Table 1 Assay parameters and method validation for the determination of ciprofloxacin HCl, fluocinolone acetonide and ciprofloxacin impurity A by the proposed spectrophotometric methods according to ICH guidelines

Range

(1–40) μg/mL

(0.6–20) μg/mL

(1–40) μg/mL

Slope

0.0054

0.2424

1.2969

0.5433

0.0423

0.0161

0.005

0.0727

0.0197

Intercept

0.0021

0.0764

− 0.1976

0.0433

0.0029

0.0546

0.0132

0.1897

− 0.0078

SE slope

3.6949 × 10^–5

1.4273 × 10^–3

8.0659 × 10^–3

2.3690 × 10^–3

3.0186 × 10^–4

1.5795 × 10^–4

9.8110 × 10^–5

9.0012 × 10^–4

1.0932 × 10^–3

SE intercept

9.0549 × 10^–4

0.0350

0.1977

0.0581

3.2484 × 10^–3

3.8317 × 10^–3

2.5945 × 10^–3

0.0238

0.0287

Correlation coefficient (r)

0.9998

0.9999

0.9999

0.9999

0.9998

0.9996

0.9995

0.9996

0.9996

LOD (μg/mL)

0.281

0.210

0.202

0.196

0.193

0.329

0.325

0.312

0.287

LOQ (μg/mL)

0.852

0.636

0.612

0.594

0.585

0.997

0.985

0.945

0.870

Accuracy^a ± SD

100.19 ± 0.871

101.02 ± 0.917

100.94 ± 1.564

100.66 ± 1.146

99.54 ± 1.293

100.09 ± 1.353

100.31 ± 0.792

99.32 ± 0.925

99.25 ± 1.081

Robustness ^b (RSD%)

Wavelength

1.060

1.226

1.851

1.141

1.825

1.691

1.606

0.820

1.220

Buffer pH

0.963

1.032

1.056

0.874

1.281

1.630

1.613

0.435

1.165

KOH %

0.736

0.837

1.013

0.523

0.648

1.539

0.847

0.385

0.748

Repeatability ^c (RSD%)

1.214

1.441

1.693

1.021

1.506

1.548

1.281

1.225

1.274

Intermediate ^d precision (RSD%)

1.391

1.739

1.950

1.556

1.787

1.941

1.715

1.728

1.866