Macroalgal Phycocolloids 157
Table 6.
13
C-NMR chemical shifts for the most common carrageenan structural units
a
(adapted from van de Velde et al. 2004;
Pereira 2004; Pereira 2016).
Carrageenan
Unit
b
Chemical shift (ppm) relative to DSS as internal standard
C-1
C-2
C-3
C-4
C-5
C-6
β (beta)
G DA
104.81
96.81
71.72
72.40
82.58
81.64
68.56
80.33
77.55
79.26
63.49
71.72
ι (iota)
G4S DA2S
104.43
94.29
71.53
77.15
79.06
80.04
74.34
80.55
77.04
79.29
63.52
72.02
κ (kappa)
G4S DA
104.70
97.34
71.72
72.11
80.98
81.41
76.25
80.54
77.00
79.07
63.49
71.72
λ (lambda)
G2S D2S,6S
105.61
93.85
79.61
77.04
77.99
71.76
66.35
82.61
76.51
70.89
63.45
70.25
µ (mu)
c
G4S D6S
107.00
100.26
72.69
70.7
80.54
72.8
76.25
81.40
77.1
70.5
63.48
69.89
ν (nu)
G4S D2S,6S
106.96
100.53
72.40
78.58
82.42
70.37
73.36
d
82.13
77.15
70.37
63.58
70.02
θ (theta)
e
G2S DA2S
102.57
97.81
79.8
77.05
79.4
79.6
69.97
81.75
77.05
79.2
63.38
72.35
ξ (xi)
f
G2S D2S
105.44
94.94
66.92
a
Carrageenan (30 mg ml
–1
), DSS (10 mM) and Na 2 HPO 4 (20 mM) in D 2 O recorded at 65°C.
b
Codes refer to the nomenclature developed by Knutsen et al. 1994.
c
Chemical shifts given with one decimal place are obtained from literature and corrected with the offset calculated for the
chemical shifts of the anomeric carbon atoms (Chiovitti et al. 1998).
d Chemical shift differs from the value given in literature (Chiovitti et al. 1998).
e
Chemical shifts given with one decimal place are recalculated from literature (van de Velde et al. 2004), moreover they may
be interchanged. TSP is used as the internal standard; however chemical shifts are given relative to DSS.
f
Only a few resonances of the ξ-carrageenan spectrum are assigned in literature (Falshaw and Furneaux 1995). TSP is used
as the internal standard; however chemical shifts are given relative to DSS.
Table 7. Chemical shifts (ppm) of the α-anomeric protons of carrageenans referred to DSS as an internal standard at 0 ppm
a
(adapted from van de Velde et al. 2004; Pereira 2004).
Carrageenan
Monosaccharide
b
Chemical shift (ppm)
β (beta)
ι (iota)
κ (kappa)
λ (lambda)
ν (nu)
µ (mu)
θ (theta)
ξ (xi)
DA
DA2S
DA
D2S,6S
D2S,6S
D6S
DA2S
D2S
5.074
5.292
5.093
5.548
5.501
5.238
5.30
5.49
a
Carrageenan (30 mg ml
–1
), DSS (10 mM) and Na 2 HPO 4 (20 mM) in D 2 O recorded at 65°C.
b
Codes refer to the nomenclature developed by Knutsen et al. (1994).
However, application of the IUPAC recommendations in NMR-spectroscopy to carrageenans
results in changed chemical shifts for all common carrageenan types. Pereira et al. (2003) reported
chemical shift values relative to DSS for κ- and ι-carrageenan that are 2.5 ppm larger than those
reported by Usov (1984). Therefore, the detailed applications of DSS as internal standard for NMR
spectroscopy of carrageenans are published by Pereira (2004) and van de Velde et al. (2004).
13
C- and
1
H-NMR shift data of representative carrageenan samples containing the most common
repeating units, e.g., κ-, ι-, λ-, µ-, ν-, θ-, β-, and ξ-carrageenan are presented in Tables 5 and 6
Table 6.
13
C-NMR chemical shifts for the most common carrageenan structural units
a
(adapted from van de Velde et al. 2004;
Pereira 2004; Pereira 2016).
Carrageenan
Unit
b
Chemical shift (ppm) relative to DSS as internal standard
C-1
C-2
C-3
C-4
C-5
C-6
β (beta)
G DA
104.81
96.81
71.72
72.40
82.58
81.64
68.56
80.33
77.55
79.26
63.49
71.72
ι (iota)
G4S DA2S
104.43
94.29
71.53
77.15
79.06
80.04
74.34
80.55
77.04
79.29
63.52
72.02
κ (kappa)
G4S DA
104.70
97.34
71.72
72.11
80.98
81.41
76.25
80.54
77.00
79.07
63.49
71.72
λ (lambda)
G2S D2S,6S
105.61
93.85
79.61
77.04
77.99
71.76
66.35
82.61
76.51
70.89
63.45
70.25
µ (mu)
c
G4S D6S
107.00
100.26
72.69
70.7
80.54
72.8
76.25
81.40
77.1
70.5
63.48
69.89
ν (nu)
G4S D2S,6S
106.96
100.53
72.40
78.58
82.42
70.37
73.36
d
82.13
77.15
70.37
63.58
70.02
θ (theta)
e
G2S DA2S
102.57
97.81
79.8
77.05
79.4
79.6
69.97
81.75
77.05
79.2
63.38
72.35
ξ (xi)
f
G2S D2S
105.44
94.94
66.92
a
Carrageenan (30 mg ml
–1
), DSS (10 mM) and Na 2 HPO 4 (20 mM) in D 2 O recorded at 65°C.
b
Codes refer to the nomenclature developed by Knutsen et al. 1994.
c
Chemical shifts given with one decimal place are obtained from literature and corrected with the offset calculated for the
chemical shifts of the anomeric carbon atoms (Chiovitti et al. 1998).
d Chemical shift differs from the value given in literature (Chiovitti et al. 1998).
e
Chemical shifts given with one decimal place are recalculated from literature (van de Velde et al. 2004), moreover they may
be interchanged. TSP is used as the internal standard; however chemical shifts are given relative to DSS.
f
Only a few resonances of the ξ-carrageenan spectrum are assigned in literature (Falshaw and Furneaux 1995). TSP is used
as the internal standard; however chemical shifts are given relative to DSS.
Table 7. Chemical shifts (ppm) of the α-anomeric protons of carrageenans referred to DSS as an internal standard at 0 ppm
a
(adapted from van de Velde et al. 2004; Pereira 2004).
Carrageenan
Monosaccharide
b
Chemical shift (ppm)
β (beta)
ι (iota)
κ (kappa)
λ (lambda)
ν (nu)
µ (mu)
θ (theta)
ξ (xi)
DA
DA2S
DA
D2S,6S
D2S,6S
D6S
DA2S
D2S
5.074
5.292
5.093
5.548
5.501
5.238
5.30
5.49
a
Carrageenan (30 mg ml
–1
), DSS (10 mM) and Na 2 HPO 4 (20 mM) in D 2 O recorded at 65°C.
b
Codes refer to the nomenclature developed by Knutsen et al. (1994).
However, application of the IUPAC recommendations in NMR-spectroscopy to carrageenans
results in changed chemical shifts for all common carrageenan types. Pereira et al. (2003) reported
chemical shift values relative to DSS for κ- and ι-carrageenan that are 2.5 ppm larger than those
reported by Usov (1984). Therefore, the detailed applications of DSS as internal standard for NMR
spectroscopy of carrageenans are published by Pereira (2004) and van de Velde et al. (2004).
13
C- and
1
H-NMR shift data of representative carrageenan samples containing the most common
repeating units, e.g., κ-, ι-, λ-, µ-, ν-, θ-, β-, and ξ-carrageenan are presented in Tables 5 and 6