simple, and less expensive than HPLC and has fewer problems associated with the
matrix effect. However, due to the low volatility, high polarity, and thermal fragility
of the NSAIDs, it requires previous derivatization of the compound, which lengthens
the time of the analysis, although the microextraction techniques, which allows
extraction and derivatization in one step shorten the analysis time. GC-MS/MS has
been used less in aqueous samples [93, 123].
Derivatization is performed by methylation, acetylation, or silylation. Methylation uses diazomethane [32, 64, 70, 85, 94, 101, 113, 114, 117], pentafluorobenzyl
bromide (PFBBr) [76], methyl chloroformate [47, 54, 106], dimethyl sulfate (DMS)
[58], or tert-butyl ammonium sulfate (TBA-HSO4) [58, 70, 94]. Acetylation is
carried out by the addition of acetic anhydride/triethanolamine [101, 114]. In
silylation, different silyl reagents are used, such as N-(tert-butyldimethylsilyl)-Nmethyl-trifluoroacetamide (MTBSTFA) [5, 16, 45, 59, 79, 93, 98], N-methyl-N(trimethylsilyl)-trifluoroacetamide (MSTFA) [16, 33, 35, 64, 93], bis
(trimethylsilyl)-trifluoroacetamide (BSTFA) [48, 67, 75, 90, 93], and dimethyl
(3,3,3-trifluoropropyl)silyldiethylamine (DIMETRIS) [53].
The GC capillary columns for NSAIDs in water samples generally consist of a
stationary phase composed of 5% diphenyl/95% dimethylpolysiloxane or equivalent
[16, 43, 45, 47, 48, 54–56, 58, 67, 73, 75, 78, 79, 81, 85, 86, 93, 94, 96, 98, 106, 108,
109, 116, 119, 121] with different lengths, internal diameters, and film thicknesses.
Preferred injectors are split/splitless and automatic/not, which are very suitable for
trace determination [16, 34, 43, 45–47, 53, 56, 58, 59, 67, 73, 75, 76, 78, 85, 86, 90,
94, 98, 106, 116, 121]. As a carrier gas, high-purity helium (He) is commonly used,
[16, 45, 46, 53, 54, 58, 59, 64, 66, 75, 78, 86, 90, 106, 116, 119, 121] although some
authors prefer argon (Ar) [68]. The programmed temperature ranges between 50 and
300
C [16, 45–47, 53, 54, 59, 62, 64, 66, 67, 70, 75, 76, 90, 93, 106, 117, 123] and
run times between 2 and 45 min [45, 64, 70, 75, 76, 123].
MS used in combination with the GC for the NSAIDs determinations in water are
usually quadrupole, single, or triple analyzers [16, 26, 32, 48, 53, 54, 58, 62, 73–76,
90, 106, 108] or ion traps [30, 46, 59, 66, 70]. The ion sources consist of the electron
impact ionization (EI) type [46, 47, 53, 54, 59, 66, 70, 73–76, 85, 106, 108], which
are very suitable for molecules of polar nature. Sources with chemical ionization
(CI) are less used [46]. The analysis in the collecting system is executed in the mode
of selective ion monitoring (SIM) [16, 45, 46, 53, 54, 56–58, 64, 67, 70, 74–76, 90,
98, 106, 108, 121]. Some equipment uses high sensitivity detectors [16, 32, 70, 74,
78] that offer detection limits of the order of pgL
À1 [78]. Spectra libraries that assist
the researcher in the identification of compounds [123] are on the market.
GC-FID In addition to the GC-MS combination, GC with flame ionization detectors (FID) has also been used in combination with the DLLME [119] with good
results.
Liquid Chromatography Although the advantages of GC-MS are unquestionable,
HPLC is widely used for the detection of NSAIDs in water, especially in recent times
[121]. This technique does not require derivatization, and it offers the possibility of
96
K. Isaac-Olivé et al.
matrix effect. However, due to the low volatility, high polarity, and thermal fragility
of the NSAIDs, it requires previous derivatization of the compound, which lengthens
the time of the analysis, although the microextraction techniques, which allows
extraction and derivatization in one step shorten the analysis time. GC-MS/MS has
been used less in aqueous samples [93, 123].
Derivatization is performed by methylation, acetylation, or silylation. Methylation uses diazomethane [32, 64, 70, 85, 94, 101, 113, 114, 117], pentafluorobenzyl
bromide (PFBBr) [76], methyl chloroformate [47, 54, 106], dimethyl sulfate (DMS)
[58], or tert-butyl ammonium sulfate (TBA-HSO4) [58, 70, 94]. Acetylation is
carried out by the addition of acetic anhydride/triethanolamine [101, 114]. In
silylation, different silyl reagents are used, such as N-(tert-butyldimethylsilyl)-Nmethyl-trifluoroacetamide (MTBSTFA) [5, 16, 45, 59, 79, 93, 98], N-methyl-N(trimethylsilyl)-trifluoroacetamide (MSTFA) [16, 33, 35, 64, 93], bis
(trimethylsilyl)-trifluoroacetamide (BSTFA) [48, 67, 75, 90, 93], and dimethyl
(3,3,3-trifluoropropyl)silyldiethylamine (DIMETRIS) [53].
The GC capillary columns for NSAIDs in water samples generally consist of a
stationary phase composed of 5% diphenyl/95% dimethylpolysiloxane or equivalent
[16, 43, 45, 47, 48, 54–56, 58, 67, 73, 75, 78, 79, 81, 85, 86, 93, 94, 96, 98, 106, 108,
109, 116, 119, 121] with different lengths, internal diameters, and film thicknesses.
Preferred injectors are split/splitless and automatic/not, which are very suitable for
trace determination [16, 34, 43, 45–47, 53, 56, 58, 59, 67, 73, 75, 76, 78, 85, 86, 90,
94, 98, 106, 116, 121]. As a carrier gas, high-purity helium (He) is commonly used,
[16, 45, 46, 53, 54, 58, 59, 64, 66, 75, 78, 86, 90, 106, 116, 119, 121] although some
authors prefer argon (Ar) [68]. The programmed temperature ranges between 50 and
300
C [16, 45–47, 53, 54, 59, 62, 64, 66, 67, 70, 75, 76, 90, 93, 106, 117, 123] and
run times between 2 and 45 min [45, 64, 70, 75, 76, 123].
MS used in combination with the GC for the NSAIDs determinations in water are
usually quadrupole, single, or triple analyzers [16, 26, 32, 48, 53, 54, 58, 62, 73–76,
90, 106, 108] or ion traps [30, 46, 59, 66, 70]. The ion sources consist of the electron
impact ionization (EI) type [46, 47, 53, 54, 59, 66, 70, 73–76, 85, 106, 108], which
are very suitable for molecules of polar nature. Sources with chemical ionization
(CI) are less used [46]. The analysis in the collecting system is executed in the mode
of selective ion monitoring (SIM) [16, 45, 46, 53, 54, 56–58, 64, 67, 70, 74–76, 90,
98, 106, 108, 121]. Some equipment uses high sensitivity detectors [16, 32, 70, 74,
78] that offer detection limits of the order of pgL
À1 [78]. Spectra libraries that assist
the researcher in the identification of compounds [123] are on the market.
GC-FID In addition to the GC-MS combination, GC with flame ionization detectors (FID) has also been used in combination with the DLLME [119] with good
results.
Liquid Chromatography Although the advantages of GC-MS are unquestionable,
HPLC is widely used for the detection of NSAIDs in water, especially in recent times
[121]. This technique does not require derivatization, and it offers the possibility of
96
K. Isaac-Olivé et al.