in the process of eutrophication,
because in many aquatic systems it is the nutrient
that limits the growth of phytoplankton.

Phosphorus occurs in a variety of physically and

functionally different inorganic and organic forms in
aquatic systems (Figure 1). An understanding of these
forms is important because it is the speciation that
controls their physical and chemical behavior and
their biological availability.

The simplest definition of phosphorus species

involves separation of the dissolved and particulate
components of a sample by ﬁltration (Figure 1). The
dissolved component is operationally deﬁned by the
ﬁlter pore size; for this reason, the term ‘ﬁlterable’ is

PHOSPHORUS

167

preferred to either ‘dissolved’ or ‘soluble’, both of
which are used extensively and interchangeably in
the literature. The ﬁlterable total phosphorus (FTP)
component is comprised of the ﬁlterable reactive
(FRP), condensed (FCP), and organic (FOP), frac-
tions. Of these, the FRP consists of inorganic ortho-
phosphates (H

, HPO

, PO

) and some labile

organic and colloidal phosphates that will react with
acidic molybdate to form the phosphomolybdate
complex that is the basis for most phosphorus anal-
ysis. FCP consists of inorganic polyphosphates, meta-
phosphates, and branched ring structures, and the

FOP fraction is composed of compounds such as
nucleic acids, phospholipids, inositol phosphates,
phosphoamides, phosphoproteins, sugar phosphates,
aminophosphonic acids, phosphorus-containing pesti-
cides, and organic condensed phosphates.

The particulate phosphorus (PP) fraction refers to

the fraction retained by the ﬁlter (usually 0.45 or
0.2 mm pore size membrane). PP may consist of
biological material (animal, plant, bacterial), weath-
ering products (primary and secondary minerals),
precipitates (authigenic minerals), organic and inor-
ganic coprecipitates and aggregates, in addition to
phosphorus associated with aggregates through metal
binding or adsorbed to the surface of clay and min-
eral particles. Determination of FTP, FOP, FCP, and
PP in natural waters requires a preliminary dig-
estion step to convert the various phosphorus species
to the detectable orthophosphate form (Table 1).

Spectrophotometric Detection

The analysis of phosphorus in waters has historically
been based on the photometric measurement of
12-phosphomolybdate or the phosphomolybdenum
blue species, which are produced when phospho-
molybdate is reduced. The majority of manual and
automated methods of phosphate determination are
based on the spectrophotometric determination of
phosphorus as phosphomolybdenum blue, i.e.,

þ 12MoO

þ 27H

-H

ðMoO

Þ þ 12H

followed by

ðMoO

reduction

phosphomolybdenum blue

Phosphorus species that are determined in this man-
ner are referred to as molybdate reactive, or simply
reactive, and much of the nomenclature of phospho-
rus speciation derives from this origin.

There have been numerous variations on this

method, usually involving different reductants (tin(

)

chloride, ascorbic acid, 1-amino-2-naphthol-4-sulfonic

Membrane filtration
(0.2 or 0.45

µm)

Filterable fraction
Orthophosphates

Condensed phosphates

Organic phosphates

Colloidal phosphates

Abiotic

Phytoplankton

Bacteria

Zooplankton

Biotic

Particulate fraction

−

Mineral,

or occluded

Organic

−

Figure 1

Representation of phosphorus species in aquatic

systems operationally deﬁned by ﬁltration. (McKelvie ID, Peat D,
and Worsfold PJ (1995) Techniques for the quantiﬁcation and
speciation of phosphorus in natural waters. Analytical Proceed-
ings 32: 437–445; reproduced by permission of The Royal
Society of Chemistry.)

Table 1

Speciﬁcation scheme for phosphorus (P) based on determination of molybdate reactive (R), phosphorus in total (T),

ﬁlterable (F), and particulate (P) forms; O and C designate organic and condensed forms, respectively

Total sample (T)

Filterable fraction (F)

Particulate fraction (P)

Total P determination: digestion

þ colorimetry TP (TOP þ TCP þ TRP) FTP (FOP þ FCP þ FRP)

¼ PTP (POP þ PCP þ PRP)

Condensed P determination:

hydrolysis

þ colorimetry

TCP

þ TRP

FCP þ FRP

¼ PCP þ PRP

Organic P determination (by subtraction)

TOP

FOP

¼ POP

Colorimetry (reaction with molybdate)

TRP

FRP

¼ PRP

168

PHOSPHORUS

acid, sodium sulﬁte, hydrazine sulfate, or combi-
nations thereof) or different acid concentrations,
in attempts to improve the selectivity and stability
of the chromophore produced. The most commonly
used methods for both manual and automated anal-
yses are based on the ascorbic acid reduction with
potassium antimonyl tartrate as a catalyst, which is
used because it is more tolerant of temperature and
salinity variations, and is less susceptible to interfer-
ence from silica.

Speciation of Phosphorus Based on
Digestion and Molybdate Reactivity

Major differences in size (ﬁlterable, particulate) and
chemical reactivity (condensed, organic) of phospho-
rus forms in samples can be used as the basis for
speciation, as shown in Table 1. Of these fractions,
total phosphorus (TP) and FRP are perhaps the most
commonly measured, although it is arguable that
the understanding of the aquatic phosphorus cycle
is somewhat lopsided because of that bias. For
example, wastewater discharge licenses often specify
a maximum permissible concentration of TP, and
provide an indication of the maximum potentially
bioavailable phosphorus discharged. However, FRP,
comprising mostly orthophosphate, is a measure of
the amount of most readily bioavailable phosphorus.

The determination of TP, condensed and organic

phosphorus all require predigestion and/or hydrolysis
of the water sample prior to detection of the ortho-
phosphate produced. Complete conversion of partic-
ulate and ﬁlterable components requires conditions
that are conducive to dissolution of phosphate min-
eral phases, hydrolysis of condensed phosphates, and
oxidation of organic phosphorus species. Numerous
methods have been proposed, but whichever proce-
dure is selected for the determination of TP or FTP,
the digestion efﬁciency should be assessed using ap-
propriate certiﬁed reference materials and a range of
organic or condensed phosphorus model com-
pounds. The latter should include compounds such
as tripolyphosphate, inositol hexakisphosphate, and
2-aminoethylphosphonic acid that contain P–O–P,
C–O–P, or C–P chemical bonds, respectively, and
that are known to be more refractory.

Condensed Phosphorus Hydrolysis

Determination of the condensed phosphorus compo-
nent requires hydrolytic conditions without oxida-
tion, and is typically achieved by boiling samples
with 0.05 M sulfuric acid for 90 min or autoclaving
for 30 min, prior to determination as molybdate
reactive phosphorus.

TP Digestion

Thermal Digestion Methods

Wet chemical digestions with either alkaline or acid
peroxydisulfate are the most common digestion
methods for determining TP. If the alkaline per-
oxydisulfate digestion is used, sufﬁcient time must be
allowed for complete breakdown of peroxydisulfate
to sulfuric acid if the condensed component is to
be hydrolyzed. Similarly, if nitric–sulfuric acid or
nitric–sulfuric–perchloric acid is used, it must be
established that the conditions used are sufﬁciently
oxidizing to digest the most refractory organic com-
pounds, like aminoethyl phosphonates. Digestion
may be performed at ambient pressure, or, for greater
speed, at elevated pressure and temperature using a
pressure cooker or autoclave. Recovery tests for
autoclave methods involving peroxydisulfate and
nitric–sulfuric acid digestion reagents for determina-
tion of TP in waters with high suspended load have
shown that recovery of TP at 4100 mg P l

is in-

complete using the peroxydisulfate reagent. Dilution
to

p100 mg P l

is recommended to overcome this

problem.

A number of workers have also reported the use of

microwave ovens for thermal digestion of samples
for TP analysis. Digestion times can be reduced
signiﬁcantly by the use of microwave heating, which
can be performed both in batch and online ﬂow
injection modes.

As alternatives to the wet chemical methods de-

scribed above, high-temperature combustion with
magnesium sulfate followed by acid leaching or high-
temperature fusion with magnesium nitrate have
been proposed. The latter method has been shown to
decompose phosphonates that are quite refractory.

Photochemical Methods

Ultraviolet (UV) photooxidation may be employed to
convert organic phosphorus to phosphate prior to
detection, and can be performed either in batch mode
using a high-intensity, ventilated UV source and a
quartz reactor vessel, or in continuous-ﬂow mode
using either quartz or polytetraﬂuoroethylene (PTFE)
photoreactors. Because batch UV radiation systems
usually involve the use of high wattage UV lamps
(e.g., 1000 W) and extended irradiation times,
condensed phosphates are hydrolyzed due to the
elevated temperature and gradual acidiﬁcation of the
sample as peroxydisulfate degrades to form sulfuric
acid. Thus, UV photooxidation alone is insufﬁcient
to convert condensed phosphates to orthophosphate,
and the use of UV photooxidation with alkaline
peroxydisulfate may provide a basis for discrimination

PHOSPHORUS

169

between the organic and condensed phosphorus
fractions.

Photooxidation of organic phosphorus may be per-

formed by UV irradiation on the untreated sample,
and relying on the dissolved oxygen present in the
sample to provide an adequate source of oxygen or
hydroxyl radicals. However, it is more common that
hydrogen peroxide, peroxydisulfate, ozone, or other
oxidizing agents are added to enhance the complete-
ness of the oxidation process.

When H

is exposed to UV light, it forms

hydroxyl radicals:

þ hn-2OH

This radical is among the strongest oxidizing agents
found in aqueous systems and initiates a series of
radical chain reactions with organic substances,
resulting in mineralization of the sample to bicarbo-
nate and orthophosphate.

Photooxidation using peroxydisulfate also produces

hydroxyl radicals and oxygen by the following route:

þ hu-2SO

þH

-HSO

þOH

-HSO

þSO

1
2

þOH

-HSO

1
2

Titanium dioxide-mediated oxidation of organic

phosphorus can also be achieved using long-wave-
length UV. Excitation of an electron from the valence
band (v) into the conduction band (c) creates an
electron–hole pair, which may then react with, for
example, oxygen adsorbed to the TiO

surface to

produce radicals such as O

and OH

In order to determine the TP concentration in

water, the digestion process must involve both oxi-
dative and hydrolytic processes in order to hydrolyze
P–O–P linkages (e.g., polyphosphates) and oxidize
phosphoesters and C–P compounds to inorganic
phosphate. For example, in an online TP digestion
system, which involves both thermal digestion and
UV photooxidation, it is necessary to use a mixture
of sulfuric acid and peroxydisulfate in order to ob-
tain high recoveries of both organic and condensed
phosphorus.

Bioavailable Phosphorus

Analysis of phosphorus species in natural waters is
driven largely by a need to assess the likely potential
for eutrophication, and a number of phosphorus

analysis parameters have been employed as estima-
tors of bioavailable phosphorus (BAP).

Algal Bioassay

BAP has traditionally been determined using algal
bioassays (e.g., the algal assay bottle test). However,
these take 7–21 days to perform, are labor intensive
because they require daily measurement of the growth
rate, are susceptible to large statistical variability,
and are relatively insensitive. Furthermore, caution
should be exercised in the interpretation of the BAP
concentration obtained, because native algae may
have a much wider range of phosphorus substrate
activity than the axenic algal monocultures that are
used for this purpose. Consequently, there has been a
great deal of research effort into replacing algal bio-
assay by some chemical parameter that will provide a
rapid and more convenient means of determining the
BAP concentration.

TP and FRP

Because of the time and labor involved in algal as-
says, FRP (0.45 or 0.2 mm) has often been used as a
surrogate for readily BAP, and TP (which includes
the particulate, condensed, and organic phosphorus
components) as a measure of potentially BAP. How-
ever, a number of studies have shown that neither
FRP nor TP correlate well with algal assay-measured
BAP. This may be because FRP tends to overestimate
the true orthophosphate due to hydrolysis of labile
organic and condensed species. Use of ultraﬁltration
through a low molecular mass ﬁlter prior to mea-
surement of reactive phosphorus has been proposed
as better estimator of BAP than other available
chemical methods.

Iron Strip and DGT Methods

A proposed alternative for estimating the amount of
BAP in waters involves the use of iron strip adsorp-
tion techniques used in soil science to measure plant-
available phosphorus. This approach involves the
equilibration of dissolved and particulate-bound
phosphorus with an iron-oxide-impregnated paper
strip for a period of hours to days, and this is fol-
lowed by acid leaching and spectrophotometric anal-
ysis for FRP. These exchangeable phosphorus tests
have been shown to be well correlated with BAP
determined by algal bioassay in waters. However,
co-adsorbed organic phosphorus or adsorbed partic-
ulate material may also be hydrolyzed at the
iron-oxide surface and during the acid leaching
and colorimetry stages of the process, leading to an
overestimation of the amount of BAP.

170

PHOSPHORUS

An alternative approach is the use of diffusive

gradients in thin ﬁlms (DGT). Phosphate diffuses
through a thin polyacrylamide gel and is bound in
a second gel layer containing iron-oxide. In situ
deployment is followed by sectioning, leaching, and
analysis for molybdate reactive phosphorus. From a
knowledge of the diffusion coefﬁcient of phosphate
in the gel and the measured phosphate concentration,
the bulk solution phosphate concentration can be cal-
culated from Fick’s ﬁrst law of diffusion (Figure 2).
This enables a time-integrated measurement of FRP
concentration, and can also be used to determine
sediment–water ﬂuxes of phosphate.

Enzymatic Methods

Algae and bacteria are known to release extracellular
alkaline phosphatase, which facilitates utilization of
otherwise unavailable dissolved and particulate
organic phosphorus species. This behavior has been
used as the basis for a speciation technique aimed at
estimating BAP in the dissolved fraction. Alkaline
phosphatase has been used in soluble and immobi-
lized forms to hydrolyze FOP in natural waters, and
the resultant orthophosphate is detected as FRP. Use
of the soluble enzyme technique has essentially been
discarded because of product inhibition of the alka-
line phosphatase by orthophosphate already present

in the water. However, if an immobilized alkaline
phosphatase reactor is used in a ﬂow injection con-
ﬁguration, the problem is obviated because the hy-
drolysis product is transported away from the active
sites of the enzyme. The technique has been success-
fully applied to the determination of alkaline
phosphatase hydrolyzable phosphorus (APHP) in a
range of natural and wastewaters. The enzyme
phytase has also been used in a similar manner to
hydrolyze organic phosphates in waters. The use of
these enzyme techniques thus provides additional in-
formation as to the functionality of the phosphorus
species present.

Selective Extraction Techniques for
Phosphorus in Sediments and Soils

In soils and sediments, chemical fractionation or
sequential extraction methods offer another approach
to speciation of the forms of phosphorus. Tradition-
ally, there has been more emphasis on bioavailable or
plant available inorganic forms, e.g., Olsen’s extrac-
tion used for soils.

The SEDEX procedure has emerged as the bench-

mark extraction scheme for sediments. It uses only
magnesium chloride, acetate buffer, and citrate/di-
thionite–bicarbonate reagents at pH values between
4 and 8 to leach sediments of the inorganic associ-
ated phosphorus fractions before ashing at 550

and a ﬁnal extraction with 1 M HCl to determine the
so-called residual organic phosphorus.

However, extraction of organic phosphorus from

sediments and soils should be carried out in a manner
that, as far as possible, avoids hydrolysis or oxidation
to orthophosphate, and this is often incompatible
with the procedures used for inorganic phosphorus
extraction. Some authors have suggested that
strongly acidic and basic conditions are intrinsically
unsuitable for extraction because of the likely hy-
drolytic breakdown that they cause, and have
suggested instead that chelating extractants such as
NTA or ethylenediamine tetraacetic acid (EDTA) at
near-neutral pH should be used as an alternative
(Table 2).

Determination of Specific
Phosphorus Compounds

Chromatographic Methods

High-performance liquid and ion chromatography
Phosphate is commonly determined by ion chro-
matography, both in suppressed and unsuppressed
modes. The sensitivity of the conductivity detection
techniques commonly used may be inadequate for
direct application to the analysis of pristine waters,

∆g

Diffusive gel

Distance

Fe oxide in gel

Concentration

Diffusive boundary layer

Solution

Figure 2

Representation of a steady-state concentration gra-

dient in a DGT device. Dg is the thickness of the ion-permeable
gel membrane, d is the thickness of the diffusive boundary layer,
and C is the concentration of reactive phosphorus species in the
bulk of solution. (Adapted from Zhang H, Davison W, Gadi R,
and Kobayashi T (1998) In-situ measurement of dissolved
phosphorus in natural waters using DGT. Analytica Chimica Acta
370: 29–38, with permission from Elsevier.)

PHOSPHORUS

171

and some form of preconcentration is required. For
analysis of seawaters, extensive dilution or chloride
removal is necessary. The advantage of this technique
is that it is true orthophosphate rather than FRP that
is determined.

Anion exchange chromatography and ion ex-

change chromatography have been used extensively
for the separation and quantitation of condensed
phosphates. Because phosphate is a poor UV chro-
mophore, direct UV detection cannot be used, and
fraction collection for subsequent acid hydrolysis and
detection as molybdate reactive phosphorus (MRP)

has been the norm. High-performance liquid chro-
matography (HPLC)-ion chromatography with post-
separation hydrolysis and detection using ﬂow
injection analysis has advantages of speed of analy-
sis, sensitivity, and selectivity. A schematic diagram
of this instrument setup and typical separations ob-
tained from a hyphenated system of this type is
shown in Figure 3.

Interest in characterization of organic phosphorus

present in natural waters has also prompted the
development of ion chromatographic separation sys-
tems for compounds such as inositol phosphates.

Waste

300

0.5 mm id

690

Anion exchange
column 250 x 4.1 mm id

100

−500 µl

KCl/EDTA
mobile phase
1.2 ml/min

/molybdate 0.25

0.25

Tin(II)chloride

Heater

Peltier
cooler

Debubbler

Alternative injection valve

Retention time/min

5.76

8.51

12.24

Orthophosphate

Pyrophosphate

Triphosphate

0.02 AU

Figure 3

(A) Ion-exchange chromatography–FIA system for separation of polyphosphates. (B) Optimized separation of orthophos-

phate (50 mg P l

), diphosphate (50 mg P l

), and triphosphate (50 mg P l

) with an injection volume of 500 ml. (Halliwell DJ, McKelvie

ID, Hart BT, and Dunhill RH (1996) Separation and detection of condensed phosphates in waste waters by ion chromatography
coupled with ﬂow injection. Analyst (Cambridge, UK) 121: 1089–1093; reproduced by permission of The Royal Society of Chemistry.)

Table 2

Sequential chemical extraction for isolation of various phosphate fractions involving use of chelating agents at near-neutral pH

Fraction designation

Abbreviation

Extractant used

Iron-bound phosphate

Fe(OOH)

0.02 M Ca-NTA/dithionite, pH 7.8–8.0

Calcium-bound phosphate

CaCO

0.05 M Na-EDTA, pH

B8.0

Acid-soluble organic phosphate

ASOP

0.5 M HCl or 0.025 M H

(30 min)

NaOH-extractible phosphate

NaOH

extr

-P

2.0 M NaOH (90

1C, 30 min)

172

PHOSPHORUS

Online UV photooxidation has been utilized for oxi-
dation and subsequent detection of these organic
phosphate species. While ion exchange HPLC is used
extensively for separation of FOP species, a reversed-
phase partition HPLC has a definite role in the
separation of even quite charged or polar organic
phosphorus species. Phospholipids are commonly
separated and quantiﬁed using either reversed- or
normal-phase HPLC. Reversed-phase HPLC has also
been used in the study of inositol phosphates. Use of
ion-pair reversed-phase HPLC is also advantageous
for the separation of highly charged species and may
avoid some of the adsorption problems that are en-
countered using gel ﬁltration or ion exchange chro-
matography, especially of highly charged species.
Reversed-phase ion-pair chromatographic separa-
tions have been described for inositol phosphates,
and some common nucleotides and sugar phosphate
phytate.

Gel ﬁltration/size exclusion chromatography

Sepa-

ration using gel ﬁltration gained popularity as a
means of separating high and low molecular mass
phosphorus fractions, and as a means of estimating
BAP concentrations, i.e., the reactive low molecular
mass phosphorus. Most involve the use of large sepa-
ration columns, long elution times, and the use of
fraction collection and off-line digestion/digestion to
measure total or reactive phosphorus, and as such
are unsuitable for routine monitoring applications.
However, an on-line postcolumn ﬂow injection de-
tection system for detection of organic phosphorus
species has also been described. Potential difﬁculties
associated with the use of gel ﬁltration include early
elution due to anion exclusion and late elution due to
hydrophobic interactions, and specific adsorption.

Capillary Electrophoresis

Capillary electrophoresis (CE) techniques have been
used for selective orthophosphate analysis. CE sepa-
rations of anions in waters are much faster than ion
chromatography, but detection of phosphate by UV
absorbance is very insensitive. This may be overcome
by on-capillary preconcentration using isotacho-
phoresis, which enables sub-mg l

detection limits

to be achieved in high ionic strength matrices.

Gas Chromatography

Gas chromatography (GC) with either ﬂame photo-
metric or mass spectrometric detection is commonly
used for determination of organophosphate pesti-
cide. In some cases, GC may be used for separation
of organic phosphorus species if they or their
degradation products are derivatized, e.g., inositol

phosphates have been characterized by GC separa-
tion of their acetylated dephosphorylation products.

Other Spectroscopic Methods

Nuclear magnetic resonance, especially

P NMR,

offers a powerful means of characterizing and iden-
tifying individual phosphorus species in soils and
sediments. In the case of waters, there is usually
the need for preconcentration, and interferences
may arise because of the corresponding increase in
concentration of paramagnetic substances. However,
if these difﬁculties are resolved,

P NMR provides

a qualitative means of detecting the presence of
functionally different phosphorus groups, such as
phosphonates, orthophosphates, orthophosphate mono-
and diesters, and pyrophosphates, within a sample.

GC–Mass spectrometry combines high-efﬁciency

separation with sensitive and highly selective detec-
tion, and is a powerful tool for characterization of
organic phosphorus.

See also: Nuclear Magnetic Resonance Spectroscopy-
Applicable Elements: Phosphorus-31.